A summer-winter comparison of zooplankton in the oceanic area Around South Georgia

Summary Zooplankton was sampled with RMT (1+8) gear on a synoptic grid of stations centred on South Georgia during the austral summer (November/December 1981) and winter (July/August 1983). This initial paper compares zooplankton biomass, vertical distribution and species composition from RMT 1 catches in the oceanic portion of the grid (water depth greater than 2000 m) during the two surveys. In the winter survey, mean zooplankton biomass within the top 1000 m of the water column was 68% of its summer level. This drop was largely due to a decrease in abundance of krill (Euphausia superba), although biomass of copepods and remaining zooplankton also decreased. Copepods averaged 48% of total biomass in summer and winter, but outnumbered all other taxa put together by a factor of 10. Antarctic epipelagic species predominated around the island in the summer survey but tended to be replaced by sub-Antarctic or cosmopolitan species during the winter survey. The majority of zooplankton also showed a downwards seasonal migration out of the top 250 m layer in winter. However, several epipelagic species, including E. superba, did not migrate, and these tended to have the largest summer-winter differences in overall abundance. These trends were attributed to variation in the position of the Polar Front, which lay north of the island during the summer survey but lay across the survey area in winter, resulting in a greater influence of sub-Antarctic water and the displacement of Antarctic species.     

Distribution of six major copepod species around South Georgia during an austral winter

Summary A net sampling survey was conducted around the island of South Georgia during July/August 1983. This study compares the age structure and vertical and horizontal distributions of the dominant copepods Calanoides acutus, Calanus simillimus, C. propinquus, Rhincalanus gigas, Metridia lucens and M. gerlachei. The chief physical and biological factors affecting the distributions of these species are assessed and the results are compared with those from a similar survey around the island carried out in early summer (1981/1982). The survey grid lay within the Polar Front during the winter survey, and horizontal changes in copepod abundance corresponded well to the temperature gradient across the front. This pattern was interrupted by the South Georgia shelf where the seasonal migrants (Calanoides acutus, Rhincalanus gigas and Calanus simillimus) occurred in high abundance. The concentration of these migrants over the shelf relative to the oceanic surface layer was attributed to the shelf having prevented their seasonal migration. Within the oceanic area the copepods occupied differing depths, with Calanoides acutus and Metridia gerlachei living deeper than Calanus simillimus, C. propinquus and M. lucens. The populations also tended to live deeper in the warmer (NW) portion of the oceanic survey area. In contrast to the summer survey the age structure of each species showed little variation throughout the survey area. This was attributed mainly to the decreased rates of copepod growth and metabolism in winter.     

Microphytoplankton assemblages in the waters surrounding South Georgia, Antarctica during austral summer 1994

The composition and distribution of microphytoplankton assemblages in the vicinity of South Georgia were examined during a krill survey conducted during voyage 119 the RV Africana in austral summer (January/February) 1994. Microphytoplankton distribution was studied at 83 stations along a zig-zag transect in the waters surrounding South Georgia. Oceanographic and zooplankton data suggest that conditions were anomalous during the investigation, in that sub-Antarctic surface waters had probably been advected southwards and were present around the island. The two most widely distributed species were Corethron criophilum and Eucampia antarctica, which were recorded at all stations sampled. Also well-represented amongst the microphytoplankton assemblages were temperate, neritic species such as Chaetoceros atlanticus, Proboscia alata and Odontella weissflogii. This can probably be related to the intrusion of sub-Antarctic surface waters unusually far south. Cluster and ordination analysis identified three distinct groupings of stations in the waters surrounding the islands. These were found to the east, west and north of the islands. The diatom groupings identified during this investigation broadly correspond to three water masses previously described in the vicinity of South Georgia. Despite the anomalous hydrographical conditions that existed during the investigation, the differences in phytoplankton were negligible when compared to normal years. Small mesoscale features are, however, important in imposing biogeographic patterns on microphytoplankton. Received: 21 February 1996 / Accepted: 3 November 1996     

The terrestrial Protozoan fauna of South Georgia

Summary 75 taxa of Protozoa (18 flagellates, 9 naked rhizopods, 20 testate rhizopods and 28 ciliates) were found in 14 samples of mineral materials, peats, soils and guano collected from the sub-Antarctic island of South Georgia. The results confirm the existence of distinct natural communities of protozoan species related to the different classes of habitat in the sub-Antarctic and maritime Antarctic, but suggest that species characteristic of the maritime Antarctic also occur in the sub-Antarctic and species characteristic of bryophyte peats also occur in soils with angiosperm vegetation. The diversity of the fauna of different habitats can be related to degree of soil development and successional stage of associated vegetation. Comparison of the data on the testate rhizopod fauna of South Georgia with those from other sub-Antarctic locations shows a clear trend of faunal pauperization with latitude.     

