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- 1. The community composition and spatial distribution of the macrobenthic fauna in relation to abiotic factors was investigated at 20 sites along the River Minho estuarine gradient, in the north‐west Iberian Peninsula.
- 2. A total of 68 taxa were identified and the non‐indigenous invasive species Corbicula fluminea dominated both numerically (43.1%) and by biomass (97.7%).
- 3. Multivariate analysis identified spatial differences in structure and composition of assemblages and suggests a continuum between five distinct assemblages along the length of the estuary. This situation fits the two‐ecocline model in which an ecocline from the sea to mid‐estuary overlaps with an ecocline from freshwater to mid‐estuary.
- 4. Each assemblage was found in a particular physico‐chemical environment and had a specific composition. The distribution and diversity patterns were linked to salinity. However, inside each assemblage the sediment characteristics (granulometry and organic matter content) played an important role.
- 5. The highest abundances, biomasses and total species numbers were recorded from upstream freshwater tidal areas, indicating the importance of these habitats within estuarine ecosystems.
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Influence of oceanographic conditions on abundance and distribution of post‐larval and juvenile carangid fishes in the northern Gulf of Mexico 
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下载免费PDF全文 John A. Mohan Tracey T. Sutton April B. Cook Kevin M. Boswell R. J. David Wells 《Fisheries Oceanography》2017,26(5):526-541
Relationships between abundance of post‐larval and juvenile carangid (jacks) fishes and physical oceanographic conditions were examined in the northern Gulf of Mexico (GoM) in 2011 with high freshwater input from the Mississippi River. Generalized additive models (GAMs) were used to explore complex relationships between carangid abundance and physical oceanographic data of sea surface temperature (SST), sea surface height anomaly (SSHA) and salinity. The five most abundant carangid species collected were: Selene setapinnis (34%); Caranx crysos (30%); Caranx hippos (10%); Chloroscombrus chrysurus (9%) and Trachurus lathami (8%). Post‐larval carangids (median standard length [SL] = 10 mm) were less abundant during the spring and early summer, but more abundant during the late summer and fall, suggesting summer to fall spawning for most species. Juvenile carangid (median SL = 23 mm) abundance also increased between the mid‐summer and early fall. Most species showed increased abundance at lower salinities and higher temperatures, suggesting entrainment of post‐larval fishes or feeding aggregations of juveniles at frontal convergence zones between the expansive river plume and dynamic mesoscale eddy water masses. However, responses were species‐ and life‐stage specific, which may indicate fine‐scale habitat partitioning between species. Ordination methods also revealed higher carangid abundances at lower salinities for both post‐larval and juvenile life stages, with species‐ and life‐stage specific responses to SST and SSHA, further suggesting habitat separation between species. Results indicate strong links between physical oceanographic features and carangid distributions in the dynamic northern GoM. 相似文献
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Beaver dams shift desert fish assemblages toward dominance by non‐native species (Verde River,Arizona, USA) 下载免费PDF全文
下载免费PDF全文 The reintroduction of beaver (Castor canadensis) into arid and semi‐arid rivers is receiving increasing management and conservation attention in recent years, yet very little is known about native versus non‐native fish occupancy in beaver pond habitats. Streams of the American Southwest support a highly endemic, highly endangered native fish fauna and abundant non‐native fishes, and here we investigated the hypothesis that beaver ponds in this region may lead to fish assemblages dominated by non‐native species that favour slower‐water habitat. We sampled fish assemblages within beaver ponds and within unimpounded lotic stream reaches in the mainstem and in tributaries of the free‐flowing upper Verde River, Arizona, USA. Non‐native fishes consistently outnumbered native species, and this dominance was greater in pond than in lotic assemblages. Few native species were recorded within ponds. Multivariate analysis indicated that fish assemblages in beaver ponds were distinct from those in lotic reaches, in both mainstem and tributary locations. Individual species driving this distinction included abundant non‐native green sunfish (Lepomis cyanellus) and western mosquitofish (Gambusia affinis) in pond sites, and native desert sucker (Catostomus clarkii) in lotic sites. Overall, this study provides the first evidence that, relative to unimpounded lotic habitat, beaver ponds in arid and semi‐arid rivers support abundant non‐native fishes; these ponds could thus serve as important non‐native source areas and negatively impact co‐occurring native fish populations. 相似文献
