scholarly journals Fish and macrozoobenthos in the Vlára stream drainage area (Bílé Karpaty Mountains)

2008 ◽  
Vol 52 (No. 7) ◽  
pp. 214-225 ◽  
Author(s):  
P. Jurajda ◽  
Z. Adámek ◽  
M. Janáč ◽  
Z. Valová
Keyword(s):  
Salmo Trutta ◽  
Fish Assemblages ◽  
Fish Fauna ◽  
Mesh Size ◽  
Drainage Area ◽  
Aquatic Communities ◽  
Similar Frequency ◽  
Gammarus Fossarum ◽  
A Minor

Fish fauna and macrozoobenthos were surveyed at 51 and 32 sampling sites, respectively, in mountain and submountain streams of the Vlara stream drainage area in the Bílé Karpaty Mountains. The aim of the study was to bring wide knowledge of their aquatic communities with their indicative value of the ecological quality of particular sites. Fish were sampled by electrofishing and macrozoobenthos was collected by kick-sampling using a bottom net (mesh size 500 &mu;m) at the majority of the respective sites. In total, 15 fish species were registered in all profiles. At four headwater sites no fish were recorded at all. Brown trout (<i>Salmo trutta</i> m. <i>fario</i>) and stone loach (<i>Barbatula barbatula</i>) were the most frequent species at the sites under study (73% and 67%, respectively). A similar frequency (41%) was documented for chub (<i>Leuciscus cephalus</i>), gudgeon (<i>Gobio gobio</i>) and minnow (<i>Phoxinus phoxinus</i>). The species richness increased downstream in the mainstream of the Vlára stream with the maximum of 10 species found at the lowest study site. Qualitative data on fish assemblages did not fully correspond with the environmental stress. On the other hand, macrozoobenthos indicated a minor decrease in water quality downstream of small villages and farms. Larvae of dipterans (Chironomidae and Simuliidae in particular) and mayflies (Ephemeroptera) dominated among the temporary water macroinvertebrates while numerous populations of <i>Gammarus fossarum</i> (Amphipoda) and in some cases also of <i>Asellus aquaticus</i> (Isopoda) were recorded as permanent inhabitants of clean and polluted stretches, respectively.

Macrophytes banks as potential fish nursery areas in small hydropower reservoirs

2021 ◽  
Vol 33 ◽  
Author(s):  
Rafaela Shizuko Yamashita Kimura ◽  
Eduardo Meneguzzi Brambilla ◽  
João Felipe Denys Pereira ◽  
Marcos Gomes Nogueira
Keyword(s):  
Spatial Organization ◽  
Aquatic Vegetation ◽  
Fish Assemblages ◽  
Fish Fauna ◽  
Mesh Size ◽  
Small Hydropower ◽  
Initial Development ◽  
Fish Nursery ◽  
Ecological Requirements ◽  
Fish Collection

Abstract: Aim This study verified if the macrophyte banks found in two reservoirs of small hydroelectric plants (SHPs) have a functional ecological role for the initial development of ichthyofauna. Additionally, we compared the differences in the structure of the fish assemblages along each reservoir compartment and between reservoirs. Methods Sampling was performed in March 2018, in lotic, intermediate, and lentic compartments of Palmeiras and Retiro reservoirs, Sapucaí-Mirim River (SP). Three distinct macrophyte banks in each stretch (triplicates), considering the most representative in terms of composition (recurrency/dominance), were sampled, resulting in 18 samples (nine per reservoir). For fish collection we used a sieve of 1 m2 of area, mesh size of 1 mm, which was manually hauled, from the boat, in the marginal aquatic vegetation (three hauls per sample). Simultaneously, we measured basic limnological parameters with a Horiba U-52 water probe, adjacent to the banks. Results The presence of juveniles of all fish orders found in the river, Characiformes, Siluriformes, Synbranchiformes, Gymnotiformes and Cichliformes, demonstrates that, at least in certain moment of their development cycle, the macrophyte banks are used by species with different ecological requirements. It was observed significant statistical differences in the structure of the ichthyofauna along the longitudinal axes of the reservoirs, but not between reservoirs. The same was seen for the limnological data (PCA). Conclusions The macrophyte banks found in the SHPs reservoirs have a potential role as nurseries for the local ichthyofauna, mainly, but not exclusively, for sedentary species and with parental care. This association is ecologically relevant, given the absence of typical lateral habitats for the initial development of the fish fauna. Additionally, despite the reservoirs small size, spatial organization was also important for the assemblage’s structure, with differences in terms of composition, size and development stages along the distinct sampling stretches.

