Vertical and seasonal variation in the abundance and the species richness of Attelabidae and Cantharidae (Coleoptera) in a suburban mixed forest

A continuous sampling of canopy beetles was carried out to determine variation in the abundance and the species richness of the Attelabidae and Cantharidae in a suburban mixed forest. Changes in the abundance and the species richness were monitored in three vertical strata of the forest from May to November in 1999, using yellow and blue water pan traps. The results showed significant variation in the abundance and the species richness of Attelabidae and Cantharidae between the layers, trap colors and seasons. Rare species were found in the bottom and middle layers, but were absent in the upper layer. In contrast, common species were more abundant in the upper layer than in the lower layers. The yellow traps had better trapping efficiency than the blue traps for both families, with the exception of an attelabid species, Cycnotrachelus reolofsi, which was more abundant in the blue traps. The abundance and the species richness were generally greater in spring than in summer. In spring, the abundance was consistently highest in the yellow traps in the upper layer. Season and layer were determinant factors in the species composition of the Attelabidae, while only season explained variation in species composition of the Cantharidae.     

Seasonality and vertical structure of light-attracted insect communities in a dipterocarp forest in Sarawak

Nocturnal flying insects were collected monthly for 13 months using ultra violet light-traps set at various vertical levels in a weakly-seasonal, tropical lowland dipterocarp forest in Sarawak, Malaysia. Abundance, faunal composition, size distribution and guild structure of these samples were analyzed with respect to temperal and vertical distributions. The nocturnal flying insect community in the canopy level was highly dominated by fig wasps (84%) in individual number, and by scarabaeid beetles (28%) in weight. A principal component analysis on monthly catches detected non-random, seasonal trends of insect abundance. The first two principal trends were an alternation of wetter (September to January) and less wet seasons (February to August) and an alternation between the least wet (January to March) and the other seasons. Many insect groups were less abundant in the least wet season than the other seasons, whilst inverse patterns were found in Scarabaeidae and Tenebrionidae. Significantly positive and negative correlations between monthly catch and rainfall were detected only in ovule-feeders and in phloem-feeders, respectively. Delayed, significant negative correlations between monthly catch and 1–3 month preceding rainfall were more frequently detected in phytophages, phloem-feeders, seed-feeders, wood-borers and scavengers. The peak in abundance along vertical levels were found at the canopy level (35 m) for phloem-, ovule-, seed-, root-, fungal-feeders and nectar collectors, at an upper subcanopy level (25 m) for scavengers and aquatic predators, and at a middle subcanopy level (17 m) for ants. Catches at the emergent level (45 m) did not exceed those at the canopy level.     

First Quantitative Study of Rove Beetles in Oklahoma Winter Wheat Fields

Adult rove beetles (Staphylinidae) were sampled every 7–14 days from one winter wheat field located in each of the four major wheat growing regions of Oklahoma during the 1999–2000 and 2000–2001 growing seasons. The number of cereal aphids per tiller, wheat plant growth stage, and wheat tiller density also were estimated. A total of 12 genera representing 13 species of beetles were collected from the field. The density of rove beetles was generally low, ranging from 0.003 beetles per m² in fall to 0.106 beetles per m² in spring. Rove beetle communities differed among seasons. After accounting for the effect of season, there was no statistically significant association between rove beetle community structure and field location, aphid density, wheat plant growth stage, or wheat plant density. Most rove beetle species showed no association with a particular season, however, Aleochara notula Erichson, Lathrobium sp., and Oxypoda sp. were present predominantly in fall, while Bisnius inquitus Erichson was associated with winter. Oxypoda sp. was the most abundant rove beetle in winter wheat fields in spring and was relatively abundant in winter, but was not collected from wheat fields in fall. Tachyporus jocosus Say was present in wheat fields during all seasons. T. jocosus was the most abundant rove beetle species in the winter wheat fields in fall and winter and was the second most abundant species during spring.     