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Hannele M. Honkanen Jessica Rodger Alastair Stephen Keith Adams James Freeman Colin E. Adams 《Ecology of Freshwater Fish》2020,29(1):31-39
There is generally a very poor understanding of how anadromous brown trout, Salmo trutta, use marine ecosystems. In this study, we use acoustic telemetry techniques to test four alternative hypotheses for estuarine coastal habitat use by this species on a population in the Clyde, west-central Scotland. Anadromous brown trout in their second (or more) summer feeding in the marine environment did not show patterns of estuarine use predicted from studies on other populations of this species. They did not (a) use the inner Clyde Estuary as a staging post for onward migration to open coastal waters, nor did they (b) pass through the estuary rapidly nor did they (c) make multiple incursions into freshwater. In contrast, fish utilised a very geographically constrained area of the inner estuary (<8 km in length), within which fish were highly mobile, exhibiting more activity during a flooding tide and exhibited high survivorship compared with reports from other studies. The reasons why estuarine use by anadromous brown trout in the Clyde may differ from that reported elsewhere is discussed. 相似文献
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Daverat F, Martin J, Fablet R, Pécheyran C. Colonisation tactics of three temperate catadromous species, eel Anguilla anguilla, mullet Liza ramada and flounder Plathychtys flesus, revealed by Bayesian multielemental otolith microchemistry approach.Ecology of Freshwater Fish 2011: 20: 42–51. © 2010 John Wiley & Sons A/S Abstract – The colonisation of Gironde (SW France) river catchment by juvenile, eel, Anguilla anguilla, flounder Platychtys flesus and thinlipp mullet Liza ramada was investigated comparatively using Sr:Ca and Ba:Ca composition of otolith. The relation between Sr, Ba and habitat was investigated based on Sr and Ba water composition sampled each month along the estuary‐river gradient. A total of 50 mullets, 30 eels and 47 flounders were collected in the Gironde river catchment. Analysis was performed with a Femtosecond LA‐ICPMS along a trajectory from the core to the edge. Sr and Ba water concentrations discriminated three habitats within the Gironde system, the lower estuary, the upper estuary and the freshwater sites. A signal processing method based on Gaussian hidden Markov models was applied to the multielemental life‐history data. The linear model used to allocate a Gironde habitat to coupled Sr, Ca values was parameterised with seasonal patterns and magnitude of Sr and Ba water values in the different habitats. The results showed that the three species used three different habitats and they had a large diversity of habitat use patterns with resident and nomadic tactics. Resident tactics were less frequent than nomadic tactics that suggested individual fish used two or more habitats. Mullet used a wider range of habitats in the lower part of the estuary than eel and flounder and switched habitats more frequently. Flounders tended to colonise initially freshwater, and then estuarine habitats later in life while mullets used the entire range of available catchment habitats throughout their life. 相似文献
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Understanding post‐release dynamics of stocked fish is essential to successful stock enhancement. This study aimed to match existing life history knowledge to optimise productivity of releases of mulloway, Argyrosomus japonicus (Temminck & Schlegel) into an urban estuary. Passive acoustic telemetry was used to monitor the movement of juvenile mulloway in the Georges River, New South Wales, Australia, and assess the effect of release site and abiotic factors on broad‐scale movements of individuals for 26 weeks. This study found that release site primarily determines the location within the estuary where individuals reside. Water temperature, atmospheric pressure and rainfall did not correlate with fish distribution, although a flood drove fish stocked from upper and mid‐river sites down the estuary in February 2008. Fish gradually returned to these sites over the following 9 weeks. Emigration rates showed an initial downstream migration and an overall egression of ~50% of fish from the release site over 26 weeks. Fish released in this study showed a degree of site‐ and group‐fidelity, with fish distributing according to release site. It is recommended that future releases of mulloway are undertaken directly into nursery habitat in upper estuarine regions to minimise emigration and maximise efficiency of stocking programmes. 相似文献