Recent range expansions in non-native predatory beetles on sub-Antarctic South Georgia

The human-assisted establishment of two non-native predatory carabid beetles (Merizodus soledadinus (Guerin-Ménéville), Trechisibus antarcticus (Dejean)) on the sub-Antarctic island of South Georgia occurred 30–50 years ago, but the distribution of these species has never been the subject of regular monitoring, and was last assessed in the mid-1990s. Based on opportunistic collection records and directed field survey activities on South Georgia over four summer seasons between 2002/3 and 2008/9, we describe recent and important range expansions in both species on the island. The new distributional ranges of both species are highly suggestive of a continuing inadvertent human role in transferring them across the obstructions presented by tidewater glaciers or higher-altitude mountain passes. Both species now have the potential to spread unchecked by any other geographical obstructions across a large section of the north-east coast of the island and are likely to have considerable negative impacts on the elements of the native (including endemic) terrestrial invertebrate fauna.     

The lichen genus Stereocaulon in Antarctica and South Georgia

Summary Six species of Stereocaulon and one unnamed taxon (close to S. glabrum) are reported from South Georgia, the maritime Antarctic islands and Antarctic Peninsula. S. caespitosum is new to the western sub-Antarctic. Variations in morphology and secondary chemistry are provided, and the ecology and geographical distribution in the sub-Antarctic and Antarctic biomes are given for each taxon.     

Plankton community structure in the physical environment surrounding the Prince Edward Islands (Southern Ocean)

The results are presented of a macroscale physical and biological oceanographic survey conducted during the second Marion Island Offshore Study in the upstream and downstream regions of the Prince Edward Islands in the austral autumn (April/May) 1997. Upstream of the islands, the Sub-Antarctic Front appeared to combine with the Antarctic Polar Front to form an intensive frontal feature. Closer to the islands, the fronts appeared to separate. Influenced by the shallow topography of the southwest Indian ridge, the Sub-Antarctic Front was steered northwards around the islands while the Antarctic polar front appeared to meander eastwards, where it was again encountered in the southeastern corner of the survey grid. Downstream of the islands, an intensive cold-core eddy within the Polar Frontal Zone was observed. Its exact genesis is unknown but it is possibly generated by instabilities within the meandering Antarctic polar front as its surface signature was characteristic of Antarctic surface water masses found south of the Antarctic polar front. The cold-core eddy appeared to displace the sub-Antarctic front northwards. South of the eddy, a warm patch of sub-Antarctic surface water was observed; its position appeared to be controlled by the meandering Antarctic Polar Front which lay on either side of this feature. No distinct microphytoplankton groupings could be distinguished by numerical analyses, although four distinct zooplankton groupings were identified. These corresponded to the sub-Antarctic surface waters, Antarctic surface waters and the polar frontal zone waters. The fourth grouping comprised those stations where the lowest zooplankton abundances during the entire investigation were recorded and, as a consequence, does not reflect any spatial patterns. These results suggest that the species composition and distribution of plankton in the vicinity of the islands were consistent with the prevailing oceanographic regime. Accepted: 15 March 1999     

Extinction and recolonization of maritime Antarctica in the limpet Nacella concinna (Strebel, 1908) during the last glacial cycle: toward a model of Quaternary biogeography in shallow Antarctic invertebrates

