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1.
In October 2005 spatial distribution of live and dead Acartia clausi and Acartia tonsa was studied in the Black and Marmara Seas and near the Marmara Sea inlet of the Bosphorus, in order to understand their fate upon transportation between two seas. The morphometric characteristics in both species from all studied areas, and the decreased abundance of A. clausi and A. tonsa from the Black Sea towards the Marmara Sea indicate that the Marmara Sea Acartia populations are formed by recruitment from the Black Sea. We observed mass mortality of A. clausi in the Marmara Sea near the Prince Islands. The majority of carcasses (66% of total A. clausi numbers in the Marmara Sea) were found in the salinity gradient layer.  相似文献   

2.
Noctiluca scintillans is a common and numerous component of the heterotrophic plankton living in the Black Sea. It can play a significant role in the trophic dynamics of the pelagial community. The ingestion rate for the Black Sea Noctiluca is experimentally measured in this article, and its influence on the plankton community over the spring period is estimated. The average grazing of phytoplankton by the N. scintillans population made up about 0.8% in March. In local swarms, it was up to 11%. Noctiluca grazed 4.6% of the primary production per day in June. The grazing of Calanus euxinus eggs by the Noctiluca population varied from 1% to 42% in March. Then, it was 16% in April and 23% in June. The grazing of Acartia clausi eggs was from 1% to 7% in March–April (up to 80% in Noctiluca swarms), from 60% to 817% in May, and 45% in June. The grazing of Calanus faecal pellets was less than 1% in March–April and more than 20% in the beginning of June. It is the first time when the cumulative daily ration (subject to its various food components) for N. scintillans has been measured. The size of the ration was significantly higher than the energy expenditures on metabolism both in March (0.21 μg of C/ind/day) and in the beginning of June (0.28 μg of C/ind/day). Thus, the rapid growth of the population was enabled.  相似文献   

3.
The effect of environmental factors (river discharge, water temperature and dissolved oxygen saturation) on the abundance and distribution of Acartia populations and the interactions between their congenerics was evaluated by means of transfer function (TF) models in the estuary of Bilbao during the period 1998–2005. The recorded species were Acartia clausi, Acartia tonsa, Acartia margalefi and Acartia discaudata. Acartia clausi dominated in the entire euhaline region of this estuary until 2003 when it was displaced from the inner part by A. tonsa. This invasive species (A. tonsa) was found for the first time in 2001 and colonized successfully the inner (salinity 30) and intermediate (salinity 33) waters of this estuary since 2003. The TF models revealed an immediate and negative effect of A. tonsa on A. clausi in the intermediate salinity (33) waters, where these species showed the highest spatial overlap. The results indicate that environmental changes from 2003 influenced the abundance of Acartia species, being unfavourable for A. clausi. The decrease of A. clausi abundance in low salinity waters was related to a significant decrease of dissolved oxygen saturation levels, whereas the increase of temperature was linked to a significant increase of A. tonsa. Acartia margalefi and A. discaudata were scarce over the entire period, but they were found to be valuable indicators of hydrological changes, which were associated to climate factors. These two latter species increased in abundance and expanded their seasonal distribution, and in the case of A. margalefi also its spatial distribution, in 2002, coinciding with the period in the time-series when autumn–winter rainfall and summer temperatures were lowest, and dissolved oxygen saturation levels were highest.  相似文献   

4.
Studies were conducted at the end of June 2011 in the coastal region of the northeastern part of the Black Sea. The bulk of the Noctiluca scintillans population was observed in the thermocline and reached a density of 40000 ind./m3. Analysis of digestive vacuoles content showed that Noctiluca could consume cells of Neoceratium tripos and N. furca, which had been considered inedible for Black Sea zooplankton, as well as temporary cysts of dinoflagellates, presumably of the toxic genus Alexandrium. The Noctiluca population consumed in total 10–30% of the abundance of temporary cysts, 2–29% of primary production, and 2–9% of potential Calanus euxinus egg production. For the first time, the excretion rates of ammonium nitrogen and mineral phosphorus were measured for N. scintillans. Our calculations showed that in summer, excretion by Noctiluca contributed from 4 to 18% and from 15 to 53% of phytoplankton total nitrogen and phosphorus requirements, respectively. The specific growth rate of Noctiluca (0.17–0.35) in summer, estimated from data on the daily food intake and respiration rate, was close to the values obtained in spring.  相似文献   