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Large‐scale,seasonal habitat use and movements of yellow American eels in the St. Lawrence River revealed by acoustic telemetry 下载免费PDF全文
下载免费PDF全文 Mélanie Béguer‐Pon Martin Castonguay José Benchetrit Daniel Hatin Michel Legault Guy Verreault Yves Mailhot Valérie Tremblay Julian J. Dodson 《Ecology of Freshwater Fish》2015,24(1):99-111
Large‐scale habitat use and movements of yellow American eels (Anguilla rostrata) from the St. Lawrence River were examined using acoustic telemetry from early summer to late fall in 2010 and 2011. Sixty‐seven eels were tagged, and their passage or presence was recorded using fixed acoustic arrays covering a 400 km distance along the St. Lawrence River and Estuary. Sixty‐four per cent of the 67 tagged eels were detected. Most eels were detected at only one array; the closest to their release location and at several occasions during the tracking period, suggesting a high proportion of freshwater residency in the upstream part of the St. Lawrence River. Downstream movements towards the brackish estuary (63–418 km distance) were demonstrated for 16.4% of the eels, particularly for those caught at the most downstream site that is close to the brackish estuary. Our results strongly suggest a lower activity of freshwater resident yellow eels during summer, a behaviour that may be related to day length, which defines time available for their nocturnal foraging. Indeed, yellow eels were detected primarily at night; no effect of moon phase was revealed. Movements in the vicinity of arrays (up to 116 km in the fluvial estuary) were suggested and smaller‐scale movements within Lac St. Louis were demonstrated, highlighting a yellow‐eel home range far more extensive than previously reported in smaller systems. Evidence for within‐season homing and site fidelity is also reported. 相似文献
8.
Sea lice are significant parasites of marine and brackish farmed fishes. Freshwater bathing is a potential control option against numerous sea lice species, although has been viewed as futile against those that are capable of tolerating freshwater for extended periods. By comparing freshwater survival times across host‐attached stages of Lepeophtheirus salmonis (Krøyer), a key parasite in Atlantic salmon farming, we show the first attached (copepodid) stage undergoes 96–100% mortality after 1 h in freshwater, whereas later attached stages can tolerate up to 8 days. Thus, regular freshwater bathing methods targeting the more susceptible attached copepodid stage may successfully treat against L. salmonis and potentially other sea lice on fish cultured in marine and brackish waters. 相似文献
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Mark S. Peterson Marisa R. Weber Melissa L. Partyka Stephen T. Ross 《水产资源保护:海洋与淡水生态系统》2007,17(6):602-618
- 1. The ultimate determination of coastal habitat suitability requires the integration of both dynamic (i.e. water mass characteristics) and stationary (structural) habitats. An approach using real‐time streamed data collection, remote sensing, and GIS modelling to compare and contrast seasonal and spatial patterns in these habitat components of the eastern and western distributaries of the lower Pascagoula River estuary is described.
- 2. Structural and dynamic habitat characteristics are described using GIS and integrated with published growth data on juvenile mullet (Mugil spp.) and spot (Leiostomus xanthurus) to reveal zones of accelerated growth. Both mullet and spot had their greatest growth when water temperature and salinity (dynamic habitat) were physiologically optimal. The lack of spatial difference in the dynamic habitat between distributaries resulted in no growth zone differences for both species.
- 3. The integration of the growth zones with the structural habitat component showed that the west distributary, with its greater availability and reduced fragmentation of main channel marsh edge, should provide a greater area of essential fish habitat than the east distributary for juvenile spot, a marsh‐edge associate. Because juvenile mullet are less associated with structural wetland habitat, growth zones and the stationary (structural) habitat were not integrated.
