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1.
The purpose of this study was to determine if seasonal anoxia affects the community composition and abundance of benthic diatoms in an estuarine basin. Subtidal benthic diatoms were collected monthly at 1-m water depth intervals from 2 to 7 m in an estuarine basin of Pettaquamscutt River, Rhode Island, during 1981. Water samples were collected at the same depths to measure temperature, salinity, oxygen and sulfide levels. The basin became stratified above 7 m in June and the interface between oxic and anoxic waters remained at 5 or 5·5 m until December when it rose to above 4 m. Motile, biraphid diatoms dominated on the muddy sediments and live cell counts of these were insignificant below 5·5 m. At shallower depths, abundance was seasonally bimodal. In the spring, a peak began in April at 3 m (later in the season with increasing depth) and a smaller fall peak began in October at 4 and 5 m (later at shallower depths). Highest standing crop in August was at 5·5 m when 1% PAR (Photosynthetically Active Radiation) was at 4 m.The position of the interface between oxic and anoxic waters after stratification of the water column affected both abundance and species composition of benthic diatoms within 1·5 m above it. Navicula gregaria Donkin and N. ammophila Grunow dominated the spring and summer assemblages at all depths, but after September N. gregaria vanished from the basin below 3 m. In fall and winter, distinctly different populations were present at 4–5·5 m and at 2 m. The assemblage at 4 m and below consisted of sulfide-tolerant species of Navicula. Healthy populations of Navicula ammophila Grunow, N. pseudocrassirostris Hustedt, and N. peregrina (Ehrenberg) Kützing together reached 138 × 103 cells cm?2 at less than 1% light levels and up to 88 μM sulfide. 相似文献
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Vypeen, an island of Cochin estuarine system, acts as the spawning site of several marine and estuarine fishes. We assumed that, physical process(upwelling) make changes in hydrography and the production of chlorophyll a in coastal waters off Vypeen. These alterations can influence the zooplankton abundance and copepod community structure in that area. For justifying this hypothesis, samples were collected from Vypeen at 10 m and 30 m locations during January(pre-southwest monsoon), August(late-southwest monsoon) and November(postsouthwest monsoon) 2014. During August, subsurface water column was cool, nutrient rich and less oxygenated(signatures of upwelling) than in November and January. Maximum concentrations of nitrate and chlorophyll a were recorded during August. In the present study, 15 zooplankton groups were recorded; of which copepods were the most predominant group(73%–90%). Copepod density in the present study ranged between 527.2 ind./m~3 and 5 139.2 ind./m~3. Totally, 37 copepods species were reported in present study and copepod species richness was higher during January. The abundance of zooplankton and copepods was high in August during late-southwest monsoon. These variations were closely associated with the coastal upwelling in August and weakening of moderate upwelling in November. In SIMPER analysis, it was found that the copepods species distribution was similar within season and dissimilar between the three seasons. Moreover, the higher abundance of upwelling indicator species Temora turbinata was recorded in August, which confirms the signs of seasonal upwelling in Vypeen. The present study emphasized on the influence of hydrographical parameters associated with physical process, in governing the copepod community organization of the Vypeen Island. 相似文献
4.
