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1.
Bocher P.; Cherel Y.; Alonzo F.; Razouls S.; Labat J. P.; Mayzaud P.; Jouventin P. 《Journal of plankton research》2002,24(12):1317-1333
The importance of the euchaetid copepod Paraeuchaeta antarcticain the subantarctic pelagic ecosystem was quantified in thecoastal waters of the Golfe du Morbihan at Kerguelen Islandsby comparing food samples from two diving seabirds with concurrentnet samples taken within the predator foraging area. Paraeuchaetaantarctica occurred in very high densities (up to 30 individualsm-3 and 96 mg dry weight m-3) in the water column, being moreabundant in the deepest part of the gulf than in shallow watersor at the more offshore shelf stations. The common diving petrelfeeds almost exclusively on crustaceans, its diet being dominatedby the amphipod Themisto gaudichaudii (52% by number and 84%by reconstituted mass) and P. antarctica (33% and 16%, respectively).Rockhopper penguins preyed upon crustaceans and fish, with fourtaxa being important, namely T. gaudichaudii (37% and 23%, respectively),Euphausia vallentini (24% and 41%), postlarval fish (10% and24%), and P. antarctica (13% and 3%). Paraeuchaeta antarcticadominated numerically in 21% of the diving-petrel food samplesand in 12% of penguin samples. The two bird species segregatedby preying upon different developmental stages of P. antarctica,diving petrels fed equally on CV of both sexes and CVI, whilepenguins fed on CVI only. Comparison of P. antarctica foundin net and food samples indicated no prey selection by commondiving petrels that caught the different copepod stages in proportionto their availability in the water column. On the other hand,the diving performance of penguins, which is better than thatof the petrels (mean maximum dive depths 69 m for penguins versus32 m in petrels), allows them to catch CVI in deeper waters,probably near the bottom. Our study shows that P. antarcticais a major component of the coastal macrozooplankton communityand a significant prey for two species of diving seabirds inhabitingKerguelen. This is also the first record of a copepod speciesas a prey for penguin, and the first to highlight P. antarcticain the food of austral seabirds. 相似文献
2.
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 相似文献
3.
The seasonal variations of bacterial and phytoplanktonic biomass were studied during several pluri-annual surveys in the subantarctic Morbihan Bay (Kerguelen Islands, 49 ° 20 S; 70 ° 10 E). Large interannual variation was observed. Phytoplanktonic biomass showed moderate values during winter and autumn. They increased sharply in spring, reaching a maximum value of about 1 mg C l–1 corresponding to an important depletion of nutrients. A second phytoplanktonic bloom of similar amplitude occurred in late summer. During algal blooms which were roughly associated with optimal values of solar irradiation for the first one and with the highest temperatures for the second one, phytoplanktonic material represented near 100% of particulate and living carbon. Bacteria showed maximal abundance (0.2 to 0.7 mg C l–1) during summer or autumn. Their relative abundance, which represented less than 1% of the living biomass in spring and summer, can reach more than 95% in autumn and winter. 相似文献
4.
Seventeen surveys were performed fortnightly from January to December 1990 and covered a grid of 16 stations in the large
Morbihan Bay at Kerguelen Island. Temperature and salinity were measured at four or five standard depths. Chlorophyll, carbon
and nitrogen contents of surface water particulate matter were determined along with mesozooplanktonic biomass and abundance
of copepods. The dominant species (90%) of mesozooplankton wasDrepanopus pectinatus, and two other taxa,Oithona spp. andCalanus simillimus, accounted for 8.6 and 0.4% respectively. A Multiple Correspondence Analysis was used to determine the influence of abiotic
(temperature and salinity) and biotic factors (potential food supply) on the spatio-temporal distribution of copepods and,
more specifically, on that of the growth stages ofD. pectinatus. No specific hydrological features were found. The distribution of copepods was fairly homogeneous in the whole bay while
the quantitative changes were influenced by the seasonal rhythm. Only a slight trend of increasing values for the biotic or
abiotic parameters and the neriticD. pectinatus was observed from the central to the inner back area of the bay. 相似文献
5.