- 4. The approach of integrating real‐time geo‐referenced water quality data with regional fish growth‐rate data is an important step towards a quantitative understanding of the hierarchical nature and inherent variability of dynamic coastal environments. The use of this holistic approach should lead to more effective management of estuarine systems, especially in regard to potential impacts within the estuary's watershed and to its coupling with offshore environments.
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Diana Jaramillo Stewart Fielder Richard J. Whittington Paul Hick 《Journal of fish diseases》2019,42(2):167-180
Australian bass Macquaria novemaculeata were challenged by immersion with nervous necrosis virus (NNV) at different ages and under controlled conditions to investigate factors affecting disease expression. Fish challenged at 3 weeks of age with 103 TCID50/ml and higher doses developed clinical disease; a lower dose of 102 TCID50/ml resulted in incidence below 100% and 101 TCID50/ml was insufficient to cause infection. Additionally, fish were challenged at 5, 6 and 13 weeks of age at 17 and 21°C to assess the role of the age of the host and water temperature on disease expression. Although Australian bass challenged at all ages had evidence of replication of NNV, only those challenged at 3 weeks of age (20 and 24 days post?hatch [dph]) developed clinical disease. Higher water temperature had an additive effect on disease expression in larvae challenged at 24 dph, but it did not affect the disease outcome in older fish. Finally, isolates of NNV derived from fish with clinical or subclinical disease presentations caused similar cumulative mortality and clinical signs when larvae at 24 dph were challenged, suggesting that agent variation was not responsible for variation in clinical presentation in these field outbreaks of NNV infection. 相似文献
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Growth and survival of selected aquatic animals in two saline groundwater evaporation basins: an Australian case study 总被引：3，自引：0，他引：3
Evaluation trials were undertaken in two evaporation basins filled with saline groundwater to identify finfish and shellfish that have the potential to survive and grow in these conditions. Test animals were reared in replicate culture units in each of two basins filled with saline groundwater located in the Goulburn–Murray Irrigation District (GMID), south‐eastern Australia. Salinity in basin 2 (9.5–24.6 p.p.t., mean 16.8 p.p.t.) was significantly higher than in basin 1 (8.8–15.2 p.p.t., mean 11.6 p.p.t.). Some differences were observed between the ionic concentrations in the groundwater and sea water (at 10 p.p.t.) and may have affected growth and survival of some species. Survival and growth for oysters (Crassostrea gigas and Saccostrea glomerata) in the basins were low. Shrimps (Penaeus monodon and Marsupenaeus japonicus) did not survive beyond 3 weeks. Of the eight species of fish stocked into the basins, Salmo salar, Macquaria novemaculeata and Acanthopagrus butcheri survived and grew in both basins. Oncorhynchus mykiss did not survive in the low‐salinity basin, whereas Bidyanus bidyanus did not survive in the high‐salinity basin. These results indicate that some species of fish in particular can be cultured in saline groundwaters within the GMID. 相似文献
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Susceptibility of a number of Australian freshwater fishes to dwarf gourami iridovirus (Infectious spleen and kidney necrosis virus) 下载免费PDF全文
下载免费PDF全文 Megalocytiviruses cause high mortality diseases that have seriously impacted aquaculture, with the most frequent outbreaks occurring in East and South‐East Asia. The international trade of juvenile fish for food and ornamental aquaculture has aided the spread of these viruses, which have spread to Europe and Australia and other regions. Australian freshwater fishes were examined for susceptibility to infection with the exotic megalocytivirus, dwarf gourami iridovirus (DGIV), which belongs to a group with the type species, Infectious spleen and kidney necrosis virus (ISKNV). Fish were held at 23 ± 1 °C and challenged by intraperitoneal (IP) injection or by cohabitation with Murray cod, Maccullochella peelii (Mitchell) infected with DGIV. A species was deemed to be susceptible to DGIV based on evidence of viral replication, as determined by qPCR, and megalocytic inclusion bodies observed histologically. Horizontal transmission occurred between infected Murray cod and golden perch, Macquaria ambigua (Richardson), Macquarie perch, Macquaria australasica (Cuvier) and Murray cod. This indicated that DGIV shed from infected fish held at 23 °C can survive in fresh water and subsequently infect these naïve fish. Further, DGIV administered IP was highly pathogenic to golden perch, Macquarie perch and Murray cod. Compared to these species, the susceptibility of southern pygmy perch, Nannoperca australis (Gunther) was lower. Freshwater catfish (dewfish), Tandanus tandanus (Mitchell), were not susceptible under the experimental conditions based on the absence of clinical disease, mortality and virus replication. This study showed the potential risks associated with naïve and DGIV‐infected fish sharing a common water source. 相似文献