Seasonal and inter-annual variation of mesozooplankton in the coastal upwelling zone off central-southern Chile 总被引：1，自引：0，他引：1
Ruben Escribano Pamela Hidalgo Humberto González Ricardo Giesecke Ramiro Riquelme-Bugueño Karen Manríquez 《Progress in Oceanography》2007,75(3):470-485
Zooplankton sampling at Station 18 off Concepción (36°30′S and 73°07′W), on an average frequency of 30 days (August 2002 to December 2005), allowed the assessment of seasonal and inter-annual variation in zooplankton biomass, its C and N content, and the community structure in relation to upwelling variability. Copepods contributed 79% of the total zooplankton community and were mostly represented by Paracalanus parvus, Oithona similis, Oithona nana, Calanus chilensis, and Rhincalanus nasutus. Other copepod species, euphausiids (mainly Euphausia mucronata), gelatinous zooplankton, and crustacean larvae comprised the rest of the community. Changes in the depth of the upper boundary of the oxygen minimum zone indicated the strongly seasonal upwelling pattern. The bulk of zooplankton biomass and total copepod abundance were both strongly and positively associated with a shallow (<20 m) oxygen minimum zone; these values increased in spring/summer, when upwelling prevailed. Gelatinous zooplankton showed positive abundance anomalies in the spring and winter, whereas euphausiids had no seasonal pattern and a positive anomaly in the fall. The C content and the C/N ratio of zooplankton biomass significantly increased during the spring when chlorophyll-a was high (>5 mg m−3). No major changes in zooplankton biomass and species were found from one year to the next. We concluded that upwelling is the key process modulating variability in zooplankton biomass and its community structure in this zone. The spring/summer increase in zooplankton may be largely the result of the aggregation of dominant copepods within the upwelling region; these may reproduce throughout the year, increasing their C content and C/N ratios given high diatom concentrations. 相似文献
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《African Journal of Marine Science》2013,35(1):545-560
Main features of the zooplankton distribution and the ecological characteristics of the dominant species in the northern Benguela during different phases of upwelling are discussed. The composition of the zooplankton between 17 and 27°S was similar each year. Among the 20°30 most abundant species, 3°4 copepods dominated, influencing the distribution of total zooplankton biomass. During quiescent upwelling, zooplankton abundance was low and there were no significant differences in the inshore-offshore distribution of zooplankton biomass, the maximum occurring over the slope. During active upwelling, zooplankton biomass increased significantly, the maximum over the shelf being constituted almost entirely of developmental stages of herbivorous copepods. Over the inner shelf, all stages of the copepod Calanoides carinatus were feeding actively, removing up to 5 per cent per day of the standing stock of phytoplankton. Comparison of daily ration, respiration rate and biochemical composition of C. carinatus revealed active storage of energy inshore. Offshore populations of C. carinatus, found deeper than 200 m, comprised mainly copepodite stage V, which were not feeding and were characterized by decreased mobility and respiration and a high lipid content. It is estimated that the energy stored during active upwelling enables copepods to survive up to six months without any additional source of energy. 相似文献
7.
Frank W. Steimle 《Estuarine, Coastal and Shelf Science》1982,15(1):1-16
The benthic invertebrates of Block Island Sound have not been adequately studied, in contrast to other adjacent southern New England sounds. This study examines the species composition, abundance and biomass of benthic macrofaunal invertebrates at nine locations within Block Island Sound. The sites sampled, represent a wide range of subtidal habitats within the Sound, and were visited in February and September.Some 224 species were identified, of which almost half (104) were polychaetes. The benthic assemblages at most stations were dominated numerically by tube dwelling, surface detritus or suspension feeding amphipods, e.g. Ampelisca agassizi and A. vadorum, as well as the protobranch bivalve, Nucula proxima. This dominant Ampelisca-Nucula assemblage was associated with silty fine sand sediments. The average macrofaunal biomass for all stations was 158 g (wet weight) m?2, two thirds the average benthic biomass of Georges Bank, an important fishery area. Based on the examination of the records of earlier surveys in Block Island Sound, there is evidence that this silty-sand, ampeliscid-dominated assemblage has persisted since at least the mid-1940s. 相似文献
8.
《Estuarine, Coastal and Shelf Science》2005,62(1-2):205-215
Plankton samples collected in November 2002, February, May and August 2003 were used to examine seasonal variation in tidal exchange of zooplankton biomass, abundance and species composition between Lough Hyne Marine Nature Reserve and the adjacent Atlantic coast. Micro- to mesozooplankton were collected by pump over 24-h sampling periods during spring and neap tides from the narrow channel connecting the semi-enclosed water body to the Atlantic. Sample biomass (dry weight) and total zooplankton abundance peaked in the summer and were lowest in winter, showing a positive relationship with temperature. Zooplankton biomass, total abundance and numbers of holo- and meroplankton revealed import during some diel cycles and export in others. However, the tidal import of these planktonic components was generally dominant, especially during May. The greatest import of numbers of holoplankters and meroplanktonic larvae occurred during May and August, respectively. There was no significant variation in sample biomass between periods of light and dark, but some variation in zooplankton abundance could be explained by this diel periodicity. Significant differences in sample assemblage composition between flood and ebb tide samples were always observed, except during winter neap tides. There was a net import of the copepods Temora longicornis and Oithona helgolandica and the larval stages of Mytilus edulis during spring and summer. Proceraea cornuta and Capitellid trochophores were imported during winter, and a hydrozoan of the genus Obelia during the spring spring tides. Seasonal export from the lough was shown by Pseudopolydora pulchra larvae (autumn and spring), Serpulid trochophores (autumn) and veligers of the bivalve Anomia ephippium (summer). It is suggested that the direction of tidal exchange of meroplanktonic taxa is related to the distribution of the adult populations. Copepod naupliar stages dominated the assemblages except during May spring tides when the copepod Pseudocalanus elongatus made up over 22% of the abundance. The general import of micro- to mesozooplankton may, in part, explain the higher densities of this size-class of zooplankton within the semi-enclosed system of Lough Hyne. 相似文献
9.