Quaternary glaciations in Antarctica drastically modified geographical ranges and population sizes of marine benthic invertebrates and thus affected the amount and distribution of intraspecific genetic variation. Here, we present new genetic information in the Antarctic limpet Nacella concinna, a dominant Antarctic benthic species along shallow ice‐free rocky ecosystems. We examined the patterns of genetic diversity and structure in this broadcast spawner along maritime Antarctica and from the peri‐Antarctic island of South Georgia. Genetic analyses showed that N. concinna represents a single panmictic unit in maritime Antarctic. Low levels of genetic diversity characterized this population; its median‐joining haplotype network revealed a typical star‐like topology with a short genealogy and a dominant haplotype broadly distributed. As previously reported with nuclear markers, we detected significant genetic differentiation between South Georgia Island and maritime Antarctica populations. Higher levels of genetic diversity, a more expanded genealogy and the presence of more private haplotypes support the hypothesis of glacial persistence in this peri‐Antarctic island. Bayesian Skyline plot and mismatch distribution analyses recognized an older demographic history in South Georgia. Approximate Bayesian computations did not support the persistence of N. concinna along maritime Antarctica during the last glacial period, but indicated the resilience of the species in peri‐Antarctic refugia (South Georgia Island). We proposed a model of Quaternary Biogeography for Antarctic marine benthic invertebrates with shallow and narrow bathymetric ranges including (i) extinction of maritime Antarctic populations during glacial periods; (ii) persistence of populations in peri‐Antarctic refugia; and (iii) recolonization of maritime Antarctica following the deglaciation process.     

The summer zooplankton community at South Georgia: biomass,vertical migration and grazing

Zooplankton abundance and biomass were determined during January 1990 at two stations to the north-west of South Georgia using a Longhurst Hardy Plankton Recorder (LHPR). At both shelf and oceanic station sites, zooplankton biomass, (excluding Euphausia superba), was found to be ca. 13 g dry mass m^–2. Copepods and small euphausiids dominated the catches. These estimates are over 4 times higher than values generally reported for the Southern Ocean and may reflect firstly, the high productivity of the study area, secondly, the time of year, summer, when biomass for many species is maximal, and thirdly, the high sampling efficiency of the LHPR. Principal components analysis disclosed similarities and differences between adjacent depth strata in terms of abundance, biomass and species composition. At both stations most variability occurred in the mixed layer (0–60 m) and thermocline (60–120 m) with depth horizons below this being more homogeneous. Diel migrations were observed for most taxa with abundance increasing in the mixed layer at night. At the oceanic station, species and higher taxa belonging to the mesopelagic community were generally well spread throughout this domain and, with the exception of Pleuromamma robusta and Metridia curticauda, showed little evidence of migration. The grazing impact of the epipelagic community (copepods and small euphausiids) was estimated to remove 3–4% of the microbial standing stock day^–1 and a conservative 25% and 56% of daily primary production at the oceanic and shelf stations respectively.     

Distribution of six major copepod species around South Georgia in early summer

Summary An intensive net sampling survey was conducted around the island of South Georgia during November/December 1981. The distribution and copepodite stage structure of the dominant copepods Calanoides acutus, Calanus simillimus, C. propinquus, Rhincalanus gigas, Metridia lucens and Metridia gerlachei were compared. The herbivorous species had completed their spring vertical migration and their summer generations were developing during the survey. At every station, Calanoides acutus was noticeably more advanced than Rhincalanus gigas in its reproductive cycle. The species were also more advanced in their development in the SE oceanic part of the survey area than in the NW. However, copepod development rates are rapid at this time of year, and this apparent regional difference may be due mainly to temporal variation during the four weeks of the survey. A truly regional variation in timing of reproduction was found when development was compared between shelf and oceanic waters. Spawning of Rhincalanus gigas and particularly of Calanoides acutus was later over the shelf. The age structure of the epi-mesopelagic metridinids also differed between shelf and oceanic waters, but no age differences were found for either Calanus simillimus or C. propinquus, both of which live and spawn higher in the water column than the other species. The presence of the South Georgia shelf also limited the overall abundance of the two deeper living metridinids. However, the length of time between spawning (and production of large numbers of early copepodids) and sampling had the largest influence on observed species abundance within the survey area.     

