共查询到20条相似文献，搜索用时 31 毫秒
1.
Juveniles of both stone flounder Platichthys bicoloratus and starry flounder Platichthys stellatus utilize estuaries as nursery grounds. To understand their habitat selection and the functions of habitats such as food supply, we defined the seasonal distribution of recently settled fish of these species in shallow nursery areas and investigated their feeding habits in the Natori River estuary, Japan. Distribution of stone flounder was limited to the lower estuary (<3 km upriver from the mouth) and stone flounder were most abundant near the mouth. Recently settled starry flounder were first detected further upstream in areas characterized by low salinity <10 and by the absence of the predatory sand shrimp Crangon uritai. Early juvenile stone and starry flounders consumed mainly siphons of the bivalve Nuttallia olivacea and the mysid Neomysis awatschensis, respectively; however, 1- and 2-yr-old fish of both stone and starry flounders fed mainly on the bivalve siphons. These results indicate that habitat selections of juvenile stone and starry flounders enable utilization of preferred prey and predator avoidance, respectively, and that non-overlap of these species' habitats results in avoidance of inter-specific competition for food between these two species. 相似文献
2.
Although flatfish species utilise a wide range of habitats as adults, several species are confined to a very limited habitat as juveniles. Recruitment levels are dependent on the quality and quantity of these nursery areas and changes therein. In the Baltic Sea, these shallow environments are often subject to influxes of drifting macroalgae, which add structure to otherwise bare sandy substrate. Structure, such as vegetation, alters predator–prey interactions of a wide range of fauna and in an array of marine, freshwater, and terrestrial systems. The aim of our study was to assess the inhibition potential of drifting macroalgae on the foraging efficiency of juvenile flatfish (young of the year Scophthalmus maximus L., young of the year- and group 1 + Platichthys flesus L.) through a series of microcosm experiments. Our results show that foraging success is restricted by drift algae as predation efficiency of all predator species and size classes was negatively affected by the presence of macroalgae. Overall, there was a reduction in predation success by 80 ± 12% due to structural effects and/or the induced changes in water chemistry associated with the algae. Flatfish depend on shallow sandy areas as feeding and nursery grounds during their juvenile stage and frequently occurring macroalgal assemblages drastically change the features of the otherwise bare substrate, setting the stage for small-scale, localised processes potentially affecting population dynamics. 相似文献
3.
利用实验生态学方法研究不同个体大小的海蜇浮游幼体[平均伞径(2.5±0.1),(4.1±0.2),(11.7±0.5),(21.1±0.6)mm]对不同密度(10,30,50,80ind/L)的褐牙鲆卵[卵径(0.92±0.01)mm]和初孵仔鱼[全长(3.01±0.08)mm]的捕食率,解析海蜇浮游幼体对初孵仔鱼的捕食率随捕食时间(0.5,1,2,3,4,5h)的变化特征。结果表明,各个体组海蜇浮游幼体对卵的捕食率均显著低于对仔鱼的捕食率;它们对卵的捕食率与卵密度和海蜇个体大小的关系不显著,但对仔鱼的捕食率随海蜇个体大小及仔鱼密度的增大而显著升高;伞径21.1mm的个体对仔鱼的捕食率在开始捕食后1h时达到最大值[17.3ind/(predator.h)],此后随捕食时间的延长而逐渐下降。在自然水域中,如果二者发生时空上的匹配关系,海蜇浮游幼体对仔鱼的捕食可能影响褐牙鲆的早期存活及其资源补充量的变动。 相似文献
4.
Recruitment of flatfish species to an estuarine nursery habitat (Lima estuary, NW Iberian Peninsula)
One of the present concerns of fish biologists involves defining and identifying nursery habitats in the context of conservation and resource management strategies. Fish nursery studies usually report upon nursery occupation during the latter juvenile stages, despite the fact that recruitment to nurseries can start early in life, during the larval phase. Here we investigated the use of a temperate estuarine nursery area, the Lima estuary (NW Portugal), by initial development stages of flatfish species before and after metamorphosis, integrating the larval and juvenile phases. The Lima estuarine flatfish community comprised twelve taxa, seven of which were present as pelagic larvae, six as juveniles and three as adults. There was a general trend of increasing spring–summer abundance of both larvae and juveniles, followed by a sharp winter decrease, mainly of larval flatfishes. The Lima estuary was used by Solea senegalensis, Platichthys flesus and Solea solea as a nursery area, with direct settlement for the two first species. In contrast, indirect settlement was suggested for S. solea, with metamorphosis occurring outside the estuarine area. Estuarine recruitment of S. senegalensis varied between years, with young larvae occurring in the estuary throughout a prolonged period that lasted 6–9 months, corroborating the protracted spawning season. P. flesus, the second most abundant species, exhibited a typical spring estuarine recruitment, without inter-annual variations. Developed larvae arrived in the estuary during spring, whereas the 0-group juveniles emerged in the following summer period. The present study contributes new insight to our understanding of the economically important S. senegalensis, and highlights the importance of integrating the planktonic larval phase into traditional flatfish nursery studies. 相似文献
5.
