Species-specific differences in lipid composition and omnivory indices in Arctic copepods collected in deep water during autumn (North Water Polynya) (original) (raw)
Related papers
Journal of Plankton Research, 2012
Tisbe furcata, Nitokra lacustris, Calanus finmarchicus and Calanus glacialis were reared for several months in the laboratory prior to feeding selected diets. Copepods were fed Isochrysis galbana, Tetraselmis sp., Dunaliella tertiolecta, Thalassiosira pseudonana, Rhodomonas sp., Rhodomonas lens and Oxyrrhis marina individually or in combination. Oxyrrhis marina itself was fed up to four of the algae species. The lipid class and fatty acid composition of the copepods was determined and compared with each other, the diets and with wild C. finmarchicus, C. glacialis and Pseudocalanus sp. Cultured O. marina, T. furcata and N. lacustris had greater proportions of essential 22:6v3 or 20:5v3 acids than in their diets suggesting nutritional enrichment through synthesis or preferential retention. Lower proportions of 18:3v3 than in their diets fed individually or in combination suggests desaturation and elongation of 18:3v3. Stable isotope analysis of the heterotroph samples and their dietary sources revealed similar values for 18:3v3 in each dietary pair and different ones for 22:6v3 and 20:5v3 supporting derivation from precursors rather than trophic magnification. Principal components analysis of copepods and their diets showed cultured Calanus spp. to have the most similar fatty acid composition to their diet indicating little modification or sequestration of polyunsaturated fatty acids.
Journal of Experimental Marine Biology and Ecology, 1994
To verify the potential of fatty acids as trophic markers, feeding experiments were carried out with the dominant herbivorous copepods Calanusfimarchicus, C. hyperboreus and C. glacialis from the Greenland Sea during two Arctic expeditions in June/July 1991. Depending on the fatty acid composition of these copepods, the diatom Thalassiosira antarctica or the dinoflagellate Amphidinium carterae were offered as food to induce deviating fatty acid compositions. Since the copepodite Stages CV of C. jnmarchicus had very low amounts of the 16: l(n-7) fatty acid but high amounts of 18:4(n-3), the specimens were fed on 7'. antarctica rich in 16:l(n-7) over a period of up to 42 days. At the end of the feeding experiment the portion of the 16: l(n-7) fatty acid had strongly increased by 11%) while the 18:4(n-3) fatty acid was almost depleted. In contrast, high amounts of the 16:l(n-7) fatty acid in C. hyperboreus (CV) suggested feeding on diatoms, therefore its diet was changed to A. carterae dominated by high amounts of the 18:4(n-3) fatty acid. After 47 days the portion of 18:4(n-3) increased by 8%, whereas 16:l(n-7) decreased by 3 %. In female C. glacialis the changes in the fatty acid composition after feeding with A. carterae were less pronounced as compared to the other species, due to a severe lipid loss during the experiment. The feeding experiments document the incorporation and turnover of dietary fatty acids under controlled laboratory conditions and provide clear evidence for the potential of specific fatty acids as trophic marker lipids.
Deep Sea Research Part I: Oceanographic Research Papers, 2004
To deduce spatial patterns in copepod lipid composition and feeding strategy (i.e., degree of omnivory) in the North Water Polynya (Baffin Bay), three dominant species were sampled extensively over a broad geographical area ($75-781N; 77-691W). Calanus hyperboreus CV, C. glacialis CV and Metridia longa females were collected in shallow and deep strata at 16 stations during autumn 1999 (August-October). Principal components analysis (PCA) revealed that all species fed omnivorously in the southeastern (SE) region of the polynya. Here, copepods generally had elevated levels of carnivorous (e.g., 18 : 1ðn À 9Þ), dinoflagellate (e.g., 18 : 4ðn À 3Þ; 22 : 6ðn À 3Þ) and bacterial fatty acid markers (e.g., odd-numbered and/or branched; 18:1(n À 7)). Copepods in the SE contained low proportions of diatom (e.g., 16 : 4ðn À 1Þ; 20 : 5ðn À 3Þ) and phytoplankton (e.g., polyunsaturated fatty acids) markers, relative to animals from northwest stations. Values of the omnivory index 'UC' (i.e., unsaturation coefficient) were also low in SE copepods, which implied reduced phytoplankton ingestion. Spatial patterns in seston fatty acid composition resembled the dietary signatures in that dinoflagellate and bacterial indices were highest in SE waters. Estimates of primary production, particulate organic carbon, carbon to chlorophyll ratios, and abundances of diatoms, dinoflagellates and bacteria, provided further evidence of the importance of the microbial loop at SE stations. Comparable spatial patterns in feeding strategy were observed in both sampling layers, indicating that copepods from the entire water column were feeding on a similar food source. Several interesting species-specific trends also emerged from the PCA. In general, C. hyperboreus fed the most herbivorously, followed by C. glacialis and M. longa. C. glacialis showed a stronger connection to the microbial food web than the other two species, and M. longa fed herbivorously throughout much of the polynya. These latter two findings contradict the conventional wisdom and highlight the need for future work. In particular, the microbial community should be emphasized and characterized in subsequent studies on the feeding ecology of C. glacialis. Although the three species investigated responded quite differently to available prey by adopting specialized feeding strategies, copepod omnivory in the polynya was generally inversely related to the availability of diatoms.
