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1.
An examination of the feasibility of passive transport from coastal spawning grounds to estuarine nursery areas for English sole 总被引：1，自引：0，他引：1
Christopher N. Rooper Donald R. Gunderson Barbara M. Hickey 《Estuarine, Coastal and Shelf Science》2006,68(3-4):609
English sole recruitment has been linked to environmental conditions occurring during their 6–10 week pelagic egg and larval stages, prior to their appearance in nursery estuaries during their first summer. The purpose of this study was to predict the spawning locations of juvenile English sole observed in estuaries to assess the feasibility of passive transport of egg and larval stages. Current meter data were used to back-calculate the transport trajectories of 19 cohorts of English sole observed as juveniles during estuarine trawl surveys. Only six of these cohorts were predicted to be spawned outside the Oregon–Washington shelf system, assuming passive transport of eggs and larvae. Predicted egg and larval trajectories indicate that most of the English sole found in Oregon and Washington estuaries were spawned off the coast of Washington, with some spawning off northern California and central Oregon. Although these results are not consistent with the presumed spawning locations for the Oregon and Washington shelf, they indicate that passive transport assumptions may be adequate to preserve the larvae in the coastal system until settlement. 相似文献
2.
Connectivity between spawning and potential nursery areas of northern rock sole, Lepidopsetta polyxystra, in the eastern Bering Sea was examined using an individual-based biophysical-coupled model. Presumed spawning areas were identified using historical field-collected ichthyoplankton data, and nursery habitats were characterized based on previously described settlement areas. Simulated larvae were released from spawning areas near the Pribilof Islands, south of the Pribilof Islands along the outer continental shelf, on the north side of the Alaska Peninsula, and in the Gulf of Alaska south of Unimak Island. Simulated larvae were transported along two general pathways: 1) northwards along the outer continental shelf from Unimak Island towards the Pribilof Islands and further north offshore of mainland Alaska, and 2) eastward along the Alaska Peninsula. At the end of the 2-month simulation, drift pathways placed pre-settlement stage larvae offshore of known nursery areas of older juveniles near mainland Alaska, consistent with a hypothesis that initial settlement may be followed by substantial post-settlement redistribution. 相似文献
3.
Spawning in Greenland halibut (Reinhardtius hippoglossoides) occurs along the continental slope and in submarine canyons in the eastern Bering Sea. It is assumed that these bathymetric features and their associated circulation patterns deliver eggs and larvae to suitable nursery habitats over the continental shelf. However, there have been no directed field studies examining spawning areas or transport of Greenland halibut early life stages in the Bering Sea, nor is it known how large-scale oceanographic forcing modulates specific physical mechanisms of delivery. The present study was undertaken to: better define spawning areas of Greenland halibut, examine development and distribution of larvae, and understand the influence of climate variations on interannual patterns of transport, distribution and abundance. Eggs were found in Bering and Pribilof Canyons and over the adjacent slope in February and early March, confirming that spawning occurs in these regions. Larvae were present over the slope, outer shelf and middle shelf in winter and spring, and settled juveniles were collected over the shelf in September. Oceanographic modeling approaches that simulate larval advection from spawning to nursery habitats indicate that depth-discrete variations in transport pathways from submarine canyons to the adjacent shelf contribute to interannual variability in transport trajectories. Overall, our results highlight specific physical mechanisms of delivery that are modulated by large-scale atmospheric and oceanographic forcing, potentially varying the degree of slope–shelf connectivity for Greenland halibut and other slope-spawning species. 相似文献
4.
The Senegal sole, Solea senegalensis, is a flatfish species distributed from the Bay of Biscay to the coast of South Africa. Although it is a species of high commercial value its spawning period remains poorly known. In the Tagus estuary, Portugal, two juvenile cohorts of this species colonize two independent nursery areas within the estuarine system. Left lapilli otoliths of these 0-group juveniles were used to estimate age and back-calculate hatch dates, thus allowing the estimation of S. senegalensis spawning period in the Portuguese coast. The two cohorts of S. senegalensis completed the colonization of the two nurseries in July. The ages of juveniles were estimated to range between 46 and 111 days in nursery A, and between 33 and 61 days in nursery B. Hatch dates ranged from April to early June for juveniles colonizing nursery A, and from May to early June for juveniles colonizing nursery B. The mean hatch date in nursery A was the 7th of May, while in nursery B it was the 25th of May. It was concluded that the spawning period for this species off the Portuguese coast was from April to June. 相似文献
5.