Drepanopus pectinatus, the most numerous species of Copepod in the Kerguelen Archipelago completes 4 generations a year. The succession of generations follows the hydrological seasons. Each generation may be characterized by the cephalothorax length of the developmental stages C1 to C6. The mean lengths of stages C2 to C6 are shown to be significantly different (P > 0.05) between seasons (i.e. between generations). The size-classes have a unimodal distribution from stages C1 to C4. For copepodite C5 and adults, bimodal histograms reflect the differentiation of males and females.A reverse trend of the development pattern of lengths is demonstrated in this subantarctic species: a decrease with decreasing temperatures (6° to 2°) from April to September, and an increase with the rising temperatures (2° to 7°) from October to February.Two populations of females are distinguishable in spring and summer, by their small (0.950–1.299 mm length of cephalothorax, 55%) or large (1.300–1.800 mm, 45%) size, respectively.The differences in mean length cannot be explained by their relation to the mean temperature alone. Pigment content is suspected to play a role. 相似文献
6.
The culture of copepods under different feeding regimes hasallowed us to determine the effects of food availability onegg laying. In Temora stylifera spawning appears to be modifiedby the food resources of the adult. Conditions encountered duringdevelopment have little effect on spawning. The life span offemales is reduced by high food availability. In such casesthe sex organs are hypertrophied, the oviducts being distendedby the large oocytes. The ovary is little affected by changesin food availability, while the size of the oviducts variesin relation to feeding. The size of the genital system is reducedin older females. Variations in food concentration induce variationsof several days in the time required for egg laying. A rapidmaturation of the oocytes, combined with nutrition and the availabilityof food permits Temora stylifera to optimize egg laying. 相似文献
7.
The total and heterotrophic bacterial microflora of gut andfecal pellets of the copepod Temora stylifera was studied inthe coastal zone of the northwestern Mediterranean basin. Digestivetracts and feces were always found to contain bacteria. Withmean values close to 1011 cells ml1and 1010 colony-formingunits (CFU) ml1, both total and heterotrophic communitiesfound in fecal pellets largely exceeded the corresponding bacterialmicroflora observed in surrounding seawater (105 cells ml1 and103 CFU ml). In the same way, the frequency of dividingcells and mean cell volumes increased, respectively, from 3%and 0.12µm3 in seawater to >6% and 0.24 µm3 infecal pellets. The bacterial community structure was investigatedby carrying out 29 morphological and biochemical tests on 147isolated strains. Although Pseudomonas was always the most frequentlyencountered genus, the bacterial communities found in copepodfecal pellets clearly differ from those inhabiting seawater.Vibrio species, which were not detected in seawater microflora,were always present in fecal pellet communities. The close correspondenceobserved between the potential metabolic characteristics ofthe fecal bacterial communities isolated from a subantarcticdeposit feeder (Mytilus edulis) and from zooplankton in thisMediterranean study suggests that the fecal community differentiationis an even more general feature. 相似文献
8.
9.
Biological cycle of a population of subantarctic copepod,Drepanopus pectinatus (Clausocalanidae), Kerguelen Archipelago 总被引:2,自引:2,他引:0
Summary Depending on seasons, 73% to 99% of the copepod number in the subantarctic ecosystem of the Kerguelen Archipelago consists of Drepanopus pectinatus. All developmental stages from copepodid 1 to 5 and adults are found all year through. The annual population cycle fluctuates between a maximum abundance during the summer (150×103 individuals per m2) and a minimum during the winter (80 individuals per m2). A succession of 4 generations a year is discussed, based on the percentages of the various developmental stages in the population and changes in size of specimens in the various stages. 相似文献
10.
Suzanne Razouls 《Journal of experimental marine biology and ecology》1977,26(3):265-273
The change in dry weight over a year for the five copepodid states of Centropages typicus and Temora stylifera is given. The amounts of carbon and nitrogen, expressed as percentages of dry weight, are higher for copepodids than for adults. The values of the ratios may be regarded as constant for the different stages and of the same order as those of the adults. The calorific values of young stages are higher than those of adults, because of the relatively high carbon content. A good correlation was found between the caloric value per animal (or per unit dry weight) and the dry weight of individuals.It seems that the ecological efficiency in terms of energy transport will be greater when the copepod populations are younger. 相似文献