Vertical stratification of beetles in tropical rainforests as sampled by light traps in North Queensland,Australia

How arthropods are distributed within the vertical structure of tropical rainforests is of considerable interest to ecologists. Here, we examine how light trapped beetles are distributed in tropical rainforest in North Queensland, Australia. In January and July 2012, traps were suspended 0 m, 10 m, 20 m and 30 m above the ground in five locations with no more than one trap at any single location on any night. Maximum canopy height at the sites was 35 m. A total of 7299 individuals of 492 morphospecies and 66 families were collected. The species abundance‐based coverage estimator predicted a total species richness of 765. Sample completeness decreases with increasing height from the ground suggesting higher strata were less well sampled. Distance‐based redundancy analysis showed species richness was significantly different between 30 m and all other levels but not between other paired strata. In contrast, both species composition and family composition were significantly distinct for all strata pairs except 10 m with 20 m, and 20 m with 30 m, suggesting that the most distinct strata were 0 m and 30 m. The first two axes of ordination and hierarchical clustering accounted for 46.5% and 17.4% of species composition variation corresponding with season and stratum, respectively. Family level analyses gave similar results to those at the species level. We found stratification of different feeding guilds with herbivores comprising a larger percentage of species in higher strata, whereas saprophages were restricted to the lower strata, reflecting the availability of key resources for these guilds. Fewer species or families were found to be indicators of strata, as measured using IndVal, than for Malaise and flight interception traps (FIT). Dytiscidae and Hydraenidae were abundant but had not been collected using Malaise and FIT. Which species or families are indicators of strata depends on sampling method suggesting multiple sampling methods should be used to establish indicators.     

High temporal variability of zooplankton,but only weak evidence for a near-bottom effect on composition and distribution in the deep Levantine Basin,eastern Mediterranean

Abundance and composition of the near-bottom zooplankton between 10 and 100 metres above the bottom (mab) were studied in the Levantine Basin, eastern Mediterranean, during four cruises of RV Meteor in June 1993, January 1998, April/May 1999 and October 2001. Copepoda made up 91% of all zooplankton caught. A strong dominance of one single species was observed on all cruises, with Lucicutia longiserrata reaching 50–90% of all Copepoda except in 1993, when Subeucalanus monachus was the most abundant species, with more than 90% of all Copepoda. The year 1993 was also exceptional in terms of total zooplankton abundance, being more than one order of magnitude higher than in the other years. Vertical differences in abundance and composition were small and did not indicate a near-bottom effect or a specialized benthopelagic zooplankton community in the layers sampled.     

Composition and vertical distribution of the motile epifauna on a vertical rock wall in Gullmarsfjorden, western Sweden, using an alternative sampling approach

The main purpose of this study was to evaluate the efficiency of the alternative quantitative sampling approach and if it was possible, by using this method, to elucidate temporal variations concerning the composition, vertical distribution, and abundance of the motile epifaunal community. The study was performed on a vertical rocky bottom in Gullmarsfjorden on the Swedish west coast. Quantitative sampling was performed at four depths (2, 6, 10 and 15 m) on three occasions (19 June, 23-24 July and 23 September 1996) by means of a water jet powered suction sampler (venturi principle). In total, 53 macrofaunal taxa were found, of which 29 taxa occurred on all sampling dates. Significant vertical zonation patterns were recorded in July and September, but not in June, with amphipods, polychaetes, and echinoderms (mainly Asterias rubens) as the most important contributors to these patterns. A temporal variation in the faunal assemblage also occurred. Species abundance was significantly different between the sampling dates at 2, 6 and 10 m, but not at 15 m. The abundance was higher in July and September than in June. Species with the highest observed differences in abundance were juvenile Asterias rubens, abundant in July, while juvenile shrimp, especially Thoralus cranchii, and some amphipods, especially Microdeutopus spp., increased in abundance in September. This sampling approach was highly effective, and the high abundance and diversity of the motile epifauna indicate that these species play an important role in hard-bottom communities.     

Seasonal and annual dietary changes in Lesser Kestrels Falco naumanni wintering in Lesotho

The diet of Lesser Kestrels Falco naumanni wintering in an agriculturally-transformed area in Lesotho was studied by means of pellet analysis. Orthopterans, beetles and solifugids (sun spiders) comprised the staple food of the wintering Lesser Kestrels. Small vertebrates, termite alates, earwigs and scolopendrans supplemented the diet. The proportion of pellets containing scarabaeid and carabid beetles, as well as those containing locusts and crickets, increased as the wintering season progressed, while the proportion of pellets containing solifugids decreased during the same period. Significant differences in diet composition were recorded between the 1998/1999 and 1999/2000 wintering seasons.     