5.
It is indeed my great honor to receive the Okada Prize (1983) for my studies on the population dynamics and production of inshore marine copepods. This article summarizes the lecture I gave under the above title. It has long been postulated that there is some mechanism whereby a species can repopulate after its disappearance from the plankton, since the appearance of many temperature marine copepods clearly occurs on a seasonal basis. During the last decade, evidence of resting egg production has been found for more than 20 species belonging to Temoridae, Centropagidae, Pontellidae, Acartiidae and Tortanidae. In the Inland Sea of Japan, a summer-fall copepodTortanus forcipatus lays diapause (obligatory resting) eggs in the fall, which overwinter in the sediment on the sea floor until the following summer when water temperature reachesca. 15°C. On the other hand, in Onagawa Bay,Acartia clausi is perennial and produces only subitaneous eggs, many of which, however, sink to the bottom and undergo quiescence (facultative resting eggs) due to adverse environmental conditions (e.g. low temperature, deoxygenation, darkness). There are a large quantity (0.5–2.0×106 eggs m−2) ofA. clausi resting eggs in the sediments of Onagawa Bay, which may play an important role in maintaining a more constant planktonic population. The parameters of population dynamics,i.e. the rates of egg production, recruitment and mortality, have been analyzed forA. clausi in Onagawa Bay, by an integration of field and laboratory studies. Recruitment into the planktonic population older than NIII only accounts for 10–20% of egg production. This apparent loss of eggs, which coincides with the benthic resting phase, may be a characteristic feature of the population dynamics of this species. Stage-specific mortality is generally similar in most of the stages, although CI and CVI suffer more severe mortality, possibly as a result of great morphological change in the former stage and heavy predations in the latter. The seasonal change in daily production byA. clausi has also been investigated, its annual production being 2.45 gC m−2. Daily production and biomass (P:B) ratios increase linearly with temperature. Estimated values of production for other inshore marine copepods are reviewed in relation to P:B ratios and the ratio between secondary and primary production.  相似文献   

6.
Diel changes in vertical distribution and gut pigment contents of Acartia clausi andPseudodiaptomus hessei were studied during several 24-h time series performed between 1993 and 1997 in four sites of the Ebrié Lagoon (Côte d'Ivoire). The sites differed by their morphology and their hydrological structure and by the vertical distribution of chlorophyll biomass. Both species showed classical diel vertical migrations (DVM). Copepodites and adult stages of P. hessei were almost benthic during the day and evenly distributed through the water column at night. The amplitude of DVM of A. clausi increased from copepodites I–III to adults. Copepodites and adults of A. clausi increased significantly their gut fluorescence at night, whereas those of P. hessei showed no clear diel feeding rhythm (DFR). These results suggest that A. clausi feed mostly at night on phytoplanktonic particles and P. hessei feed mostly on benthic algal particles during the day and on sestonic particles at night. No relationship was observed between DFR and DVM because both patterns occurred when food was either vertically homogeneous or vertically stratified. The daily average gut fluorescence of A. clausi increased with ambient chlorophyll concentration until around 12–15 μg l−1, whereas no relationship was found for P. hessei. The implication of these patterns on the adaptation capacities and the behaviour of the two species are discussed. The DVM of P. hessei should explain its rarity in the estuarine area. The comparison of our results with previous ones suggests an evolution of A. clausi DFR between 1981–1982 and 1996–1997, in relation to an intensification of eutrophication.  相似文献   

