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1.
Food differentiation among coexistent species in the field is important strategy for copepods to acquire materials and maintain population stabilization.In situ diet analysis of co-occurring six copepod species in coral waters of the Sanya Bay was conducted using a PCR protocol based on 18 S ribosomal gene.Various prey organisms were uncovered,including dinoflagellate,diatom,green algae and plant,protozoa and metazoan.All these spatially coexisting six species showed different dietary diversity,with the food niche breadth(B)ranging from 1.00(Temora turbinate in morning)to 10.68(Calanopia elliptica in night).While food overlap between all these copepods were low,with the average value of the diet niche overlap index being approximately 0.09.Even temporally co-existing species sampled from the same time point fed on different groups of prey items with the food overlap index of 0.04 to 0.07 in midday and night but 0 in morning.As the most important dominant copepod in the Sanya Bay,Subeucalanus subcrassus seems to be capable to regulate its feeding,by exhibiting a rhythm of herbivorous feeding in midday and carnivorous feeding in morning and night,to better coordinate with other competitors for utilization of food resources.For most copepods,none of the prey items belonged to the dominant phytoplankton in the ambient water,indicating that copepod can better their survival by widening the choice of potential food resources in food limited environment.The dietary separation observed here might be important strategy for copepod to maintain population stabilization and thriving in the Sanya coastal waters. 相似文献
2.
Food and feeding of small fish in the Rakaia River,New Zealand 总被引：1，自引：1，他引：0
Benthic macroinvertebrates and fish species were collected at monthly intervals during a 12‐month period, from 3 areas of the lower Rakaia River. The composition and abundance of the benthos and stomach contents of the fish were analysed for seasonal trends, food niche breadth and overlap between pairs of fish species, and overlap between the benthos and the diet of each fish species. The diets of bluegilled bully (Gobiomorphus hubbsi), upland bully (G. breviceps), juvenile longfinned eel (Anguilla dieffenbachii), Galaxias brevipinnis, G. paucispondylus, and juvenile brown trout (Salmo trutta) were similar to the proportions of prey species in the benthos. Deleatidium and chironomid larvae dominated the benthos in all seasons and formed the majority of food items in the diet of these species. Food niche overlap between these species was high, indicating potential competition, but preferred habitat and feeding habit differences plus low fish population density and abundance of main prey items probably eliminate the occurrence of any serious competition. The diet of the other fish species differed from this pattern. The common bully (Gobiomorphus cotidianus) ate proportionally more chironomid larvae and fish eggs than occurred in the benthos; torrentfish (Cheimarrichthys fosteri) ate proportionally more chironomid larvae than occurred in the benthos; and quinnat salmon (Oncorhynchus tshawytscha) depended largely upon prey species of terrestial origin, such as adult Deleatidium and dipterans. 相似文献
3.
A nearshore fish assemblage inhabiting a shallow bay in the southern Bothnian Sea, Sweden, with demanding environmental conditions (c. 5‰; >15°C during 4 months 1980 and 1 month 1981) was studied during a two-year period, in 1980 and 1981. Seasonal distribution patterns, dietary relationships, and growth rates were studied in Pungitius pungitius (L.), Pomatoschistus minutus (Pallas.), Gasterosteus aculeatus (L.), Phoxinus phoxinus (L.), Pomatoschistus microps (Krøyer) and Gobius niger L. The structure of the juvenile populations changed both over seasons and years but the adult populations remained constant. Lower water temperature, fewer individuals, lower and delayed fish growth, and lower interspecific food overlaps were found in 1981 compared to 1980. Few significant correlations were found in both years between the following community parameters: diversity, niche width, food overlap, and the proportion of each species in the fish assemblage.According to these results it is suggested that food competition and resource partitioning were of minor importance for the structuring of the fish community in the present area. Rather, the extreme salinity and the fluctuations in temperature regulated the fish populations. One may conclude that the populations of juveniles were more influenced by short-term changes in the environment than those of the adults. 相似文献
4.
