Population dynamics of the ctenophore Mnemiopsis leidyi and its impact on the zooplankton in the coastal regions of the Black Sea of the Crimean coast in 2004–2008

The abundance, biomasses, and population structure of the ctenophore Mnemiopsis leidyi were monitored in the coastal waters of the northern part of the Black Sea (Sevastopol Bay and the adjacent continental shelf regions) in 2004–2008. The abundance and species composition of the comb jelly’s food in the sea were obtained along with experimental data on the digestion time. Based upon these data, the feeding intensity of the ctenophore in situ was estimated. This information was used to calculate the predatory impact of the comb jelly population on certain groups of forage organisms and the forage zooplankton community as a whole. The predatory impact of the M. leidyi population on the bivalve veligers was the highest (up to 90% of the abundance a day) compared to the Copepoda and Cladocera (30% and 40%, respectively). In the summers of 2004–2008, the daily consumption rates of the zooplankton by the ctenophore population in the shelf zone and in the bay were similar to each other: up to 15% and 12% of the abundance a day, respectively. The highest pressure of the ctenophore upon the zooplankton was observed in 2004 and 2008, when M. leidyi was especially abundant in the plankton for a long time.     

Mnemiopsis leidyi (Ctenophora) in Narragansett Bay, 1975–1979: Abundance,size composition and estimation of grazing

Surveys of the distribution, abundance and size of the ctenophore Mnemiopsis leidyi were carried out in Narragansett Bay, R.I. over a 5-year period, 1975–1979. Yearly variations were observed in time of initiation of the ctenophore increase and maximum abundance. Biomass maxima ranged from 0·2 to 3 g dry weight m^?3 at Station 2 in lower Narragansett Bay while maximum abundance varied from 20 to 100 animals m^?3. Ctenophores less than 1 cm in length generally composed up to 50% of the biomass and 95% of the numerical abundance during the peak of the M. leidyi pulse. During the 1978 maxima and the declining stages of the pulse each year, 100% of the population was composed of small animals. M. leidyi populations increased earlier, reached greater maximum abundances, and were more highly dominated by small animals in the upper bay than toward the mouth of the bay. The averageclearance rate of M. leidyi larvae feeding on A. tonsa at 22°C was 0·36 l mg^?1 dry weight day^?1, with apparent selection for nauplii relative to copepodites. Predation and excretion rates applied to ctenophore biomass estimated for Narragansett Bay indicated that M. leidyi excretion is minor but predation removed a bay-wide mean of 20% of the zooplankton standing stock daily during August of 1975 and 1976. Variation in M. leidyi predation at Station 2 was inversely related to mean zooplankton biomass during August and September, which increased 4-fold during the 5-year period.     

Ctenophores-invaders and their role in the trophic dynamics of the planktonic community in the coastal regions off the Crimean coasts of the Black Sea (Sevastopol Bay)

The abundances, biomasses, and population structures of two introduced ctenophore species—Mnemiopsis leidyi and Beroe ovata—were monitored along with mesoplankton in the near-shore waters of the northern Black Sea (Sevastopol Bay and adjacent regions) over a period of four years (2000–2003), after the B. ovata invasion. The annual dynamics of the M. leidyi population were similar in these years: very low abundances and biomass values were observed during the major part of the year (unlike previous years) with a shortterm peak in the summer-early autumn. B. ovata development during the growth in the M. leidyi biomass resulted in a sharp fall in the M. leidyi biomass down to extremely low values. The interannual differences in the populations of both ctenophore species were reflected by their quantitative parameters: the maximum biomass of M. leidyi varied from 790 g/m² in 2001 to 211–266 g/m² in other years. The maximum biomass values of B. ovata (38.9 and 32.5 g/m²) were observed in 2001 and 2003, respectively. In 2000–2003, from July to September, during the peak in mnemiopsis development, the population consumed from 1.9 ± 0.4 to 13.4 ± 5.7% of the mesoplankton biomass per day, while in the years of B. ovata absence, these values were as high as 30–40%. For the first time, the grazing rate of microzooplankton by M. leidi larvae was estimated. In August 2003, the maximum daily consumption rate was as great as 23–25% of the microzooplankton biomass. The daily rations of the mnemiopsis larvae on microzooplankton were close or even higher than those on mesoplankton.     