7.
The feeding of abundant herbivore plankton species has been investigated during different stages of coccolithophorid development in the northeastern Black Sea, namely, at the initial stage of development (March 2009) and at the massive bloom stage (June 2011 and May 2013). The role of coccolithophorids as a food source for Black Sea copepods Calanus euxinus, Acartia clausi, and Pseudocalanus elongatus; the heterotrophic dinoflagellate Noctiluca scintillans; and the larvacean Oikopleura dioica has been characterized for the first time. The contribution of coccolithophorids to copepod ration was low (0.2 to 13% of total carbon intake) during all study periods. The content of these organisms in the diet of N. scintillans ranged from 17 to 100%. The coccolithophorid bloom apparently had a stronger positive effect on the nutrition of fine filter feeders, such as N. scintillans and O. dioica, than on copepod nutrition. Daily coccolithophorid consumption by zooplankton ranged from 0.7 to 39.4% of the biomass in different study periods. The grazing of N. scintillans and O. dioica populations made the greatest contribution to coccolithophorid consumption (up to 26 and 23% of the coccolithophorid biomass, respectively).  相似文献   

8.
The monthly distribution of zooplankton communities in Han River estuary was investigated at two stations from July 1998 to June 1999. Monthly mean abundance of total zooplankton varied remarkably, with the range from 20 indiv.·m-3 to 19,600 indiv.·m-3. During the study period, dominant species of zooplankton community were dinoflagellateNoctiluca scintillans, copepodsParacalanus indicus, Paracaanus crassirostris, Acartia hongi, Acartia ohtsukai, and meroplanton cirriped larvae. According to tidal states, relative high abundance occurred at high tide without regard to season. The temporal distribution of abundance implied that the reduced salinity probably limited the zooplankton populations and the fluctuations of salinity were an important factor in the variation of abundance. However, the results of salinity tolerance test shows that the variations in salinity do not directly influence the decrease of abundance. This study shows that the relatively high abundance of zooplankton near high tide seems to be related with the expansion of abundant zooplankton inhabiting Incheon coastal waters through tidal currents.  相似文献   

9.
The influence ofNoctiluca's predation on theAcartia population in Ise Bay was examined by taking samples at 27 stations once a month from May to December, 1974.The copepod eggs were found inNoctiluca mainly in May and June. Considering from various spawning types of copepods, the eggs were presumed to beAcartia, the most numerous species of all copepods in the bay.Noctiluca was dominant plankton in May and June whenAcartia was abundantly distributed.Acartia eggs were found in 33.2–39.3% of individuals ofNoctiluca in May and June.Noctiluca was more frequently observed to contain one egg ofAcartia per individual. It was suggested that 55.0 eggs perAcartia female per day were eaten by theNoctiluca population in May wherease 3.5 eggs in June. It was deduced that 74% of the eggs produced byAcartia was preyed on byNoctiluca (about 5% in June). The predation byNoctiluca as well as that by the sand-eel must influence greatly to the production ofAcartia in the bay.  相似文献   

10.
Acartia bifilosa (Copepoda: Calanoida) is a common species in offing of global waters and it often becomes dominant species in some estuaries. This species develops different strategy according to variation of environment. Despite its ecological role, Acartia bifilosa also has been concerned as live feeds in aquaculture, but study on egg production rate of this species in saturated diet in different temperature and different diet is so far not available. In order to interpret the importance of temperature and diet on natural population variation and also on aquaculture as foods of larval fish, the functional response of reproductive success of Acartia bifilosa was quantified in the laboratory using different temperatures and diets. Acartia bifilosa was captured in Jiaozhou Bay and acclimated to corresponding temperature for 3~4 days. In order to reduce the effect of large extent temperature range on organism, we captured Acartia bifilosa from March to June and acclimated them to temperature which is adjacent to natural temperature. Daily egg production rate (EPR, eggs female-1day-1) was detected for 11~15 days at 5 different temperatures ranged from 8.0 to 23 °C and all the females was feed on saturated diet all through the experiments. EPR on first day was not calculated in the mean EPR to eliminate the effect of different diets. This result showed that Acartia bifilosa spawned continuously during the experiment days and no obvious regulation was found. EPR was positively correlated with temperature from 8.0 to 23 °C. The highest mean EPR was observed at 23 °C (7.3 eggs female-1day-1), and the lowest value was found at 8 °C (3.8 eggs female-1day-1). The effect of diets on EPR was evaluated at two different temperatures (8.0 °C and 12.5 °C). Same trends were found at the two temperatures: mean EPR fed on Chaetoceros sp. was higher than that fed on Skeletonema costatum, and during the 14-day experiments, EPR was higher for females fed on Skeletonema costatum than chaetoceros sp. in the first few days (3~5 days), but it changed reversely in the subsequent days until the end of the experiments. Hatched eggs were observed in the two experiments at temperature 8°C and 12.5 °C and no diapause eggs were found. The hatching success rate was low at 8°C but reached 93.2% at 12.5 °C. According to the results in this paper, we detected the comfortable temperature range for EPR, and evaluated the effect of Skeletonema costatum which often brings out red tide in natural waters. These results are beneficial to ecological research for explaining population variation and population recruitment of this species, These data also can be used in Acartia bifilosa aquaculture.  相似文献   