Chemical defenses shift with the seasonal vertical migration of a Panamanian poison frog

Dendrobatid poison frogs sequester lipophilic alkaloids from their arthropod prey to use as a form of chemical defense. Some dendrobatid frogs seasonally migrate between the leaf litter of the forest floor in the dry season to the canopy in the wet season, which may yield differences in prey (arthropods) and therefore alkaloid availability over space and time. Here, we document a seasonal vertical migration of Andinobates fulguritus (the yellow‐bellied poison frog) from ground to canopy between dry and wet seasons. We observed turnover in alkaloid composition between seasons and found that dry season frogs contained a lower relative quantity of alkaloids; however, there was no change in alkaloid richness between seasons. The 77 alkaloids of 13 structural classes identified in this population appear to be derived mostly from mites and ants, though the two most common alkaloids were mite derived. Our observed shifts in defensive profiles are consistent with well‐documented turnover in mite and ant communities between seasons and vertical strata. As climate change is expected to lengthen and strengthen dry seasons in many tropical regions, our results suggest that arboreal poison frogs forced to the ground for longer periods of time may see a shift in the abundance of alkaloids, possibly decreasing their defensive potential. This study provides further predictions for the wide‐reaching effects of climate change, even as nuanced as charismatic poison frogs losing their poisons. Abstract in Spanish is available with online material.     

Potential of yellow sticky traps for lady beetle survey in cotton

A 2-yr study was conducted to investigate the potential of using yellow sticky traps to survey lady beetles in cotton and to quantify seasonal activity patterns. The performance of sticky traps was compared with that of a 2-cycle vacuum sampler. The most common lady beetle species captured by sticky traps and vacuum sampler in cotton were Hippodamia convergens Guerin-Meneville and Scymnus loewii Mulsant. Sticky traps captured significantly more of both species of lady beetles, had greater capture efficiency, and more effectively detected lady beetles compared with the vacuum sampler. These data indicate that the sticky trap can be a valuable tool in monitoring lady beetle populations in cotton. In the second part of this study, a year-round survey of lady beetle populations in the periphery of a cotton farm using sticky traps showed that lady beetles remained active throughout the year in the Texas Rolling Plains, but the activity was influenced by winter severity. Over a 2-yr period, H. convergens, S. loewii, Coccinella septempunctata (L.), and Olla v-nigrum (Mulsant) comprised 89.6, 8.2, 1.9, and 0.3% of the specimens, respectively. Sticky trap captures were affected by year, trap height, and cropping season. Traps placed at 0.75 m above ground captured significantly more (80%) lady beetles than traps placed at 1.50 m (20%) above ground; traps at 0.75 m above ground also detected the rarer species while the traps at 1.50 m above ground detected only the abundant species. Trap captures were higher during the noncotton season (November to April) compared with the cotton season (May to October). A significant positive correlation between cotton aphid abundance during the growing season and H. convergens abundance during the following noncotton season was also detected, indicating a significant movement of H. convergens from cotton to the periphery of the farm to seek refuge after cotton termination.     

Seasonal variation in the diet of juvenile lake sturgeon,Acipenser fulvescens,Rafinesque, 1817, in the Winnipeg River,Manitoba, Canada

The lake sturgeon, Acipenser fulvescens, is a threatened species across most of its range. To understand any potential shifts in diet across season or habitat, stomach contents were examined from juvenile lake sturgeon caught in the Winnipeg River, Manitoba, Canada. This information will aid in assessment of environmental impacts and conservation initiatives for this threatened species. From 2006 to 2008 gut contents were collected from juvenile lake sturgeon using a non‐lethal gastric lavage methodology. Juvenile lake sturgeon were sampled from four discrete deep water habitat types (13.7–27.4 m depths), during the months of May, June, July and October. In total, 13 066 prey items belonging to 14 prey groups were collected from 345 juvenile lake sturgeon (251–835 mm TL). Overall, juvenile lake sturgeon consumed a low diversity of organisms; insect larvae from three invertebrate orders, Trichoptera, Diptera and Ephemeroptera, accounted for 97.4% of the total numeric abundance of prey items recovered. A relationship between size of juvenile lake sturgeon and prey quantity or type was not observed. Diet of juvenile lake sturgeon varied in relation to season, with Diptera (77.6%) being the most abundant prey in May, Trichoptera the most abundant in June (n = 3,056, 60.4%) and July (n = 2,055, 52.6%). During October, 96% of stomachs examined were empty. In terms of habitat type, the standardized abundance of invertebrate prey items was highest in deep water habitats characterized by medium water velocity (depths > 13.7 m) and coarse substrate (particle sizes > 0.063 mm) in May and June when compared to deep water habitats characterized by low water velocity (<0.2 m.s^?1) and fine substrate (particle sizes < 0.063 mm). However, in July, the opposite was observed and prey abundance in juvenile lake sturgeon stomachs decreased with increasing particle size. Results suggest a high degree of dietary overlap among juvenile lake sturgeon from multiple size/age classes occupying deep‐water habitats of the Winnipeg River.     