《Journal of Sea Research》2008,59(4):335-341
Although flatfish species utilise a wide range of habitats as adults, several species are confined to a very limited habitat as juveniles. Recruitment levels are dependent on the quality and quantity of these nursery areas and changes therein. In the Baltic Sea, these shallow environments are often subject to influxes of drifting macroalgae, which add structure to otherwise bare sandy substrate. Structure, such as vegetation, alters predator–prey interactions of a wide range of fauna and in an array of marine, freshwater, and terrestrial systems. The aim of our study was to assess the inhibition potential of drifting macroalgae on the foraging efficiency of juvenile flatfish (young of the year Scophthalmus maximus L., young of the year- and group 1 + Platichthys flesus L.) through a series of microcosm experiments. Our results show that foraging success is restricted by drift algae as predation efficiency of all predator species and size classes was negatively affected by the presence of macroalgae. Overall, there was a reduction in predation success by 80 ± 12% due to structural effects and/or the induced changes in water chemistry associated with the algae. Flatfish depend on shallow sandy areas as feeding and nursery grounds during their juvenile stage and frequently occurring macroalgal assemblages drastically change the features of the otherwise bare substrate, setting the stage for small-scale, localised processes potentially affecting population dynamics. 相似文献
6.
The density of macrobenthos was evaluated in the nursery grounds for flatfish of six estuarine systems along the coast of Portugal by comparison with adjacent non-nursery areas. The dry weight and density of macrobenthic fauna were significantly higher in the nursery grounds. Polychaeta, Bivalvia, Oligochaeta and Isopoda were found to be significantly more abundant in the nursery than in the non-nursery grounds. For Isopoda and Bivalvia, total dry weight was also significantly higher in the nursery areas. Correspondence analysis based on density showed that the nursery areas of the different estuaries grouped together relative to non-nursery sites, with a relative similarity in the abundance of Oligochaeta, Spionidae, Amage spp., Scrobicularia plana and Cerastoderma edule. Taking into consideration the generally opportunistic feeding ecology and low dietary selectivity of the flatfish species, the results indicated higher prey availability in the nursery grounds of the Portuguese estuaries, an important factor contributing to the quality of these areas. The relatively high macrobenthic productivity in the nursery areas might be linked to physical and biological interactions favouring the recruitment and maintenance of the communities. 相似文献
7.
Chris D.B. Leakey Martin J. Attrill Simon Jennings Mark F. Fitzsimons 《Estuarine, Coastal and Shelf Science》2008
Estuaries are regarded as valuable nursery habitats for many commercially important marine fishes, potentially providing a thermal resource, refuge from predators and a source of abundant prey. Stable isotope analysis may be used to assess relative resource use from isotopically distinct sources. This study comprised two major components: (1) development of a spatial map and discriminant function model of stable isotope variation in selected invertebrate groups inhabiting the Thames Estuary and adjacent coastal regions; and (2) analysis of stable isotope signatures of juvenile bass (Dicentrarchus labrax), sole (Solea solea) and whiting (Merlangius merlangus) for assessment of resource use and feeding strategies. The data were also used to consider anthropogenic enrichment of the estuary and potential energetic benefits of feeding in estuarine nursery habitat. 相似文献
8.
Juvenile Japanese flounder Paralichthys olivaceus usually inhabit high salinity inshore sandy areas. In June–August 1997, 25 individuals of juvenile Japanese flounder (33–75 mm total length) were collected in the Natori and Nanakita River estuaries in Sendai Bay, Japan. This is the first record of this species being collected in brackish estuaries in which salinities fluctuate from 0 to 30 over a spring tidal cycle. Factors of rainfall, river flow, or year class strength of Japanese flounder were unable to explain the unusual occurrence of this species in the estuaries. The collected juvenile Japanese flounder were considered to have migrated into the estuaries around the time of the passage of an unusually early typhoon that affected this area, indicating the possibility that this species utilizes estuaries for refuge from strong disturbance in its usual habitats. The juveniles fed mainly upon mysids both in the estuaries and the sandy beach area, indicating that estuaries can be a substitute nursery habitat for this species. 相似文献
9.