《Journal of Sea Research》2011,65(4):473-486
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
6.
小黄鱼Larimichthys polyactis体长-体重关系幂指数与产卵群体空间分布相关性研究 总被引：1，自引：0，他引：1
鱼类产卵群体的相关研究一直是渔业领域关注的热点,对鱼类的产卵期、产卵场的研究是鱼类生态习性研究方向的重要组成部分。本文在前期研究证实鱼类体长-体重关系幂指数可以指示鱼类产卵期的基础上,利用2004年4个季节的东海大面积调查数据,尝试利用同一时间点上的各个调查点幂指数信息来分析鱼类产卵场分布特征,结果发现,成熟产卵个体仅在春季出现,而未成熟产卵个体4季均有分布,以此推测小黄鱼存在"跳过产卵"现象。另外发现,单靠幂指数大小,不能区分各个产卵成熟阶段,也不能区分产卵个体与非产卵个体;而怀卵个体出现站点的幂指数平均值偏低于匀速生长,空间上也具有类似特征,即幂指数相对低的地方一般对应怀卵个体相对集中的水域。本文依据幂指数分布,推断小黄鱼成熟产卵群体有3块相对集中水域,即舟山渔场近海、济州岛西南侧和江外与舟外渔场临近水域。 相似文献
7.
The spring-spawning Baltic Sea herring spawn in coastal areas that also serve as nursery areas for the young fish during their first summer. In a bay known as a herring spawning and nursery area, the pelagic fish abundance was quantified using hydroacoustics every second week from late spring to autumn in 2000 and 2001. A dense system of survey transects allowed determination of the acoustic index (the nautical area scattering coefficient) for fish abundance with high precision. The variation, expressed as the geostatistical coefficient of variation, was on average 5% both years and ranged from 3–11% (2000) and 3–8% (2001). Through the hydroacoustic data intra-annual dynamics in acoustic fish abundance, densities and size composition could be followed, which showed similar trends in both years. In spring and early summer acoustic fish densities were low, followed by a drastic, 20-fold increase in late summer. Hydroacoustic data and biological samples suggest that the increase was caused mainly by the recruitment of young-of-the-year herring to the acoustically assessable pelagic fish community. This age class is commonly not well represented in catches when using traditional sampling gears such as gill nets and trawls, and hydroacoustics may help to improve quantitative estimates of small juvenile fish in order to increase the understanding of biological processes in coastal nursery areas. 相似文献
8.
We report the size, abundance, and distribution (horizontal, vertical) of northern rock sole, Lepidopsetta polyxystra, larvae collected from ichthyoplankton surveys on the southeastern Bering Sea shelf near Unimak Island, in Unimak Pass, and in the Gulf of Alaska south of Unimak Island. The greatest abundances of larvae occurred within Unimak Pass and in the Bering Sea northeast of Unimak Island. Larvae were smaller and more abundant in 2002 than in 2003. Larval abundance and size varied with depth. Highest abundances were at depths of 10-30 m during the day, and larger fish appeared to migrate from below 20 m to 0-10 m at night. There was evidence of multiple spawning locales and larval dispersal pathways that were depth- and area-specific. Northern rock sole larvae spawned west of Unimak Pass along the Aleutian Islands may be transported northward by the Bering Slope Current. Larvae spawned in the Gulf of Alaska and advected through Unimak Pass are differentially dispersed, primarily to the middle and outer shelves along the 100 m and 200 m isobaths, or along the Alaska Peninsula. Larvae spawned along the Alaska Peninsula east of Unimak Island appear to have the greatest chance of being transported to nursery areas in the coastal domain. Dispersal of near-surface northern rock sole larvae in any of these locations is likely influenced by wind-driven advection, but below-surface (>10 m) northern rock sole larval transport is probably more affected by factors that modulate geostrophic flow rather than wind-driven surface currents. 相似文献
9.
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
10.