scholarly journals Can dams affect the trophic structure of ichthyofauna? A long-term effects in the Neotropical region

2018 ◽  
Vol 108 (0) ◽  
Author(s):  
Felipe P. de Lima ◽  
André B. Nobile ◽  
Diogo Freitas-Souza ◽  
Edmir D. Carvalho ◽  
Ana P. Vidotto-Magnoni
Keyword(s):  
Power Plants ◽  
Trophic Structure ◽  
Fish Assemblages ◽  
Feeding Activity ◽  
Fish Fauna ◽  
Neotropical Region ◽  
Hydroelectric Power ◽  
Long Term Effects ◽  
Aquatic Communities

ABSTRACT Dams are considered an important source of modification upon the structure of aquatic communities and their reflexes are diverse on the fish fauna. Although there are several hydroelectric power plants in Brazil, the long-term effects on feeding activity of ichthyofauna are unknown. Thus, this study aimed to investigate the long-term effects of an old reservoir (fifty years) on the trophic dynamics of fish fauna. The diet of 20 fish species was analyzed, identifying 37 food items belonging to six trophic categories, which enable to create six trophic groups. The results found here suggests that throughout the creation of a reservoir, the trophic structure of the fish assemblages tend to reach trophic homeostasis, in which the fish community will be capable of exploring the most available food resources being maintained primarily by the items placed in the categories organic matter and fragments of fish and vegetal.

scholarly journals Relationships between environmental conditions and fish assemblages in the Lohore River of Dailekh, Western Nepal

Our Nature ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. 18-26
Author(s):  
Sushil Shrestha ◽  
Dipak Rajbanshi ◽  
Dil Kumar Limbu ◽  
Jash Hang Limbu
Keyword(s):  
Fish Species ◽  
Environmental Conditions ◽  
Fish Assemblages ◽  
Mesh Size ◽  
Influential Factors ◽  
Fish Diversity ◽  
Fish Community Structure ◽  
Aquatic Communities ◽  
Riverine Ecosystems ◽  
Fish Samples

The Lohore River is one of the important riverine ecosystems of Dailekh which support diverse aquatic communities. The present study was carried out to assess the fish diversity status with relation to environmental conditions in both to space and time. The survey was conducted at three different sampling stations in three different seasons. For the fish sampling, two cast nets of different mesh sizes were used, one having large mesh size of 2 cm, 6 m diameter and 6 kg weight and another having mesh size of 0.5 cm, 3 m diameter and 2 kg weight. Moreover, drag net and gill net were also used to collect the fish samples. A total of 11 fish species belonging to 2 orders, 3 families and 7 genera. Results from the similarity percentage analysis (SIMPER) suggested that fish species of Puntius gelius, Schizothorax plagiostomus, Tor chelynoides and Schistura sovana were major contributing species each contribute more than 9%. An analysis of similarity (ANOSIM) pointed that fish community structure in the Lohore River differ in spatial scale (p<0.01) but not in temporal scale (P>0.01). Water temperature, dissolved oxygen and water velocity was found as influential factors for fish species distribution.

scholarly journals Evaulation of the Quality of an Aquatic Habitat on the Drietomica River

2014 ◽  
Vol 22 (1) ◽  
pp. 43-48
Author(s):  
Ivan Stankoci ◽  
Jana Jariabková ◽  
Viliam Macura
Keyword(s):  
Salmo Trutta ◽  
Ecological Status ◽  
Aquatic Habitat ◽  
Main Step ◽  
Northwestern Part ◽  
River Habitat ◽  
Habitat Simulation ◽  
Brown Trout Salmo Trutta ◽  
The One