Abstract. The diets of three syntopic Gulf of California Acanthemblemaria (A. balanorum, A. crock-eri and A. macrospilus) and A. castroi from the Galapagos Island are nearly uniformly composed of harpacticoid copepods and other small benthic-vagile or planktonic crustaceans. On occasion, large prey items such as crabs or other small fishes are taken. HORN'S index of niche overlap indicates that the three syntopic Acanthemblemaria are not separated along the food resource utilization axis. Slight variations in diets among the syntopic species seem to be related to differences in degree of microhabitat specialization. 相似文献
5.
In 1978 the food and habitat resource partitioning of three small and common fish species, viz. Pomatoschistus microps (Krøyer), Gasterosteus aculeatus (L.) and Pungitius pungitius (L.) were studied in river Broälven estuary on the Swedish west coast (58°22′N, 11°29′E). The area was divided into three habitats, based on environmental features. In July, September, and October stomach contents and size distribution of each species present were analysed.In July there was high food and habitat overlap between the species. Interference interactions probably occurred between some size classes of P. microps and the other two species. P. pungitius was exposed to both intra- and interspecific interactions. In September the food and habitat overlaps between G. aculeatus and P. pungitius were high, while both had low food and habitat overlaps in relation to P. microps. Interactions between G. aculeatus and P. pungitius were probably influenced by more severe abiotic conditions in one habitat, which caused lower abundances there, and higher abundances in the other two habitats. In October no interactions were observed. These results indicate that competition for food at least temporarily determines the species distribution in a temperate estuary, and that estuarine fish populations are sometimes food limited. 相似文献
6.
汕头沿岸水体沙壳纤毛虫季度变化 总被引：1，自引：0，他引：1
在2007年枯水期(4月)和丰水期(11月)期间,对汕头沿岸海区沙壳虫进行了采样研究,探讨了沙壳虫的空间分布和种类组成.调查发现,除了表层海水温度以外,表层海水盐度、硝酸盐浓度、硅酸盐浓度均是春季低于秋季.在两个季节的5个采样点共鉴定出7属14种沙壳纤毛虫,其中优势种均为简单薄铃虫Lepmtintinnus simpl... 相似文献
7.
毛颚类是热带近岸海域中上层鱼类的食物来源, 同时又是重要的肉食性浮游动物, 数量丰富, 然而其维持种群结构的生存策略尚不清晰。本文运用分子生物学技术, 分析了三亚湾海域毛颚类优势种肥胖软箭虫(Flaccisagitta enflata)成体与幼体的肠道食物组成, 以期从食物资源利用的角度揭示其维持种群结构的营养策略。研究结果显示, 幼体和成体摄食的浮游生物种类分别为21种和19种, 共同的食物类群有桡足类、小型水母类、硅藻和多毛类。成体与幼体食物偏好差异显著, 成体主要的食物来源是小型水母类(59%), 而幼体主要的食物来源是桡足类(60%); 幼体营养生态位(5.16)高于成体(2.89), 且二者食物重叠度低(0.21), 表明成体与幼体食物分化明显。研究结果揭示, 即使成体与幼体大量共存, 它们也可以通过摄食分化避免食物资源竞争, 这种分配策略对毛颚类保证足够幼体存活率和维持种群数量具有重要意义。 相似文献
8.
三亚蜈支洲岛热带海洋牧场渔业资源现状及季节变动 总被引：1，自引：0，他引：1
蜈支洲岛海洋牧场为海南省首个国家级海洋牧场示范区,为评估蜈支洲岛海洋牧场的资源养护效果,进而为下一步海洋牧场的渔业资源科学管理提供依据。采用渔业资源水声学调查方法,对蜈支洲海洋牧场近岛人工鱼礁区及海棠湾湾区的渔业资源现状及其季节变动进行了研究。2019年4月、8月、12月进行了3次调查,结果显示：4月近岛人工鱼礁区域共捕获游泳生物63种,平均资源量密度为63.71 t/km2,8月、12月海棠湾湾区共捕获游泳生物68种和120种,平均资源量密度分别为8.29 t/km2和7.21 t/km2。4-12月物种多样性指数（H''）均值分别为3.532、3.478、4.414。三次调查中,鱼类优势种中多齿蛇鲻（Saurida tumbil）、短鳄齿鱼（Champsodon snyderi）、宽条鹦天竺鯛（Ostorhinchus fasciatus）均出现2次,其余种类均只出现一次。4-12月重要经济生物占总资源量的比重依次为72.46%、64.74%、57.59%。综上所述,蜈支洲岛海洋牧场近岛人工礁区及海棠湾湾区渔业资源丰富、物种多样性高,尤其是海洋牧场建设对于渔业资源的聚集起到了积极的作用,但仍存在重要经济鱼类少,个体较小等问题。 相似文献
9.
