Sigrun Huld Jonasdottir

Marja Koski

Sigrún Huld Jónasdóttir

Biological processes in the North Sea: Comparison of Calanus helgolandicus and Calanus finmarchicus vertical distribution and production

Keywords: Calanus helgolandicus, Calanus finmarchicus, egg production, Vertical distribution, Dogger Bank Calanus helgolandicus, Calanus finmarchicus, egg production, Dogger Bank

Biological activities in the

North Sea I. Comparison of Calanus helgolandicus and Calanus finmarchicus vertical distribution and production.

First I would like to thank the reviewers for constructive criticism of the MS which has helped to improve the MS. In the response below, "I" refers to the first author. In addition to my response to the authors listed below I have now slightly changed the title of the manuscript exchanging "on the Dogger Bank" with "in the North Sea" to match the accompanying manuscript by Koski et al. (in response to the reviewer's comments on the title of that MS) -removed superfluous headings in the result section under "In situ egg production and hatching" in addition to minor corrections and clarifications. -made small improvements, mainly related to better clarification, in results and discussion.

Reviewer: 1

General evaluation

The paper compares vertical distribution and production of Calanus helglolandicus and Calanus finmarchicus in the North Sea, as estimated from data collected during four years. To my mind this is an interesting study that casts novel light on the productivity and life strategies of the sibling Calanus species in an area where they coexist.

On the whole, I enjoyed reading the paper. Its content clearly falls within the scope of Journal of Plankton Research. I have but a few relatively minor comments to make, and advice publication assuming the authors will consider them.

A few minor comments Page 4, l.1-2: The information presented here ('Peak production for C. helgolandicus occurred in July compared to April for C. finmarchicus') is inconsistent with what is stated on the same subject on P.14, l.4-5, where it is stated that the production of C.fin peaked in March and that of C.helg in May. This apparent inconsistency must be resolved.

These two turned out to be quite mixed up in our text and has both been corrected and clarified. We are glad it was caught -while quite embarrassed over the mistake. This is now changed after discussion with 2 statisticians and other colleagues about best presentation and statistical test of the data (see comment to the figure 4 here below). The statisticians suggested against standardizing the data, and suggested plotting the sum in the water masses. If standardizing the data, then it should be weighted with the number behind the data, so it would be the same as presenting the original abundance. Therefore we added up the abundance data per temperature bins, to better show the separation of the females and stages and for more straight forward statistical comparison of the data. Additionally, I replaced the word density with the words abundance and concentration.

Page 9, l.12: From Table IV I read that EPR differed between years (2001 different from 2002) so the statement that the EPR of C. helgolandicus did not differ between years is incorrect. In addition the EPR ranged from 8-29 eggs fem-1 d-1 (instead of 9-29).

This has been corrected

Page 12, 1st line: a word is missing after 'understanding', add 'of'. P.13, l.9: replace 'be' with 'been'. P.14, l.22: Delete 'this'?

All corrected P.14, l.4-5: Inconsistent with what is stated on P.4, as mentioned before. This one is correct -the other is now corrected. P.14, l.5-7: I think you are confusing names here (C.fin and C.helg). According to Jónasdóttir et al. (2005, their Fig.5) C. helg is showing generally low rates (<50 eggs m-3 d-1), while C.fin has max EPR in May (~150 eggs m-3 d-1). Please check if this has consequences for the discussion on this matter. Yes this is mixed up (see above). It does not change the discussion as it was correct in the mind, but not on paper! P.14, l.26: The temperature difference is rather ~7°C. The abstract gives temperatures as 9°and 16°. This accords also better with the temperature intervals reported in Results. Changed to 7 °C (P. 8), implies that the younger stages are also included. This could be made clearer. This figure has been changed -after discussion with statisticians on best way of presenting this data (see answer to comment above). In the new figure the separation of species is clear. Figure legend has been corrected to include the stage 5 copepodides.

I have not checked if all the cited references are listed in the reference list or vice versa.

After revision, some new references have been added and other removed. I have now gone over the references 2 times before this re-submission and would surprised if it is not correct.

Introduction and Discussion are mostly concise and well written. There are a few mistakes (left-out words mainly, please check). Both parts nevertheless lack deeper insight and the manuscript would benefit from a more thorough discussion, including data from other areas and information on the physiology, which are available for both species (e.g. Williams 1980, Hirche 1983, Pond et al. 1996, both MEPS). For example, the discussion on food and feeding (page 12/13) includes only 4 references and all of these present data on C. finmarchicus, literature on C. helgolandicus is not included. (Given, that there are so many tables on this topic, the discussion is surprisingly short anyway.) I admit our bias towards Calanus finmarchicus studies and have now made an effort to corrected that bias. In the Introduction I have added a sentence on a study I had missed before on a lab study on CF and CH food selection. In the Discussion I have now improved and deepened out discussion on selection and feeding and effects of diets on EPR for both species (current page 14). We did not go in our discussion (or introduction) much beyond the scope of our study -comparison of the 2 species and their importance on the Dogger Bank. The results did not give a major reason to go into food quality studies (then I would cite more of my own papers too) or egg composition. Williams 1980 was (and is) in the paper (discussion). The suggested study of Hirche 1983 does not fit into this paper. In that paper he does not compare the species and over-wintering is not an issue here.

Moreover, the authors often rely on reviews (e.g. [START_REF] Bonnet | An overview of Calanus helgolandicus ecology in European waters[END_REF], Harris et al. 2000) instead of citing original publications, which I find irritating.

We totally agree about using original references before reviews. However, in our case there are 3 citations to Bonnet et al.; one to their comparison of the 2 species (their table 2), as a reference to the surprisingly few comparisons of the 2 species (even though they compiled the data from different sources, the mini-comparison is theirs). The other 2 citations refer to a study conducted by Rabea Diekman and only published in this review on the vertical co occurrence of the 2 species in the North Sea during spring. The reference to Harris et al 2000 is now removed and we refer to [START_REF] Niehoff | A high frequency time series at Weathership M, Norwegian Sea, during the 1997 spring bloom> the reproductive biology of Calanus finmarchicus[END_REF] that has the original population egg production estimates. Methods and Results sections need thorough work as the paper presents many data and lacks some focus. As I have quite a few comments, I'll go through them consecutively: page 4 line 29: 3 North Sea cruisesabstract says 4 page 4 line 41: "…described in (Jonasdottir et al., 2005)"to my knowledge this does not match the JPR layout, consult Instructions for authors

We added into the abstract that comparison was done on data collected on 4 cruises. The correct citation format is now used and we checked the whole MS (and references) to correct the citation formats.

page 4 line 59: 2-4 intensive stations… -There is some confusion in the text about which station was sampled when. Is it two or four stations? Please, add a table on sampling dates and stations and indicate which measurements (abundance, EPR, temperature of incubation) have been done. The sampling procedure seems rather inconsistent (2001, depth integrated, 2002, 10 m intervals at buoy station: why are two sampling sites indicated in Fig 1, 2003 and2005 5m interval sampling of transect stations). Wouldn't it make sense to only use the latter two years, sine these are the ones, which can be compared in terms of sampling procedure?

I have added a table (current Table I) with our sampling procedure to clarify our admittedly somewhat inconsistent sampling between years. From start we did seriously evaluate if to include abundance data from 2003 as we did not focus on Calanus production on that cruise in favour of other copepod species. However, as the distribution of the cousin species is also a focus of our paper, we decided to include the 2003 data, also to show the yearly variation in abundance. Station locations per se do not matter in this case, as all environmental measures are taken at the same stations as the production measurements are conducted. The problem arises when the abundance and production are not measured at the same location as was the case in 2002. This is however, pointed out and is only used for approximate estimate of population egg production rates in the discussion.

Obviously based on the following comment the method description was not clear enough and we use the reviewer's comments to clarify the method section.

page 5 egg production measurements -sampling for egg production was done at which stations? Line 24: sampling depth was 50 or 70m. Did you sample at that depth only? Meaning: did you take horizontal catch net towsif yes at which speed was the net towed, what was the sampling depth for surface sampling, what was the depth for Chlorophyll max? The water depth in our sampling area is maximum 70 m. We now clarify that we took a vertical tow from about 5 m above the bottom and up. We have now added in the towing speed.

Did you incubate 40 females at a time in a 600ml bottle? Absolutely not, this we NEVER would do!

Were the numbers of females per bottle (volume) the same in the two species? If not, is it possible that the lacking difference in EPR between the two species can be attributed to the incubation method (which does not match the standard according to Runge and Roff 2000 ICES manual)? With increasing female abundance, cannibalism increases (see Ohman and Hirche 2001, Nature).

The method says that females were "individually introduced into 300 or 600 mL bottles" Therefore the rest of the reviewers comment does not apply. Because we cannot recognize the 2 species from life samples with 100% certainty, the species were randomly introduced into these bottles, but NB individually. Why is there only one bar for each station (Figure 5)? I am not sure I understand the question, but the bars represent the average egg production (combined surface and chl max as there was no significant difference between those (as explained in the text current p. 9), and pellet production at chl max and surface for each station. In 2002 the replicate incubations for each station are combined to increase number of replicate incubations as the second incubation had new animals. In 2005 the bars represent only the first day of incubation to be comparable to the other years. This is explained in the result section page 9 but to clarify I have added clarification in the figure text.

F

What do you mean: In 2005 females were only sampled once on route to transect? Figure 5 shows EPR data from 4 stations (1,3,5,8). What is the purpose of incubating the female for 4 days? The results are not very enlightening either, thus, you may want remove these parts from the manuscripts.

After visiting the site for several years, we wanted to improve our understanding of the importance of the bloom for secondary production. In the back of our mind was the idea to test if the quality of the bloom decreased away from the bank -where the nutrient input is highest and we could use that to generate a natural experiment with changing food quality. The best way to compare the species in changing food environment is to use a bioassay -that is, to incubate the same population of copepods in waters at stations with increased distance from the bank. In 2003 we used cultured Acartia tonsa (accompanying MS by Koski et al) and in 2005 we sampled Calanus from one station (on our way to the transect). We can use the first day to compare with the incubations in 2001 and 2002, while the cumulative egg production or final 4 day egg production can show us how the 2 species react to the immediate food environment. We find this study important for the manuscript and do not want to remove it from the paper but have tried to make the purpose of the study more enlightening for the potential reader. To avoid misunderstanding I have clarified this in the methods, results and in the discussion. This has been reworded. page 7, line 43: total fatty acid composition…was correlated with the chl a contenthow can COMOSITION correlate to chl a CONTENT? Statistics correct? (Spearman rank test not mentioned in Method section)

The reviewer is absolutely correct here, that the fatty acid composition is not correlated… this has been corrected to that seston fatty acid concentration (total) was correlated to cha. The Spearmen rank test is now mentioned in the Method section.