Abstract The ecological status of a river is influenced by many factors, of which the most important are fauna and flora; in this paper they are defined as a habitat. During the years 2004, 2005, 2006 and 2011, research on the hydroecological quality of a habitat was evaluated in the reference section of the Drietomica River. Drietomica is a typical representative river of the Slovak flysch area and is located in the region of the White Carpathians in the northwestern part of Slovakia. In this article the results of modeling a microhabitat by means of the Instream Flow Incremental Methodology (IFIM) are presented. For the one-dimensional modeling, the River Habitat Simulation System (RHABSIM) was used to analyse the interaction between a water flow, the morphology of a riverbed, and the biological components of the environment. The habitat ´s hydroecological quality was evaluated after detailed ichthyological, topographical and hydro-morphological surveys. The main step was assessing the biotic characteristics of the habitat through the suitability curves for the Brown trout (Salmo trutta m. fario). Suitability curves are a graphic representation of the main biotic and abiotic preferences of a microhabitat´s components. The suitability curves were derived for the depth, velocity, fish covers and degree of the shading. For evaluating the quality of the aquatic habitat, 19 fish covers were closely monitored and evaluated. The results of the Weighted Usable Area (WUA = f (Q)) were evaluated from a comprehensive assessment of the referenced reach of the Drietomica River.

Tidal fish connectivity of reef and sea grass habitats in the Indo-Pacific

2007 ◽  
Vol 87 (5) ◽  
pp. 1287-1296 ◽  
Author(s):  
Richard K.F. Unsworth ◽  
James J. Bell ◽  
David J. Smith
Keyword(s):  
Shallow Water ◽  
National Park ◽  
Fish Assemblages ◽  
Fish Fauna ◽  
Subsistence Fisheries ◽  
Tidal State ◽  
Sea Grass ◽  
Water Fish ◽  
Tidal Changes ◽  
Near Shore

The present study considered the influence of the tide on shallow water fish assemblages within the Wakatobi Marine National Park, Indonesia. Timed underwater visual observations were made across a gradient of intertidal to subtidal habitats from near-shore to reef crest at different tidal heights. Transient fish were found to dominate shallow water fish assemblages and the assemblage composition varied with tidal state. Fish assemblages were more diverse and abundant at higher tides in both coral and sea grass habitats, however, this was more pronounced within sea grass habitats. A tidal reduction from ≈2.0m to ≈0.8m (above chart datum) corresponded to a 30% reduction in fish abundance, while species richness also significantly decreased from 13.5 to 10.8 species per standardized timed observation. Fifty fish groups were reported from sea grass habitats with the most abundant being from the Engraulidae family and Lethrinus harak, which form important local subsistence fisheries. This research confirms the importance of tidal changes in structuring the fish fauna of Indonesian sea grass habitats and underlines the connectivity that exists between these habitats and nearby coral reefs.

scholarly journals PARALLEL DELAUNAY REFINEMENT: ALGORITHMS AND ANALYSES

2007 ◽  
Vol 17 (01) ◽  
pp. 1-30 ◽  
Author(s):  
DANIEL A. SPIELMAN ◽  
SHANG-HUA TENG ◽  
ALPER ÜNGÖR
Keyword(s):  
Mesh Size ◽  
Constant Factor ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Delaunay Refinement ◽  
Steiner Points ◽  
Input Domain ◽  
Set Of Points ◽  
Refinement Algorithm

We present a parallel Delaunay refinement algorithm for generating well-shaped meshes in both two and three dimensions. Like its sequential counterparts, the parallel algorithm iteratively improves the quality of a mesh by inserting new points, the Steiner points, into the input domain while maintaining the Delaunay triangulation. The Steiner points are carefully chosen from a set of candidates that includes the circumcenters of poorly-shaped triangular elements. We introduce a notion of independence among possible Steiner points that can be inserted simultaneously during Delaunay refinements and show that such a set of independent points can be constructed efficiently and that the number of parallel iterations is O( log 2Δ), where Δ is the spread of the input — the ratio of the longest to the shortest pairwise distances among input features. In addition, we show that the parallel insertion of these set of points can be realized by sequential Delaunay refinement algorithms such as by Ruppert's algorithm in two dimensions and Shewchuk's algorithm in three dimensions. Therefore, our parallel Delaunay refinement algorithm provides the same shape quality and mesh-size guarantees as these sequential algorithms. For generating quasi-uniform meshes, such as those produced by Chew's algorithms, the number of parallel iterations is in fact O( log Δ). To the best of our knowledge, our algorithm is the first provably polylog(Δ) time parallel Delaunay-refinement algorithm that generates well-shaped meshes of size within a constant factor of the best possible.

