Dominance Of Fish Species Research Articles

Composition and Dominance of Fish Species on the Coast of Deli Serdang District, North Sumatra

Composition and Dominance of Fish Species on the Coast of Deli Serdang District, North Sumatra

Diversity, abundance and dominance of fish species in the Churute River, Ecuador

En esta investigación se evaluó la diversidad de especies nativas e introducidas en el río Churute, el cual atraviesa la Reserva Ecológica Manglares Churute, en Ecuador, utilizando para ello un enfoque empírico-inductivo, con diseño no experimental de corte transversal-explicativo. Las capturas se realizaron con atarraya, arte de pesca tradicional en época de sequía, a lo largo del río Churute. Se muestrearon 25 sitios, considerando 33 lances como esfuerzo de pesca por cada sitio, y los peces capturados fueron clasificados taxonómicamente, contados y pesados para estimar los índices ecológicos de riqueza, abundancia, diversidad y dominancia en el área de estudio. Se identificaron 20 especies ícticas (19 nativas y 1 introducida) distribuidas en 18 géneros de 13 familias y 5 órdenes; las familias con mayor número de especies fue CICHLIDAE con cuatro especies, BRYCONIDAE, CHARACIDAE, ELEOTRIDAE y HEPTAPTERIDAE con dos especies cada una. De las especies identificadas, siete calificaron como importantes, sobresaliendo la tilapia, pez introducido con un Índice de Importancia Relativa (IRI) de 40.075,58, dominando en los sitios de muestreo en un 61,13 %. Se concluye que la tilapia es una especie dominante, con tasas de reproducción superiores al de las especies nativas presentes en el río Churute, por lo que su presencia constituye una seria amenaza a la biodiversidad de este ecosistema.

Freshwater Landscape Reconstruction from the Bronze Age Site of Borsodivánka (North-Eastern Hungary)

This multiproxy work presents the archeozoological analysis of fish and microvertebrate remains from the Middle Bronze Age tell site of Borsodivánka (Borsod Plain, North-eastern Hungary). The fish faunal assemblage provides valuable data on the choice of exploited consumption patterns, taphonomy, and aquatic paleoenvironmental conditions at the site during the Bronze Age. Only freshwater taxa are present in the assemblage, for example, northern pike (Esox lucius); cyprinids: roach (Rutilus rutilus), common carp (Cyprinus carpio), common chub (Squalius cephalus) and common nase (Chondrostoma nasus); and percids: European perch (Perca fluviatilis) and pikeperch (Sander lucioperca). Herpetofaunal and micromammal remains are also part of this study, improving our knowledge of the site’s freshwater ecosystem. The grass snake (Natrix cf. natrix) and the European pond terrapin (Emys orbicularis), typical of aquatic ecosystems, are associated with the Aesculapian ratsnake (Zamenis longissimus), more typical of forest, shrubland, and grassland. The presence of amphibians such as toads (Bufo/Bufotes sp.) and frogs (Rana sp.) complete the herpetofaunal list. The microvertebrates also support a mature fluvial system, as represented by taxa like the European water vole (Arvicola amphibius). Other micromammals are present, such as the wood mouse (Apodemus sylvaticus), the group of the common/field vole (Microtus arvalis/agrestis), the European mole (Talpa europaea), and the house mouse (Mus musculus). All of them are common in forests, shrubland, and grassland. However, the commensal house mouse is more commonly associated with anthropogenic areas. In conclusion, Borsodivánka is characterized by a diverse landscape mosaic, displayed by the co-existence of a well-developed forest and a freshwater inland ecosystem with agricultural land in the wider area. Finally, the Tisza River and its flood plain represented the main water source close to the site, distinguished by the dominance of fish species from deep and slow-flowing waters.

The Diversity of Fish in Seagrass Beds and Bare Sand channel In Tablolong Waters, Kupang Regency

Seagrass ecosystems in Tablolong waters have important values related to the availability of fish resources. However, this seagrass meadow experiences a lot of fragmentation in the form of empty sand areas without vegetation (bare sand), both in the form of channels and tidal pools which provide many small living spaces (microhabitats) that are interesting for aquatic ecology studies. The aim of this research was to analyze the diversity and dominance of fish species in the seagrass beds and bare sand channels, as well as to determine the dominant species of seagrasses in the seagrass beds. The study was conducted through direct observation by catching fish specimens using gillnets (# 1.5 inches and #1.25 inches, @ length 20 m x height 1.5 m) and scoop nets three (3) times sampling with time intervals. 7-10 days in the time period of October-November 2021. The results showed that the seagrass beds in the Tablolong Waters are classified as heterospecific from at least 6 (six) seagrass species with an average density of all species reaching 219.2 stands/m2 and an average cover of 40.0% (medium level of cover) where Thalassia hemprichii was the dominant seagrass species in terms of density value (more than 50%of total species) and cover value almost 40% of total species. The fish collection obtained as a whole consisted of 22 fish species from 17 families with 86 individuals where the fish community in the seagrass beds (9 species, 8 families, 17 individuals) was recorded to be lower than the fish community in the empty sand tunnel (13 species, 11 families, 49 individuals), each with a ratio of 41%:59% in species, a ratio of 47%:65% in families and a ratio of 43%:57% in the number of individuals. The status of the fish species that dominates was the occasional visitor fish of 90% (20 species) compared to seasonal visitor fish and whole life resident fish of 5% (1 species). The index value of fish species diversity in seagrass beds was moderate (H’ 2) which was lower than the fish community in empty sand tunnels which was high (H’ 4) and the total number of fish species on Tablolong beach was high (H’ > 4). The fish species dominance index value showed that in both fish in seagrass beds (D 0.28), in empty sandtunnels (D 0.11), and the whole area (D 0.25) in Tablolong waters there were no dominant fish species. So that the structure of the fish community tends to be stable or the diversity of fish species tends to be high.