Page 8: Plotting Gaussian 3 parameter curves without any statistical significance does not make much sense, does it? It seems rather arbitrary.

As pointed out in our response to Reviewer 1 we have now re-plotted the figure after a discussion with couple of statisticians and colleagues. I copy here the answer to reviewer 1.: The statisticians suggested against standardizing the data, and suggested plotting the sum in the water masses in temperature ranges (we used 2 degree bins). If standardizing the data, then it should be weighted with the number behind the ratio, so in the end it would be the same as presenting the original abundance. Therefore we added up the abundance data per temperature bins, to better show the separation of the cousin females and C5 stages, and to be able to do a clear statistical test on the data. Therefore we do not use Gaussian curves anymore -it also turns out it requires rather complicated statistical test to compare such curves. As we are interested to test if there is a different temperature preference by these species the statisticians suggested that we use a simple chi square test making the temperature cut where there were equal abundance on each side. This was done and the text changed accordingly.

page 8 line 52: First you refer to egg production and hatching, then it is "however pellet production in only compared for the chlorophyll max incubations" Compared to what anyway? Among each other? Relation to egg production? Why is this remark not included in the fecal pellet production chapter, page 9?

This has been corrected and moved to a one combined faecal pellet section; Faecal pellet production as I agree the faecal pellet paragraphs were too scattered in the MS.

page 9, lines 6 to 16: How did you calculate clutch sizes if you have not incubated single females and if you have not checked for eggs more often? At these temperatures, there were likely some females, which had spawned more than once within 23-24hrs, while others may not had spawned at all.

The reviewer is correct and this should not be called clutch size but more correctly maximum egg production at each station. I have come across many researchers that insist on excluding zero producing females in their average EPR and while I see problems with that approach (depends on the purpose of the production measure) I feel this should be separately reported. The reviewer is absolutely correct that I should not use clutch size as it is has another meaning. This has been corrected and clarified in the manuscript and now called either maximum egg production or EPR max page 9bioassayand then again fecal pellet production? Why? Which stations are compared, here you seem to refer to the surface layerline 27, FP was significantly higher in chl.max layer for both species (higher than what?), See comment above on faecal pellets. We have now added an explanation to the bioassay in our introduction and again in the method section page. We also have combined the faecal pellet discussion in one paragraph as it was obviously not very clear. line 33, C. finmarchicus had significantly higher FP in BOTH layers compared to C. helgolandicushow does that relate to page 8, line 52? See comment above.

These are 2 different approaches and now they are combined -and hopefully better explained in the result section. In 2002 there is not surprisingly a big difference in FP production between the surface and chl max and between species in the chl max. There is no explanation for why there are more pellets in the surface 2005 compared to 2002 and a sentence on this matter is now added to the discussion. page 10, line 41, females at station 3 and 5 were significantly larger at station 1 and 5???? That does not make sense. No I agree, and it is a typo. This has been corrected and simplified, as basically station 1 had the smallest C. helgolandicus size and that is how it is now written.

page 10, Interaction between environmental factors and production; pearsons product moment correlation between female properties does not appear in the Statistics chapter. More important, I wonder what the purpose of some of these tests is: What do you expect from a correlation between female size and FP, the latter in terms of number of FP per female? Does this imply any biological consequences?

This comment made me realize that it is not necessary to show the correlation matrix in the paper, as it is only a tool to help us to see if the data is reasonable and if correlations make sense -and as in this case to make a size normalization of egg production data. I have removed the table and only included the relevant information in the text. I agree with the reviewer that there is nothing biological interesting in the correlation of size and FPproduction (or some other correlations shown). It is just one way of normalizing to length. Most often size is normalized to a carbon content based on standardized length, but as we do not trust carbon conversions of Calanus based on size (due to variable lipid contents and a lack of a good standardized value) we mean that volume might be a better indicator of size that prosome length. EPvol is now explained in the text (now EPRvol).

page 11 line 20 versus page 10 line 60: page 11 says "EPR of C. helgolandicus could not be explained by any of the environmental parameters, neither microplankton nor fatty acid concentrations" page 10 states "The in-situ egg production of C. helgolandicus was best explained by the concentration of ciliates, heterotrophic dinoflagellates and flagellates…."This is contradictory, isn't it? This is due to the two different methods used, immediate measure v.s. a bioassay approach. We mean that the results from those are now better explained and discussed (due to this and the previous comments -thanks). page 11, line 46: "assuming 250 µg C per egg"must be 0.25 µg C per egg, same mistake has been made in the discussion. Oops, this has been corrected. page 11, line 46-47, the references for egg carbon content seem not to be all correct: I did not find any reference to egg carbon measurements in Hygum et al. 2000 (only CI to females) and [START_REF] Koski | High reproduction of Calanus finmarchicus during a diatom-dominated bloom[END_REF] did not measure egg carbon but cites unpublished data by E. Arahkevich; I suggest to refer to these unpublished data in the present manuscript, too, rather than giving the somewhat misleading impression that there are actually egg carbon data published. There are 3 [START_REF] Hygum | Growth and development of Calanus finmarchicus (Gunnerus) nauplii during a diatom spring bloom[END_REF] papers and the reviewer may have looked at a wrong paper. The egg C value is given in their table 1 in the cited paper and mentioned in the text under the section "Carbon content of Calanus finmarchicus eggs". One of the other papers (Importance of food..) also gives egg carbon value, but cites the "Growth and development" paper which we use. The citation to Koski is now removed, but an additional paper by [START_REF] Cabal | Egg production rates of Calanus finmarchicus in the Northwest Atlantic (Labrador Sea)[END_REF] is now added. The values are corrected accordingly (did not change much -a decimal point in GGR).

Introduction

The Dogger Bank is situated in the central North Sea and is a well known feeding ground for planktivorous fish [START_REF] Daan | Ecology of North Sea fish[END_REF]. While thermally stratified during summer, the area north of Dogger Bank is characterized by subsurface chlorophyll blooms the primary production of which has been estimated to be greater than the spring production in the same area [START_REF] Richardson | Subsurface phytoplankton blooms fuel pelagic production in the North Sea[END_REF]. The area around Dogger Bank is also the area where the two Calanus species, the boreal Calanus finmarchicus and the more temperate Calanus helgolandicus overlap. C. finmarchicus is usually located north of the bank in deeper waters while C. helgolandicus is more evenly distributed in the North Sea basin [START_REF] Planque | Calanus and environment in the eastern North Atlantic. I. Spatial and temporal patterns of C. finmarchicus and C. helgolandicus[END_REF][START_REF] Jónasdóttir | Egg production and hatching success in the calanoid copepods Calanus helgolandicus and Calanus finmarchicus in the North Sea from March to September 2001[END_REF].

Calanus helgolandicus and C. finmarchicus are of major importance as food for planktivorous fish in the North Sea ecosystem [START_REF] Munk | Trophodynamics of the plankton community at Dogger Bank: predatory impact by larval fish[END_REF] and numerous studies have been able to correlate fish recruitment to the presence of one or other of these species [START_REF] Beaugrand | Plankton effect on cod recruitment in the North Sea[END_REF]Heath and Lough, 2006). There is an indication that Calanus finmarchicus is more important for recruitment of many fish stocks in the North Sea than is C. helgolandicus, and this may be related to the timing of their abundance and seasonal production [START_REF] Van Deurs | Recruitment of lesser sandeel Ammodytes marinus in relation to density dependence and zooplankton composition[END_REF][START_REF] Beaugrand | Plankton effect on cod recruitment in the North Sea[END_REF]. Calanus finmarchicus enters the North Sea in early spring from its over-wintering in the Faroe Shetland Channel and Norwegian Sea (Heath et al., 1999) while C. helgolandicus is generally a Mediterranean species and disperses in the North Sea from south. Long term data from the Continuous Plankton Recorder (CPR) suggest that C. finmarchicus is retreating north from the North Sea and C. helgolandicus is gaining ground due to warmer temperatures [START_REF] Planque | Calanus and environment in the eastern North Atlantic. I. Spatial and temporal patterns of C. finmarchicus and C. helgolandicus[END_REF]. This has been shown to have affected the survival of fish larvae [START_REF] Beaugrand | Plankton effect on cod recruitment in the North Sea[END_REF][START_REF] Van Deurs | Recruitment of lesser sandeel Ammodytes marinus in relation to density dependence and zooplankton composition[END_REF] probably due to the mismatch with the production of C. helgolandicus, which occurs later in the season [START_REF] Jónasdóttir | Egg production and hatching success in the calanoid copepods Calanus helgolandicus and Calanus finmarchicus in the North Sea from March to September 2001[END_REF][START_REF] Van Deurs | Recruitment of lesser sandeel Ammodytes marinus in relation to density dependence and zooplankton composition[END_REF].

However, whether the reduction of the population C. finmarchicus is due to increased temperatures in the North Sea or a failure in restocking in the spring from the over-wintering habitat off the shelf is debated [START_REF] Beare | Temporal patterns in the surface abundance of Calanus finmarchicus and C. helgolandicus in the northern North Sea (1958-1996) inferred from Continuous Plankton Recorder data[END_REF].

There is actually remarkably little known on the biology of these two closely related species cooccurring in the North Sea. Therefore a comparison of the two Calanus species is of considerable interest in evaluating their importance in the North Sea ecosystem and understanding how/if they interact while overlapping. Only one direct comparative study on C. finmarchicus and C. helgolandicus egg production has been conducted [START_REF] Jónasdóttir | Egg production and hatching success in the calanoid copepods Calanus helgolandicus and Calanus finmarchicus in the North Sea from March to September 2001[END_REF] [START_REF] Bonnet | An overview of Calanus helgolandicus ecology in European waters[END_REF] list in their review on C. helgolandicus some comparative aspects between C. finmarchicus and C. helgolandicus (their Table 2) where they demonstrate differences in distribution and temperature ranges, as well as their differences in maximum egg production rates and development times. A concurrent comparison on feeding selection by most of the development stages of both species has been conducted in the laboratory by Meyer and co workers [START_REF] Meyer | Feeding rates and selectivity among nauplii, copepodites and adult females of Calanus finmarchicus and Calanus helgolandicus[END_REF]. They showed that there were no differences between the species in selection of the food mixtures offered.