Spatial distribution of zooplankton in the intertidal marsh creeks of the Yangtze River Estuary,China 总被引：1，自引：0，他引：1
Shuchan Zhou Binsong JinLi Guo Haiming QinTianjiang Chu Jihua Wu 《Estuarine, Coastal and Shelf Science》2009
Zooplankton are important grazers of primary production within intertidal marshes and are the optimal prey of higher trophic consumers; however, the patterns of their spatial distribution in marsh creeks are rarely reported. The zooplankton in the intertidal creeks with different salinities at Dongtan marshes of the Yangtze River Estuary was surveyed. The mean zooplankton densities in the intertidal creeks were 53,638 ind. m−3 in April and 132,916 ind. m−3 in July, respectively, which were as high as in the near-shore subtidal waters of the Yangtze River Estuary. This high abundance implied the important roles of zooplankton in the matter flux between marshes and near-shore waters through complex intertidal creek systems. Zooplankton total densities changed significantly from northern to southern creeks. ANOSIM and CCA analyses revealed that the zooplankton community structure were significantly different among the northern, eastern and southern creeks, and between two sampling seasons. Salinity accounted for most of the spatial variation of zooplankton community, whereas water temperature, chlorophyll a concentration, and pH were the main reasons of the temporal variation observed. Copepods were the most abundant zooplankton group. A total of 24 copepod species, belonging to 15 families and 20 genera, were recorded. Planktonic copepods preferred the northern and eastern creeks, with higher densities in July than in April, while benthic copepods predominated only in the northern creeks in April. Since the role of benthic and planktonic copepods may differ in transporting nutrients in the intertidal creeks, it is suggested that the variations in their distribution may influence the ecological functions of zooplankton in the estuarine matter fluxes both spatially and temporally. 相似文献
10.
Katherine M. Papastephanou Stephen M. Bollens Anne M. Slaughter 《Deep Sea Research Part II: Topical Studies in Oceanography》2006,53(25-26):3078
Cross-shelf distribution and abundance of copepod nauplii and copepodids were measured during three summer upwelling seasons (2000–2002) in a coastal upwelling zone off northern California. These 3 years varied considerably in the intensity of winds, abundance of chlorophyll, and water temperature. The cruises in 2000 were characterized by relaxation conditions, with generally high levels of chlorophyll and high water temperature. The cruises in 2001 and 2002 were dominated by strong and persistent upwelling events, leading to lower chlorophyll and water temperatures. The copepod assemblage was dominated by Oithona spp., Acartia spp. and Pseudocalanus spp., with Metridia pacifica (lucens), Microsetella rosea, Oncaea spp. and Tortanus discaudatus also common during all 3 years. The cross-shelf distribution of copepods was generally shifted offshore during upwelling and onshore during relaxation events, although some variability between species occurred. Abundance of all life stages generally exhibited a negative correlation with cross-shelf transport averaged over at least 1–4 days and lagged by 0–3 days, indicating lower abundances during and immediately after active upwelling. However, copepod nauplii seemed to respond positively to wind events lasting 1–5 days followed by a period of relaxation lasting 6 or 7 days. These rapid rates of change in abundance are probably too great to be due to in situ growth and reproduction alone; physical processes must also play a role. These results suggest a highly dynamic relationship between copepods and upwelling events off northern California, with species-specific responses to upwelling to be expected. 相似文献
11.