Interannual variability of the zooplankton on the shelf of the northeastern Black Sea in the autumn period

The variability of the mesozooplankton stock in the shelf pelagic communities was studied in the late summer and autumn of 2006–2008. The plankton community’s structure and distribution were described for the shoreward transect (Gelendzhik city vicinity). The indirect and direct effect of the ctenophores Mnemiopsis leidyi and Beroe ovata on the mesozooplankton community was studied. The long-term changes in the meso- and macroplankton communities of the Black Sea were analyzed for the period of 2001–2008. The effects of the climatic factors, the water mass circulation, and the factors’ interplay on the mesozooplankton dynamics were assessed. Despite the wide range of the environmental conditions, the stock biomass of Mnemiopsis leidyi appeared to be quite stable within the studied period.     

Gelatinous macroplankton in the Black Sea in the autumn of 2010

In October and November of 2010, the gelatinous macroplankton in the northwestern Black Sea and at the Crimean shelf was represented by the scyphozoan jellyfish Aurelia aurita, three species of ctenophores (Beroe ovata, Mnemiopsis leidyi, and Pleurobrachia pileus), and three species of hydromedusae. A. aurita was more common at the shelf, M. leidyi and P. pileus prevailed at the deeper sea stations, and B. ovata was almost ubiquitous with a biomass from below 1 to 49 g/m² A. aurita, which had an average biomass of 82–224 g/m², was dominant at all the stations. M. leidyi, which had a biomass from below 1 to 115 g/m², was recorded in October at only 14 of the 52 stations and in November at 20 of the 46 stations. The highest biomass of M. leidyi in October (105 to 116 g/m²) was recorded in the deep sea areas; in November, it was also the highest in these areas, but it reached at most 100 g/m². The average daily ration of Aurelia ranged from 19.4 to 27.3 mg/m² in October and from 7.0 to 17.2 mg/m² in November; in both cases, it was insufficient to provide for the minimal physiological requirements. The average daily ration of the Mnemiopsis population (2.8–20.5 mg of zooplankton per m²) was invariably more than sufficient to provide for the minimal physiological requirements. Both predatory species together consumed less than 5% of the daily zooplankton production of the sea.     

Annual variability of planktonic ostracods (Crustacea) in the South Adriatic Sea

Temporal variability and population structure of planktonic ostracods were investigated for the first time in the South Adriatic Sea during 1996. The maximal total ostracod abundance (1167 ind·100 m⁻³; 69% juveniles, 18% females and 13% males) was recorded in February. Thirteen species of marine planktonic ostracods were identified. Porroecia spinirostris and Archiconchoecia striata dominated the ostracod assemblage, accounting respectively for 62% and 18% of the total abundance. Their annual peaks were recorded during the cold season, which was the period of their intense reproduction, with favourable temperature conditions and lack of predators. The females surpassed the males in abundance in most species. The presence of the mesopelagic species indicated a strong influence of intermediate layer water masses from the Eastern Mediterranean Sea.     

Seasonal variability of the zooplankton community in the southwest of the Huanghai Sea (Yellow Sea) Cold Water Mass

Samples were collected with a plankton net in the four seasonal cruises during 2006-2007 to study the seasonal variability of the zooplankton community in the southwest part of Huanghai Sea Cold Water Mass (HSCWM, Yellow Sea Cold Water Mass). The spatial and temporal variations of zooplankton species composition, biomass, abundance and biodiversity were examined. A total of 122 zooplankton species and 30 pelagic larvae were identified in the four cruises. Calanus sinicus and Aidanosagitta crassa were the most dominant species, and Themisto gaudichaudi and Euphausia pacifica were widely distributed in the HSCWM area. The spatial patterns of non-gelatinous zooplankton (removing the high water content groups) were similar to those of the total zooplankton biomass in autumn, but different significantly in the other three seasons. The seasonal means of zooplankton biomass in spring and summer were much higher than that in autumn and winter. The total zooplankton abundance averaged 283.5 ind./m~3 in spring (highest), 192.5 ind./m~3 in summer, 165.5 ind./m~3 in autumn and 65.9 ind./m~3 in winter (lowest), and the non-gelatinous groups contributed the most total abundance. Correlation analysis suggests that the non-gelatinous zooplankton biomass and abundance had a significant positive correlation in the whole year, but the relationship was insignificant between the total zooplankton biomass and abundance in spring and summer. The diversity index H of zooplankton community averaged 1.88 in this study, which was somewhat higher than historical results. Relatively low diversity in summer was related to the high dominance of Calanus sinicus, probably due to the strongest effect of the HSCWM in this season.     

Species Composition and Distribution of Zooplankton from Northeastern Sakhalin Shelf (Sea of Okhotsk)

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.     