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Prioritising culvert removals to restore habitat for at‐risk salmonids in the boreal forest 下载免费PDF全文
下载免费PDF全文 In the boreal forests of Canada, industrial development has resulted in the installation of thousands of culverted road crossings that act as barriers to fish movement and degrade habitat for native freshwater fishes. In view of culvert removals being expensive, prioritisation methods have been developed, but the efficacy of such methods has not been thoroughly investigated nor have they been tested on low‐gradient boreal forest watersheds containing at‐risk salmonids. The management utility of a novel GIS‐based optimisation‐planning tool to prioritise fish barrier remediation was tested in two highly developed watersheds. Region‐specific parameter estimates of monetary variables (e.g. budget, individual barrier remediation costs), barrier passability and biologically relevant information for species on conservation concern (e.g. habitat suitability, dispersal ability) were incorporated. Results indicate that for Arctic grayling, Thymallus arcticus Pallas, and bull trout, Salvelinus confluentus Suckley, a large proportion (~61–83%) of currently isolated habitat can be reconnected with low investment (~$200–$500 K). This study demonstrates the management utility of barrier optimisation methods for use in boreal watersheds, particularly as it significantly reduces the technical expertise needed to perform relatively complex optimisation analyses. 相似文献
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Richard R. Budnik Joseph D. Conroy Richard D. Zweifel Stuart A. Ludsin Elizabeth A. Marschall 《Ecology of Freshwater Fish》2021,30(1):31-47
Rising temperatures caused by climate change are likely to affect cool‐water and warm‐water fishes differently. Yet, forecasts of anticipated temperature effects on fishes of different thermal guilds are lacking, especially in freshwater ecosystems. Towards this end, we used spatially explicit, growth rate potential (GRP) models to project changes in seasonal habitat quality for a warm‐water piscivore (largemouth bass Micropterus salmoides), a cool‐water piscivore (walleye Sander vitreus) and a hybrid piscivore (saugeye S. vitreus × S. canadensis) in two Midwestern reservoirs. We assessed habitat quality for two periods (early and middle 21st century) under two realistic greenhouse gas emission scenarios (a mid‐century emissions peak and a rapid continuous increase in emissions). Largemouth bass were projected to experience enhanced or slightly reduced habitat during all seasons, and throughout the mid‐21st century. By contrast, walleye habitat was projected to decline with anticipated warming, except during the spring in the smaller of our two study reservoirs and during the fall in the larger of our two study reservoirs. Saugeye habitat was projected to either increase modestly or decline slightly during the spring and fall and declines in habitat quality and quantity that were smaller than those for walleye were identified during summer. Collectively, our findings indicate that climate warming will differentially alter habitat suitability for reservoir piscivores, favouring warm‐water species over cool‐water species. We expect these changes in habitat quality to impact the dynamics of reservoir fish populations to varying degrees necessitating the consideration of climate when making future management decisions. 相似文献
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D. STARRS B. C. EBNER M. LINTERMANS C. J. FULTON 《Fisheries Management and Ecology》2011,18(5):360-374