The purpose of this paper is to compare the production and abundance of these two congeneric species at the northern/southern edge of their distribution during summer. Sampling was conducted off the northern flank of the Dogger Bank and was a part of a long term study on the biology and production of the subsurface chlorophyll maximum off the Dogger Bank. The questions asked are if there is a spatial overlap between C. helgolandicus and C. finmarchicus and if their production is controlled by the same factors, lending insight into the relative importance of these two species in this highly productive area. I). In 2001 samples were taken as described by Jónasdóttir and co-workers [START_REF] Jónasdóttir | Egg production and hatching success in the calanoid copepods Calanus helgolandicus and Calanus finmarchicus in the North Sea from March to September 2001[END_REF].

Method

Measurements of the physical environment, chlorophyll and zooplankton abundance were taken on each station shown in Fig. 1. Temperature, salinity, and fluorescence profiles were taken with a Seabird  CTD (model 911+) equipped with a Wetstar fluorometer. Stratification was calculated as the energy needed to mix the water column [START_REF] Simpson | The shelf-sea fronts: implications of their existence and behaviour[END_REF]. Simultaneously, samples of chlorophyll a were taken with Niskin bottles from various depths to calibrate the fluorometer measurements. An overview of the experiments and sampling is given in Table I. I) zooplankton was sampled with a submersible pump.

Additionally, in 2002 sample profiles were taken 12 times with ca 6 hour intervals at a drifting buoy station north of the transect (Fig. 1) and in 2005 additional night profiles were taken at 2 stations.

The water was pumped directly into an attached 30 µm plankton net protected by an outer 200 µm mesh net bag. The submersible pump (Homa, H-500, with the plankton net fitted to the outlet) was lowered to a pre-determined depth where it sampled for 3 minutes (1.2 m 3 min -1 ). In 2002 samples were taken at 10 m depth intervals, while at 5 m intervals in 2003 and 2005. In 2001 a depth integrated sample was taken where the pump was lowered to 50 m depth or to 5 m above the bottom depth, if shallower, and sampled (1.2 m 3 min -1 ) while towed vertically to the surface at an average rate of 15 cm sec -1 . The samples were fixed in 4% borax buffered formalin. Zooplankton were counted from a 1/4 to 1/64 fraction of the total sample, so the counts exceeded 200 individuals from the main copepod species. From these samples C. finmarchicus and C. helgolandicus females and copepodite stages 5 (not in 2001) were identified. Copepodite stages 1-4 (stage 5 included in 2001) were counted but these stages cannot be differentiated morphologically between the species.

In 2001 and 2005 Calanus nauplii were specifically identified. Species separation was done on the basis of the different morphology of the 5 th swimming legs [START_REF] Rees | Continuous plankton records: the distribution of Calanus finmarchicus (Gunn.) and its two forms in the North Sea[END_REF] I) with a 220 µm mesh size plankton-net (1 m in diameter) fitted with a 5 L non-filtering cod-end. No females were found at station A in 2001. The sampling depth was usually about 5 m off the bottom depth, usually 50 or 70m and the net was towed vertically with a towing speed of ca 4 m min -1 . The contents of the cod-end were gently transferred into a bucket with surface (4 m) water from the respective station. Immediately after sampling 14 to 40 active undamaged females were selected under a stereomicroscope and individually introduced into 300 or 600 mL bottles filled with 64 µm screened ambient water. Screening was done in order to remove all ambient eggs from the incubation water. Females were incubated in darkness for 22-25 hours at temperatures appropriate for the ambient temperatures (Table I) at the station where they were collected. There was no physical barrier between the females and their eggs. However, in order to minimize cannibalism on eggs the incubation bottles chosen were tissue culture flasks. The bottles were kept upright (not rotating) during incubation and the eggs sank to the bottom of the bottle. The temperature controlled room was mid ship on lower level so physical stirring due to the ships movement was minimal. While these actions do not eliminate the possibility of cannibalism it was minimized. In 2002 females were incubated in either surface or chlorophyll max waters for 24 hours. This procedure was repeated when visiting the stations 3 days later with new net tows and incubations. In [START_REF] Müller-Navarra | Seasonal patterns of food limitation in Daphnia galeata: Separating food quantity and food quality effects[END_REF] to further test how the two species responded to potentially different food quality at the different stations. Over 200 females were sampled on route to the transect, in Skagerrak at 57.66 N and 7.33 W and incubated as above, individually in 24 replicates in both chlorophyll max and surface waters from each of the 4 intensive stations. The water changed every day for 4 days when the station was re-visited at approximately 24 hours intervals. Egg production was not measured on Calanus spp. in 2003 but incubations for 2001 are described in [START_REF] Jónasdóttir | Egg production and hatching success in the calanoid copepods Calanus helgolandicus and Calanus finmarchicus in the North Sea from March to September 2001[END_REF].

Measurement of egg production and hatching success

After the 24 hr incubations, eggs and faecal pellets were collected by filtering the bottle content gently through a 20 µm mesh and immediately counted directly on the mesh through a stereo microscope. The prosome lengths of the females were measured after which they were fixed in 4% formalin in seawater for later identification as C. finmarchicus or C. helgolandicus. Eggs from all females from a specific station were incubated in one or two 600 mL glass bottles containing 20 µm previously screened incubation water. Because of the pooling of the eggs separate hatching data for C. finmarchicus and C. helgolandicus eggs are not available. The eggs were further incubated for 48 h after which time nauplii and un-hatched eggs were preserved in 4% Lugol's solution for later estimation of hatching success. Unfortunately hatching samples taken in 2005 were destroyed.

Phytoplankton and lipid sampling

Water samples for protist counts were taken from the surface and chlorophyll maximum at the intensive stations with Niskin bottles attached to the CTD rosette from several depths. Water samples were fixed in 4% acidic Lugol's solution for phytoplankton and ciliates, and gluteraldehyde for separation of autotrophic versus heterotrophic organisms. Lugol's samples were allowed to settle in a settling chamber [START_REF] Uttermöhl | Zur vervollkommung der quantitativen phytoplankton-methodik[END_REF][START_REF] Hasle | The inverted-microscope method[END_REF] and gluteraldehyde samples handled according to Haas [START_REF] Haas | Improved epifluorescence microscopy for observing planktonic microorganisms[END_REF]. Phytoplankton and ciliates were enumerated and geometrical axes measured under inverted microscope (Lugol's samples) or epifluorescence microscope (gluteraldehyde samples). Volumes were calculated using the software program Planktonsys 3.11 from BioConsult A/S, and carbon content calculated according to Edler [START_REF] Edler | Recommendations on methods for marine biological studies in the Baltic Sea -Phytoplankton and chlorophyll[END_REF] and Mullin and co-workers [START_REF] Mullin | Relationship between carbon content, cell volume and area in phytoplankton[END_REF]. Additional data on ciliate counts from the cruises were obtained from Arendt and co-workers [START_REF] Arendt | Effects of dietary fatty acids on the reproductive success of the calanoid copepod Temora longicornis[END_REF].

One to 5 L of water from surface and chlorophyll maximum were filtered onto combusted GF/C (Whatman) filters and immediately frozen in cryo-vials -80°C. Fatty acids were extracted from filters containing the field collected seston using chloroform:methanol (2:1 by volume). A known amount of the fatty acid C23:0 was added to the sample and used as an internal standard for 7 quantification of specific fatty acids. After at least 24 hours extraction at -20°C, the chloroform:methanol phase was collected and the filters were washed three times with chloroform:methanol. The extracts were washed according to the modified Folch method [START_REF] Hamilton | Extraction of lipids and derivative formation[END_REF]. After saponifcation, the samples were transmethylated to fatty acid methyl esters (FAME) using boron trifluoride (BF 3 ) and then stored in air-tight vials in an argon atmosphere at -80°C until GC analysis. The FAME sample was injected into a gas chromatograph (Hewlett Packard 5809A, with a 30 m omegawax 320 µm column, and equipped with a split/splitless injection system) using helium as a carrier gas at 1.8 mL min -1 . Fatty acid methyl esters were identified based on comparison with retention times of several standards; Larodan PUFA standard, fatty acid from the dinoflagellate Prorocentrum minimum to locate 18:5(n-3), Matreya PUFA-3 and Supelco 18919, resulting in identification of 42 fatty acids.

Statistics

Test of associations between the female properties were made by Pearson product moment correlation. Egg production, spawning percentage, brood size and prosome length were tested for differences between stations within years using one-way ANOVA or Kruskal Wallis ANOVA on ranks if the requirement of equal variances were not met. Tukey HSD or Dunn's post hoc pair-wise comparisons were carried out when ANOVAs gave significant differences. Principle component analysis (PCA) was used to reduce the number of environmental variables to be used in the multiple regressions and correlations. Chi-square analysis of contingency tables was used to compare the temperature preference of C. helgolandicus and C. finmarchicus based on preference for above and below thermocline. Spearman rank test was used for nonlinear correlations and a Pearsons product moment correlation matrix was generated between female properties The statistical programs SPSS and Sigma Stat were used for the analyses.

Results

Physical and biological environment

The average temperature in the upper 20 m differed between the years, being 14.7, 17.5, 18.4 and 14.8 °C in 2001, 2002, 2003 and 2005 respectively (Table II). The thickness and concentration of the chlorophyll maximum layer also differed between the years (Fig. 2 III). The dominant microplankton class was autotrophic dinoflagellates of which Ceratium species were the major group in both years. m -3 ) at the transect stations (Fig. 2; Table II), but at the buoy station (Fig. 3) the abundance of both species was similar. A vertical separation of the species was observed in 2003 and 2005 and at the buoy station in 2002 where C. finmarchicus females were below the thermocline while C. helgolandicus females were in the upper warmer surface waters. To better compare the optimal temperature ranges that the two congeneric species occupied, female and C5 concentrations were plotted against their respective sampling temperatures. Peak abundance, was at 9 and 16 °C for C. finmarchicus and C. helgolandicus respectively (Fig. 4a). There was a highly significant difference in the abundance of the 2 species above and below the thermocline (Chi-square = 666, df = 1, P<0.001). The copepodite stage 5 (C5) stages had a similarly significant vertical distribution (Chisquare = 815, df =1, P<0.001); C. finmarchicus having higher abundances in deeper cooler layers In situ egg production and hatching.