2001—2002年粤东柘林湾浮游动物的生态学研究

2001年4月-2002年4月,利用生态学方法对粤东柘林湾浮游动物进行的周年调查结果表明,粤东柘林湾浮游动物有桡足类34属60种,枝角类3属3种,及端足类、磷虾、糠虾、多毛类、毛颚类、被囊类、水母和各种浮游幼体虫.浮游动物的群落构成小型化趋势明显,因为体长不足0.6 mm的小型优势种强额拟哲水蚤(Paracalanus crassirostris)、短角长腹剑水蚤(Oithona brevicornis)和鸟喙尖头(氵蚤)(Penilia avirostris)在浮游动物总个体数中所占比例合计高达57.1 %.浮游动物的种类数、总个体数和生物量的平面分布模式大体相似,即湾外大于湾内,外侧大于内侧,东部大于西部.总个体数与生物量的周年变化曲线与水温的变化趋势非常相似,高峰位于高温季节的8-9月,低谷位于冬季2月.调查期间柘林湾浮游动物非常丰富,年均总个体数达15.8×103 ind/m3,生物量达227.8mg*dW/m3.在单一调查年度内,浮游动物丰度与水温、浮游植物细胞数呈显著正相关关系.在不同年份,浮游动物丰度与浮游植物密度则表现为负相关的趋势.     

Collapse of zooplankton stocks during Liriope tetraphylla (Hydromedusa) blooms and dense mucilaginous aggregations in a thermohaline stratified basin

A growing number of studies report an increase in jellyfish populations worldwide that may have consequences for marine planktonic food web dynamics. The principal objective of this study was to understand the changes in a zooplankton community during blooms of Liriope tetraphylla and subsequent mucilage events in the Sea of Marmara, a small highly stratified transitional basin between the Black and Aegean Seas. Liriope blooms observed in 2006 and 2007 reached a maximum abundance of 2978 ind.·m^?3, following the species' first observation in 2005. Jellyfish species are known to play a key guild role by restructuring plankton communities and in the Sea of Marmara Liriope caused a temporal regime shift from a crustacean‐ to a jellyfish‐controlled system. A rapid decline in abundance of most important zooplankton species followed the Liriope increase, together with a drastic shift in community structure. The dominant summer–autumn species Penilia avirostris (Cladocera) vanished in the autumn of 2006 and was diminished ~30‐fold in 2007 when compared with years without Liriope. The decline in zooplankton and the devastating effects of mucilage on pelagic ecosystem and socio‐economics through restricting commercial fisheries implied sensitivity of the already perturbed Marmara ecosystem to changes in predator densities and environmental stability.     

2010年夏季雷州半岛沿岸海域浮游动物群落结构特征

2010年7月对雷州半岛海岸带的浮游动物群落结构及相关环境因子进行了调查,共鉴定出浮游动物87种和34类浮游幼体,其中原生动物4种,占总种类数的4.6%;腔肠动物20种,占总种类数的23.0%;介形类1种,占总种类数的1.1%;枝角类2种,占总种类数的2.3%;桡足类37种,占总种类数的42.5%;十足类2种,占总种类数的2.3%;毛颚动物7种,占总种类数的8.0%;被囊动物6种,占总种类数的6.9%;浮游软体动物8种,占总种类数的9.2%。优势种有13种和3类浮游幼体,孔雀强额哲水蚤和小毛猛水蚤是该海域重要的优势种群,几乎在全海域均为优势种,桡足类幼体为全海域优势类群。半岛沿岸海域浮游动物种类数由近岸往远岸逐渐增多,浮游动物丰度分布则相反。浮游动物种类数由多到少的顺序为东北部、东南部、西北部和西南部、南部,丰度由大到小的顺序为西北部、西南部、东北部、东南部、南部,生物量由大到小的顺序为东北部、西南部、西北部、东南部、南部,浮游动物丰度和生物量的平面分布反映了人类对海岸带开发利用的活动概貌。多样性指数和均匀度平均值分别为2.96和0.57。相关分析表明:浮游动物丰度与水温、细菌总数、浮游动物生物量均呈极显著的正相关关系,与磷酸盐呈显著的负相关关系;浮游动物生物量与TOC、细菌总数、叶绿素a、浮游植物丰度均呈极显著的正相关关系,与pH呈显著的正相关关系,与盐度呈显著的负相关关系。     