In this work, we analysed the latitudinal trends in the nursery habitat colonization processes of the European flounder (Platichthys flesus). This was accomplished by estimating the duration of the pelagic and metamorphic stages, as well as the duration of the spawning period, in several nursery areas across its geographical distribution range in the European Atlantic Coast: Mondego estuary (Portugal), Vilaine estuary (France), Slack estuary (France), Wadden Sea (Netherlands) and the Sørfjord (Norway). All juvenile flounders were captured with beam trawls in June/July 2010, and otolith microstructure was used to determine the duration of each stage by means of daily growth increments. The pelagic and metamorphic stages were longer at the middle of the distribution range, and lasted in total up to two months after hatching. The spawning period occurred between mid-January and early-July over the species' distribution range, with a time lapse of nearly two months between the Mondego estuary and the Sørfjord, as a consequence of warmer water temperature earlier in the season in southern areas. In general, total length of the captured fish showed a latitudinal cline between the northernmost and southernmost sampling sites, with higher values at the middle of the distribution range. The results also suggested the existence of a countergradient growth compensation mechanism in the northernmost populations. Apart from temperature, which sets the general metabolic pace of organisms, differences between sites were also related with local features, such as the extension of the continental platform and adaptations to transport and retention mechanisms. 相似文献
11.
We explored the hypothesis that spawning ground locations of North Sea plaice reflect the locations of nursery grounds using drift scenarios based on a baroclinic, shallow-water circulation model (HAMSOM). The transport of pelagic eggs and larvae was simulated each year from 1975 to 2006 using in situ forcing, temperature-dependent development and stage-specific behaviour of eggs and larvae. This long-term simulation period also allowed us to explore climate effects. A release position was considered a potential and suitable spawning site if larvae from that area reached coastal nurseries after the onset of metamorphosis. In general, larvae were transported in an anti-clockwise direction and settled in nurseries that were relatively close to the release positions. Spawning locations that were offshore were poorly connected to nursery grounds while those closer to the shore had higher connectivity. Simulated suitable spawning locations broadly agreed with the main centres of egg production (English Channel, Southern Bight, German Bight), except for the known spawning grounds south of Dogger Bank. Over the 31-year simulation period, positive and negative trends in transport success were found for the western and eastern parts of the North Sea, respectively. Changes in the west (Flamborough Head) were mainly due to changes in water circulation patterns whereas those in the east (northern German Bight) were induced by changes in both currents and water temperature. The implications of these findings, and the significant correlation between changes in drift and recruitment, suggest that climate-driven changes in the suitability of nursery grounds will directly affect the distribution and productivity of plaice in the North Sea. 相似文献
12.
13.
Several flatfishes spawn in oceanic waters and pelagic larvae are transported inshore to settle in the nursery areas, usually estuaries, where they remain during their juvenile life. Nursery areas appear as extremely important habitats, not only for juveniles but also for the earlier planktonic larval fish. Yet, the majority of nursery studies tend to focus only on one development stage, missing an integrative approach of the entire early life that fishes spent within a nursery ground. Thus, the present study assessed the influence of environmental parameters on the dynamics of the larval and juvenile flatfishes, throughout their nursery life in the Lima Estuary. Between April 2002 and April 2004, fortnightly subsurface ichthyoplankton samples were collected and juveniles were collected from October 2003 until September 2005. Larval assemblages comprised nine flatfish species, while only six were observed among the juvenile assemblages. Solea senegalensis and Platichthys flesus were the most abundant species of both fractions of the Lima Estuary flatfishes. Larval flatfish assemblages varied seasonally, without relevant differences between lower and middle estuary. Platichthys flesus dominated the spring samples and summer and autumn periods were characterized by an increase of overall abundance and diversity of larval flatfishes, mainly S. senegalensis, associated with temperature increase and reduced river flow. On the contrary, during the winter abundance sharply decreased, as a consequence of higher river run-off that might compromised the immigration of incompetent marine larvae. Juvenile flatfishes were more abundant in the middle and upper areas of the estuary, but the species richness was higher near the river mouth. Sediment type, distance from the river mouth, salinity, temperature and dissolved oxygen were identified as the main environmental factors structuring the juvenile flatfish assemblages. Juveniles were spatially discrete, with the most abundant species S. senegalensis and P. flesus associated with the middle and upper estuary, while the remaining species were associated with the lower estuarine areas. The larval fraction exhibited distinct dynamics from the juvenile estuarine flatfish community. Larval flatfishes showed a strong seasonal structure mainly regulated by biological features as the spawning season and also by seasonal variations of water characteristics. On the other hand, juvenile flatfishes were markedly controlled by site specific characteristics such as sediments structure, distance from the river mouth and salinity regime. The present study emphasized the idea that the environmental control varies throughout the ontogenetic development, stressing the importance of integrating all the early life of a species in flatfish nursery studies. 相似文献
14.