Shareholder risk-taking incentives in the presence of contingent capital

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mahmoud Fatouh ◽  
Ayowande A. McCunn
Keyword(s):  
Risk Taking ◽  
Banking System ◽  
Capital Requirements ◽  
Content Type ◽  
Basic Model ◽  
Conversion Rates ◽  
A Minor ◽  
The Impact ◽  
Practical Implications

Purpose This paper aims to present a model of shareholders’ willingness to exert effort to reduce the likelihood of bank distress and the implications of the presence of contingent convertible (CoCo) bonds in the liabilities structure of a bank. Design/methodology/approach This study presents a basic model about the moral hazard surrounding shareholders willingness to exert effort that increases the likelihood of a bank’s success. This study uses a one-shot game and so do not capture the effects of repeated interactions. Findings Consistent with the existing literature, this study shows that the direction of the wealth transfer at the conversion of CoCo bonds determines their impact on shareholder risk-taking incentives. This study also finds that “anytime” CoCos (CoCo bonds trigger-able anytime at the discretion of managers) have a minor advantage over regular CoCo bonds, and that quality of capital requirements can reduce the risk-taking incentives of shareholders. Practical implications This study argues that shareholders can also use manager-specific CoCo bonds to reduce the riskiness of the bank activities. The issuance of such bonds can increase the resilience of individual banks and the whole banking system. Regulators can use restrictions on conversion rates and/or requirements on the quality of capital to address the impact of CoCo bonds issuance on risk-taking incentives. Originality/value To model the risk-taking incentives, authors generally modify the asset processes to introduce components that reflect asymmetric information between CoCo holders and shareholders and/or managers. This paper follows a simpler method similar to that of Holmström and Tirole (1998).

scholarly journals Documentation of multiple species of marine fish trapped in Atlantic salmon sea-cages in Norway

2018 ◽  
Vol 31 ◽  
pp. 31
Author(s):  
Per Gunnar Fjelldal ◽  
Monica F. Solberg ◽  
Kevin A. Glover ◽  
Ole Folkedal ◽  
Jonatan Nilsson ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Salmo Trutta ◽  
Gadus Morhua ◽  
Mesh Size ◽  
Anguilla Anguilla ◽  
Wild Fish ◽  
Melanogrammus Aeglefinus ◽  
European Eel ◽  
Farmed Salmon ◽  
Sea Trout

The production of salmonids in sea-cages has been developed for monoculture of the target species. However, we show here for the first time, that wild fish may enter sea-cages used for farming of Atlantic salmon (Salmo salar L.) in Norway, out-grow the mesh size, and thereafter become permanently trapped. Within seven different sea-cages located in western Norway, eight different species of wild fish were identified; European eel (Anguilla anguilla), sea trout (Salmo trutta L.), cod (Gadus morhua), haddock (Melanogrammus aeglefinus), saithe (Pollachius virens), pollack (Pollachius pollachius), hake (Merluccius merluccius) and whiting (Merlangius merlangus). In the two most extreme cases, a 5 × 5 × 7 m cage with 311 farmed salmon (903 g) also contained 542 whiting (79 g), 77 haddock (43 g), and 5 cod (26 g), and a 12 × 12 × 15 m cage with 1695 farmed salmon (559 g) also contained 1196 haddock (35 g), 1115 whiting (31 g), 46 cod (23 g), 23 saithe (48 g), 15 pollock (22 g), 5 sea trout (54 g), and 2 hake (29 g). The present study thus demonstrates that aquaculture cages designed for monoculture may attract and effectively ‘trap’ wild fish. We did not investigate the frequency of this occurrence, and the ecological significance of these observations remains unclear. However, with the ever-increasing number of sea-cages used for global aquaculture, this is clearly a topic for further research.

