The impact of small physical obstacles on the structure of freshwater fish assemblages

2009 ◽  
pp. n/a-n/a ◽  
Author(s):  
C. M. Alexandre ◽  
P. R. Almeida
Keyword(s):  
Freshwater Fish ◽  
Fish Assemblages ◽  
The Impact

Fish farming in Denmark: environmental impact of regulative legislation

1995 ◽  
Vol 31 (10) ◽  
pp. 73-84 ◽  
Author(s):  
T. M. Iversen
Keyword(s):  
Organic Matter ◽  
Environmental Impact ◽  
Freshwater Fish ◽  
Aquatic Environment ◽  
Action Plan ◽  
Fish Farming ◽  
Fish Farms ◽  
Nitrogen And Phosphorus ◽  
Local Impact ◽  
The Impact

The main environmental problems associated with fish farming in Denmark are attributable to the dam, the “dead reach” and nutrient and organic matter discharge. The environmental regulation of fish farming in Denmark started with the Environmental Protection Act of 1974, the Statutory Order of 1985 forbidding wet feed, and the Action Plan on the Aquatic Environment of 1987. In the case of freshwater fish farms, the latter was implemented through the measures stipulated in the 1989 Statutory Order on Fish Farms. The impact of Danish legislative measures to reduce and regulate the environmental effects of freshwater fish farms can be summarized as follows: - the number of fish farms has been reduced from about 800 in 1974 to about 500 at present; - production has tripled since 1974 and has been stable since 1989; - a change from wet to dry feed has reduced the environmental impact of the farms; - the national goals of the Action Plan on the Aquatic Environment of 1987 for reducing fish farm discharges of organic matter, nitrogen and phosphorus have been fulfilled. The main remaining problems are that: - the local impact of fish farms on downstream stream quality is still much too high in about 15% of cases; - the problem of the passage of migrating invertebrates and fish is still unsolved at some farms; - the problems posed by “dead reaches” are still unsolved. It is concluded that sustainable fish farming is possible in Denmark, but with the present technology production will have to be significantly reduced.

Performance of a pool-and-weir fish pass for small bottom-dwelling freshwater fish species in a regulated lowland river

2007 ◽  
Vol 57 (4) ◽  
pp. 423-432 ◽  
Author(s):  
Evelien Maerten ◽  
Marcel Eens ◽  
Guy Knaepkens
Keyword(s):  
Freshwater Fish ◽  
Fish Species ◽  
Fish Assemblages ◽  
Regulated River ◽  
Lowland River ◽  
Stone Loach ◽  
Spined Loach ◽  
Freshwater Fish Species ◽  
Cottus Gobio ◽  
Fish Pass

AbstractAlthough small benthic freshwater fish species are an important biological component of fish assemblages and free instream movement is indispensable for their survival, they are often neglected in fish pass performance studies. In this study, a capture-mark-recapture approach was used to assess whether small bottom-dwelling species, including gudgeon (Gobio gobio), stone loach (Barbatula barbatula), spined loach (Cobitis taenia) and bullhead (Cottus gobio), were able to cross a pool-and-weir fish pass in a regulated lowland river. Some tagged individuals of stone loach (18%), gudgeon (7%) and spined loach (2%) managed to successfully ascend the fish pass under study, despite the fact that water velocity levels in the different overflows of the facility (between 0.55-1.22 m/s) exceeded the critical swimming speed of all three species. Although this suggests that a pool-and-weir fish pass is a able to facilitate upstream movement of some small benthic species in a regulated river, more detailed research incorporating advanced tagging and retrieving techniques is necessary.

scholarly journals Testing hypotheses of diversification in Panamanian frogs and freshwater fishes using hierarchical approximate Bayesian computation with model averaging

2018 ◽  
Author(s):  
Justin C Bagley ◽  
Michael J Hickerson ◽  
Jerald B Johnson
Keyword(s):  
Freshwater Fish ◽  
Dna Sequences ◽  
Approximate Bayesian Computation ◽  
Bayes Factor ◽  
Fish Assemblages ◽  
Model Averaging ◽  
External Information ◽  
Bayesian Computation ◽  
Genetic Structuring ◽  
Approximate Bayesian

Most Neotropical frog and freshwater fish species sampled to date show phylogeographic breaks along the Pacific coast of the Isthmus of Panama, with lineages in Costa Rica and western Panama isolated from central Panama. We examine temporal patterns of diversification of taxa across this ‘western Panama isthmus’ (WPI) break to test hypotheses about the origin of species geographical distributions and genetic structuring in this region. We tested for synchronous diversification of four codistributed frog taxon-pairs and three fish taxon-pairs sharing the WPI break using hierarchical approximate Bayesian computation with model averaging based on mitochondrial DNA sequences. We also estimated lineage divergence times using full-Bayesian models. Several of our results supported synchronous divergences within the frog and freshwater fish assemblages; however, Bayes factor support was equivocal for or against synchronous or asynchronous diversification. Nevertheless, we infer that frog populations were likely isolated by one or multiple Pliocene–Pleistocene events more recently than predicted by previous models, while fish genetic diversity was structured by Pleistocene events. By integrating our results with external information from geology and elevational sea level modeling, we discuss the implications of our findings for understanding the biogeographical scenario of the diversification of Panamanian frogs and fishes. Consistent with the ‘Bermingham/Martin model’ (Mol. Ecol. 1998, 7: 499-517), we conclude that the regional fish assemblage was fractured by processes shaping isthmian landscapes during the Pleistocene glaciations, including drainage basin isolation during lowered sea levels.