The concept of essential fish habitats (EFHs) is widely accepted for conservational and management purposes. EFHs are often considered as high quality habitats for fisheries species and subsequently of high values for society. In this study, fish and Substrate-Associated Prey (SAP) were sampled during the productive summer season 1998 (fish) and 2003 and 2004 (SAP) in shallow coastal rocky- and soft-bottom habitats on the Swedish west coast. The aim was to study the spatial and monthly variation of SAP as well as abundance and biomass of fish, and to examine if food items found in the diet of the fish assemblage were derived from SAP. We also examined if the diet of Ctenolabrus rupestris, a resident and abundant fish species in the shallow coastal habitats, and the diet of four seasonally abundant and commercially important fish species (Gadus morhua, Pleuronectes platessa, Salmo trutta and Scomber scombrus) were derived from SAP. There were significantly higher mean species number and abundance of the SAP assemblage on rocky compared to soft bottoms and the highest values were found on the rocky bottoms in August and in the shallowest (0–3 m) depth strata. There were no significant differences in number of fish species caught in the two habitats, although mean number of fish and mean biomass were significantly higher on rocky bottoms. Both habitats showed the same seasonal variation and the highest values of number of fish species, abundance and biomass were observed in June. On rocky bottoms, gastropods and amphipods were the most frequent food items in the diet of the entire fish assemblage and these items were also the most abundant SAP in this habitat. The dominant food items of the soft-bottom fish assemblage were decapods and fish, which were not common SAP. However, except for S. scombrus, the diet of the selected fish species showed a strong association to the SAP availability. Gadus morhua displayed the strongest association to SAP on rocky bottoms and P. platessa and C. rupestris to SAP on soft bottoms. Further, for C. rupestris, multivariate statistical analysis showed a significant association to the SAP assemblage on both rocky and soft bottoms. These results provide vital new information for the management and conservation of Essential Fish Habitats on the Swedish west coast. 相似文献
10.
拟哲水蚤是莱州湾桡足类中周年出现的优势种;是上层鱼类幼鱼早期开口饵料的重要贡献者;掌握其种群动态分布特点;有利于了解湾内生物环境状况、次级生产力生产水平。基于2011年5月至20 12年4月采集的浮游生物资料的分析结果显示;莱州湾拟哲水蚤的发育期丰度组成和个体大小均表现了明显的季节变化。调查季节中;4-6月以成体居多;其他季节以桡足幼体CⅢ-CⅤ较多;其中10-11月和3月主要由后期桡足幼体CⅣ和CⅤ期构成。成体中以雌体为主导;雌/雄比介于1.46~9.62;该比值在3-4月最低;10-11月最高。拟哲水蚤各期桡足幼体和成体个体大小以4-5月最大、8月最小;并与水温表现出明显的负相关。拟哲水蚤桡足幼体和成体的总生物量月变化与丰度变化相同;即以8月值最高;3-5月值最低;月均值为2.69 mg/m3（以碳计）;日生产力估算值为0.74 mg/（m3·d）（以碳计）。由上述结果;推测莱州湾拟哲水蚤的种群结构周年变化主要可分3个阶段;4-6月是莱州湾拟哲水蚤开始繁殖期;7-8月为种群数量快速增长期;9月之后为种群增长相对停滞期。 相似文献
11.
Abstract. Despite its commercial value, little is known about the feeding ecology of the greater forkbeard, Phycis blennoides (Brünnich 1768). The stomach contents of 2631 greater forkbeard were taken at monthly intervals off the coast of the Gulf of Valencia (western Mediterranean). They were examined in order to assess the diet and to determine the fish size- and season-related dietary variation of the species. Prey items were identified to the lowest taxonomic level possible. The basic food consisted of epibenthic species, mostly Decapoda, Mysidacea and Teleostei. A change in food composition based on fish size was observed and seasonal variation in diet was also recorded. The food overlap analysis indicated a high convergence in diet among similar size groups. 相似文献
12.