Composition and community structure of pelagic copepods in the Indian sector of the Antarctic Ocean during the end of the austral summer

The present paper describes latitudinal and vertical changes in the composition, abundance and diversity of copepods in the Indian sector of the Antarctic Ocean, during the end of austral summer along a transect on 66°30′E between 43 and 62°S, within three layers (600–0, 200–0, 100–0 m). Highest copepod densities were noted in the central part of the transect, between the Antarctic Divergence and the Antarctic Convergence, with a maximum in the Antarctic Divergence zone, particularly in the upper levels of the water column. A total number of 80 copepod species were identified over the entire survey area. The south end and the central part of the transect comprised a small number of species. North of the Antarctic Convergence, this number increased markedly with the progressive disappearence of those species characteristic of Antarctic waters and their replacement by temperate and subtropical species. Generally, small copepods, particularly Oithona similis, Oithona frigida and Ctenocalanus citer, dominated in numbers in both Antarctic and sub-Antarctic areas. The contribution of large species to total copepod numbers was much lower, with Calanus simillimus in the central part of the transect, Pleuromamma borealis in the subtropical zone and Calanus propinquus in the southern part. Correspondence analysis showed a marked latitudinal gradient in population structure with four groups of samples and species corresponding to four latitudinal zones. Community structure (species richness, relative dominance index, evenness, Shannon species diversity index) and species abundance patterns (as rank-frequency diagrams) suggested that the maturity and species richness increased gradually from south to north. A low diversity index and evenness were observed in the area of the Antarctic Divergence, whereas the convergence zone showed high diversity and evenness. Conversely, the frontal zone showed high diversity and evenness. Distribution appeared unrelated to chlorophyll concentrations and on the large scale was related to the hydrologic characteristics. Received: 8 May 1996 / Accepted: 27 August 1996     

Structure and grazing impact of the mesozooplankton community during late summer 1994 near South Georgia, Antarctica

Mesozooplankton abundance, community structure and grazing impact were determined during late austral summer (February/March) 1994 at eight oceanic stations near South Georgia using samples collected with a Bongo and WP-2 nets in the upper 200-m and 100-m layer, respectively. The zooplankton abundance was generally dominated by copepodite stages C3–C5 of six copepod species: Rhincalanus gigas, Calanus simillimus, Calanoides acutus, Metridia spp., Clausocalanus laticeps and Ctenocalanus vanus. Most copepods had large lipid sacs. All copepods accounted for 41–98% of total zooplankton abundance. Juvenile euphausiids were the second most important component contributing between 1 and 20% of total abundance. Pteropods, mainly Limacina inflata, were important members of the pelagic community at two sites, accounting for 44 and 53% of total abundance. Average mesozooplankton biomass in the upper 200 m was 8.0 g dry weight m⁻², ranging from 4.3 to 11.5 g dry weight m⁻². With the exception of Calanussimillimus, gut pigment contents and feeding activity of copepod species were low, suggesting that some species, after having stored large lipid reserves, had probably started undergoing developmental arrest. Daily mesozooplankton grazing impact, measured using in situ gut fluorescence techniques and in vitro incubations, varied widely from <1 to 8% (mean 3.5%) of phytoplankton standing stock, and from 5 to 102% (mean 36%) of primary production. The highest grazing impact was found northeast of the island co-incident with the lowest phytoplankton biomass and primary production levels. Received: 30 October 1996 / Accepted: 23 February 1997     

Possible latitudinal clines in Antarctic intertidal and subtidal zone communities encrusting ephemeral hard substrata

Aim Encrusting faunal communities on rocks were examined from Southern Ocean intertidal and subtidal (6 m) zones to investigate potential change with latitude. Location The site locations were South Georgia (54°S [sub-Antarctic]), Signy Island (60.5°S [maritime Antarctic]) and Adelaide Island (68°S [high Antarctic]). Methods The number of taxa, degree of colonization and bryozoan growth and mortality were measured. Results The communities present were relatively simple in terms of composition and interactions. Spirorbid polychaetes (Annelida) and cheilostomatid bryozoans were the principal components. The community simplicity and dominance of unitary (compared to colonial) fauna increased with latitude. Mean annual mortality of subtidal cheilostomatids also significantly increased with latitude. The number of bryozoan species and potential aspects of community complexity increased with latitude. The growth of the bryozoan Inversiula nutrix increased with latitude reversing the general trend of decreased growth rate. Conclusions These findings suggest that disturbance may significantly increase with latitude within the Southern Ocean. The apparent reversal of typical latitudinal growth trends is probably a result of classical island biogeography, with species decreasing away from a centre of high diversity.     