For comparisons between years, we only used data from day 1 in 2005. There were no significant differences in egg production rates (EPR) between surface water and chlorophyll maximum incubations in any of the years after 1 day incubation. Therefore, to increase the number of replicates, surface and chlorophyll maximum data are pooled

The proportion of spawning females was 75-83 % for C. helgolandicus and 58-79 % C. finmarchicus during the 3 years (Table V). However, this difference was not significant between the species (F 1 = 2.3; P = 0.15) and not different between years for either species (F 2, 1 = 1.15; P = 0.3). The highest egg production rate for an individual C. helgolandicus was 79 eggs d -1 (Table V) V). There was a significant difference (F 3 = 6.1; P = 0.009) between stations in 2002 and hatching was significantly lower in 2002 than 2001, 91% compared to 98% respectively (F 1 = 12.2; P = 0.013).

Bioassay 2005

In 2005 the females were collected at a single station at the start of the cruise and the same females incubated for 4 days in either surface or chlorophyll maximum waters at the 4 intensive stations to assess potential difference in the food environment in the incubations. This should also show if the two species respond differently with time to the same food environment.

Significant differences were found in total number of C. helgolandicus eggs produced over the 4 days (cumulative egg production) between stations in the surface layer (F 2 = 4.3; p = 0.04) but not in the chlorophyll maximum layer (Fig. 6 a). The opposite was true for C. finmarchicus where the difference between stations in chlorophyll maximum was significant (F 3 = 3.3; p = 0.03) but not in the surface layer. The difference between surface and chlorophyll maximum total egg production was significant for C. finmarchicus (F 1 = 89.8; p = 0.003) but not for C. helgolandicus. C.

finmarchicus produced significantly more eggs in the chlorophyll maximum than did C. helgolandicus (H1=7.9; p=0.005), but the difference was not significant between the species feeding in the surface water. EPR decreased from day 1 to 4 at different rates for both species at all stations.

When we separate the analyses between the surface and chlorophyll maximum layer, C.

helgolandicus differed in size between stations in the surface incubations (significant interaction between water layer and station, 2-way ANOVA F 3, 35 = 75; p = 0.008) where the female at station 1 was significantly smaller than at the other stations (Holm Sidack p < 0.05). No difference was observed in C. finmarchicus size between stations or in C. helgolandicus in the chlorophyll maximum layer where more females were behind the mean measurements.

Interaction between environmental factors and production

A Pearsons product moment correlation between female properties showed a significant positive correlation between size of C. finmarchicus females and egg production (r = 0.49, n = 39, p < 0.001). A negative correlation was found between faecal pellet production and hatching success for both species (r = -0.70, n = 12, p < 0.05). The in-situ egg production of C. helgolandicus (after 1 day of incubation all years) was best explained by the concentration of ciliates, heterotrophic dinoflagellates and flagellates resulting in a predictive model with r 2 =0.87 p = 0.01 (Stepwise Regression, Table VI). None of the fatty acid concentrations of the seston could contribute to explain the observed C. helgolandicus EPR. As egg production of C. finmarchicus was highly correlated with female prosome length it was standardized to female volume calculated according to [START_REF] Mauchline | The Biology of Calanoid Copepods[END_REF]:

logV (mm 3 ) = 3.614 log PL (µm) -10.69

where V is female volume, and PL is prosome length. EPR normalized to size, EPR vol was best explained with the fatty acid 22:6n3 that is typical for dinoflagellates (Stepwise Regression, Table VI).

The egg production rates of C. finmarchicus after the 4 days of acclimation to the chlorophyll maximum and surface food sources were best explained with the concentration of autotrophic dinoflagellates and flagellates as well as diatoms (stepwise regressions r 2 = 0.87; F 3 = 17, p = 0.01;

Table VI) . However the EPR of C. helgolandicus could not be explained with any of the environmental parameters measured, neither microplankton nor fatty acid concentrations.

Secondary production

The population egg production rate (EPR pop ) for C. finmarchicus was on average 3 times higher than of C. helgolandicus in both 2001 and 2005 but the reverse in 2002 when the EPR pop measured was about 10 times higher for C. helgolandicus (Table VII). The secondary production of C. helgolandicus and C. finmarchicus was highest in 2005 for both species with highest production of about 21 mg C m -2 d -1 at station 5 respectively, for C. helgolandicus and C. finmarchicus assuming 0.254 µg C per egg for both species (average value from [START_REF] Ohman | Sustained fecundity when phytoplankton resources are in short supply: Omnivory by Calanus finmarchicus in the Gulf of St[END_REF][START_REF] Cabal | Egg production rates of Calanus finmarchicus in the Northwest Atlantic (Labrador Sea)[END_REF][START_REF] Hygum | Growth and development of Calanus finmarchicus (Gunnerus) nauplii during a diatom spring bloom[END_REF][START_REF] Mayor | Feeding and reproduction of Calanus finmarchicus during non-bloom conditions in the Irminger Sea[END_REF]. At other stations and years the secondary production ranged from 0-5 mg C m -2 d -1 (Table VII). Naupliar survival was estimated from egg production, hatching and female abundance, and compared to observed naupliar densities. The highest naupliar survival was estimated to be only 8 % from egg to N6.

Faecal pellet production

The comparison of faecal pellet production (FP) between years was only conducted on copepods that could actively feed, that is in the chlorophyll maximum layer even though some pellet production was measured in surface waters in 2005 (Fig. 5). There was a significant difference in finmarchicus and H 3 = 9.9; P = 0.02 C. helgolandicus). There was a significant difference in FP between years for both species (H 1 = 15.1 and 21.3; P<0.001 for both) with higher production in 2005. When pooled, no significant difference was found between FP of the two species.

The sum of 4 days of feeding (the bioassay in 2005) resulted in a significant difference between stations in faecal pellet production (FP) in the surface waters for both C. helgolandicus and C. finmarchicus (F 3 = 5.8; p = 0.02 and H 3 = 18.5; p < 0.001, respectively; Fig. 6 b). The difference between stations in chlorophyll maximum was only significant for C. finmarchicus (F 3 = 16.6; p < 0.001) where highest production was at stations 5 and 8. FP was significantly higher in the chlorophyll maximum layer for both species (F 1 = 12.5; p < 0.001 for C. helgolandicus and H 1 = 45.1; p < 0.001 for C. finmarchicus). C. finmarchicus had significantly higher faecal pellet production in both layers compared to C. helgolandicus (H 1 = 6.6; p = 0.01, F 1 = 11.8; p < 0.001 in surface and chlorophyll maximum, respectively).

Faecal pellet production of C. finmarchicus was best explained with the in situ concentration of autotrophic flagellates (stepwise regressions r 2 = 0.81; F 1 = 31, p = 0.001) while the faecal pellet production of C. helgolandicus was best explained with both in situ concentrations of autotrophic flagellates and ciliates (stepwise regressions r 2 = 0.96; F 2 = 77, p < 0.001).

Discussion

The congeneric species, the temperate C. helgolandicus and the boreal C. finmarchicus overlap both in time and space in the northern North Sea. As species identification is difficult with live specimens, comparative studies of their reproduction and physiology under natural conditions have been limited to date. Therefore this study is an important piece in a larger puzzle, improving our understanding of the co-occurrence and dynamics of these species especially under changing climatic conditions in the North Sea.

Vertical distribution

The present study shows that when C. helgolandicus and C. finmarchicus co-occur C. finmarchicus prefers to stay in deeper, cooler waters (7.5-9 °C) and C. helgolandicus above the thermocline in 15-16°C waters. While C. finmarchicus was also found above the thermocline and C. helgolandicus below the thermocline (e.g. in 2003 station closest to the bank, Fig . 2) the majority of the population in all 3 years was separated by the thermocline and the separation is highly significant.

Separation of C. finmarchicus and C. helgolandicus in different water masses has been observed

Formatted: Font: Italic 13 before in the North Atlantic [START_REF] Williams | Feeding and reproduction by Calanus finmarchicus, and microzooplankton grazing during mesocosm blooms of diatoms and the coccolithophore Emiliana huxleyi[END_REF] where the vertical distribution also was associated with thermal stratification. Such separation of C. finmarchicus and C. helgolandicus was however, not reported in the North Sea in May 2001 in the review by [START_REF] Bonnet | An overview of Calanus helgolandicus ecology in European waters[END_REF] where both species stayed below 10m depth with maximum abundance at 20-40 m. However, during this period the water column was well mixed with Simpson's stability index <10 Joules m -3 [START_REF] Jónasdóttir | Egg production and hatching success in the calanoid copepods Calanus helgolandicus and Calanus finmarchicus in the North Sea from March to September 2001[END_REF] with little vertical temperature contrast. Instead of retreating from the North Sea as surface temperatures increase, as may be inferred from CPR data [START_REF] Beaugrand | Plankton effect on cod recruitment in the North Sea[END_REF], it appears that C. finmarchicus could just as likely migrate down into cooler waters in summer. This deep maximum in C. finmarchicus abundance would not be observed in the CPR data, as the CPR samples to a maximum of 10 m depth. Diel vertical migration appears to be minimal and when taking place, C. finmarchicus ascends to about 15 m depth, still below the range of the CPR sampling depth. The high abundance in 2005 shows that C. finmarchicus may stay active longer in the North Sea than previously believed [START_REF] Bonnet | An overview of Calanus helgolandicus ecology in European waters[END_REF][START_REF] Jónasdóttir | Egg production and hatching success in the calanoid copepods Calanus helgolandicus and Calanus finmarchicus in the North Sea from March to September 2001[END_REF]. There is however, a large yearly variation in abundance of both species between the years reported here. This yearly variation is most likely due to variation in the strength of the spring invasion into the North Sea from the Faroe Shetland Channel [START_REF] Beare | Temporal patterns in the surface abundance of Calanus finmarchicus and C. helgolandicus in the northern North Sea (1958-1996) inferred from Continuous Plankton Recorder data[END_REF]Heath et al., 1999), which is the prerequisite for the success of C. finmarchicus in the North Sea.