《Deep Sea Research Part I: Oceanographic Research Papers》2000,47(2):259-275
Global scale patterns of species diversity for modern deep-sea benthic foraminifera, an important component of the bathyal and abyssal meiofauna, are examined using comparable data from five studies in the Atlantic, ranging over 138° of latitude from the Norwegian Sea to the Weddell Sea. We show that a pattern of decreasing diversity with increasing latitude characterises both the North and South Atlantic. This pattern is confirmed for the northern hemisphere by independent data from the west-central North Atlantic and the Arctic basin. Species diversity in the North Atlantic northwards from the equator is variable until a sharp fall in the Norwegian Sea (ca. 65°N). In the South Atlantic species diversity drops from a maximum in latitudes less than 30°S and then decreases slightly from 40 to 70°S. For any given latitude, North Atlantic diversity is generally lower than in the South Atlantic. Both ecological and historical factors related to food supply are invoked to explain the formation and maintenance of the latitudinal gradient of deep-sea benthic foraminiferal species diversity. The gradient formed some 36 million years ago when global climatic cooling led to seasonally fluctuating food supply in higher latitudes. 相似文献
13.
《African Journal of Marine Science》2013,35(1):447-465
It is argued that, in the more productive areas of the world, fish production appears to be based on relatively short food chains. The dynamics of energy transfer are therefore largely concerned with the dynamics of relatively short food chains and in particular with the dynamics of short chains when these are seasonally perturbed. To investigate the process, extensive simulations have been made with models of the marine ecosystem in which simple food webs have been constrained within a closed nitrogen model consisting of animals, plants, inorganic nitrogen and dead organic nitrogen. Within such a closed system, when seasonally perturbed, food limitation at some time or other seems unavoidable, and consideration is given to differences in the ways this might affect larval, juvenile and adult stages. The principal conclusion from this study is that the efficiency of transfer of energy from primary production to fish can be improved in the model by modifications to the inputs that take advantage of seasonal variation in biomasses. The corollary of this finding is that, in nature, efficiency is likely to be gained by adaptations that benefit from, instead of being disadvantaged by, the effects of seasonal variations in biomass at different trophic levels. Factors that may be important in this context are: Migratory habits that can ensure that individuals are located in geographical areas of predictable high food concentrations, at different times of the year; omnivory, which permits an individual to change from feeding at one trophic level to feeding at another trophic level at different times of the year; horizontal displacement of trophic levels, as occurs, for example, in upwelling areas, which could be advantageous because this should avoid many of the difficulties that are expected theoretically when all trophic levels are present in the same vertical column. This study is consistent with classical thinking about species replacement. Thus, if the stock of one species is reduced, by fishing for example, other species cannot be expected to benefit from food that would otherwise have been consumed to the same extent, i.e. it is unlikely that any one species would be able to take over fully the ecological niche of any other species. Differences in behaviour and geographical location are likely to lead to a less efficient use of a resource by species other than those which had evolved to utilize that resource in the first place. 相似文献
14.
深圳海域弧菌种类组成、数量分布及其与环境因子的关系研究 总被引：2，自引：0，他引：2
研究了深圳海域2008年4月、9月的水体弧菌数量、种类组成及其分布,探讨了弧菌总数及各优势类群的数量分布与环境因子间的相关关系。结果表明:弧菌总数分布具有季节性,东部海域春季(4月)的弧菌数量高于秋季(9月)的,其均值分别为1.50×104,8.89×102CFU/cm3;在西部海域秋季的略高于春季的,其均值分别为5.09×102,2.66×102CFU/cm3;弧菌数量最高值出现在大亚湾(4.40×104CFU/cm3)。弧菌的优势类群具有季节性分布特征:春季特有的优势类群有Vibrio gigantis类似种和V.splendidus类似种,秋季特有的优势类群有V.natriegens类似种;V.alginolyticus类似种是两个季节共有的优势类群,其数量春季高于秋季的。弧菌种类、数量与海水温度、盐度及细菌总数、Chl-a等环境因子有一定的相关性,其中盐度为弧菌种类及数量分布的主要影响因子。 相似文献
15.