2008年初冷事件对南海北部夏季浮游动物的影响

2008年初,我国南方出现了罕见的低温冰冻极端天气过程。通过对2007年8月和2008年8月南海北部现场调查所获得的数据分析研究了浮游动物种类组成。结果表明,与2007年8月相比2008年8月浮游动物丰度和生物量有很大的下降。聚类分析结果表明浮游动物群落被分为近岸和远海两大类群。浮游动物近岸类群和远岸类群的分界点在不同的时间有所不同,这是由于外海水向近岸的入侵所致。与2007年8月相比,2008年8月浮游动物优势种发生了很大的演替,主要是因为四种浮游动物优势种亚强真哲水蚤、异尾宽水蚤、锥形宽水蚤和小哲水蚤丰度急剧下降所致。相反,水母类和海樽类丰富有很大的升高,其原因可能是2008年春季极端低温导致的鱼类大量死亡所致。与远岸浮游动物群落相比,近岸浮游动物群落变化更剧烈,这说明近岸浮游动物群落结构不稳定。南海北部浮游动物群落结构的变化与2008年初的冷事件有很大关系。     

A study on zooplankton distribution patterns and indicator species in Kuroshio upstream area and adjacent East China Sea

On the basis of the data of zooplankton biomass and three major taxa—— Copepoda, Chaetognatha andSiphonophora of May-June 1986, July-August and December 1987, the distributional patterns and the indicator species of zooplankton in the Kuroshio and adjacent waters of the East China Sea are preliminarily studied. The results are as follows:The horizontal distribution of zooplankton biomass and the abundance of copepods, chaetognaths and siphonophores arecurred in the continent area northwest of Taiwan and the south-centre section of the East China Sea continent, which are the mix front of different waters. Zooplankton in the water area inside of Ryukyu Islands presented low abundance and high diversity. There are clear seasonal variations in zooplankton biomass and abundance in the study area. The strength or weakness of different water masses and fronts is the basic reason for the variations of zooplankton biomass and abundance.The species composition of zooplankton in the study area is complex and var     

Length-weight relationships of important zooplankton from the Inland Sea of Japan

Measurements of dry weight, carbon- and nitrogen contents together with the body length of important zooplankton from the Inland Sea of Japan were made using freshly caught specimens. The values of the former three parameters were found to be highly correlated to length, and species specific regression equations were calculated for 10 species of Copepoda (Calanus sinicus, Euchaeta plana, E. concinna, Centropages abdominalis, Sinocalanus tenellus, Acartia clausi, A. tsuensis, Tortanus forcipatus, Oithona brevicornis andO. similis), 3 species of Cladocera (Podon leuckarti, P. polyphemoides andPenilia avirostris), 1 species of each of Mysidacea (Neomysis japonica), and Natantia (Acetes japonicus), and two forms of Chaetognatha (Sagitta crassa andS. crassa f.naikaiensis).     

珠江口无瓣海桑(Sonneratia apetala)湿地中浮游动物构成及富营养化评价

选择珠江口南沙区两处典型的以大面积人工种植红树植物无瓣海桑(Sonneratia apetala)为主的感潮河涌,进行湿地区域中的浮游动物研究。于2011年5月和11月对开放性河涌湿地14涌(A区)和封闭性河涌湿地19涌(B区)中的浮游动物进行调研,从种类数和丰度、污染指示种和优势种、营养指数E和污染指数A等方面对浮游动物进行群落结构和功能的分析,并以此对湿地水质和无瓣海桑的净化能力进行评价。结果表明,B区林内原生动物总丰度可达106ind/L数量级,7种丰度优势种均为纤毛虫类,优势种哑铃中缢虫(Mesodinium rubrum),1种赤潮原生动物种类,单种丰度在春秋两季可达1.8×105ind/L、5.1×105ind/L。桡足类、枝角类在春季B区林内丰度最高,分别可达576ind/L和46ind/L,显示春季可能为其繁殖季节。轮虫相对不耐污染生境。指数E和指数A均远高于判断阈值。提出了二项浮游动物的富营养判断标准和二条原则。据此判断,B区湿地存在极重的有机污染现象,主要可能与无瓣海桑林内凋落物量较大或根系分泌物的作用且林内水流不畅有关。     

Condition of coastal mesoplankton communities in the northeastern area of the Black Sea in 2005

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.     

春季长江口及毗邻海域浮游动物空间分布及与环境因子的关系

于2009年4月15～23日在长江口及其邻近海域进行了32个站位的浮游动物生态调查,分析了浮游动物的种类组成、优势种、丰度和生物量的空间分布,并利用PRIMER生物统计学软件中的PCA、BIOENV和RELATE程序分析了浮游动物与环境因子的关系.共发现浮游动物成体72种,浮游幼虫9种,合计种类数为81.中华哲水蚤(C...     