We cannot explain the vertical separation of the species most prominent in 2005 and at the Buoy station in 2002. There are several possible reasons; interspecies competition for food, avoiding predation of each other's eggs and nauplii and differences in optimal temperature tolerance. Most

Calanus nauplii were found in the upper 20 m (Table II) where temperature would augment their development time. At this depth they are also out of reach of the females of both Calanus species and can therefore avoid cannibalism that can be high at high naupliar concentrations [START_REF] Bonnet | Calanus the cannibal[END_REF]. However, different temperature preference is the most likely explanation for the vertical separation at this southern/northern boundary of the species (Fig 4 ).

Food and feeding

New production is continuously taking place at the deep chlorophyll maximum along the flanks of the Dogger Bank due to tidal pumping of nutrient rich water from the deeper layer (Richardson et al., 2000). It is an area of plentiful and high quality food, promoting copepod growth and survival, at a time when the surface waters are mostly depleted in food (Table III, Fig. 2). The quality of the food ingested is also reflected in the high hatching success of the eggs produced. The faecal pellet production indicated that feeding in the chlorophyll maximum was highest at the stations closest to the bank, decreasing away from the bank (Figs. 5 and6b). Typically, for summer and subsurface data to calculate ingestion rates as we did not measure the faecal pellet sizes, it is probable that ingestion rates must have been higher for C. finmarchicus, having higher faecal pellet production compared to C. helgolandicus. Either the ingestion rates were lower or the assimilation efficiency higher in C. helgolandicus as the egg production rates of the species were similar and we can assume similar respiration rates during incubation as the temperatures were the same. There is however, no clear explanation for higher pellet production for both species in the surface layer in 2005 compared to 2002. The food abundance and composition was similar these years (Table III).

C. helgolandicus has been shown to be able to feed efficiently on Ceratium furca in the North Sea [START_REF] Jansen | Copepod feeding behaviour and egg production during a dinoflagellate bloom in the North Sea[END_REF] [START_REF] Meyer | Feeding rates and selectivity among nauplii, copepodites and adult females of Calanus finmarchicus and Calanus helgolandicus[END_REF].

Reproduction and food environment

The environmental parameters found to affect the immediate egg production rates (1 day in-situ incubation) were similar for both species, indicating they are likely to be feeding on similar diets.

Both were significantly correlated to the autotrophic dinoflagellates, flagellates and ciliates while the specific nutritionally important fatty acids could not explain any of the variation in the observed egg production rates which may indicate that essential fatty acids were not limiting in the copepod diet. Hirche [START_REF] Hirche | The reproductive biology of the marine copepod Calanus finmarchicus -A review[END_REF] reports that egg production of C. finmarchicus reduced sharply after 2 days of starvation at 0 ºC. Therefore, in the one day incubations the egg production was based on food they encountered approximately 1-2 days before the incubation. Only few studies have made a simultaneous measure of egg production and selection for these two species and their results show both positive [START_REF] Meyer-Harms | Selective feeding on natural phytoplankton by Calanus finmarchicus before, during, and after the 1997 spring bloom in the Norwegian Sea[END_REF][START_REF] Niehoff | A high frequency time series at Weathership M, Norwegian Sea, during the 1997 spring bloom> the reproductive biology of Calanus finmarchicus[END_REF][START_REF] Koski | High reproduction of Calanus finmarchicus during a diatom-dominated bloom[END_REF]) and negative [START_REF] Nejstgaard | Zooplankton growth, diet and reproductive success compared in simultaneous diatom-and flagellate-microzooplanktondominated plankton blooms[END_REF] relation between EPR and diatom diets and both positive [START_REF] Irigoien | Feeding selectivity and egg production of Calanus helgolandicus in the English Channel[END_REF] and negative [START_REF] Nejstgaard | Zooplankton growth, diet and reproductive success compared in simultaneous diatom-and flagellate-microzooplanktondominated plankton blooms[END_REF] 15 studies, like the present one, make a correlation with microplankton biomass, bypassing ingestion.

One of these shows that ciliates can be important for egg production of both Calanus finmarchicus and C. helgolandicus [START_REF] Jónasdóttir | Egg production and hatching success in the calanoid copepods Calanus helgolandicus and Calanus finmarchicus in the North Sea from March to September 2001[END_REF].

The bioassay study that ran over 4 days gives a better indication of the food environment in the deep chlorophyll maximum layer and how the congeneric species can utilize the subsurface bloom.

The differences in feeding and reproduction between the two species became more pronounced showing higher egg-and faecal pellet production for C. finmarchicus compared to C. helgolandicus.

C. finmarchicus production was again highly significantly correlated to autotrophic flagellates and dinoflagellates, and to lesser extent diatoms, even though they were present in low concentrations.

No measured variables could explain the EPR of C. helgolandicus while faecal pellets of both species were highly correlated to the abundance of autotrophic flagellates. Both species had reduced EPR with time, which indicates that they may have had a better food source for production at their original sampling location, in the Skagerrak. This lack of correlation for C. helgolandicus underlines the importance of making an estimate of food ingestion and selection to better understand how the food environment affects egg production rates.

Population egg production

The timing of production and distribution of C. helgolandicus varies with location in the North Sea [START_REF] Bonnet | An overview of Calanus helgolandicus ecology in European waters[END_REF] but a seasonal study in a similar area as in the present study [START_REF] Jónasdóttir | Egg production and hatching success in the calanoid copepods Calanus helgolandicus and Calanus finmarchicus in the North Sea from March to September 2001[END_REF] strongly indicated that the peak production season for both species was drawing towards the end in July and August. These authors showed the 2001 peak egg production of C. finmarchicus in March and C. helgolandicus in May; with relatively constant low population egg production rates (EPR pop ) of C. helgolandicus (< 50 eggs m -3 d -1 ) and the highest average rates in May for C.

finmarchicus (150 eggs m -3 d -1 ). Our measurement shows remarkably higher EPR pop in July and August of 21 -1600 eggs m -3 d -1 (160 -82000 eggs m -2 d -1 ) for C. finmarchicus and 15 -890 eggs m -3 d -1 (450 -44000 eggs m -2 d -1 ) for C. helgolandicus (Table VII). The contribution of C.

finmarchicus was therefore on the average 15 times larger in August 2005 compared to its highest in 2001 but similar for C. helgolandicus and 2 times higher in August 2005 compared to May 2001 [START_REF] Jónasdóttir | Egg production and hatching success in the calanoid copepods Calanus helgolandicus and Calanus finmarchicus in the North Sea from March to September 2001[END_REF]. Our measurements are in the same order of magnitude as the spring EPR pop of Calanus finmarchicus at the peak of their spring production in Northern Norwegian Fjords; 60000-120000 eggs m -2 d -1 [START_REF] Koski | High reproduction of Calanus finmarchicus during a diatom-dominated bloom[END_REF] and the maximum reported for Station M in the Norwegian Sea in June of about 35000 eggs m -2 d -1 [START_REF] Niehoff | A high frequency time series at Weathership M, Norwegian Sea, during the 1997 spring bloom> the reproductive biology of Calanus finmarchicus[END_REF]. It was somewhat surprising that C. finmarchicus had a larger contribution to total production during late summer for 2 years, based on the fact that this species was not expected to be dominant in the North Sea in late resulting in 10 times higher EPR pop for C. helgolandicus. However, at the buoy station the abundances were similar and if assuming the same egg production rates there for both species as measured at the transect stations, the EPR pop of the species was the same. However, only 2-20% of this production may make past the N6 stage, but according to Eiane and Ohman [START_REF] Eiane | Stage-specific mortality of Calanus finmarchicus, Pseudocalanus elongatus and Oithona similis on Fladen Ground, North Sea, during a spring bloom[END_REF]) mortality is highest in naupliar stages 1-3 for C. finmarchicus.

The individual egg production rate of the two species did not appear to differ at any time. The incubations of both species were carried out at the same temperatures, while the copepods inhabit in-situ water masses of about 7 °C difference. We do not know if the production rates of the species at the same incubation temperature would be affected by their previous in-situ temperature preference, but as there was no significant difference in the instant (day 1) egg production rates in the surface (ca 15°C) and chlorophyll maximum (ca 7°C) incubations in 2002 and 2005 (Table V)

we can conclude that the previous temperatures do not affect the immediate production rates. The EPR of C. finmarchicus was always higher than of C. helgolandicus but due to high variation in some of the measurements the difference was never significant. However, C. finmarchicus had a significantly higher maximum rate compared to C. helgolandicus. The highest EPR of 79 and 94 eggs for C. helgolandicus and C. finmarchicus respectively represents about 80 and 85 % of their reproductive potential based on their size and are therefore high for the end of the reproductive season (see Fig. 6a in [START_REF] Jónasdóttir | Egg production and hatching success in the calanoid copepods Calanus helgolandicus and Calanus finmarchicus in the North Sea from March to September 2001[END_REF] in the North Sea. It is difficult to calculate the specific egg production rates for Calanus due to the variable content of their lipid reserve that can give them a relatively high carbon weight. However, if we use a carbon weight of 77 µg C female -1 (estimated from dry weight of similar sized lipid free females from the North Sea, Jónasdóttir unpublished, assuming carbon to be ca 47% of dry weight; [START_REF] Båmstedt | Chemical composition and energy content[END_REF]) and an egg weight of 0.254 µg C (see above) the specific egg production was 4 -9% and 3-15% for C. helgolandicus and C. finmarchicus respectively. This is similar to the values for C. finmarchicus production in Greenland waters [START_REF] Madsen | Importance of feeding for egg production in Calanus finmarchicus and C. glacialis during the Arctic spring[END_REF], but lower than that reported by Koski for Norwegian fjords [START_REF] Koski | High reproduction of Calanus finmarchicus during a diatom-dominated bloom[END_REF]. The deep chlorophyll maxima in the North Sea appears to give both species a refuge, offering both a high quality food away from the surface waters where highest predation pressure may occur, as well as offering optimal temperatures for both species. This suggests that the summer productivity of both species is as high as during the spring bloom, further underscoring the central importance of subsurface primary production in fuelling the North Sea ecosystem. based on observed hatching success assuming 1 stage per day for 6 stages. Nauplii observed are the depth integrated naupliar stages 1 -6 at each station (no m -2 ) and % survival is the estimated survival of the nauplii produced. abundance (no m -3 ) in temperature bins of 3 degrees. There was as significant difference between stations in faecal pellet production (FP) in the surface waters for both C. helgolandicus and C. finmarchicus (F 3 = 5.8; p = 0.02 and H 3 = 18.5; p < 0.001, respectively; Fig. 6 b). The difference between stations in chlorophyll max was only significant for C. finmarchicus (F 3 = 16.6; p < 0.001) where highest production was on stations 5 and 8. FP was significantly higher in chlorophyll max layer for both species (F 1 = 12.5; p < 0.001 for C.

helgolandicus and H 1 = 45.1; p < 0.001 for C. finmarchicus). C. finmarchicus had significantly higher faecal pellet production in both layers compared to C. helgolandicus (H 1 = 6.6; p = 0.01, F 1 = 11.8; p < 0.001 in surface and chlorophyll max, respectively).