珠江口底栖动物生态学研究

采泥样调查所获底栖动物一般为体形较小,活动能力较弱的种类,往往是一些底层鱼类和虾类等良好的天然饵料。珠江口海域渔业资源丰富,是中国南海区的主要渔场之一,因此,对该海域饵料底栖动物进行研究有重要意义。通过1999年9月和2000年4月分别对珠江口底栖生物进行的两个航次的采泥样调查,分别鉴定出底栖动物15衙睡21种,共计32种。底栖动物的优势种,秋季为光滑河篮蛤Potamocorbula laevis(Hinds)(Y=0.387),春季为光滑河篮蛤（Y＝0．464）和欧虫Owenia fusformis Delle Chiaje(Y=0.120)。平均个体数量和生物量,春季为591.7ind./m^2和26.7g/m^2,秋季为85.0ing./m^2和7.4g/m^2;而在各类群生物中,软体动物占绝大部分,其次为多毛类,其它各类群所占比例都不足5％。生物多样性,个体数量和生物量的分布均呈由北向南增加的趋势。另外,与近20a中的历史资料相比,珠江口底栖动物个体数量变化不大,除2000年春季较高为591.7ind./m^2外,其变化范围在72.4-128ing./m^2之间。春季生物量除1991年较高为27．0g/m^2外,变化不是很大,大约10g/m^2;但秋季生物量呈明显下降趋势,1980年为30.1g/m^2,1990年为27.8g/m^2,1999年秋季急剧下降至7.4g/m^2。此外,从底栖动物各大类群的百分组成变化情况来看,一般以软体动物个体数量（22．7％－83．2％）和生物量（57．9％－82．5％）都最高;多毛类的个体数量百分组成占第二倍,其范围是13．4％－52．3％;其它各类群的百分组成除个别时候所占比例较大外,一般都较小。     

Vertical Stratification and Caloric Content of the Standing Fruit Crop in a Tropical Lowland Forest1

Fruit abundance in tropical forests thus far has been studied in relation to consumer populations. Area–based surveys that focus on the quantity and quality of the standing fruit crop of an entire plant community, however, are lacking. This paper presents the results of a four–month study on the seasonality and vertical distribution of the standing fruit crop within a tropical forest during the dry season in southern Venezuela. Fruit numbers ranged from 262,000 to 424,000 fruits/ha. The standing crop was between 39 and 92 kg/ha, yielding 67,000 to 126,000 kj. Fruits were not evenly distributed in different forest layers. They were most abundant in the canopy above 16 m and scarce between 4 and 12 m above the ground. Despite a scarcity of fruits in the mid–strata, the caloric value of the total fruit supply peaked within a narrow layer of subcanopy at 12 to 16 m above ground due to a high amount of energy per fruit. Palms fruited mostly in this layer, their fruits contributing 59 percent of the energy supplied by all fruits. Above 12 m, we found a broader range of fruit sizes than in the forest below 12m. Small–sized fruits were distributed in the understory and in the canopy but were nearly absent from die mid–story. Corresponding to the abundance of small–sized fruits in the canopy, small frugivorous species, such as members of the Thraupidae, limited their foraging to the canopy strata whereas larger avian frugivores foraged mainly in die mid–story.     

Composition, abundance and distribution of macrozooplankton in Culebra Bay, Gulf of Papagayo, Pacific coast of Costa Rica and its value as bioindicator of pollution

The abundance, distribution and composition of the macrozooplankton of Culebra Bay, Costa Rica (10 degrees 38' N - 85 degrees 40' W) were studied at four stations throughout the dry (February-May) and rainy (September-November) seasons of 2000. The samples were collected at two-week intervals using a 500 microm mesh net with a 0.5 m diameter opening. Copepods (23-31%) and ostracods (20-34%) were predominant throughout the year, followed by cladocerans (2.5-14%), zoea (6.6-9.5%), and siphonophores (2.5-7.2%). High densities of zooplankton were obtained in February and March with peak abundance on March 18. The lowest densities were observed on September 3 and November 5. Significant differences in abundances at each station were observed for the groups Acartia tonsa (Copepoda), Ctenophora, Medusae, Ostracoda, Zoea, and Amphipoda. Comparison of the dry and rainy seasons revealed significantly higher zooplankton abundance in the dry season and copepod domination of all stations; during the rainy season ostracods dominated the off-shore areas. Zooplankton abundance and distribution are influenced by upwelling, which occurs during the dry season in Culebra Bay.     