钦州湾丰水期和枯水期浮游动物群落特征

在2011年丰水期(7月)和2012年枯水期(3月),分别对钦州湾的内湾和外湾开展了浮游动物调查,研究了枯水期和丰水期钦州湾浮游动物的种类组成、数量分布和季节变化特征。丰水期和枯水期浮游动物种类数量分别为27种和44种,以优势度指数Y0.02确定的优势种丰水期和枯水期分别为3种和4种。丰水期浮游动物丰度为4.0~133.6ind/m3,平均丰度为50.9ind/m3;枯水期浮游动物丰度为1.2~1 725.0ind/m3,平均丰度为272.2ind/m3。丰水期浮游动物(包含鱼卵仔鱼)生物量为1.7~179.2mg/m3,平均生物量为44.0mg/m3;枯水期浮游动物(包含鱼卵仔鱼)生物量为3.1~3 530.0mg/m3,平均生物量为474.9mg/m3。无论是浮游动物的种类数量、丰度和生物量,均显示出内湾低于外湾的空间分布特征,以及枯水期高于丰水期的变化特征。钦州湾浮游动物的这种季节变化和空间分布特征主要是与浮游植物生物量、贝类养殖、环境的稳定度以及人为干扰等有着密切的关系。     

Abundance, Biomass, C- and N- Content of Flaccisagitta enflata and Mesosagitta minima (Chaetognatha)

Abstract The annual variability in abundance and biomass of Flaccisagitta enflata (Grassi, 1881) and Mesosagitta minima (Grassi, 1881), along with the C‐ and N‐content of their different maturity stages, were investigated in the South Adriatic Sea on a weekly basis throughout 1996. Increases in abundance and biomass of F. enflata [maximum 554 indiv. · (10 m³)^–1 and 16.3 mg C · (10 m³)^–1] and M. minima [maximum 336 indiv. · (10 m³)^–1 and 3.1 mg C · (10 m³)^–1] were found in summer and autumn, a time of intense reproduction for these species. Mean carbon content (as a percentage of dry weight) varied from 30.41 to 40.39 % among maturity stages for F. enflata, and from 27.73 to 39.31 % for M. minima. Nitrogen contents of both species were ～ 3 to 3.5 times less than carbon contents and varied less. Accurate estimates of chaetognath biomass as carbon should be based on the separate contribution of each maturity stage present in the total population.     

Ecohydrographic constraints on biodiversity and distribution of phytoplankton and zooplankton in coral reefs of the Red Sea,Saudi Arabia

An integral concept of ecological research is the constraint of biodiversity along latitudinal and environmental gradients. The Red Sea features a natural example of a latitudinal gradient of salinity, temperature and nutrient richness. Coral reefs along the Red Sea coasts are supported with allochthonous resources such as oceanic and neritic phytoplankton and zooplankton; however, relatively little is known about how the ecohydrography correlates with plankton biodiversity and abundance. In this article we present the biodiversity of phytoplankton and zooplankton in Red Sea coral reefs. Oceanographic data (temperature, salinity), water samples for nutrient analysis, particulate organic matter, phytoplankton and zooplankton, the latter with special reference to Copepoda (Crustacea), were collected at nine coral reefs over ~1500 km distance along the Red Sea coast of Saudi Arabia. The trophic state of ambient waters [as indicated by chlorophyll a (Chl a)] changed from strong oligotrophy in the north to mesotrophy in the south and was associated with increasing biomasses of Bacillariophyceae, picoeukaryotes and Synechococcus as indicated by pigment fingerprinting (CHEMTAX) and flow cytometry. Net‐phytoplankton microscopy revealed a Trichodesmium erythraeum (Cyanobacteria) bloom north of the Farasan Islands. Several potentially harmful algae, including Dinophysis miles and Gonyaulax spinifera (Dinophyceae), were encountered in larger numbers in the vicinity of the aquaculture facilities at Al Lith. Changes in zooplankton abundance were mainly correlated to the phytoplankton biomass following the latitudinal gradient. The largest zooplankton abundance was observed at the Farasan Archipelago, despite high abundances of copepodites, veligers (Gastropoda larvae) and Chaetognatha at Al Lith. Although the community composition changed over latitude, biodiversity indices of phytoplankton and zooplankton did not exhibit a systematic pattern. As this study constitutes the first current account of the plankton biodiversity in Red Sea coral reefs at a large spatial scale, the results will be informative for ecosystem‐based management along the coastline of Saudi Arabia.