Polar Biology, 2003
The fatty acid and alcohol compositions of the Antarctic copepods Oithona similis, Oncaea curvata, Oncaea antarctica and the Arctic Oncaea borealis were determined to provide the first data on their lipid biochemistry and to expand the present knowledge on their feeding modes and life-cycle strategies. All these tiny species contained high amounts of wax esters (on average 51.4-86.3% of total lipid), except females of Oithona similis (15.2%). The fatty-acid composition was clearly dominated by 18:1(n-9), especially in the wax-ester-rich Oncaea curvata (79.7% of total fatty acids). In all species, 16:0 and the polyunsaturated fatty acids 20:5(n-3) and 22:6(n-3), which are structural components of all membranes, occurred in significant proportions. The dominant fatty alcohols were 14:0 and 16:0. In Oncaea antarctica and Oncaea borealis, the 20:1(n-9) and 22:1 (n-11) alcohols and, to a lesser extent, the corresponding fatty acids were also found in high proportions. This indicates carnivorous feeding, although de novo biosynthesis cannot be excluded. The variable composition might be due to a wider range of food items and parasitic feeding. Typical trophic marker fatty acids for phytoplankton ingestion occurred only in small amounts, which suggests that the species were feeding on particles such as detritus or aggregates and not on living phytoplankton. From the compositional data of fatty acids and alcohols, it can be concluded that feeding behaviour of all species is omnivorous and/or carnivorous.
Frontiers in Marine Science, 2022
Consumer regulation of lipid composition during assimilation of dietary items is related to their ecology, habitat, and life cycle, and may lead to extra energetic costs associated with the conversion of dietary material into the fatty acids (FAs) necessary to meet metabolic requirements. For example, lipid-rich copepods from temperate and polar latitudes must convert assimilated dietary FAs into wax esters, an efficient type of energy storage which enables them to cope with seasonal food shortages and buoyancy requirements. Lipidpoor copepods, however, tend to not be as constrained by food availability as their lipidrich counterparts and, thus, should have no need for modifying dietary FAs. Our objective was to test the assumption that Temora longicornis, a proxy species for lipid-poor copepods, does not regulate its lipid composition. Isotopically-enriched (13 C) diatoms were fed to copepods during a 5-day laboratory experiment. Compound-specific stable isotope analysis of algae and copepod samples was performed in order to calculate dietary FA assimilation, turnover, and assimilation efficiency into copepod FAs. Approximately 65% of the total dietary lipid carbon (C) assimilated (913 ± 68 ng C ind-1 at the end of the experiment) was recorded as polyunsaturated FAs, with 20 and 15% recorded as saturated and monounsaturated FAs, respectively. As expected, T. longicornis assimilated dietary FAs in an unregulated, non-homeostatic manner, as evidenced by the changes in its FA profile, which became more similar to that of their diet. Copepods assimilated 11% of the total dietary C (or 40% of the dietary lipid C) ingested in the first two days of the experiment. In addition, 34% of their somatic growth (in C) after two days was due to the assimilation of dietary C in FAs. Global warming may lead to increased proportions of smaller copepods in the oceans, and to a lower availability of algae-produced essential FAs. In order for changes in the energy transfer in marine food webs to be better understood, it is important that future investigations assess a broader range of diets as well as lipid-poor zooplankton from oceanographic areas throughout the world's oceans.
Lipid turnover reflects life-cycle strategies of small-sized Arctic copepods
Journal of Plankton Research
This study aimed at understanding how life-cycle strategies of the primarily herbivorous Pseudocalanus minutus and the omnivorous Oithona similis are reflected by their lipid carbon turnover capacities. The copepods were collected in Billefjorden, Svalbard, and fed with 13 C labeled flagellates and diatoms during 3 weeks. Fatty acid (FA) and fatty alcohol compositions were determined by gas chromatography, 13 C incorporation was monitored using isotope ratio mass spectrometry. Maximum lipid turnover occurred in P. minutus, which exchanged 54.4% of total lipid, whereas 9.4% were exchanged in O. similis. In P. minutus, the diatom markers 16:1(n-7), 16:2(n-4) and 16:3(n-4) were almost completely renewed from the diet within 21 days, while 15% of the flagellate markers 18:2(n-6), 18:3(n-3) and 18:4 (n-3) were exchanged. In O. similis, 15% of both flagellate and diatom markers were renewed. P. minutus exhibited typical physiological adaptations of herbivorous copepod species, with a very high lipid turnover rate and the ability to integrate FAs more rapidly from diatoms than from flagellates. O. similis depended much less on lipid reserves and had a lower lipid turnover rate, but was able to ingest and/or assimilate lipids with the same intensity from various food sources, to sustain shorter periods of food shortage.