Fig. 2 :

 2 Fig. 2: In my version of the MS, the figure that is meant to show vertical distribution of C.fin in July (the uppermost panel) is rotated 90°. Must be improved. -The reason is (as stated in the methods) that in 2001 the zooplankton abundance was unfortunately only from a total vertical tow, not depth separated. This has now been pointed out in figure legend, and the graph made clearer including station numbers on xaxes to avoid misunderstanding of the orientation of the plot. (New Table I -as suggested by Rev 2, should also clarify this).

Fig. 4 :

 4 Fig. 4: Impossible to see which curve is for Cfin and which is for C.helg. Must be improved. What is meant by relative abundance here? Please explain. I am also a bit confused if the Fig shows females only as the legend suggests, or if younger stages are included also, as the discussion on this Fig in main text (P. 8), implies that the

  page 7, line 23: chlorophyll was DIFFUSED between the years -What do you mean?

  page 11: Why did you transform length to volume? What is EPvol? Please, explain!

  on a one year seasonal production of these species. Here it was demonstrated that C. finmarchicus and C. helgolandicus distribution differed both spatially and seasonally where C. helgolandicus had lower egg production the season compared to C. finmarchicus. Peak egg production for C. helgolandicus occurred in May compared to March for C. finmarchicus. Bonnet and co-workers

  Physical, chemical and biological measurements were carried out during 4 North Sea cruises on R/V Dana (DTU-Aqua) 7-11 August 2002, 2003 and 27 July -7 August 2005, along a transect across the northern flank of Dogger Bank and at 4 stations 19 July 2001(Fig. 1). The transect had 15-17 CTD stations of which 4 were sampled intensively for other biological measurements. On these intensively sampled stations, shipboard egg production and hatching success experiments on C. finmarchicus and C. helgolandicus were carried out, fatty acid analysis of seston and samples for zooplankton vertical distribution and abundance were taken (see though exceptions in Table

  In 2001 and 2002 Calanus females were sampled at the intensive stations (Fig 1; Table

  2005 we Deleted: (stations 1, 3, 5 and 8) Deleted: . Deleted: I Deleted: some Deleted: o Deleted: were counted Deleted: on Deleted: as much as possible Deleted: sampled at each station and Deleted: Separate incubations were carried out on each station 2 times

  ), with a strong chlorophyll maximum in 2001 and 2002 and more vertically diffused in 2003 and 2005. The stratification in 2003 was 131 Joules m -3 and markedly higher than in the other years where it was 98, 105 and 95 Joules m -3 for 2001, 2002 and 2005, respectively. Average chlorophyll concentrations in the chlorophyll maximum layer varied from 1.4 to 4.1 µg L -1 (Table

  concentrations were highest in 2001 (ca 1 µg L -1 ) but between 0.4 and 0.6 µg chl a L -1 in 2002 and 2005. There were no dominant groups of microplankton in the surface waters but the assemblage was equally composed of flagellates, autotrophic and hetetrotrophic dinoflagellates, and ciliates but with slightly lower contribution of flagellates in 2005. Diatoms were only found in comparable amounts to other groups in the chlorophyll maximum at station 8 in 2005. Carbon:chlorophyll ratios of the counted microplankton ranged from 21 to 102 (TableIII).Total seston fatty acids were positively correlated with the chl a content (Spearman Rank Order Correlation: ρ = 0.52, p = 0.03, n = 17). Polyunsaturated fatty acids were most abundant in the chlorophyll maximum in 2001 and 2005 or 7 to 27 µg L -1 , but were more uniformly low (about 1 µg L -1 ) in 2002 (TableIV).AbundanceBoth Calanus finmarchicus and C. helgolandicus were found at the transect stations in all years, but abundances varied both annually and spatially. In 2001 and 2003 C. finmarchicus was found in higher abundance than C. helgolandicus but the reverse was true in 2002. The species occurred in similar numbers in 2005. In 2002 C. finmarchicus was found in very low concentrations (1 indiv.

(

  max at 7.5 °C) while the C5 stage of C. helgolandicus were in the upper layers in 2002 and 2005 but more evenly distributed through the water column in 2003 (Table II; Fig. 4b) resulting in broader temperature preference with a maximum abundance at 13.5°C. Stages C1-4 were most abundant in the upper 40 m all years, and nauplii only separated for Calanus in 2005 were in the upper 20 m (TableII).There was no indication of diel vertical migration of either species at the buoy station in 2002, while there was some indication of upward migration to 15 m during night by C. finmarchicus at station 3 in 2005 Fig.3b). Yearly densities of C. finmarchicus and C. helgolandicus standardized to the maximum density each year potted against temperature show that p Deleted: as determined by best fit 2005 no difference was observed in the size between C. finmarchicus and C. helgolandicus (Table V). However, in 2002 C. helgolandicus was significantly larger than C. finmarchicus (2.46 ± 0.01 v.s. 2.40 ± 0.01 mm, Kruskal-Wallis One Way Analysis of Variance on Ranks, H 1 = 19.4, P = <0.001) and both species were significantly larger in 2005 compared to 2001 and 2002 (Kruskal-Wallis One Way Analysis of Variance on Ranks, C. helgolandicus H 2 = 36.3; P = <0.001 and C. finmarchicus H 2 = 93.1; P = <0.001.

  and the EPR max (EPR from spawning females only) were significantly higher in 2002 than the other years (Kruskal-Wallis ANOVA, H 2 = 23.1; P < 0.001, Dunn's post-hoc pairwise comparison). The highest EPR of a single C. finmarchicus was 94 eggs d -1 . No differences were observed in EPR max between years for C. finmarchicus. The difference between the species was significant in 2001 (33 ± 4 and 21 ± 3 eggs female -1 day -1 ; F 1 = 5.7; P = 0.02) and 2005 (38 ± 2 and 20 ± 5 eggs female - 1 day -1 ; F 1 = 11.7; P < 0.001) for C. finmarchicus and C. helgolandicus respectively.The average egg production rate (EPR, zero production included) for C. helgolandicus ranged from 8-29 eggs female -1 d -1 and was significantly lower in 2001 compared to 2002 (Kruskal-Wallis ANOVA, H 2 = 10.5; P = 0.005, Dunn's post-hoc pairwise comparison). EPR ranged from 8-43 eggs female -1 d -1 for C. finmarchicus and was significantly higher in 2005 compared to the 2001 and 2002 (Kruskal Wallis ANOVA, H 2 = 7.9, P = 0.02; Fig.5, TableV). No statistically significant difference was observed in EPR between species in any of the years.Deleted: . However pellet production is only compared for the chlorophyll max incubations. always over 90% with the exception of station 3 in 2002 (Table

  Faecal pellet production ¶ Faecal pellets production (FP) was only compared on copepods that could actively feed, that is in the chlorophyll max layer even though some pellet production was measured in surface waters in 2005 (Fig.5). Faecal pellet production was significantly different between stations in 2002 for C. helgolandicus (H3 = 30.5 P <0.001) but not for C. finmarchicus. In 2005 the FP differed between station for both species (F3 = 11.1, P<0.01 for C. finmarchicus and H3 = 9.9; P = 0.02 C. helgolandicus). There was a significant difference in FP between years for both species (H1 = 15.1 and 21.3; P<0.001 for both) with higher production for both species in 2005. When pooled, no significant difference was found between FP of the two species. ¶ There was as significant difference between stations in faecal pellet production (FP) in the surface waters for both C. helgolandicus and C. finmarchicus (F3 = 5.8; p = 0.02 and H3 = 18.5; p < 0.001, respectively; Fig.6 b). The difference between stations in chlorophyll max was only significant for C. finmarchicus (F3 = 16.6; p < 0.001) where highest production was on stations 5 and 8. FP was significantly higher in chlorophyll max layer for both species (F1 = 12.5; p < 0.001 for C. helgolandicus and H1 = 45.1; p < 0.001 for C. finmarchicus). C. finmarchicus had significantly higher faecal pellet

C

  . helgolandicus faecal pellet production between stations in 2002 (H 3 = 30.5 P <0.001) but not for C. finmarchicus. In 2005 the FP differed between station for both species (F 3 = 11.1, P<0.01 for C. Faecal pellet production of C. finmarchicus was best explained with the concentration of autotrophic flagellates (stepwise regressions r 2 = 0.81; F1 = 31, p = 0.001) while the faecal pellet production of C. helgolandicus was best explained with both autotrophic flagellates and ciliates (stepwise regressions r 2 = 0.96; F2 = 77, p < 0

Formatted

  microplankton community in the chlorophyll maximum was mainly composed of autotrophic and heterotrophic dinoflagellates, and flagellates. While we cannot use our faecal pellet

  2002 C. finmarchicus was in much lower abundance on the Dogger Bank transect

Formatted

  Fig. 1, Chl max: sub surface chlorophyll maximum. SAFA, MUFA and PUFA: saturated, monounsaturated and polyunsaturated fatty acids and include minor fatty acids not shown in the table.

Figure 1 .

 1 Figure 1. Stations sampled in 2002, 2003 and 2005(stars) where intensive stations are filled stars and CTD stations are all stars. Stations used from the cruise in 2001 are marked with A, B, C and D (Jónasdóttir et al., 2005). The drifting buoy station B in 2002 is labelled with open triangles.

Figure 2 .