Living on the edge: feeding of subtropical open ocean copepods 总被引：2，自引：0，他引：2
The objective of this study was to provide quantitative information on environmental feeding rates of warm water oceanic epipelagic copepods. We determined clearance rates at 23 °C for various particle size ranges in shipboard studies in the western oligotrophic subtropical Atlantic Ocean for females of the calanoid species Clausocalanus furcatus and Mecynocera clausii. These in situ clearance rates were then applied to the various particle size ranges of environmental particle spectra of auto‐ and heterotrophs at different depths from three stations in the western Atlantic. After calculating the metabolic demands of each of these two copepod species and applying an assimilation efficiency of 90%, we determined that C. furcatus meets its metabolic demands in all six cases, and M. clausii in two of six cases. Clausocalanus furcatus would also meet its energy demands at 25 °C, where it is often found, while M. clausii at 20 °C, where it is regularly found, would cover its metabolic needs in four of six cases. It is hypothesized that these species, and most likely most of the other co‐occurring copepod species, are limited in their abundance by food availability, or, better said, are ‘living on the edge’ in relation to food abundance. 相似文献
12.
根据珠江口枯水期(2013年11月)和丰水期(2014年8月) 24个站位调查资料,对中小型浮游动物种类组成、丰度分布、群落结构及其主要影响因子进行了研究.结果表明,枯水期和丰水期分别鉴定浮游动物成体91种和70种,以桡足类最为丰富.浮游动物种类从河口上游向外围逐渐增加.浮游动物丰度时空分布差异显著,丰水期平均值高达11 619. 78 ind/m~3,显著高于枯水期的1 707. 13 ind/m~3.桡足类在珠江口中小型浮游动物中占绝对优势,枯水期和丰水期分别占总丰度的80. 3%和93. 0%,对浮游动物的丰度分布起关键作用.强额孔雀哲水蚤(Parvocalanus crassirostris)、中华异水蚤(Acartiella sinensis)和刺尾纺锤水蚤(Acartia spinicauda)在两个水期均为主要优势种,小拟哲水蚤(Paracalanus parvus)和厦门矮隆哲水蚤(Bestiolina amoyensis)则分别在枯水期和丰水期具有较高的优势度.聚类分析的结果显示,枯水期和丰水期该水域浮游动物均可划分为3个群落.相关性分析表明,珠江口中小型浮游动物群落结构受多个环境因子的影响,但盐度是其中最为关键的非生物因子. 相似文献
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《Deep Sea Research Part I: Oceanographic Research Papers》2006,53(8):1363-1378
Deep-sea hydrothermal vents occur along the mid-ocean ridges and back-arc basins around the globe. There are very few community analyses of vent meiobenthos. The central objectives of this study were to identify and quantify for the first time the entire metazoan meiobenthic community associated with mussel aggregations of Bathymodiolus thermophilus Kenk and Wilson, 1985 from the EPR, 11°N and of Bathymodiolus puteoserpentis Cosel et al., 1994 from the Mid-Atlantic Ridge (MAR), 23°N. Using a quantitative sampling method, abundance, biomass, sex ratio, species richness, diversity, evenness, and trophic structure were studied based on three samples from each site. Meiobenthic abundance in each sample was unexpectedly low, but similar between sites. The community was composed of nematodes, copepods, ostracods, and mites, with a total of 24 species at EPR vents, and 15 species at MAR vents. While most copepod species were vent endemics within the family Dirivultidae, nematodes and harpacticoid copepods belonged to generalist genera, which occur at a variety of habitats and are not restricted to hydrothermal vents or the deep sea. The meiobenthos of hydrothermal-vent mussel beds constitutes a unique community unlike those of other sulfidic habitats, including the thiobios of shallow-water sediments and the meiobenthos of deep-sea, cold-seep sediments. The trophic structure was dominated by primary consumers, mainly deposit feeders, followed by parasites. Predatory meiofaunal species were absent. 相似文献
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台湾以东副热带环流区大中型浮游桡足类的生态特征 总被引：1，自引：0，他引：1
根据1995~1997年期间在台湾岛以东副热带环流区进行4个季度月的综合调查资料,分析了该海域浮游桡足类的数量分布及其群落的生态特征,探讨其与环境因素的相关性.结果表明,本区大中型浮游桡足类呈低丰度(4个季度平均为6.75个/m3)、低优势度(Y<0.131)以及季节变化幅度小等特点.所记录的206种浮游桡足类中,5种生态类群共存.不同性质水系在测区间的动态制约着不同生态类群的配比,但丝毫左右不了热带大洋广布类群的主导地位. 相似文献
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《Deep Sea Research Part I: Oceanographic Research Papers》2000,47(11):2029-2060