Effects of habitat complexity on cannibalism rates in European green crabs (Carcinus maenas Linnaeus, 1758) 
下载免费PDF全文
下载免费PDF全文 The habitat in which predator–prey interactions take place may have a profound influence on the outcome of those interactions. Cannibalism is an intriguing form of predation whereby foraging by predators may contribute to the regulation of their own populations.This is particularly interesting in the case of invasive species, like the widely distributed European green crab (Carcinus maenas). This study explores how habitat complexity influences cannibalism rates in green crab populations of Prince Edward Island, Atlantic Canada. Both laboratory and field experiments were conducted to measure feeding rates by individual adult green crabs on a standard number of smaller conspecifics. In the laboratory, experimental treatments mimicked unstructured to increasingly structured habitats: water, sandy bottom, oyster shells, mussel shells, oyster shells with sandy bottom and mussel shells with sandy bottom. In those trials, adult green crabs consumed several times more juveniles on unstructured habitats than on the most structured ones, with a gradual decrease in predation rates across increasingly complex habitats. Field inclusion experiments used the same approach and were conducted in sandy bottoms, sandy bottoms with a layer of oyster shells and sandy bottoms with a layer of mussel shells. These trials showed similar patterns of decreasing feeding rates across increasingly complex habitats, but differences among treatments were not significant. These results support the idea that complex habitats have the potential to mediate predator–prey interactions, including adult–juvenile cannibalism in green crabs. 相似文献
10.
The soles Solea solea and Solea senegalensis are marine flatfish that use coastal and estuarine nursery grounds, which generally present high food availability, refuge from predators and favourable conditions for rapid growth. Two important nursery grounds for these species juveniles have been identified in the Tagus estuary, one in the upper part of the estuary (nursery A) and another in the south bank (nursery B). While S. solea is only present at the uppermost nursery area, S. senegalensis is present at both nurseries. Although they are among the most important predators in these nursery grounds, there are no estimates on their food consumption or on the carrying capacity of the system for soles. The Elliott and Persson [1978. The estimation of daily rates of food consumption for fish. Journal of Animal Ecology 47, 977–993] model was used to estimate food consumption of both species juveniles in both nursery areas, taking into account gastric evacuation rates (previously determined) and 24 h sampling surveys, based on beam-trawl catches carried out every 3 h, in the summer of 1995. Monthly beam trawls were performed to determine sole densities over the summer. Density estimates and daily food consumption values were used to calculate total consumption over the summer period. Sediment samples were taken for the estimation of prey densities and total biomass in the nursery areas. Daily food consumption was lower for S. solea (0.030 g wet weight d−1) than for S. senegalensis (0.075 g wet weight d−1). It was concluded that thermal stress may be an important factor hindering S. solea's food consumption in the warmer months. Total consumption of S. solea over the summer (90 days) was estimated to be 97 kg (wet weight). Solea senegalensis total consumption in nursery A was estimated to be 103 kg, while in nursery B it was 528 kg. Total prey biomass estimated for nursery A was 300 tonnes, while for nursery B it was 58 tonnes. This suggests that food is not a limiting factor for sole in the Tagus estuary. However it was concluded that more in-depth studies into the food consumption of other species and prey availability are needed in order to determine the carrying capacity of this system for sole juveniles. 相似文献
11.
A model was developed to estimate the relative impacts of different functional groups of piscivores on the shallow-water estuarine nursery assemblage of tropical north-eastern Australia. Data on variability in the occurrence, number and type of fish in the diet of different piscivores was combined with estimates of the abundance of each group. The model predicts that previously overlooked small and occasional or ‘minor’ piscivores, such as sillaginids, ambassids, sparids and small juvenile carangids, inflict mortality on new recruits to shallow-water nursery habitats that is orders of magnitude greater than that imparted by more conspicuous larger piscivores. Because of their high abundance, a shift in the diet of minor piscivores to prey on new recruits results in a massive increase in the consumption of fish prey by the piscivore assemblage as a whole. Even if the evidence that minor piscivores switch to target new recruits was rejected, the model shows that the highly abundant minor piscivores must still exert a significant proportion of predation mortality experienced by recruiting fishes. As a broad functional group, minor piscivores occur in most aquatic systems around the globe and are likely to play an important but largely overlooked role as predators that shape communities through predation on critical early life stages of other fishes. 相似文献
12.