LIU Zhensheng ZHANG Zhinan WANG Chunsheng JIN Haiyan DU Mingmin ZHANG Dongsheng 《海洋学报(英文版)》2012,31(6):104-116
Seasonal variations in zooplankton abundance,biomass,species diversity and community structure were investigated in the Sanmen Bay,China.Samples were collected from 15 stations,on the seasonal basis,in April(spring),July(summer) and October 2005(autumn) and January 2006(winter),respectively.The results show that zooplankton species number,abundance and biomass varied widely and had distinct spatial heterogeneity in the Sanmen Bay.A total of 72 species of zooplankton belonging to 56 genera and 17 groups of pelagic larvae were identified.The zooplankton species richness was strongly related to salinity.Based on hierarchical cluster analysis,zooplankton in this study area were classified into three groups:coastal,neritic and pelagic groups,which corresponded to the upper,middle and lower portion of the Sanmen Bay,respectively.The coastal low-saline species were dominant in the study area.The zooplankton abundance and biomass reached a peak in summer,moderate in spring and autumn,and the lowest in winter.Zooplankton abundance decreased from the upper to lower portion of the bay in April,when the highest biomass occurred in the middle portion of the bay.There were the same spatial distribution patterns for the biomass and abundance in July,with the maximum in the middle of the bay.However,zooplankton abundance was the highest in the middle of the bay in October,when maximum biomass occurred near the lower of the bay.Zooplankton abundance and biomass were evenly distributed in the Sanmen Bay in January.Spatial and temporal variations in zooplankton and their relationship with environmental factors were also analyzed.The BIOENV results indicate that the combination of chlorophyll a(Chl-a),salinity,dissolved inorganic nitrogen(DIN),dissolved oxygen(DO) and silicate(SiO3) was responsible for the variations in zooplankton community structure in the Sanmen Bay.The environmental changes played an important role in changes in the zooplankton community structure in the Sanmen Bay. 相似文献
16.
Partitioning of the feeding niche along spatial,seasonal and size dimensions by the fish community in a tropical Bay in Southeastern Brazil 
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下载免费PDF全文 Ana Paula P. Guedes Francisco G. Araújo André L. M. Pessanha Rosana R. Milagre 《Marine Ecology》2015,36(1):38-56
Feeding guilds and spatial, seasonal and ontogenetic changes in the diets of 24 fish species in a tropical bay in Southeastern Brazil were examined. The hypotheses tested were that groups of species form specific trophic guilds and that the feeding partitioning differs along the niche dimensions. Five trophic guilds (Polychaeta, Copepoda, Teleostei, Teleostei/Crustacea and Polychaeta/Crustacea) and two species with specialised feeding, one teleost (Aspistor luniscutis) and one bivalvia (Sphoeroides testudineus), were found. Polychaeta was the most important resource for nine fish species, followed by Copepoda (6 spp.), Teleostei (5 spp.) and Caprelidae Amphipoda (3 spp.). Polychaeta was the most used resource for species in the inner bay zone, and Crustaceans in the outer bay zone. We detected a predominance of Polychaeta between the spring and autumn, whereas crustaceans were consumed at a greater rate in the winter. The most conspicuous changes in diet occurred along the spatial and seasonal dimensions, rather than the size dimensions. The hypotheses tested were accepted. Identifying and incorporating information about the bay food web is a first step towards developing management strategies that are sensitive to this particular ecosystem. 相似文献
17.
台湾海峡及邻近海域4种头足类的食性和营养级研究 总被引：7，自引：0，他引：7
本文研究中国枪乌贼、杜氏枪乌贼、目乌贼和短蛸4种头足类的食性与营养级.结果表明,中国枪乌贼和杜氏枪乌贼整年摄食率都高,目乌贼在春、夏季高,短蛸则在秋季摄食率高.4种头足类胃饱满系数皆呈现明显的季节变化.中国枪乌贼属游泳生物食性类型,杜氏枪乌贼和目乌贼属游泳动物和底栖动物混合食性类型,短蛸属浮游动物和底栖生物食性类型.4种头足类混合饵料的营养级分别为2.62、2.85、2.88和2.04级,均处于第三营养层次.其食物的重叠指数均超过0.7,食物重叠明显,对该海域的鱼类、甲壳动物(长尾类和短尾类)、头足类、糠虾类、端足类、樱虾类、腹足类等饵料生物存在激烈的竞争. 相似文献
18.