 2 Figure 2. A) Vertical distribution of chlorophyll a (filled contours in µg L -1 ) and temperature (line contours °C) on the transects north of Dogger Bank in the years 2001, 2002, 2003 and 2005. B) Vertical distribution of female Calanus helgolandicus (hatched bars) and Calanus finmarchicus (white bars) abundance (numbers m -3 ). In 2001 bars represent abundance at stations B, C and D based on a vertically integrated tow (no Calanus found at station A).

Figure 3 Figure 4 .

 34 Figure 3. a) Diurnal variation in the vertical distribution of chlorophyll a (filled contours in µg L -1 ), temperature (line contours °C) and the female abundance (numbers m -3 ) of Calanus helgolandicus (hatched bars) and Calanus finmarchicus (white bars) at the buoy station B in 2002. Whiskers are +1 SE of average 2-5 pump profiles). b) Abundance (numbers m -3 ) of female Calanus helgolandicus (hatched bars) and Calanus finmarchicus (white bars) at day and night at stations 3 and 5 in 2005.

Figure 5 .

 5 Figure 5. C. helgolandicus and C. finmarchicus. Station averages of egg production rates (EPR: eggs female -1 d -1 ) surface and chlorophyll max waters combined, and of faecal pellet production (pellets female -1 d -1 ) in surface waters and chlorophyll max in 2001, 2002 and 2005. Whiskers are +1 SE.

Figure 6 .

 6 Figure 6. C. helgolandicus and C. finmarchicus. Cumulative a) egg production and b) faecal pellet production in chlorophyll max and surface waters at the 4 stations in 2005. Whiskers are ± 1 SE.

Formatted

Figure 1 .Figure 3

 13 Figure 1. Stations sampled in 2002, 2003 and 2005(stars) where intensive stations are filled stars and CTD stations are all stars. Stations used from the cruise in 2001 are marked with A, B, C and D (Jónasdóttir et al., 2005). The drifting buoy station B in 2002 is labelled with open triangles. 210x297mm (200 x 200 DPI)

Figure 4 .

 4 Figure 4. C. helgolandicus (hatched bars) and C. finmarchicus (open bars). a) Female and b) C5 abundance (no m-3) in temperature bins of 3 degrees. 210x297mm (200 x 200 DPI)

Table I :

 I What do the blank spaces for CHc5 and CFc5 in 2001 mean? Are they zeros or not measured. Explain in Table legend what 'nm' means. Clarified -changed to na (not analysed).

Table IV :

 IV Why do you not indicate significance for hatching as for the other variables? The comparison was mistakenly left out, and it now in and in accordance to the text.

;

  Ceratium sp. was the dominant dinoflagellate in the subsurface maximum during the present study. No comparison on feeding, between the congeneric species has been conducted in the field, and was not done in the present study. Studies conducted separately on these species show that both species can be non selective (e.g. C. helgolandicus:[START_REF] Irigoien | Feeding selectivity and egg production of Calanus helgolandicus in the English Channel[END_REF][START_REF] Rees | Continuous plankton records: the distribution of Calanus finmarchicus (Gunn.) and its two forms in the North Sea[END_REF]

finmarchicus:

[START_REF] Meyer | Feeding rates and selectivity among nauplii, copepodites and adult females of Calanus finmarchicus and Calanus helgolandicus[END_REF]

, and selective for ciliates (e.g. C. helgolandicus:

[START_REF] Nejstgaard | Zooplankton growth, diet and reproductive success compared in simultaneous diatom-and flagellate-microzooplanktondominated plankton blooms[END_REF] C. finmarchicus: Mayor et al., 2006, Ohman and[START_REF] Ohman | Sustained fecundity when phytoplankton resources are in short supply: Omnivory by Calanus finmarchicus in the Gulf of St[END_REF]

or for diatoms (e.g. C.

helgolandicus:

[START_REF] Kleppel | Trophic interactions between copepods and microplankton: a question about the role of diatoms[END_REF] C. finmarchicus: Koski, 2007

). However, food particle size does seem to affect selectivity for both Calanus species (e.g. C. helgolandicus

[START_REF] Fileman | Grazing by Calanus helgolandicus and Para-Pseudocalanus spp. on phytoplankton and protozooplankton during the spring bloom in the Celtic Sea[END_REF] C. finmarchicus: Meyer et al. 2002)

while no selectivity is observed when cell sizes are similar

  relation between EPR and the haptophyte Phaeocystis spp. Most

		Deleted: mainly
		Deleted: we can roughly see
		Deleted: but
		Deleted: cousin
	F o r
	P
	e
	e r
	R
	e
	v i e
	w	Deleted: cousin

  Those studies use higher carbon content for females which means that our values are in the lower range. No published specific egg production values of were found for C. helgolandicus. The general conclusion of this study is that when C. helgolandicus and C. finmarchicus co-occur during July and August off Dogger Bank, they are vertically separated and this is best explained by the different temperature preference of the species. Due to the difference in abundance C.

	finmarchicus is a more important species during late summer than C. helgolandicus off Dogger
	Bank.

Table V .

 V Calanus helgolandicus and C. finmarchicus. Average female length (mm ± SE ), spawning

	females, EPR max (eggs female -1 day -1 ) of producing females only with highest individual EPR
	shown in parenthesis, EPR (eggs female -1 day -1 ) and hatching success of eggs (n = total number of
	eggs incubated, na: not available) at different stations on the Dogger Bank in 2001, 2002 and 2005.
	2005 data shows results from after 1 day of incubation. * From Jónasdóttir et al. 2005, +
	measurement from incubation day 2. Significant differences between stations within each year are
	indicated by different lower case letters (Holm Siddak a posteriori all pair wise comparison
	p<0.05). The capital letters describe significant differences (p<0.05) between years, pooling all
	stations (one way ANOVA).

Table VI .

 VI C. helgolandicus and C. finmarchicus. Results from multiple stepwise regression on in situ(2001)(2002)(2003)(2004)(2005) and bioassay egg production rates in 2005 (eggs female -1 d -1 or eggs mm -3 d -1 ) the ), auto-and heterotrophic flagellates, diatoms, auto-and heterotrophic dinoflagellates and ciliates (µgC L -1 ). The stepwise process selects only those variables (labelled "in") that contribute to the best regression. Variables not in the regression are labelled "out". Model statistics show R 2 : coefficient of determination of the multiple regression, F df : the F ratio with df: degrees of freedom, and significance value p of the multiple regression. For each variable in the model, "F-to-remove" is the F statistic for its coefficient within the regression; for each variable not in the model, "F-to-enter" is the F statistic that its coefficient would have if it were the next variable added in the regression. p var : significance of the variable within the regression where * : p<0.05, ** p<0.01.

	food environment , chlorophyll a (µg L -1
		Deleted: :
		Deleted: CV
		Deleted: I
		Deleted: I
		Deleted: V
		Deleted: in
	F o r	Deleted: at Dogger Bank
	P	Deleted: III
	e
	e r
		Deleted: I
	R	Deleted: no of eggs brood -1 Deleted: maximum brood
	e v i e	Deleted: size Deleted: in Deleted: at
	w	Deleted: Table V. C. helgolandicus and C. finmarchicus. Pearsons Product
		moment correlation between clutch size,
		egg production rates, spawning
		frequencies, faecal pellet production and
		hatching. n: number of samples, R 2 :
		correlation coefficient, p value of
		significance: * p<0.05, p<**0.001 ***,
		p <0.0001. ¶
		¶
	22

Table VII .

 VII C. helgolandicus and C. finmarchicus. Population dynamics on the Dogger Bank.

	Population egg production rates (eggs m -2 d -1 ) and secondary production (C m -2 d -1 ) for CH: C.
	helgolandicus and CF: C. finmarchicus and N1-6 produced: Nauplii stages 1-6 produced per m -2

Table III

 III

									Page 34 of 46
	Group	Chl-max				Surface
	2001	St A (35)	St B (33)	St C (26)	St D (29.5)	St A (5)	St B (5)	St C (5)	St D (5)
	Chl-a	2.9	4.0	3.6	2.7	1.2	1.1	1.1	1.0
	Ciliates				4.6
	2002	St 1 (36.5)	St 3 (35)	St 5 (33.5)	St 7 (30.5)	St 1 (5)	St 3 (5)	St 5 (5)	St 7 (5)
	Flagellates	39 ± 5.4	8 ± 7	12	9 ± 2	5 ± 1	7 ± 2	5	14 ± 0
	Diatoms	0.002 ± 0.002	0.005 ± 0.001	0.02	0.0003 ± 0.0004	0 ± 0	0 ± 0	0.1	0.0 ± 0.0
	Autotrophic dinoflagellates	334 ± 65	192 ± 37	21	120 ± 149	5 ± 4	3 ± 1	5	5 ± 1
	Heterotrophic dinoflagellates	32 ± 13	20 ± 1	6	19 ± 17	4.5 ± 5	3 ± 1	3	6 ± 2
	Ciliates	12 ± 11	12 ± 3	6	6 ± 3	1 ± 0.3	2 ± 0.4	5	4 ± 2
	Total	416 ± 46	232 ± 34	45	153 ± 167	16 ± 11	15 ± 4	18	29 ± 2
	Chl-a	4.1 ± 0.7	3.8 ± 0.3	1.4 ± 0.4	2.2 ± 0.8	0.4 ± 0.02	0.5 ± 0.05	0.6 ± 0.59	0.6 ± 0.59
	POC: Chl-a	102	62	41	60	31	40	31	50
	2005	St 1 (40.5)	St 3 (37)	St 5 (37.5)	St 8 (33)	St 1 (5)	St 3 (5)	St 5 (5)	St 8 (5)
	Flagellates	6 ± 3	6.7 ± 2.3	7.3 ± 3.3	5.5 ± 3.5	1.6 ± 0.7	1.8 ± 0.5	1.3 ± 0.3	1.9 ± 0.4
	Diatoms	0.4 ± 0.6	0.07 ± 0.1	0.006 ± 0.01	7.0 ± 5.1	0.2 ± 0.2	0.5 ± 0.4	0.7 ± 0.6	0.2 ± 0.3
	Autotrophic dinoflagellates	147 ± 147	119 ± 55	26 ± 3.9	12 ± 11	3.1 ± 1.2	4.1 ± 1.8	3.5 ± 1.4	6.1 ± 4.0
	Heterotrophic dinoflagellates	10 ± 8	4.7 ± 2.0	5.8 ± 3.6	4.4 ± 3.9	1.3 ± 0.4	1.6 ± 0.9	3.2 ± 1.9	2.4 ± 2.0
	Ciliates	5 ± 1	3.0 ± 3.5	2.1 ± 1.1	1.9 ± 1.0	3.2 ± 1.8	1.2 ± 0.1	4.1 ± 1.2	3.0 ± 1.7
	Total	168 ± 154	133 ± 53	41 ± 4.1	31 ± 15	11 ± 5.1	12 ± 5.2	14 ± 6.3	16 ± 9.2
	Chl-a	2.3 ± 0.8	1.6 ± 0.5	1.9 ± 0.8	1.4 ± 0.5	0.4 ± 0.1	0.4 ± 0.1	0.4 ± 0.1	0.5 ± 0.1
	POC: Chl-a	74	82	21	23	28	29	35	35

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com/jplankt Journal of Plankton Research F o r P e e r R e v i e w 27Table IV .