Diet changes in vertical distributions of larval fishes in unstratified coastal waters off southeastern Australia

Larval fishes were sampled at four depth strata during the dayand night at two locations in unstratified (winter) inner continentalshelf waters off Sydney, Australia, in May and June 1993. Assemblagesat both locations and in both sampling periods were stronglydepth stratified during the day; however, this structure weakenedat night with most taxa being found throughout the entire watercolumn. Two daytime patterns of larval fish vertical distribution(surface and deep dwellers) were evident, and taxon-specificdaytime vertical distributions were strong and not dependenton thermal stratification of the water column. Most larvae caughtwere preflexion and there was little evidence of ontogeneticdifferences in vertical distributions. For most taxa, the patternsof diel change in vertical distribution were similar at bothlocations and in both sampling periods.     

Benthic meiofaunal density and community composition in the deep White Sea and their temporal variations

In spite of the fact that shallow-water meiobenthos of the White Sea is a relatively well studied, the information on meiobenthic fauna from the deepest part of this sea is still very scanty. This study represents the first major study of the meiobenthos from the deep White Sea. The composition of the meiobenthic community, density and vertical distribution was studied during four sampling occasions in the deepest part of the Kandalaksha Depression (White Sea) in July 1998, October 1998, May 1999 and November 1999. Samples were collected from a depth of 270?m with the aid of a multicorer. The total density of meiobenthos in 1998 was twice than in 1999 (on average, 2,356 and 1,464 ind./10?cm², respectively). The most abundant meiobenthic group was Foraminifera (59?%), followed by Nematoda (26?%) and Harpacticoida (7?%). These relative and absolute abundance values are comparable with the same depth interval in Arctic and temperate regions. The density of foraminiferans and nematodes was higher in the autumn and lower in the summer. This may be explained by the mass propagation of these animals in the autumn season: the density of juvenile nematodes and small-sized foraminiferans increased significantly in the 1- to 4-cm-deep sediment layers in autumn. The size range of the meiobenthos in the deepest part of the White Sea was also comparable to deep-sea meiobenthos (the 63–125 and 125–250?μm size classes were most dominant).     

Monitoring Aethina tumida (Coleoptera: Nitidulidae) with baited bottom board traps: occurrence and seasonal abundance in honey bee colonies in Kenya

The population dynamics of the honey bee pest Aethina tumida Murray (small hive beetle) have been studied in the United States with flight and Langstroth hive bottom board traps baited with pollen dough inoculated with a yeast Kodamaea ohmeri associated with the beetle. However, little is known about the population dynamics of the beetle in its native host range. Similarly baited Langstroth hive bottom board traps were used to monitor the occurrence and seasonal abundance of the beetle in honey bee colonies at two beekeeping locations in Kenya. Trap captures indicated that the beetle was present in honey bee colonies in low numbers all year round, but it was most abundant during the rainy season, with over 80% trapped during this period. The survival of larvae was tested in field releases under dry and wet soil conditions, and predators of larvae were identified. The actvity and survival of the beetle were strongly influenced by a combination of abiotic and biotic factors. Larval survival was higher during wet (28%) than dry (1.1%) conditions, with pupation occurring mostly at 0-15 cm and 11-20 cm, respectively, beneath the surface soil during these periods. The ant Pheidole megacephala was identified as a key predator of larvae at this site, and more active during the dry than wet seasons. These observations imply that intensive trapping during the rainy season could reduce the population of beetles infesting hives in subsequent seasons especially in places where the beetle is a serious pest.     

