Search

Sea ice algae can constitute an important carbon source for high-Antarctic euphausiids during winter. To quantify the importance of this 'sympagic carbon' during summer, the three most abundant Antarctic euphausiids, Euphausia superba, E. crystallorophias, and Thysanoessa macrura, collected off the Filchner Ice Shelf, were analyzed regarding their fatty acid (FA) and stable isotope compositions. Fingerprints of diatom- and dinoflagellate-associated FAs in the euphausiids indicated a mixed carbon source composition for all three species. Bulk and FA-specific carbon stable isotope compositions ([delta].sup.13C) were used to quantify the contribution of sympagic carbon versus phytoplankton-produced carbon to the euphausiids' carbon budget, suggesting a lower proportional contribution of sympagic carbon in E. superba (5-18%) compared to E. crystallorophias (16-36%) and T. macrura (15-36%). The latter two species probably received sympagic carbon through heterotrophic prey, a hitherto overlooked source of sympagic carbon for pelagic species. Euphausiids collected close to the surface indicated a higher importance of sympagic carbon to their carbon budget compared to individuals caught at greater depths. Our results imply that, in the southern Weddell Sea, ice algae play a significant, but possibly not critical role as a carbon source for the three euphausiids during summer. Their ability to utilize carbon of different origins implies a certain resilience to environmental change during summer. The winter period, however, remains the critical bottle neck of survival when Antarctic sea ice declines, because during this season of minimal pelagic productivity, ice algae standing stocks constitute the only dependable carbon source., Author(s): Doreen Kohlbach [sup.1] [sup.2] [sup.3] , Benjamin Allen Lange [sup.1] [sup.2] [sup.3] , Martin Graeve [sup.1] , Martina Vortkamp [sup.1] , Hauke Flores [sup.1] [sup.2] Author Affiliations: (Aff1) 0000 [...]

Maternal investment (MI), the energy allocated by mothers to offspring, has important effects on the life-history traits of marine organisms. Variation in such traits shows strong correlation with latitude for several marine taxa (Thorson's rule). Large-scale latitudinal variation in MI within a single species suggests population genetic divergence, while temporal changes in MI, rather, reflect plasticity. At higher latitudes (i.e., colder waters), traits associated with MI (brood weight, fecundity, egg volume, and energy content) increase. To identify phenotypic plasticity along a latitudinal gradient in MI traits (brood weight, egg volume, density number, and egg lipid composition), five populations of the kelp crab Taliepus dentatus along the coast of Chile (30°S-42°S) were investigated during the summer (December-February) and winter months (June-August) of 2015-2016. Despite this wide latitudinal range, the sea surface temperature (SST) difference between the northernmost and the southernmost sites was only approximately 2.0 °C in winter and 5.5 °C in summer. In summer, when latitudinal variation in SST was highest, brood weight, egg density, fecundity, and egg lipids increased with latitude, while egg volume decreased. No trends in MI were observed in winter when the SST gradient was almost non-existent. These results suggest that the relationship between MI and latitude is shaped by temperature rather than being site-specific. The seasonality of latitudinal MI traits also suggests a trade-off between the costs of female maintenance and/or brooding behaviours and MI. When investigating latitudinal and temporal variation in marine brooder MI, the effect of temperature on life-history traits and the associated costs of female brooding should be quantified., Author(s): Simone Baldanzi [sup.1] , Daniela Storch [sup.2] , Sergio A. Navarrete [sup.1] , Martin Graeve [sup.3] , Miriam Fernández [sup.1] Author Affiliations: (1) Estación Costera de Investigaciones Marinas and [...]

During various seasons from May 2001 until July/August 2003, the lipid dynamics of the pteropod Clione limacina from Kongsfjorden, Svalbard, were investigated with respect to ontogenetic development and life-cycle. Polytrochous larvae, which were dominant in spring (April, May), composed the lipid-richest specimens of the population, with total lipid of about 50% of dry mass (%DM). Major lipid classes were triacylglycerols (TAG) and 1-O-alkyldiacylglycerol ethers (DAGE), accounting on average for 53.1 and 21.9% of total lipid, respectively. Until summer, larvae grew to adults by utilising their storage lipids. In July/August, lipids were depleted to about 10%DM due to maturation and reproduction. Almost all animals in autumn (September) were mature and able to replenish their lipid deposits by accumulating DAGE (26.7%) and TAG (39.6%). This is probably the prerequisite for successful overwintering. Principal component analysis (PCA), based on the fatty acid compositions, revealed ontogenetic differences between polytrochous larvae, and small and full-grown adults. Higher proportions of 18:4(n-3) and 14:0 were found in polytrochous larvae and smaller adults during spring. Both fatty acids were highly significantly correlated with the proportions of TAG, which were used for growth and development because they are presumably easier to metabolise. PCA also divided C. limacina specimens into DAGE-rich and DAGE-poor. We suggest that DAGE are a long-term energy store and hypothesise that they are necessary during periods of food scarcity, but may also serve as an energy source for reproduction. The fatty acids 17:1(n-8), 15:0, 16:1(n-7) and 18:1(n-7) were significantly correlated with the proportion of DAGE but not with TAG. These fatty acids, which do not originate from their only prey, Limacina helicina, are synthesised de novo. Their abundance reflects an efficient lipid production by C. limacina. Based on the results of lipid biosynthesis and accumulation in combination with the population structure, we suggest that C. limacina has at least a 2-year life-cycle in Svalbard waters., Introduction The pteropod Clione limacina is the most abundant gymnosome of the pelagic food web in temperate and polar waters. It is recognised as an important food for baleen whales [...]

The sea butterfly Limacina helicina was collected from May to September 2001 in Kongsfjorden, Spitsbergen, to investigate population structure and body and lipid composition with regard to life cycle and reproductive strategy. Veligers and juveniles were only found in late autumn and spring, whereas females occurred from July to September. The size of the females increased until mid-August and decreased in September. Dry and lipid mass were closely related to size; dry mass increased exponentially and lipids linearly with size. The lipid content was highest in veligers (31.5% of dry mass) and juveniles (23.6%) but low in females (< 10%). Phospholipids were the dominating lipid class followed by triacylglycerols. Females, veligers, and egg ribbons, all from September, were richest in phospholipids. Juveniles contained the highest amounts of triacylglycerols, whereas females had low levels in July and the beginning of August. In mid-August, levels of triacylglycerols were variable and higher. This suggests that females were in their main spawning period and the high variability in triacylglycerols points to different stages within the spawning cycle. Enhanced amounts of free fatty acids in females from July may be related to gonad development. The 16:1(n-7) fatty acid was more dominant in spring whereas 18:4(n-3) increased in summer and autumn, which reflects a change in diet from diatom-dominated food items in spring to dinoflagellates in summer/autumn. Small amounts of long-chain monounsaturated fatty acids suggest ingestion of copepods, and the fatty acid composition of veligers feeding on particulate matter. L. helicina has a one-year life cycle with peak spawning in August and over-winters as veligers that may grow to juveniles during the winter period. They metamorphose into juveniles during spring, develop to males in early summer, and mature into females in July and August., Introduction The sea butterfly Limacina helicina (Phipps, 1774) is the only thecosomatous pteropod found in the Arctic (Fig. 1). It has a bipolar distribution and can occur in high densities [...]