11.
Mero- and holoplanktonic organisms from 23 large taxa have been detected in the coastal waters of Morocco. Seven Cladocera species and 164 Copepoda species were identified. Copepod fauna mostly consisted of oceanic epipelagic widely tropical species, but the constant species group (frequency of occurrence over 50%) included neritic and neritic–oceanic widely tropical species. The neritic community that formed a biotopic association with coastal upwelling waters and the distant-neritic community associated with Canary Current waters were the two major communities detected. The former community was characterized by a high abundance and biomass (5700 ind./m3 and 260 mg/m3) and predominance of neritic species. The trophic structure was dominated by thin filter feeders, mixed-food consumers, and small grabbers; the species structure was dominated by Paracalanus indicus, Acartia clausi, and Oncaea curta; the indices of species diversity (3.07 bit/ind.) and evenness (0.63) were relatively low. The latter community was characterized by low abundance and biomass (1150 ind./m3 and 90 mg/m3); variable biotopic, trophic, and species structure; and higher Shannon indices (3.99 bit/ind.) and Pielou (0.75). Seasonal variation of the abundance of organisms was not detected in the communities. Anomalous mesozooplankton states were observed in summer 1998 and winter 1998–1999.  相似文献   

12.
The species composition, density, biomass, and distribution of zooplankton of the northeastern Sakhalin shelf, Sea of Okhotsk (Chaivo, Pil’tunskii, and Morskoi regions) were studied in October 2014. Zooplankton was represented by 15 taxonomic groups, which were dominated by Copepoda (13 species). The average density and biomass was highest in the Chaivo region (14112 ± 4322 ind./m3, 395 ± 107 mg/m3) and in the Pil’tunskii region (16692 ± 10707 ind./m3, 346 ± 233 mg/m3); the abundance of detected taxonomic groups was minimal (8–12). The average density and biomass of zooplankton was up to 4304 ± 2441 ind./m3, 133 ± 77 mg/m3 in the Morskoi region and increased with depth; the abundance of taxa was maximum (15). Four species of copepods made up the majority of the density and biomass of zooplankton: Acartia hudsonica, Eurytemora herdmani, Pseudocalanus newmani, and Oithona similis. In the Chaivo region, species of the genera Acartia, Eurytemora, and Oithona dominated and subdominated; in Pil’tunskii region, species of the genera Acartia and Oithona dominated and subdominated; and in the Morskoi region, species of the genera Oithona, Pseudocalanus, and Acartia dominated and subdominated.  相似文献   

13.
The occurrence of the zooplankton at 21 stations in Yatsushiro-kai, western Kyushu, was investigated in June, September and November of 1968, and March of 1969. Copepods formed the most predominant constituent among the collected Zooplankton. AlthoughParacalanus parvus was abundant in most of the surveyed region, other copepods occurred dominantly in the following order when going from the northeastern area toward the southwest: Oithona nana→Acartia clausi→Microsetella norvegica→Oithona similis→Corycaeus spp. Yatsushiro-kai can be characterized biologically by dividing it into two main regions. The northern half is more embaymental and the southern half is more oceanic, bordered by an area whereMicrosetella norvegica occurred as the dominant. The area whereAcartia clausi occurred dominantly is the most embaymental in the northern half, and the area whereCorycaeus spp. occurred dominantly is the most oceanic in the southern half.  相似文献   