Freshwater Biology, 2011
1. Analyses of zooplankton fatty acid (FA) composition in laboratory experiments and samples collected from lakes in New Zealand spanning a wide gradient of productivity were used to assess the extent to which FAs might infer their diet. We used the cladocerans, Daphnia and Ceriodaphnia, and the calanoid copepod, Boeckella, as test organisms, and monocultures of cryptophytes, chlorophytes and cyanobacteria as food. Based on reproductive success, cryptophytes were the highest food quality, chlorophytes were intermediate and cyanobacteria the poorest. 2. Several FA groups were highly correlated between zooplankton and their diets. They were monounsaturated fatty acids (MUFAs), and x3 and x6 polyunsaturated fatty acids (PUFAs) for cladocerans, and saturated fatty acids (SAFAs) and x3 PUFAs for copepods. Several FAs varied significantly less in the zooplankton than in their monoculture diets, e.g. MUFAs in Daphnia, and x3 and x6 PUFAs in Ceriodaphnia, despite clear dietary dependency for these FAs. 3. Zooplankton collected from lakes in New Zealand had more eicosapentaenoic acid (EPA) (Daphnia), more highly unsaturated x3 and x6 FAs (C 20 , C 22 ; Daphnia, Ceriodaphnia, Boeckella) and less x3 C 18 PUFAs (Daphnia, Ceriodaphnia, Boeckella) and x6 C 18 PUFAs (Daphnia, Ceriodaphnia) than measured in the same species reared on phytoplankton in the laboratory. 4. Analyses of FA composition of seston and freshwater zooplankton globally showed that, in general, zooplankton had a significantly higher proportion of arachidonic acid and EPA than seston, and copepods also had a higher percentage of docosahexaenoic acid than seston. 5. These results suggest that zooplankton selectively incorporate the most physiologically important FAs. This could be a consequence of preferential assimilation, selective feeding on more nutritious cells or locating and feeding within higher food quality food patches.
Deep Sea Research Part I: Oceanographic Research Papers, 2014
15 16 17 ABSTRACT 18 Members of the copepod family Eucalanidae are widely distributed throughout the 19 world's oceans and have been noted for their accumulation of storage lipids in high-and low-20 latitude environments. However, little is known about the lipid composition of eucalanoid 21 copepods in low-latitude environments. The purpose of this study was to examine fatty acid and 22 alcohol profiles in the storage lipids (wax esters and triacylglycerols) of Eucalanus inermis, 23 Rhincalanus rostrifrons, R. nasutus, Pareucalanus attenuatus, and Subeucalanus subtenuis, 24 collected primarily in the eastern tropical north Pacific near the Tehuantepec Bowl and Costa 25 Rica Dome regions, noted for its oxygen minimum zone, during fall 2007 and winter 2008/2009. 26 Adult copepods and particulate material were collected in the upper 50 m and from 200-300 m in 27 the upper oxycline. Lipid profiles of particulate matter were generated to help ascertain 28 information on ecological strategies of these species and on differential accumulation of dietary 29 and modified fatty acids in the wax ester and triacylglycerol storage lipid components of these 30 copepods in relation to their vertical distributions around the oxygen minimum zone. Additional 31 data on phospholipid fatty acid and sterol/fatty alcohol fractions were also generated to obtain a 32 Accepted Manuscript. © 2015, CJ Cass. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ 2 comprehensive lipid data set for each sample. Rhincalanus spp. accumulated relatively large 33 amounts of storage lipids (31-80% of dry mass (DM)), while E. inermis had moderate amounts 34 (2-9% DM), and P. attenuatus and S. subtenuis had low quantities of storage lipid (0-1% DM). 35 E. inermis and S. subtenuis primarily accumulated triacylglycerols (>90% of storage lipids), 36
Helgoläander Meeresuntersuchungen , 2017
The lipid reserves and occurrence of the cold-stenothermic, omnivorous copepod Limnocalanus macrurus were studied in the Bothnian Sea (northern Baltic Sea) during spring and summer 2013-2014 with a special emphasis on the fatty acid composition of adults and their potential food. The individual total wax ester (WE) content, determined from the size of oil sacs in the prosoma, ranged on average from 1.3 to 2.6 µg, and showed a decreasing trend towards September. Lipids were dominated by fatty acids 16:0, 18:1(n-9), 18:2(n-6), 20:5(n-3) and 22:6(n-6), forming 56-61% of total fatty acids in June-September. Decreasing abundance of adults and reduction of the lipid storage implied that during summer adults suffered from starvation and, as a result, became eliminated from the population. The lipid content and dietary fatty acid markers suggested that in May, adult L. macrurus utilized the phytoplankton bloom, consisting mainly of diatoms and dinoflagellates, but later, during July-September, consumed either algae or heterotrophic organisms sinking from upper water layers or crustaceans inhabiting the same deeper water layers as L. macrurus. In the face of the climate change, the rising temperatures may force L. macrurus permanently to deeper water levels. If also the food resources are limited, we conclude that the summer season may act as a bottleneck limiting the propagation of L. macrurus and having implications further along the food web.