scholarly journals Comparative Analysis of Distribution of Intertidal Fish Assemblages in Different Estuarine Systems on Northern Coast of Brazil

2017 ◽  
Vol 10 (2) ◽  
pp. 26 ◽  
Author(s):  
Milton Goncalves Silva Junior ◽  
Antonio Carlos Leal Castro ◽  
Ulrich Saint-Paul
Keyword(s):  
Comparative Analysis ◽  
Fish Assemblages ◽  
Coastal Region ◽  
Fish Fauna ◽  
Estuarine Fish ◽  
Northern Coast ◽  
Tidal Creeks ◽  
Estuarine Systems ◽  
Using Data ◽  
High Dynamics

The northern coast of Brazil has more than 30 estuaries distributed along 650 km of coastline. These conditions favor the presence of relatively large fish communities in estuarine environments, but published information on the fish fauna in tidal creeks in northern Brazil is only available for some mangrove systems, and comparative studies between fish estuarine communities in different tidal creeks are less common. The choice of the study area was based on the fact that it has been poorly investigated with regard to estuarine fish fauna in comparison in mangrove tidal creeks using the same fishing gear. The objective of the present study was to compare the composition of the relative biomass of taxonomic, functional and ecological guilds of fish assemblages occurring in estuarine systems along the northern coast of Brazil. The study area of the present comparative analysis extended from the southeastern edge of the Marajoara Gulf to the western edge of the Maranhense Gulf. A comparative analysis among different estuarine systems was performed using data from other studies. The abundance of juveniles was greater in the Caeté, Curuçá and Cururuca estuaries than other estuaries. Cluster analysis separated the estuaries into two distinct groups and significant differences between these groups only exist in relation to geographical proximity. The present investigation indicates that the coastal region between the states of Pará and Maranhão is characterized by high dynamics and environmental heterogeneity, particularly with regard to changes in river discharge and tidal fluctuations. The present results underscore the importance of ecological information on ichthyofauna in tropical estuaries in order to include appropriate descriptors in conservation or restoration processes of marine communities and habitats.

scholarly journals Fishes of Paranaguá Estuarine Complex, South West Atlantic

2012 ◽  
Vol 12 (3) ◽  
pp. 226-238 ◽  
Author(s):  
Ana Carolina dos Passos ◽  
Riguel Feltrin Contente ◽  
Ciro Colodetti Vilar de Araujo ◽  
Felippe Alexandre Lisboa de Miranda Daros ◽  
Henry Louis Spach ◽  
...  
Keyword(s):  
Conservation Status ◽  
Fish Fauna ◽  
Brazilian Coast ◽  
Large Dataset ◽  
Ecological Information ◽  
South West ◽  
Minor Part ◽  
Global Biodiversity ◽  
A Minor ◽  
Incomplete Sampling

The objective of this work was to present an updated checklist of the currently known fishes in the Paranaguá Estuarine Complex (PEC) and provides comments on conservation status for the treated species. We used a large dataset derived from a pool of studies which have been conducted within there along the last 30 years. Each study was based on monthly samplings and conducted in several estuarine habitat; thus, the pool covers practically all estuarine habitats and takes into account the seasonal cycle in the system. The PEC ichthyofauna represents a mixture between that fauna typical from the tropical Brazilian coast and that with affinities of temperate Argentinean and Uruguayan zones. The PEC harbors a rich fish fauna of 213 species, inserted in the families that are common along the Brazilian coast. Only a minor part (8%) of the PEC fish fauna was evaluated as regards the conservation status, mostly because of the lack of basic biological and ecological information for most species. Despite part of the among-estuaries differences are due to different and incomplete sampling efforts, the richness in the PEC is surprisingly higher than other systems in Brazil and around world, which emphasize the importance of the region for global biodiversity conservation.

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