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
15.
T. M. Ward J. Staunton-Smith S. Hoyle I. A. Halliday 《Estuarine, Coastal and Shelf Science》2003,56(5-6):1125-1140
The diverse pelagic fish assemblage of sub-tropical southern Queensland includes fishes with predominantly temperate distributions, such as tailor Pomatomus saltatrix, sardine Sardinops sagax, round herring Etrumeus teres, and Australian anchovy Engraulis australis. The peak spawning seasons of P. saltatrix, S. sagax and E. teres occur during late winter and early spring (June–October). Eggs and larvae of these three species are widely distributed in shelf waters and comprise >50% of the ichthyoplankton assemblage during this period. Mean monthly sea surface temperatures (SSTs) during late winter and early spring range from 21 to 23 °C, and are thus similar to those recorded in southern Australia during summer and autumn, which is the spawning season of these three species in those temperate waters. E. australis eggs occur mainly in inshore waters, and comprise >50% of fish eggs collected during summer and autumn when mean monthly SSTs in southern Queensland exceed 27 °C. E. australis also spawns mainly during summer and autumn in temperate Australia. Hence, water temperature may be less important as a determinant of the spawning season of E. australis than it is for the other three species. The suitability of southern Queensland for spawning by predominantly temperate species during late winter and early spring may contribute to the high diversity of the region's pelagic fish assemblage. Adult P. saltatrix, S. sagax and E. teres appear to migrate northwards into southern Queensland during early winter to spawn, and larvae may be transported southwards into temperate waters by the East Australian Current. This dispersal-migration pattern is similar to those observed for several species, including P. saltatrix, in the western boundary current systems off the east coasts of North America and Africa. Hence, pelagic fishes in ecosystems off the east coast of three continents migrate into sub-tropical waters to spawn, and larvae are transported back into temperate nursery areas by the prevailing current. 相似文献
16.
Clive J. Fox Paul McCloghrie Richard D.M. Nash 《Estuarine, Coastal and Shelf Science》2009,81(3):381-389
A coupled physics particle-tracking model, driven by realistic meteorological forcing was used to examine the dispersal and transport of plaice eggs and larvae in the year 2000 from two spawning grounds in the Irish Sea. The model included passive transport of eggs and early stage larvae, diel vertical movements for larvae between 7 and 10.5 mm in body-length and tidally synchronised, vertical movements for larger larvae (>9 mm body-length). The year 2000 was chosen because of the availability of ichthyoplankton data with which to initialise the model. The majority of larvae originating from spawning in the eastern Irish Sea settled into nursery grounds along the Scottish, English and Welsh coasts, in agreement with previous findings. In contrast, a significant portion of larvae originating from spawning in the western Irish Sea was transported eastwards to these same nursery grounds. Transport across the Irish Sea resulted from the onset of tidally synchronised vertical behaviour encoded in the model for older larvae. Settlement of larvae into local nursery grounds along the Irish coast was limited. Because of the prevailing winds and currents in the region, plaice eggs and larvae are unlikely to be transported from east to west; in most years spawning in the western Irish Sea probably acts as an additional source of juveniles for nursery grounds along the Scottish, English and Welsh coasts. 相似文献
17.