14.
浮游动物死体是海洋沉降碳通量的重要组成部分,研究浮游动物死体对于准确评估特定海区生物泵碳通量具有十分重要的意义。为了解夏季南黄海浮游甲壳动物在自然海区的死亡情况,采用2019年7~8月在南黄海获取的浮游动物样品,使用中性红染色法分析了浮游甲壳动物死体的平面分布及其受控环境因素。结果表明,夏季南黄海浮游甲壳动物平均丰度为(1 378.3±929.84) ind./m3,其死体比例在5.0%~68.8%之间,平均为33.3%±16.6%。桡足类是浮游甲壳动物的主要类群,平均丰度为(1 202.9±937.4) ind./m3,死体比例在3.6%~69.7%之间,平均为38.6%±17.0%,与全球海域浮游桡足类的平均死体比例相当。不同浮游甲壳动物优势种的死体比例存在差异。其中,拟长腹剑水蚤(Oithona similis)死体比例最高(62.0%),鸟喙尖头溞(Penilia avirostris)最低(17.9%)。与环境因子的相关性分析结果表明,海水温度和盐度是影响夏季南黄海浮游甲壳动物死体比例的主要影响因子。小拟哲水蚤(Paracalanus parvus)死体比例和表层温度显著正相关,拟长腹剑水蚤和近缘大眼剑水蚤(Corycaeus affinis)的死体比例与表底温差具有显著的正相关;而表层盐度与克氏纺锤水蚤(Acartia clausi)的死体比例存在正相关关系。该研究结果可为深入认识南黄海海洋生态动力学过程和海洋碳通量等相关研究提供重要的参考资料。  相似文献   

15.
Grazing of the copepods Acartia clausi and Pseudodiaptomus hessei on natural particles was studied from on board experiments during several 24 h time series performed between 1993 and 1997 in four sites of the Ebrié Lagoon (Côte d'Ivoire). Ingestion rates of both species increased linearly with food concentration until a concentration threshold (5.5×109 μm3 l−1 for A. clausi and 5.2×109 mm3 l−1 for P. hessei) beyond which the relation presented a plateau. Both species poorly selected the peak of available particles (range 3–6 mm equivalent spherical diameter, ESD) but A. clausi seek preferentially smaller particles (6–21 μm ESD) than P. hessei (9–33 μm ESD). When the proportion of the preferred particles in the food offered decreased, A. clausi extended its selectivity towards both smaller and larger particles whereas P. hessei extended its selectivity towards larger particles only. As a consequence of these patterns, the useful particle concentration (UPC) was higher for A. clausi than for P. hessei. In addition, the ratio of the UPC for the two species showed a positive relationship with the ratio of their respective biomass. The significance of these results for the adaptation capacities of the two species and for the ecosystem functioning are discussed. A. clausi which is more suited than P. hessei to exploit smaller particles (3–6 μm) which dominate the seston, has a food competitive advantage. The inadequacy between the seston food-size composition and the selective patterns of the two main zooplankton species of the Ebrié Lagoon explains that they could be food limited despite the high trophic level of the lagoon. It could also partly explain the low transfer efficiency between phytoplankton and zooplankton in this ecosystem.  相似文献   

16.
Abstract. Seasonal changes in zooplankton biomass, abundance and species composition were studied at a neritic station in the Balearic Sea between April 1993 and May 1994. Sampling was carried out every 10 days in a zone influenced by the main current circulating through the Mallorca channel. Three main peaks of zooplankton biomass and abundance were observed: (1) at the beginning of summer when the thermocline developed, (2) in autumn when the thermocline broke down, and (3) in early spring. The smaller zooplankton fraction (100–250 μm) comprised on average 32 % of the total biomass and 73 % of total abundance. Copepods were the predominant group (64 % of the total abundance) with Clausocalanus, Oithona and Paracalanus being the most abundant genera. Paracalanus parvus, Clausocalanus furcatus, Acartia clausi, Oithona plumifera, Temora stylifera, Centropages typicus and Oncaea mediterranea were found to be the most important species in the area. Other abundant groups were cladocerans (15 %) and meroplankton larvae (12 %), both of which were particularly numerous during the stratified period. The copepod community was characterized by the above‐cited perennial species, which were abundant during the cycle studied. However, the influence of the hydrological conditions of the Balearic Sea, such as the Atlantic water influx and the physical structure of the water column (stratification and mixing), promoted the observed variability in zooplankton as well as the appearance of characteristic species during the annual cycle.  相似文献   