The distribution of the Euchaetidae (Copepoda: Calanoida) around South Georgia

Summary Fourteen species of the genus Euchaeta (Copepoda: Calanoida) were encountered during two cruises undertaken around South Georgia during November–December 1981 (Summer) and July–August 1983 (Winter). All 14 species were present in summer but only nine in winter. The distribution of the majority of species centered on the mesopelagic (500–1000 m) and bathypelagic (1000–2000 m) depth horizons. During both cruises, four species, Euchaeta Antarctica, E. biloba, E. rasa and E. farrani were numerically dominant. Although all four species had a wide depth distribution, E. Antarctica and E. biloba had distributions centered around the 250–500 m (epi-mesopelagic) and mesopelagic depth horizons. E. rasa was most abundant in the mesopelagic whereas E. farrani, the largest species encountered, was centered on the mesopelagic and bathypelagic depth horizons. Two species, E. Antarctica and E. biloba commonly occurred in the surface 250 m, the former being far more abundant especially over the shelf and shelf break areas, with a high abundance of copepodite stages IV and V being present in summer and adults in winter.     

Modelling reproductive effort in sub-and maritime Antarctic mosses

A comparison is made of the reproductive effort (RE), considered as the investment in sporophyte relative to gametophyte biomass, of eight species of moss occurring at sub-and maritime Antarctic sites. Six of the species showed smaller sporophytes and game-tophytes at the climatically more extreme maritime Antaretic sites and one species showed no size difference between regions. The remaining species, although showing no regional difference, showed some evidence of a reverse pattern, with higher altitude samples having greater biomass than lower altitude samples. Spore counts indicated a measure of compensation in maritime Antarctic samples, with no significant decrease in spore output in several species despite smaller sporophyte biomass. The relationship between sporophyte (S) and gametophyte (G) biomass within samples was described by an allometric curve (S=aG ^b ) which gave a better fit than a straight line for six species. This form of model allows comparisons of patterns of RE to be made between samples with non-or partially overlapping size distributions, even when the relationship involves size-dependence. An allometric curve was not appropriate for describing samples of one species (Andreaea regularis), and insufficient data were available to identify any relationship in Polytrichum alpinum. The exponent (b) differed between species, but there were no statistically significant differences between exponents from samples of the same species. Samples of two species could further be described by the same coefficient (a), indicating that they lie on the same curve. However, samples of three species from sub-Antarctic South Georgia gave significantly higher coefficients, indicating increased RE relative to maritime Antarctic populations.     

Scotia Arc Acari: antiquity and origin

The Scotia Arc comprises South Georgia, South Sandwich, South Orkney and South Shetland Islands together with the Antarctic Peninsula. Free-living Acari of the Scotia Arc contain immigrant and endemic elements. Transport of immigrant species to and within the Maritime Antarctic has been via Holocene storms and ocean currents. Most immigrants are Gamasida, Oribatida and Acaridida while Actinedida dominate the endemic element. Immigrant species on South Georgia share common 'sub-Antarctic' affinities with South Indian and, to a lesser extent, South Pacific Ocean island faunas. In contrast, immigrants to the rest of the Scotia Arc and Bouvetøya on the mid-Atlantic Ridge, form a robust 'Maritime Antarctic' Province group. The endemic component is of largely Tertiary origin and, like that of Continental Antarctica, dominated by a few cosmopolitan families and genera of Actinedida. There are no bona fide pan-Antarctic species and little evidence that Continental and Maritime Antarctic faunas have a common ancestry, indeed the Continental endemic fauna is entirely montane while that of Maritime Antarctica is coastal. The presence of common Maritime Antarctic/South Pacific island genera corroborate the Antarctic Peninsula as being derived from a South Pacific island archipelago which collided with Continental Antarctica during the Tertiary period.     

Spatial distribution and secondary production of Copepoda in a tropical reservoir: Barra Bonita, SP, Brazil.

The present paper aims to describe the spatial distribution of zooplankton copepods, their biomass and instantaneous secondary production, in Barra Bonita, a large eutrophic, polymitic reservoir (22 degrees 29' S and 48 degrees 34' W) on the Tietê River, of the Paraná basin. Sampling was carried out during two seasons: dry winter and rainy summer. Species composition, age structure and numerical density of each copepod species population were analyzed at 25 sampling stations. Secondary production was calculated for Copepoda, the dominant group in zooplankton communities, taking Calanoida and Cyclopoida separately. Copepoda represented the largest portion of the total zooplankton biomass, the dominant species being Notodiaptomus iheringi among the Calanoida and Mesocyclops ogunnus and Thermocyclops decipiens among the Cyclopoida. The production of Copepoda was higher during the rainy summer (23.61 mgDW.m(-3).d(-1) in January 1995) than during the dry winter season (14 mgDW.m(-3).d(-1) in August 1995), following the general pattern of abundance for the whole zooplankton community. Among the copepods, Cyclopoida production was higher than that of Calanoida, a pattern commonly observed for tropical lakes and reservoirs. Barra Bonita copepods are very productive, but there was a great degree of spatial heterogeneity, related to the physical and chemical conditions, particularly the level of nutrients and also to phytoplankton biomass.     