13.
Anita Franco Riccardo Fiorin Matteo Zucchetta Patrizia Torricelli Piero Franzoi 《Journal of Sea Research》2010,64(4):457-464
Estuarine marshes are known as suitable nursery areas for many marine migrant fishes, such as flounder. The potential nursery value of such habitats was investigated in the Venice lagoon, by using growth and production of 0-group flounder as indicators. Size–frequency distribution analysis was performed on fish samples collected fortnightly, from March 2004 to June 2005, in two marsh sites, Dese and Tessera, differing in their origin and environmental conditions. Samples were mostly composed of juvenile individuals, belonging to 0- and 1-group cohorts (the latter being present in Tessera only). A higher total production, either annual or monthly, and faster growth of 0-group flounder was observed in Dese, associated to a higher ecological performance of 0-group individuals in this site, as indicated by the higher P:B ratio values. Dese is a site located in a marsh complex characterized by the relevant influence of a nearby river, and the observed higher potential nursery value of this marsh area with respect to the other is discussed in the light of the higher trophic status and other environmental conditions in this site. The production results were also compared to those from other estuarine environments commonly acknowledged as important nurseries for European flounder. 相似文献
14.
Survival and growth of early fish stages are maximal in coastal and estuarine habitats where natural shallow areas serve as nurseries for a variety of widely distributed species on the continental shelf. Processes occurring in these nursery grounds during the juvenile stage affect growth and may be important in regulating the year-class strength of fishes and population size. The need, therefore, exists to protect these essential fish habitats hence to develop indicators to estimate their quality.The purpose of the present study was to use the growth of juvenile sole as a means of comparing the quality of coastal and estuarine nursery habitats in the Bay of Biscay (France). These sole nurseries were clearly identified from studies based on trawl surveys carried out during the last two decades. The size of 1-group juveniles at the end of their second summer, as estimated from these surveys, is an indicator of growth in these habitats during the juvenile phase and can be used to compare habitat quality. A model taking into account the role of seawater temperature in spatial and interannual variations of juvenile size was developed to compare growth performance in the different nursery sectors.This study shows that the size of juvenile sole after two summers of life is not density-dependent, probably because the size of the population adapts to habitat capacity after high mortality during early-juvenile stages. Size is on one hand positively related to temperature and on the other hand higher in estuarine than in non-estuarine habitats. This high growth potential of juvenile fish in estuarine areas confirms the very important role played by estuaries as nursery grounds and the essential ecological interest of these limited areas in spite of their low water quality. If a general conclusion on habitat quality is to be reached about studies based on the growth of juvenile fish, it is necessary to use not only an integrative indicator of growth, like size, representative of the intrinsic habitat quality, but also more sensitive and less integrative means, such as otolith increments or caging experiments, which better respond to anthropogenic disturbance. Moreover, it is necessary to take juvenile densities into account. 相似文献
15.
16.
Spatial changes in a macrozoobenthic community along environmental gradients in a shallow brackish lagoon facing Sendai Bay, Japan 总被引：3，自引：0，他引：3
The spatial distribution, abundance, and assemblage structure of macrozoobenthos were examined at 45 stations in a brackish lagoon (Idoura Lagoon, Japan) to examine the animal–environmental relations in estuarine soft-bottom habitats. We found a total of 23 taxa; the polychaetes Heteromastus sp., Hediste spp., and Prionospio japonica and the isopod Cyathura muromiensis numerically dominated the community. Cluster analysis and one-way analysis of similarity (ANOSIM) identified seven groups of stations that had significantly different macrozoobenthic communities; these were subsequently consolidated into five habitat groups according to their association with environmental characteristics. Canonical correspondence analysis (CCA) showed that salinity, silt-clay content, and the oxidation–reduction potential (ORP) of the sediment strongly affected the macrozoobenthos distribution pattern in the lagoon, whereas other factors (e.g., relative elevation of the habitat and sediment organic content) had much weaker effects. Similarity percentages (SIMPER) procedures indicated that the polychaete Notomastus sp. and the bivalve Macoma contabulata were specific to habitats with low salinity and reduced mud, whereas the bivalve Nuttallia olivacea was specific to sandy bottoms. Heteromastus sp. and Hediste spp. achieved their highest densities in rather oxidized sediments. The acid-volatile sulfide (AVS) content in the sediment was suggested as another possible factor affecting macrozoobenthic density. Our results clearly demonstrate that macrozoobenthic assemblages in estuarine soft-bottoms have high spatial heterogeneity on a small scale (e.g., hundreds of meters) related to physical and chemical environmental changes. Our data also suggested the importance of sediment redox condition (e.g., ORP and AVS content) and sediment grain size as structuring factors in estuarine soft-bottom communities as well as the salinity in the habitat. 相似文献
17.