Testing the native invasion hypothesis to explain anthropogenic influence on stream fish assemblages

In communities or regions where non-native fish species still do not predominate, changes in the assemblage composition are driven by loss, gain or substitution by native species only. We investigated the native invasion hypothesis in small streams, in which human modifications may influence fish assemblage composition by boosting the expansion and establishment of widespread species, as well as of species commonly found in large streams and rivers. Fish community data from 54 lowland streams from South Brazil were used to investigate this hypothesis. We found a positive relationship between cropland cover at the catchment scale and the dominance of fish species that commonly inhabit large streams or rivers (inferred on museum records). We also observed a weak and negative relationship between site elevation and the percentage of widely distributed species in fish assemblages. Our results partly support the hypothesis of native invasion in lowland streams, but the low explanatory power of the models suggests that it is less pronounced compared to highland streams. Our results contribute to understand inconsistencies among studies on the effects of land use on stream fish assemblages using traditional metrics (alpha and beta diversities). For instance, land use can initially increase fish species richness in small streams by favouring the occurrence and establishment of fish species common to rivers. In this sense, alternative metrics that consider specific changes in native species distribution, such as proliferation of common species, should be used to better assess the mechanisms that drive changes in communities of aquatic ecosystems.

Projected shifts in fish species dominance in Wisconsin lakes under climate change.

Temperate lakes may contain both coolwater fish species such as walleye (Sander vitreus) and warmwater fish species such as largemouth bass (Micropterus salmoides). Recent declining walleye and increasing largemouth bass populations have raised questions regarding the future trajectories and management actions for these species. We developed a thermodynamic model of water temperatures driven by downscaled climate data and lake-specific characteristics to estimate daily water temperature profiles for 2148 lakes in Wisconsin, US, under contemporary (1989-2014) and future (2040-2064 and 2065-2089) conditions. We correlated contemporary walleye recruitment and largemouth bass relative abundance to modeled water temperature, lake morphometry, and lake productivity, and projected lake-specific changes in each species under future climate conditions. Walleye recruitment success was negatively related and largemouth bass abundance was positively related to water temperature degree days. Both species exhibited a threshold response at the same degree day value, albeit in opposite directions. Degree days were predicted to increase in the future, although the magnitude of increase varied among lakes, time periods, and global circulation models (GCMs). Under future conditions, we predicted a loss of walleye recruitment in 33-75% of lakes where recruitment is currently supported and a 27-60% increase in the number of lakes suitable for high largemouth bass abundance. The percentage of lakes capable of supporting abundant largemouth bass but failed walleye recruitment was predicted to increase from 58% in contemporary conditions to 86% by mid-century and to 91% of lakes by late century, based on median projections across GCMs. Conversely, the percentage of lakes with successful walleye recruitment and low largemouth bass abundance was predicted to decline from 9% of lakes in contemporary conditions to only 1% of lakes in both future periods. Importantly, we identify up to 85 resilient lakes predicted to continue to support natural walleye recruitment. Management resources could target preserving these resilient walleye populations.

Ecological responses to variable water regimes in arid-zone wetlands: Coongie Lakes, Australia

In dryland rivers, interactions between flow variability and complex geomorphology expose floodplain wetlands to long-term patterns of flooding and drying and highly variable short-term events. We consider whether the abundance and diversity of fish, macroinvertebrate and zooplankton communities in wetlands of the Coongie Lakes complex are influenced by long-term water regimes. To relate biological changes to changes in water regime, mean values of assemblage indices were ranked and correlated against ranked frequency of drying (i.e. water retention) in each waterbody. As water-retention time increased, fish species diversity (richness, evenness) and disease incidence rose, and fish species dominance and macroinvertebrate abundance decreased. The more mobile species of fish utilised the habitats and food resources provided by newly flooded waterbodies. We conclude that fish populations utilise wetlands with a variety of water regimes, and reductions in the frequency of inundation will decrease fish diversity with sequential losses of less mobile species.