C. Vinagre A. Maia P. Reis-Santos M.J. Costa H.N. Cabral 《Estuarine, Coastal and Shelf Science》2009,81(3):296-300
The distribution of Solea solea and Solea senegalensis in the Tagus estuary was studied following a small-scale approach. Preliminary sampling revealed that sole concentrated in two areas within their nursery grounds, the main subtidal channel and a large intertidal mudflat. Beam trawls were conducted intensively in the two areas in July 2006. Depth, salinity and water temperature were measured. Substrate samples were collected for sediment type determination and macrobenthos identification and quantification. Generalized linear models were applied in order to explain the occurrence and variability of soles' densities, using depth, salinity, water temperature and abundance of polychaetes, oligochaetes, amphipods, isopods and bivalves as explanatory variables. While S. solea was more abundant in the main subtidal channel, a deeper, warmer and lower salinity area, S. senegalensis abundance was highest at the intertidal mudflat area. Presence of both species in the two areas was associated with abundance of polychaetes (generally with another variable associated), and for S. senegalensis in the subtidal channel it was associated with amphipods and depth. Abundance of S. solea in the main subtidal channel was associated mainly with polychaetes abundance, while that of S. senegalensis was associated with amphipods density. In the intertidal mudflat, bivalves and polychaetes presented significant relationships with both species densities. Some of the factors that had been reported to be important for the distribution of these species in previous studies also do so at a finer scale; however, this small-scale approach provided an in-depth knowledge on habitat selection and spatial segregation of these species within this nursery area. 相似文献
18.
0-Group sole, Solea solea (Linnaeus, 1758) were sampled in four nursery grounds: two on the Northern French coast and two on the Portuguese coast. Juvenile sole were collected at the Vilaine estuary (Northern Bay of Biscay) in 1992, in the Authie estuary (Eastern English Channel) in 1997, and in the Douro and Tagus estuary (Northern and central Portugal, respectively) in 2005. Left lapilli otoliths were used to estimate age and investigate variability in growth rates and hatch dates. In the French study areas nursery colonisation ended in early June in the Vilaine estuary and in late June in the Authie estuary. In the Portuguese estuaries nursery colonisation ended in May in the Douro estuary and in late June in the Tagus estuary. Growth rates were higher in the Portuguese estuaries, 0.767 mm d−1 in the Tagus estuary and 0.903 mm d−1 in the Douro estuary. In the French nurseries, growth rates were estimated to be 0.473 mm d−1 in the Villaine estuary and 0.460 mm d−1 in the Authie estuary. Data on growth rates from other studies shows that growth rates are higher at lower latitudes, probably due to higher water temperature. Spawning took place between early January and early April in the Villaine estuary's coastal area in 1992. In 1997, in the Authie estuary spawning started in late January and ended in early April. On the Douro estuary's adjacent coast spawning started in mid-January and ended in late March, in 2005, while on the Tagus estuary's adjacent coast spawning started in mid-February and ended in mid-April, in the same year. Literature analysis of the spawning period of sole along a latitudinal gradient ranging from 38°N to 55°N in the Northeast Atlantic indicated that there is a latitudinal trend, in that spawning starts sooner at lower latitudes. Results support that local conditions, particularly hydrodynamics, may overrule general latitudinal trends. 相似文献
19.
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
20.
春季东海有害藻华高发区仔稚鱼时空分布 总被引：1，自引：0，他引：1
根据2011年春季(3月29日—5月27日)海洋综合调查,对东海有害藻华高发水域(28°15′36″~30°30′16″N、121°52′36″~123°15′6″E)的仔稚鱼种类组成、时空分布以及主要优势种与环境因子的相关性进行了探讨。调查共采集到仔稚鱼27种,前几位优势种分别为日本鳀Engraulis japonicus、鰕虎科sp.(Gobiidae sp.)、六丝钝尾鰕虎Amblychaeturichthys hexanema、小黄鱼Larimichthys polyactis,该4种占据了总丰度的91.23%。优势种丰度和发育阶段组成的时空变化显示,日本鳀在调查期间有两次产卵小高峰,其仔鱼孵化后向岸漂流;小黄鱼和六丝钝尾鰕虎在此期间只有一次产卵高峰,其仔鱼在舟山群岛邻近水域进行保育。可以看出,调查水域及邻近水域是部分鱼类产卵,仔稚鱼保育、向岸漂流的场所或途径,是鱼类早期生活史中重要生境,一旦暴发有害藻华,补充群体将受到不良影响。多元分析结果显示,所选环境因子对几位优势种仔稚鱼的分布影响不大,推测产卵场位置和保育方式可能是更重要的原因。 相似文献