E. González-Ortegón M.D. Subida J.A. Cuesta A.M. Arias C. Fernández-Delgado P. Drake 《Estuarine, Coastal and Shelf Science》2010
Estuaries are used as nursery grounds by numerous marine species despite being usually subject to strong anthropogenic disturbances. Abundances of marine recruits (fish and crustacean decapods) and their main prey (mysids) were monitored by monthly sampling, from June 1997 to February 2009, in the lower reaches of the Guadalquivir estuary (SW Spain). During that period, unusually high and persistent turbidity events (HPTEs) were observed twice. Both HPTEs started with strong and sudden freshwater discharges after relatively long periods of very low freshwater inflow. Data from this time-series were used to test the hypothesis that HPTEs may negatively impact the nursery function of estuaries either by decreasing prey availability or by decreasing survival/arrival of marine recruits. During HPTEs, the commonest mysid (Mesopodopsis slabberi), a key species in the estuarine food web, showed a significant decrease in abundance. Likewise, some marine recruits that prey on M. slabberi and whose peaks of abundance within the estuary occur in summer–autumn (Engraulis encrasicolus and Pomadasys incisus) were less abundant during HPTEs. It is also suggested that HPTEs might have triggered a shift in the distribution of the most euryhaline prey (Neomysis integer) and predator (Dicentrarchus punctatus and Crangon crangon) species, towards more saline waters. This could have contributed to an increase in the inter-specific competition (for food/habitat) within the estuarine nursery area. The results discussed in this study call attention to the need to reduce as much as possible the anthropogenic pressures that may stimulate the occurrence of high and persistent turbidity events (HPTEs) in order to preserve the nursery function of temperate estuaries. 相似文献
18.
Spatial intertidal distribution of bivalves and polychaetes in relation to environmental conditions in the Natori River estuary,Japan 总被引：1，自引：0，他引：1
Takeshi Tomiyama Nobuhiro KomizunaiTatsuya Shirase Kinuko ItoMichio Omori 《Estuarine, Coastal and Shelf Science》2008
This paper aims to reveal spatial variation in the abundance of infaunal bivalves and polychaetes at different spatial scales (station: 200–800 m intervals; plot: 5–20 m), and to reveal environmental variables affecting the spatial distribution of animals in the Natori River estuary, Japan. We found six bivalve species and eight polychaete species from 52 plots at 12 stations. Nuttallia olivacea and Heteromastus sp. were found to be the most abundant species of bivalves and polychaetes, respectively. Assemblage patterns of bivalves and polychaetes were classified into five distinct groups. Substrata (silt-clay contents), salinity, and relative elevation were the variables found to affect the infaunal assemblage patterns. Chlorophyll a was not a significant variable, but benthic animals were absent at sites with extremely low chlorophyll a conditions. Macrobenthic assemblage patterns were different not only between stations but often differed between plots at the same station, reflecting the complex assemblage structure of benthic invertebrates. Detailing such animal–environment relationship is essential in understanding the potential food supply for estuarine fishes. 相似文献
19.
Agonus cataphractus 《Estuarine, Coastal and Shelf Science》2002,54(6):941
Long-term data assembled from a power station on the Thames estuary were used to model fluctuations in the abundance of pogge (Agonus cataphractus) as a function of estuarine environmental, seasonal and prey availability variables using multiple regression. Temperature was the most important determinant of abundance, with seasonal variables and changes in the relative abundance of age-0 dab, Limanda limanda, possibly as prey, also holding important consequences for pogge abundance. Pogge abundance was also moderately influenced by: salinity, flow, salinity-flow interactions, changes in the relative abundance of Dover sole, Solea solea, and a trend variable. Regular patterns of seasonal (spring/winter) occurrences were associated with the use of warmer estuarine waters to optimize growth and reproductive potential and/or correlated with inshore spawning migrations and the availability of prey species. Both mechanisms suggest opportunistic use of estuarine habitats by pogge. Available temperature-abundance relationships further suggest a well-defined estuarine thermal niche, with an optimum at 9·5 °C. There remains a requirement for improved information on the biology of pogge and factors governing the population dynamics of this important estuarine species. 相似文献