On a transect across the Lomonosov Ridge stratified zooplankton tows were made to the bottom at seven stations. A species inventory was established and compared with earlier observations in the Arctic Ocean. Differences between the Amundsen and Makarov basins are relatively small and correspond well with the general circulation patterns for Atlantic, Pacific, and neritic waters, suggesting slow mixing rates for the different basins. There were no remarkable differences in the species composition or their vertical distribution between the two sides of the Lomonosov Ridge. This indicates effective faunistic exchange across the ridge, although several bathy-pelagic species were almost or completely absent on top of the Ridge. Biomass showed a strong gradient along the transect, with a pronounced peak (9.5 g dry weight m−2) in the core of Atlantic water over the ridge, and minima over the deep basins. These differences were related to the effect of bottom topography for deep-living species, and the dynamics of the Atlantic layer for the meso- and epipelagic species. The maximum was formed mainly by the copepods Calanus hyperboreus and Metridia longa together with chaetognaths and ostracods. The presence of young developmental stages in some of the abundant species (C. hyperboreus, M. longa) suggests successful reproduction at all stations but C. finmarchicus was almost exclusively represented as old stages and adults. Comparison with earlier data on abundance and biomass from the Canada Basin (Russian Drift station “North Pole-22”) shows a pronounced difference with respect to both absolute quantities and relative composition. The copepod C. finmarchicus is completely absent in the central Canada Basin, and the portion of non-copepod zooplankton is dramatically decreased. This points to a reduced advection of Atlantic water or more severe food conditions in this basin. 相似文献
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Since the late 1980s, the small-sized non-commercial flatfish species solenette (Buglossidium luteum) and scaldfish (Arnoglossus laterna) have increased in abundance in the southern North Sea. Because these species are considered as possible competitors for prey of commercial flatfish, this study aimed at advancing knowledge of their feeding ecology.Between January 2009 and January 2010 stomach contents of solenette and scaldfish and benthic infauna were sampled seasonally in a study area in the German Bight. The objectives were to investigate the seasonal variability of feeding activity and diet composition of both flatfish species related to benthic prey availability.For both flatfish, the highest feeding activity was found in summer, at the same time that the highest prey densities occurred in the study area. A reduced feeding activity was observed during the winter of 2010, but not in the winter of 2009, probably related to higher 2009 water temperatures.In all seasons, diet composition of solenette was dominated by meiofauna, mainly harpacticoid copepods. Macrofauna prey species, namely juveniles of bivalves and echinoderms became important in spring. An increase in amphipods and cumaceans was found in the stomach contents during summer and autumn, simultaneously with their increased abundance in the benthic infauna. In contrast, polychaetes were rarely found in the diet, but dominated the infauna during all seasons.Diet composition of scaldfish was dominated by larger and mobile prey, and, during all seasons, was mainly comprised of crustaceans. Amphipods characterised the diet in both winters, while decapods such as Crangon spp. and Liocarcinus spp. were the dominant prey from spring to autumn. Additionally, juveniles of flatfish (Pleuronectids) and bivalves were found in the scaldfish diet in spring, replaced by cumaceans in summer. No dietary overlap between both flatfish species was found across seasons, indicating partitioning of prey resources between solenette and scaldfish. Their different feeding strategies and prey preferences, in turn were influenced by the seasonal variability of available prey. 相似文献
17.