17.
The neritic planktonic copepodAcartia hudsonica is redescribed from the Atlantic and Pacific coasts of North America and newly from Japanese waters. This species formerly has been identified asA. clausi in the Northwest Pacific. The Atlantic and Pacific populations cannot be morphologically separated even in fine ornamentation; the variations found in the two populations overlap each other. Prosome length/width ratio of the female is negatively correlated with the body size and the ratio is not significantly different between Atlantic and Pacific females of the same size. The length/width ratio of the genital segment of Pacific females is positively correlated with their body size, and the mean value of the ratio for Atlantic females is smaller than that expected for Pacific females of the same size. The size-temperature relationship differs among localities but it is uncertain whether there is a genetic difference in copepod size between the Atlantic and Pacific populations.  相似文献   

18.
Mesozooplankton community composition at the species/taxa level was investigated from January to December 2001, at eight stations in the northern Adriatic Sea. Annual dynamics, taxonomic composition and spatial diversity in relation to different trophic conditions are discussed as related to previous studies and to different conditions, such as the presence of mucilage events. Zooplankton communities all over the northern sub‐basin were dominated by the cladoceran Penilia avirostris in summer, and by the calanoids Paracalanus parvus, Acartia clausi and the poecilostomatoids Oncaea spp. during the rest of the year. Whereas coastal communities were more variable with time and location, we were able to identify a group of offshore stations with a similar species/taxa composition and annual dynamics. Comparing the present results with previous studies, we observed significant changes in community composition in the time scale of 20 years, mostly due to a general decrease of A. clausi as the dominant species, being replaced by P. parvus. Also, P. avirostris swarms appear to have extended their temporal occurrence, and were present for longer periods of time when compared to past records. These changes might be related to the observed general increase of the average sea water temperature in the northern Adriatic Sea.  相似文献   

19.
The structure and distribution of mesoplankton in the northeastern part of the Black Sea along 6-mile and 100-mile sections in the area off Golubaya Bay (near the city of Gelendzhik) were analyzed. The studies were performed from R/V Akvanavt and the boat Ashamba. The observations were carried out during the vegetation season from the beginning of June to the first half of October 2005. Samples of mesoplankton were collected with use of a BSD net with an opening of 0.1 m2 and a mesh size of 180 μm. Both the total (over the entire water column) and layer-by-layer (separately for the upper quasi-homogeneous layer, the seasonal thermocline, and the subthermocline layer) hauls were performed down to the bottom (at sea depths of less than 200 m) or down to the upper boundary of the hydrogen sulfide waters. The particular hydrophysical conditions that were observed in 2005 resulted in an approximately one-month advance of the phenological condition of the planktonic community as compared to the usual pattern. Beroe ovata appeared in the plankton at the end of July, the mass development of Mnemiopsis leidyi was suppressed, and the duration of its influence on edible zooplankton was essentially reduced. As a result, the total mesoplankton biomass in August–October 2005 was 1.5–2 times as great as that in 2004. The abundance of Acartia clausi increased approximately 4–5 times and the quantity of Sagitta setosa also considerably increased. At selected stations, Mnemiopsis leidyias, the main predator in the community, was replaced by Sagitta setosa.  相似文献   

20.
1Introduction Benthic -pelagic coupling refers to the two -way exchange or flux of matter between benthic andpelagic environments in aquatic systems. Most stud-ies have focused on the deposition of non-living or-ganic matter to the seabed, resuspension an…  相似文献   

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