Effects of seed size and emergence time on tree seedling establishment: importance of developmental constraints

Arafura filesnakes (Acrochordus arafurae) are large (up to 2.5 m, 5 kg) aquatic nonvenomous snakes that feed entirely on fishes. A 10-year field study in the Australian wet-dry tropics revealed strong correlations between rainfall patterns, fish abundance, and snake population dynamics. All of these characteristics showed considerable annual variation. High rainfall late in the wet season (February–March) caused prolonged inundation of the floodplain. Following such years, dry-season sampling revealed that fishes were abundant, filesnakes were in good body condition, and a high proportion of adult female filesnakes were reproductive. Annual variation in recruitment to the population (as judged by the relative abundance of yearling snakes) was also correlated with fish abundance and thus, with rainfall patterns in the late-wet season. Our results fit well with those from other studies on a diverse array of aquatic and terrestrial species within the wet-dry tropics. Annual variation in rainfall patterns, via its effects on prey abundance, may drive the population dynamics of many tropical predators. Received: 28 June 1999 / Accepted: 29 February 2000     

Species assemblages of cyclopoid Copepoda from Mantecal,Venezuela

A 14 year monitoring of species composition and abundance of cyclopoid copepods throughout the rainy and dry seasons in a flooded savanna at Mantecal, Apure State, Venezuela, is presented. Two characteristic habitats within these water bodies were selected: the open center of small ponds free of emergent vegetation and the surrounding flooded grassland. In total, 13 species were registered, all of which appeared in the flooded grassland and 11 of which occurred in the open water. Ten species were common for the two habitats during the dry season. The highest abundance was found in flooded grassland during the dry season. Eight species showed abundances greater than 1.0 individual per liter in flooded grassland during both seasons; 3 and 7 species were this abundant in the open water during rainy and dry seasons, respectively. Mesocyclops meridianus and Microcyclops varicans were the most abundant species in both habitats and seasons, while Thermocyclops decipiens was the dominant species during rainy season in open water. Principal component analysis indicates that the important species were positively correlated between them (sharing habitat and season).     

Simplification of a coffee foliage-dwelling beetle community under low-shade management

Coffee agroforests may be structurally and floristically complex and may contain a significant fraction of species from biodiverse and threatened tropical montane forest biotas; hence, understanding the dynamics of tropical forest biodiversity in coffee agroecosystems has emerged as a centrally important area of tropical conservation biology research. We conducted a morphospecies analysis on foliage-dwelling beetles collected from coffee plants on four coffee farms in southern Chiapas, Mexico, to characterize variation in the abundance, species richness, and species composition of this mega-diverse taxon in relation to coffee cultivation system, spatio-temporal variation, and predator removal. We constructed thirty-two cages to exclude birds and bats on four farms, each enclosing 7–10 coffee plants and paired with an adjacent uncaged control plot, and then collected beetles from coffee foliage with D-Vac aspirators in each plot once every 3 months for one year.We classified the 2662 beetles collected into 293 morphospecies, representing 42 families of beetles. Extrapolation and interpolation analyses revealed a very high level of species richness, with no plateau and only a slight leveling trend observed in our species accumulation curves. We found that low-shade systems contain equal or higher beetle abundance, lower species richness, more highly homogenized species composition, and higher abundance of coffee berry borer pests on coffee foliage than do high-shade systems. We observed no effect of flying vertebrate exclusion on the coffee foliage beetle assemblage, but did find significant variation in abundance, species richness, and species composition of coffee foliage beetles across seasons and study sites.The increased beetle biodiversity of high-shade coffee cultivation systems has important implications both for the preservation of native biodiversity in coffee growing regions and for the control of agricultural pests such as the coffee berry borer.     

Zooplankton life under the perennial Antarctic Sea ice

Zooplankton was collected during the drift on the USA-Russia Ice Station Weddell 1 in the western Weddell Sea. Stratified tows up to 1,000 m depths were performed under perennial ice at a distance of ca. 300 km from the marginal ice zone from March to May 1992. Seasonal abundance, developmental stage composition and vertical distribution in populations of large dominant calanoid copepod species were studied. The abundance of Calanoides acutus changed inconspicuously and averaged 1,260 ind. m^-2; its developmental stage composition was characterised by the dominance of copepodites V (CV) and hardly changed in the course of observations. Calanus propinquus was at most stations in fairly low abundance and was represented by CV and adults; at the latest stations, it was not found. Rhincalanus gigas was also scarce; III-IV stages were present, but the first of them only at the southernmost stations. In contrast to this species, in the relatively abundant population of Metridia gerlachei (1,370 ind. m^-2 on average), a new generation was observed. There was a clear deepening of the median depth of occurrence of the above three species from March to early May, while in late May a shifting to upper layers was observed which remained unexplained. The data obtained were compared to the data collected in the ice-open eastern part of the Weddell Sea in the corresponding season. It can be seen that the differences in populations dynamics of the four species under the perennial ice depends on their trophic mode, i.e. capability to store lipid reserves in summer and/or to feed in winter, and with food spectra.