Accidental transfer of non-native soil organisms into Antarctica on construction vehicles

Antarctic terrestrial ecosystems currently include very few non-native species, due to the continent’s extreme isolation from other landmasses. However, the indigenous biota is vulnerable to human-mediated introductions of non-native species. In December 2005, four construction vehicles were imported by contractors to the British Antarctic Survey’s (BAS) Rothera Research Station (Antarctic Peninsula) from the Falkland Islands and South Georgia (South Atlantic) on board RRS James Clark Ross. The vehicles were contaminated with >132 kg of non-Antarctic soil that contained viable non-native angiosperms, bryophytes, micro-invertebrates, nematodes, fungi, bacteria, and c. 40,000 seeds and numerous moss propagules. The incident was a significant contravention of BAS operating procedures, the UK Antarctic Act (1994) and the Protocol on Environmental Protection to the Antarctic Treaty (1998), which all prohibit the introduction of non-native species to Antarctica without an appropriate permit. The introduction of this diverse range of species poses a significant threat to local biodiversity should any of the species become established, particularly as the biota of sub-Antarctic South Georgia is likely to include many species with appropriate pre-adaptations facilitating the colonisation of more extreme Antarctic environments. Once the incident was discovered, the imported soil was removed immediately from Antarctica and destroyed. Vehicle cleaning and transportation guidelines have been revised to enhance the biosecurity of BAS operations, and to minimise the risk of similar incidents occurring.     

First documentation of leopard seal predation of South Georgia pintail duck

Leopard seals are regular winter visitors to Bird Island, South Georgia, where they mostly prey on fur seals and penguins, and to a lesser extent on Antarctic krill and fish. Leopard seals can exploit many different species, but there are no records of predation on flying shorebirds in the wild. On 4 October 2008, an individually identified juvenile leopard seal female was observed killing and eating a South Georgia Pintail duck. It also preyed on Antarctic fur seals and gentoo and macaroni penguins during its 2-month temporary residency around the island. The varied diet of this seal exemplifies the generalist prey utilization typical of its species. Long-term diet studies at Bird Island and the published record suggest that predation on ducks is a rather exceptional finding; individual ducks are more likely to escape leopard seal attacks than penguins and provide a far less substantial ration. This note documents the first observation of this species of duck in the diet of leopard seals.     

Effects of the ice-edge bloom and season on the metabolism of copepods in the Weddell Sea,Antarctica

The metabolic responses of several species of Antarctic copepods to primary productivity and changes between seasons were investigated. To examine the influence of the spring ice-edge bloom on the metabolism of copepods, oxygen consumption rates were determined on specimens from three zones of widely different ice coverage and chlorophyll biomass: pack ice (pre-bloom), ice edge (bloom) and open water (post-bloom). Summer metabolic rates were compared with published winter rates. Field work was done in the Weddell Sea in the region of 60 °S, 36°W in late November and December 1993. Oxygen consumption rates were determined by placing individuals in syringe respirometers and monitoring the oxygen partial pressure for 10–20 hours. Higher metabolic rates were observed in the primarily herbivorous copepods, Calanoides acutus, Rhincalanus gigas and Calanus propinquus in regions of higher primary production: ice edge and open water. The carnivorous Paraeuchaeta antarctica showed a similar pattern. The omnivorous copepods Metridia gerlachei and Gaetanus tenuispinus showed no changes in metabolism between zones. Data on routine rates of copepods from the winter were available for C. propinquus and P. antarctica. In P. antarctica, rates were higher in the summer. Calanus propinquus showed a higher metabolic rate in the summer than in the winter, but the difference was not significant at the 0.05 level. It was concluded that copepods near the ice zone in the ice zone in the Antarctic rely on the spring ice-edge bloom for growth and completion of their life cycle.