Freshwater, Fish and the Future: Proceedings of the Global Cross-Sectoral Conference

2016 ◽  
Keyword(s):  
Puerto Rico ◽  
Freshwater Fish ◽  
Water Use ◽  
Large Scale ◽  
River Flow ◽  
Fish Assemblages ◽  
Physical Habitat ◽  
Resource Exploitation ◽  
Ecological Processes ◽  
Tropical Island

<em>Abstract.</em> —Freshwater tropical island environments support a variety of fishes that provide cultural, economic, and ecological services for humans but receive limited scientific, conservation, and public attention. Puerto Rico is a Caribbean tropical island that may serve as a model to illustrate the interactions between humans and natural resources in such complex ecosystems. The native freshwater fish assemblage of Puerto Rico is distinct from mainland assemblages in that the assemblage is not diverse, all species are diadromous, and they may be exploited at multiple life stages (e.g., postlarva, juvenile, adult). Primary large-scale drivers of recent water-use policy include economic growth, human population density, and urbanization, with climate change as an overarching influence. Watershed and riparian land use, water quality, river flow and instream physical habitat, river habitat connectivity, exotic species, and aquatic resource exploitation are important proximate factors affecting the ecosystem and fisheries. Research on ecological processes and components of the stream and river fish assemblages has expanded the knowledge base in the past decade with the goal of providing critical information for guiding the conservation and management of the lotic resource to optimize ecosystem function and services. The greatest challenge facing Caribbean island society is developing policies that balance the needs for human water use and associated activities with maintaining aquatic biodiversity, ecological integrity and services, and sustainable fisheries. Achieving this goal will require broad cooperation and sustained commitment among public officials, agency administrators, biologists, and the public toward effective resource management.

No detrimental effects of desalination waste on temperate fish assemblages

2020 ◽  
Author(s):  
Sasha K Whitmarsh ◽  
Greg M Barbara ◽  
James Brook ◽  
Dimitri Colella ◽  
Peter G Fairweather ◽  
...  
Keyword(s):  
Species Diversity ◽  
Fish Assemblages ◽  
Waste Product ◽  
Ecological Impacts ◽  
Global Changes ◽  
Reference Sites ◽  
Desalination Plant ◽  
Saline Waste ◽  
Temperate Fish ◽  
The Impact

Abstract Water resources are becoming increasingly scarce due to population growth and global changes in weather patterns. Desalination plants that extract freshwater from brackish or seawater are already being used worldwide, with many new plants being developed and built. The waste product from the extraction processes has an elevated salt concentration and can potentially cause substantial impacts to local marine flora and fauna. The present study assesses the impact of saline waste from a 100 GL/year desalination plant on southern Australian temperate fish assemblages, using baited remote underwater video. The study compared four reference sites to the impact site (desalination outfall) and found no evidence that the saline waste was having a detrimental effect on fish assemblages in proximity to the outfall, with species diversity and abundance comparable to those observed at reference sites. However, species diversity and abundance varied across geographical location, protection from fishing pressure, and reef type. Our study is one of the few assessing the ecological impacts of saline waste discharged from a large desalination plant and shows no decrease in fish diversity or abundance, which is the response typically associated with the negative impacts of anthropogenic activities on fish assemblages.

Factors influencing Fish Assemblages and Species Richness in Subtropical Florida Lakes and a Comparison with Temperate Lakes

1990 ◽  
Vol 47 (11) ◽  
pp. 2137-2146 ◽  
Author(s):  
A. E. Keller ◽  
T. L. Crisman
Keyword(s):  
Species Richness ◽  
Littoral Zone ◽  
Trophic State ◽  
Fish Assemblages ◽  
Temperate Lakes ◽  
Florida Lakes ◽  
Factors Influencing ◽  
Dissolved Aluminum ◽  
The Impact ◽  
Lake Size

From detailed analyses of 36 lakes, we determined that while species assemblages and richness change with lake size, trophic state, and pH, the responses were not as dramatic in Florida as in temperate lakes. At a given pH, there were more species in Florida lakes than in comparable lakes of the temperate zone. The impact of lake size on species richness was also less obvious in Florida lakes. The greater importance of centrarchids, increased contribution of the littoral zone to primary production, and lower dissolved aluminum levels may contribute to greater species richness in Florida lakes than in temperate lakes of comparable pH or size.

scholarly journals Evaluating detectability of freshwater fish assemblages in tropical streams: Is hand-seining sufficient?

2017 ◽  
Vol 100 (7) ◽  
pp. 839-849 ◽  
Author(s):  
Amy E. Deacon ◽  
Rajindra Mahabir ◽  
Devan Inderlall ◽  
Indar W. Ramnarine ◽  
Anne E. Magurran
Keyword(s):  
Freshwater Fish ◽  
Fish Assemblages ◽  
Tropical Streams

Implications of species loss in freshwater fish assemblages

Ecography ◽  
2008 ◽  
Vol 24 (6) ◽  
pp. 645-650
Author(s):  
Anne E. Magurran ◽  
Dawn A. T. Phillip
Keyword(s):  
Freshwater Fish ◽  
Fish Assemblages ◽  
Species Loss

scholarly journals Fine-scale analysis of heavily invaded Italian freshwater fish assemblages

2017 ◽  
Vol 12 (6) ◽  
pp. 500-511 ◽  
Author(s):  
Annamaria NOCITA ◽  
Elena TRICARICO ◽  
Sandro BERTOLINO
Keyword(s):  
Freshwater Fish ◽  
Fish Assemblages ◽  
Fine Scale ◽  
Scale Analysis
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