Abstract Barriers to migration are a major threat to freshwater fish populations. A novel measurement of swimming speed performance and an analytical model were used to calculate the probability that endangered Macquarie perch, Macquaria australasica Cuvier, can swim through instream structures. Over the range of river discharges (2.7–166 ML day?1) and temperatures (10–22 °C) examined, M. australasica could successfully pass through a rock‐ramp fishway and nearby natural riffles under most river discharges, whilst pipe culverts were passable only to large individuals (>17.7 cm total length) under a high river discharge. Cold water temperatures (below 16 °C) significantly reduced the likelihood of passage in each case. It was concluded that both the volume and thermal characteristics of environmental flow releases should be considered when assessing and remediating potential instream barriers to fish passage in regulated river systems. 相似文献
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This study aimed to identify the spatial and temporal patterns of composition and distribution of early life‐history stages of fish along an estuarine gradient. Samples were collected quarterly between April 2010 and January 2011 using conical‐cylindrical plankton nets in the Vaza Barris estuarine river system (NE Brazil). A total of 38,781 fish eggs and 3,526 larvae, representing 20 families and 42 taxa, were caught. The most abundant larval taxa were Microgobius meeki, Ctenogobius gr. smaragdus/boleosoma, Gobionellus oceanicus, Ctenogobius gr. stigmaticus/saepepallens/shufeldti, Bairdiella ronchus, Achirus sp., Trinectes sp., Stellifer rastrifer and S. stellifer, accounting together for 34.5% of the total catch. Ichthyoplankton distributions were characterized by high seasonal and spatial variability mainly attributed to the environmental characteristics of the estuary. Overall, lower estuarine region served as important accumulation areas for ichthyoplankton, concentrating the greatest diversity and abundance. Salinity gradient, water temperature, and inorganic nutrients were the main variables that affected the larval fish assemblages, presumably influencing spawning, development and survival of individuals or through their effect on food supply. Moreover, this study reinforced the concept that hydrological variations may have a strong influence on estuarine species retention and marine species immigration. Finally, this study highlights the importance of estuaries for the growth and maintenance of stocks of fish species, and the development of strategies to protect these habitats is of utmost relevance. 相似文献
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M. Worth Pugh Gary Pandolfi Thomas Franklin Michael M. Gangloff 《水产资源保护:海洋与淡水生态系统》2021,31(3):494-503
- Freshwater communities are threatened by the conversion of natural landscapes for urban and agricultural purposes. Changes to land use may disrupt stream nutrient and geomorphological processes and reduce water quality, increase sedimentation, and decrease habitat heterogeneity eventually leading to species loss and decreases in ecosystem productivity. Endemic species are frequently at greater risk of habitat-mediated fragmentation and extirpation due to their constrained distributions.
- The Kanawha darter (Etheostoma kanawhae) is an understudied fish endemic to the New River Drainage in North Carolina and Virginia, USA. To investigate the potential effect(s) of land-use change on Kanawha darters, naïve occupancy was modelled using instream habitat characteristics and upstream forest cover.
- Generalized linear models revealed that instream habitat and forest cover are reliable predictors of Kanawha darter site occupancy. Specifically, models demonstrated that occupancy increased in reaches with reduced stream width, velocity, and bedrock substrate but higher concentrations of coarse woody material. Kanawha darter occupancy was also positively associated with the extent of forest cover in upstream catchments.
- Although Kanawha darters are not currently considered imperilled, most populations occurred in isolated reaches separated by large sections of unoccupied habitat. Continuing ex-urban development in riparian zones is likely to be the primary threat to Kanawha darters and other endemic species in this catchment. Resource managers and stakeholders should preserve forest cover in headwaters and occupied tributaries and protect or restore riparian zones along the main-stem South and North Forks of the New River to preserve high-quality habitat and enhance connectivity among isolated Kanawha darter populations.
- As human populations in montane regions continue to grow, there is a need to understand how land-use change affects endemic freshwater species. This study further supports the importance of retaining forest cover as an effective strategy for protecting and restoring populations of endemic fishes in high-gradient streams.