Many estuarine and coastal planktonic copepods depend on the hatching of benthic resting eggs for recruitment of nauplii to the water column population. The distribution and abundance of viable resting eggs of Acartia pacifica in the Xiamen Bay were determined by the presence of nauplii in the laboratory. The number of viable eggs varied temporally and spatially. The maximum number (9.2×104m-2) of viable eggs was in summer. In spring the average abundance of viable eggs was 5.6×104 m-2. The abundances of viable eggs in fall and winter were similar, respectively 2.7×104 and 3.3×104 m-2, which were the lowest in the year. The numbers of viable eggs inside the stations of the Xiamen Bay were higher than those outside the stations. The viable eggs were found at all depths (0～10 cm),although not in every station. The maximin number did not necessarily occur in the uppermost centimeter of the sediments but often occurred several centimeters below the water-sediment interface. The accumulation of viable eggs in the seabed of a subtropical bay constitutes a potential source of recruitment of nauplii into the pelagic population. 相似文献
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We collected mesozooplankton samples in the upper 100 m in spring or early summer each year between 1995 and 2000 along a section from Hamilton Bank (Labrador) to Cape Desolation (Greenland), and along additional sections in spring 1997 and early summer 1995. The North Atlantic waters of the central basin were characterised by the presence of the copepods Calanus finmarchicus, Euchaeta norvegica and Scolecithrocella minor and euphausiids. Calanus glacialis, Calanus hyperboreus and Pseudocalanus spp. were associated with the Arctic waters over the shelves. Amongst the other enumerated groups larvaceans were concentrated over the shelves and around the margins. Amphipods, pteropods and the copepods Oithona spp. and Oncaea spp. showed no definable relationships with water masses or bathymetry, while the diel migrant ostracods and chaetognaths were confined to deep water. Metrida longa, also a strong diel migrant, and Microcalanus spp., a mainly deep water species and possible diel migrant, were both sometimes quite abundant on the shelves as well as in the central basin, consistent with their likely Arctic origins.Analysis of community structure along the section across the Labrador Sea indicated that stations could be grouped into five different zones corresponding to: the Labrador Shelf; the Labrador Slope; the western and central Labrador Sea; the eastern Labrador Sea and Greenland Slope; and, the Greenland Shelf. The boundaries between zones varied spatially between years, but community composition was relatively consistent within a given zone and a given season (spring versus early summer). The relationship between community composition and water masses was not entirely straightforward. For example, Labrador Shelf water was generally confined to the shelf, but in spring 2000 when it also dominated the adjacent slope zone, the community in the Labrador Slope zone was similar to those found in other years. Conversely, in spring 1997, when Arctic organisms were unusually abundant in the Labrador Slope zone, there was no increased contribution of shelf water. In addition, North Atlantic organisms were often found on the shelves when no slope or central basin water was present.Although other organisms were sometimes very abundant, the mesozooplankton preserved dry weight biomass was dominated everywhere by the three species of Calanus, which together always accounted for ≥70%. One species, C. finmarchicus, comprised >60% of the total mesozooplankton biomass and >80% of the abundance of large copepods in spring and summer throughout the central Labrador Sea. In western and central regions of the central basin average C. finmarchicus biomass was ca 4 g dry weight m−2 and average abundance, ca 17?000 m−2 over both seasons. Highest levels (ca 7 g dry weight m−2, >100?000 m−2) occurred in the northern Labrador Sea in spring and in eastern and southwest regions in early summer. C. hyperboreus contributed ca 20% of the total mesozooplankton biomass in the central basin in spring and <5% in early summer, while C. glacialis accounted for <1%. Over the shelves, C. hyperboreus contributed a maximum of 54% and 3.6 g dry weight m−2, and C. glacialis, a maximum of 29% and 1 g dry weight m−2, to the total mesozooplankton biomass. 相似文献
20.
A time series of zooplankton sampling carried out at Station 18 off Concepción (36°S, 73°W) from August 2002 to December 2003 allowed the study of annual life cycles of the copepods Calanus chilensis and Centropages brachiatus in association with environmental variability in the coastal upwelling zone. Changes in the abundance of eggs, nauplii, and copepodids were assessed from samples taken at a mean time interval of ca. 20 days. Upwelling variability in near-surface waters was reflected in seasonal changes in salinity, water column stratification, and oxycline depth, as well as a weak seasonal signal in sea surface temperature (1-2 °C). Both copepods exhibited similar life cycles, characterized by continuous reproduction throughout the year. Estimates of generation times, as a function of temperature, were 25-30 days for C. chilensis and 27-35 days for C. brachiatus, predicting about 12 and 10 generations a year, respectively. These estimates were consistent with reproduction pulses observed in the field. It was thus suggested that copepods may grow under non-limiting food conditions in this upwelling area. However, despite continuous reproduction, there were abrupt changes in population sizes along with the disappearance of early naupliar and copepodid stages taking place even during the upwelling season (spring/summer). These changes were attributed to sudden increases in mortality taking place in spring or early summer, after which the populations remained at low levels through the fall and winter. It is thus suggested that, in addition to variability in the physical environment, biological interactions modulating changes in copepod mortality should be considered for understanding copepod life cycles in highly productive upwelling systems. 相似文献