 IV

	Year:	2001				2002								2005
	Station:	A	B	C	D	1	3	5	7	1	3	5	7	1	3	5	8	1
		Chl max				Chl max				Surface				Chl max				Surface
	Depth (m)	30	27	34	35	38	37	35	31	5	8	12	11	37	34	35	27	5
	14:0	2.58	5.78	12.31 7.92	19.70	9.89	5.05	5.35	2.60	2.69	4.93	3.85	23.93	17.28	11.01	19.08	8.93
	16:0	7.85	13.18 21.32 14.65 28.27	19.38	16.19	14.80	9.52	6.52	12.53	9.74	25.49	15.98	8.57	16.92	11.32
	18:0	3.18	3.79	5.00	3.44	8.32	6.08	6.31	5.97	10.52	4.28	6.67	6.28	10.30	3.21	2.46	6.24	4.13
	SAFA	14.22 22.86 38.70 26.06 56.62	35.60	27.80	26.33	23.00	13.58	24.40	20.11	62.19	37.08	22.45	43.11	25.07
	16:1n7	1.33	2.37	4.28	5.82	0.10	0.04	0.07	0.07	0.03	0.01	0.08	0.07	6.99	8.17	3.47	8.38	4.59
	18.1n9	2.05	2.13	4.29	2.81						0.01	0.01	0.01	2.29	1.05	0.51	1.11	1.09
	20:1n9	0.04	0.03	0.03	0.04	0.00			0.01					2.12	0.34	0.30		0.89
	MUFA	4.50	5.72	11.49 10.49 0.14	0.04	0.07	0.09	0.04	0.04	0.08	0.08	18.36	11.61	5.41	13.16	9.82
	16:2n4	0.05	0.79	1.07	0.67	0.12	0.07	0.07	0.07	0.08	0.02	0.08	0.05
	16:4nx	0.35	0.82	0.56	1.50				0.01				0.01	1.94	0.21	0.20	0.36	0.26
	18:2n6	0.79	1.15	2.95	1.10									1.97	0.68	0.35	0.63	0.34
	18:2n4	0.33	0.01			0.09	0.01	0.06	0.03	0.07	0.01	0.10
	18:3n6	0.01				0.51		0.15	0.13	0.22	0.13	0.10	0.07
	18:3n3	0.73	1.03	2.79	1.01	0.11	0.02	0.03	0.05	0.03	0.03	0.02	0.05	1.13	1.03	0.62	0.85	0.35
	18:4n3	0.85	2.05	3.52	1.64				0.01					2.15	2.98	1.46	2.50	0.95
	18.5n3	0.28	4.06	7.78	2.75						0.04			3.87	6.18	2.26	2.94	1.36
	20:2n6	0.08	0.02	0.01	0.17						0.01			0.01	0.17		0.10	0.11
	20:3n6	0.40			0.02	0.24	0.01	0.14	0.09	0.08	0.04	0.05	0.06	0.01		0.23		0.05
	20:3n3	0.05	0.03			0.22	0.10	0.43	0.29	0.21	0.06	0.18	0.13
	20:5n3	0.97	1.95	2.71	4.64	0.00	0.00	0.01	0.01	0.04	0.01			0.48	0.74	0.23	0.32	0.19
	22:6n3	1.90	3.15	5.79	1.91	0.03	0.03	0.01	0.03					4.20	8.70	2.17	2.77	1.71
	PUFA	7.40	15.11 27.25 16.72 1.55	0.39	1.01	0.84	0.77	0.39	0.63	0.41	15.96	20.68	7.52	10.63	5.39

Total 26.12 43.69 77.44 53.27 58.30 36.04 28.88 27.27 23.81 14.01 25.11 20.60 96.51 69.37 35.37 66.89 40.27

	Table VII. Table V Table VI. Page 10: [1] Deleted	Sigrun	Deleted: Table V. ¶ 5/4/2010 5:38:00 PM	... [3]	Deleted: III Deleted: I
	2001: Station A C. helgolandicus eggs female -1 d -1 YR Station R 2 = 0.87	Length mm ± 1SE C. helgolandicus C. finmarchicus C. helgolandicus C. finmarchicus C. helgolandicus C. finmarchicus C. helgolandicus C. finmarchicus spawning females / total females EPR max ; eggs female -1 d -1 (highest individual EPR) EPR eggs female -1 d -1 A A A A A A A A a 2.5 ± 0.03 a,b 2.4 ± 0.09 6/10 2/4 a 18 ± 4 (31) a 25 ± 9 (33) a 13 ± 4 a 12 ± 8 variable F-to-remove F-to-enter p var CH chl a out -0.3 Population EPR 0.605 heterotrophic dinoflagellates in 14.4 -0.004* egg m -2 d -1	Hatching % (n) A a 98 (217)*	Deleted: 8 Deleted: 8 Deleted: No of eggs brood Deleted: -1 Deleted: max Deleted: eggs
	n3/n6 22/20 Station B F 3 = 17.0 Station C p= 0.01 Station D 2002 Station 1 Station 3 Station 5 Station 7 2005 day 1: Station 1 Station 3 Station 5 Station 8 C. finmarchicus eggs mm -3 d -1 R 2 = 0.65 F 2 = 4.7 p= 0.07 2005 (day 4) C. finmarchicus eggs female -1 d -1 R 2 = 0.87 F 3 = 17.0 p= 0.01	2.49 1.96 a 2.4 ± 0.02 5.39 1.62 autotrophic dinoflagellates 3.87 7.19 0.70 2.13 0.41 -a,b 2.4 ± 0.06 11/15 a 2.5 ± 0.02 a 2.5 ± 0.04 2/2 ciliates a 2.4 ± 0.08 b 2.3 ± 0.03 8/9 A A A a,b 2.5 ± 0.01 a 2.4 ± 0.12 37/51 a 2.5 ± 0.01 a 2.4 ± 0.03 35/43 b 2.4 ± 0.02 a 2.4 ± 0.02 39/44 a,b 2.5 ± 0.01 a 2.4 ± 0.02 59/65 B B A a 2.4± 0.10 a 2.6 ± 0.03 1/3 a 2.6 ± 0.02 a 2.7 ± 0.03 8/9 a 2.6 ± 0.05 a 2.6 ± 0.03 12/13 a 2.6 ± 0.04 a 2.6 ± 0.03 9/11 F o r P 20.92 -out in flagellates in diatoms out chl a out heterotrophic dinoflagellates out autotrophic dinoflagellates in ciliates in flagellates out diatoms out heterotrophic nanoflagellates out autotrophic nanoflagellates in heterotrophic dinoflagellates out autotrophic dinoflagellates in ciliates out diatoms in F o r P F o r P F o r P e e r R e v i e w 1.95 2.00 1.08 0.81 1.42 1.38 3.56 15.65 0.67 2.15 0 0.00 --8.72 11.75 3/9 a 24 ± 2 (36) a 24 ± 8 (39) a 17 ± 3 a 8 ± 4 -0.01 0.919 15/22 a 24 ± 0 (24) a 45 ± 4 (80) a 23 ± 0 a 29 ± 5 6.4 -0.065* 8/13 a 20 ± 4 (35) a 37 ± 8 (69) a 18 ± 4 a 23 ± 7 A B A B A 3/3 a 27 ± 2 (61) a 23 ± 10 (35) a 20 ± 2 a 23 ± 10 5.50 9.63 25/31 a 32 ± 2 (62) a 40 ± 4 (88) a,b 26 ± 3 a 32 ± 4 21/25 a 31 ± 3 (79) a 27 ± 3 (55) a,b 28 ± 3 a 16 ± 3 4/8 a 32 ± 2 (75) a 25 ± 12 (54) b 29 ± 2 a 13 ± 7 A A A AB B 15/29 a 17 (31) a,c 46 ± 5 (73) a 8 ± 8 a 33 ± 7 21/29 a 22 ± 3 (36) c 47 ± 5 (94) a 24 ± 5 a 43 ± 7 19/25 a 20 ± 3 (37) a,b 32 ± 5 (67) a 23 ± 4 a 32 ± 6 19/22 a 21 ± 4 (40) b 30 ± 3 (56) a 19 ± 5 a 27 ± 4 37.6 -0.019* -2.1 0.217 -0.5 0.52 -1.8 0.23 7.7 -0.04* 5.9 -0.06 -0.7 0.45 -1.0 0.37 -1.0 0.382 50.1 -0.002** -3.7 0.128 25.3 -0.007* -0.5 0.527 9.8 -0.035* e e e	5.43 8.54 a 96 (222)* 5.53 9.03 a 98 (196)* a 99 (155)* B a 93 ± 4 (1295) b 85 ± 9 (1537) a,b 92 ± 3 (1406) a 93 ± 6 (1565) na na na na
			e r e r e r
			R R R
			e e e	28
			v i e v i e v i e
				w w w
		29 30

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Acknowledgements

We like to thank the captain and the crew on the research vessel DANA for smooth cruise operations, L. Poulsen (2002), A.W. Visser (2002-2005), N.H. Trung (2002) and K. Arendt (2001) for help with incubations and sampling during the cruises. The study was financed by LIFECO EU Q5RS-2000-30183 (2001), CONWOY No 2052-01-0034 (2002and 2003) and No 21-03-0487 to SHJ (2005) from the Danish Research Agency.