Seasonal changes in the biochemical composition of females and offspring of red squat lobster,Pleuroncodes monodon (Decapoda,Munididae), from the Southeastern Pacific 下载免费PDF全文
下载免费PDF全文 Pleuroncodes monodon is an important fishery resource and key species from the Southeastern Pacific. During its prolonged reproductive period (from February to December), ovigerous females are exposed to seasonal variation in environmental factors (e.g. temperature and food availability), with higher levels of these environmental parameters during summer and lower in winter, and must adjust their biochemistry to ensure their own survival and that of their embryos. The aim of this study was to analyse seasonal changes in the biochemical composition of ovigerous females and their eggs. The data show that the content of lipids, proteins and organic matter in the hepatopancreases of females was significantly higher in winter than in summer. Similarly, the lipid content of the eggs was significantly higher in winter than in summer, yet the protein content of the eggs had the opposite pattern with greater values found in summer. Consistent with the ‘reproductive energetic model’, the initial and final energy produced by the hepatopancreas showed significant seasonal variations, whereas female investment in egg production (in absolute values) did not show significant seasonal differences. The seasonal differences observed in the biochemistry, organic matter and energy content of the female hepatopancreases may be related to the storage of energy for growth and reproduction. Furthermore, the seasonal variation in the content of lipids, proteins and energy in eggs is likely related to embryogenesis and larval hatching in function with environmental conditions. Seasonal variation in the biochemical composition of P. monodon has direct effects on the marine food web and also upon fisheries. 相似文献
19.
Paul Brickle Alexander I. ArkhipkinVladimir Laptikhovsky Andrew StocksAlison Taylor 《Estuarine, Coastal and Shelf Science》2009
The ontogenetic, seasonal, bathymetric and regional variations in the feeding spectrum of 922 specimens of southern blue whiting Micromesistius australis and 512 specimens of hoki Macruronus magellanicus were studied on the Falkland Islands’ shelf (Southwest Atlantic) between November 1999 and April 2003. A total of 49 different prey items were found in the stomach contents of the two species, with the hyperiid Themisto gaudichaudii and Euphausiacea being amongst the most important prey. Although the species composition did not change over fish size, the proportions of individual prey items in their diets did, with an increase in T. gaudichaudii and Euphausiacea with increasing fish size in southern blue whiting. The opposite occurred in hoki. Seasonal variations in the diet were found to mirror the seasonal abundance of prey around the Falkland Islands for the two species. Intra-specific differences in the diet of both predators reflected the distribution of prey, which in turn was determined by the water structure in the two regions sampled, leading to very different diets. In the limited time that the two species occupied the same space there was little or no competition resulting in almost total segregation of their trophic niches in space and time. 相似文献
20.
The feeding habits of the mud shrimp Solenocera melantho were studied in the East China Sea by analysing 720 stomach contents and comparing diet composition and prey diversity among seasons, sexes and size classes. Feeding activity was linked to season and ovarian condition. The stomach fullness was high during spring and summer and low in fall. Females with advanced ovaries also displayed low stomach fullness, which suggests that feeding activity is affected by the reproductive cycle. The diet of S. melantho consisted of 42 different prey categories, primarily smaller crustaceans, Foraminifera, polychaetes, mollusks and fishes (larvae and eggs). Crustacea,Foraminifera and polychaetes together constituted the dominant prey groups, accounting for 75% of total prey abundance and >50% of total prey occurrence. Diet composition differed among seasons between sexes and size classes. Females and males consumed the same prey items but with different orders of importance. In terms of body size, the small shrimps preferred relatively small food items, such as Foraminifera and algae, whereas larger shrimps preferred polychaetes and crustaceans. Trophic diversity varied among the seasons within both sexes and size classes, with the highest values being observed in fall. Niche overlap was high within both sexes and size classes among seasons (0.6051–0.8740). 相似文献