scholarly journals Effect of the Human Utilization of Northern Snakehead (Channa argus Cantor, 1842) on the Settlement of Exotic Fish and Cladoceran Community Structure

2021 ◽  
Vol 13 (5) ◽  
pp. 2486
Author(s):  
Jong-Yun Choi ◽  
Seong-Ki Kim
Keyword(s):  
Community Structure ◽  
Fish Species ◽  
Micropterus Salmoides ◽  
Lepomis Macrochirus ◽  
Nakdong River ◽  
Exotic Fish ◽  
Carnivorous Fish ◽  
Channa Argus ◽  
The Nakdong River ◽  
Exotic Fish Species

Empirical studies suggest that changes in the density of top predators, such as carnivorous fish, in freshwater food webs, strongly affect not only fish communities but also various primary and secondary consumers. Based on these findings, we explored how differences in the utilization of carnivorous fish (i.e., Northern Snakehead, Channa argus) by humans affected the fish and cladoceran community structure as well as the settlement of exotic fish species (i.e., Lepomis macrochirus and Micropterus salmoides) in 30 wetlands located in the upper and lower reaches of the Nakdong River. Our results show that in the mid–lower reaches of the Nakdong River, the density of C. argus was low, while high densities of L. macrochirus and M. salmoides were observed. Exotic fish species are frequently consumed by C. argus, leading to a low density of L. macrochirus and M. salmoides in the upper reaches, which supported a high density of C. argus. However, in the mid–lower reaches, the density of L. macrochirus was high because of the frequent collection of C. argus by fishing activities. The dominance of L. macrochirus significantly changed the structure of cladoceran communities. L. macrochirus mainly feeds on pelagic species, increasing the density of epiphytic species in the mid–lower reaches. The continued utilization of C. argus by humans induced a stable settlement of exotic fish species and strongly affected the community structures of primary consumers in the 30 wetlands. The frequency of C. argus collection has to be reduced to secure biodiversity in the mid–lower reaches of the Nakdong River, which will reduce the proportion of exotic fish species and increase the conservation of native fish.

scholarly journals Effects of Aquatic Macrophytes on Spatial Distribution and Feeding Habits of Exotic Fish Species Lepomis macrochirus and Micropterus salmoides in Shallow Reservoirs in South Korea

2020 ◽  
Vol 12 (4) ◽  
pp. 1447 ◽  
Author(s):  
Jong-Yun Choi ◽  
Seong-Ki Kim
Keyword(s):  
Fish Species ◽  
Aquatic Macrophytes ◽  
Feeding Habits ◽  
Micropterus Salmoides ◽  
Lepomis Macrochirus ◽  
Open Water ◽  
Young Fish ◽  
Exotic Fish ◽  
Shallow Reservoirs ◽  
Exotic Fish Species

Aquatic macrophytes determine the physical complexity of aquatic environments and may influence the distribution and feeding habits of fish species. We explored the influence of different microhabitats, including vegetated beds (VB), edges of vegetated beds (EVB), and open water zones (OW), on two exotic fish species (Lepomis macrochirus and Micropterus salmoides) in shallow reservoirs. Lepomis macrochirus was more abundant in VB than in other zones and M. salmoides was mainly distributed in EVB. In VB, L. macrochirus mainly consumed branchiopods and isopods, while M. salmoides in EVB relied on relatively larger food items, such as dipterans, odonatans, and young fish. The consumption of young fish by M. salmoides, including L. macrochirus, showed little difference between winter and summer. Based on these findings, we suggest that young L. macrochirus (~20 cm) utilize VB as a refuge to avoid predation by M. salmoides. Meanwhile, M. salmoides mainly occupied in areas surrounding VB, preying on animals at these edges. As such, the presence of aquatic macrophytes appears to plays a key role in the survival and population growth of L. macrochirus. Proper management of aquatic macrophytes can help reduce populations of exotic fish and support native fish species.

Quantitative comparisons of the morphology and ultrastructure of erythrocyte nuclei from seven freshwater fish species

1995 ◽  
Vol 73 (10) ◽  
pp. 1951-1959 ◽  
Author(s):  
Charles H. Jagoe ◽  
Dave A. Welter
Keyword(s):  
Fish Species ◽  
Yellow Perch ◽  
Micropterus Salmoides ◽  
Lepomis Macrochirus ◽  
Nuclear Size ◽  
Image Analysis System ◽  
Cell Nuclei ◽  
Homogeneous Population ◽  
Differentiated Cells ◽  
Rainbow Trout Oncorhynchus Mykiss

Chromosome number and genomic DNA content vary widely among fish species, and ploidy can vary within species. This suggests that the size, shape, and morphological features of cell nuclei may also vary. Nucleated erythrocytes of fish are an easily sampled homogeneous population of differentiated cells ideal for inter- and intra-species comparisons. We collected blood samples from largemouth bass (Micropterus salmoides), bluegill (Lepomis macrochirus), chain pickerel (Esox niger), yellow perch (Perca flavescens), mosquitofish (Gambusia holbrooki), redeye bass (Micropterus coosae), and rainbow trout (Oncorhynchus mykiss) and removed cytoplasm and nuclear membranes from blood cells. Individual nuclei were examined and measured using scanning electron microscopy and a computerized image analysis system, and inter- and intra-species differences evaluated by nested analysis of variance. Nuclear size and shape varied significantly among species. Isolated nuclei had conspicuous apertures or holes, and the number and size of these holes also varied significantly among species. Variations in nuclear size and structure within species were small compared with interspecies differences. Little is known of the ultrastructure of erythrocyte nuclei in lower vertebrates, but their structure differs considerably from that of other vertebrate non-erythroid cells, suggesting that the organization of their DNA and associated proteins may be different.

scholarly journals Limnological changes in Dom Helvécio Lake (South-East Brazil): natural and anthropogenic causes

2010 ◽  
Vol 70 (3 suppl) ◽  
pp. 795-802 ◽  
Author(s):  
PM. Maia-Barbosa ◽  
LG. Barbosa ◽  
SL. Brito ◽  
F. Garcia ◽  
CFA Barros ◽  
...  
Keyword(s):  
Species Composition ◽  
Fish Species ◽  
Environmental Data ◽  
Exotic Fish ◽  
Biological Features ◽  
Physical Chemical ◽  
Exotic Fish Species ◽  
Plankton Species

In order to verify changes in physical, chemical and biological features of Dom Helvécio Lake (South-East Brazil), this study compares previous and recent data obtained from limnological investigations over three decades. Plankton species composition and density together with environmental data from 1978, 1983, and during 1999 to 2006 showed changes driven by seasonal climatic forces or by anthropogenic causes. Changes in diversity are shown as a consequence of alternation of rainy and dry periods and introduction of exotic fish species. Finally, suggestions are made for improving conservation efforts in the area, through planned actions and monitoring programmes.

scholarly journals Modelling critical factors affecting the distribution of the vulnerable endemic Eastern Iberian barbel (Luciobarbus guiraonis) in Mediterranean rivers

2015 ◽  
Vol 17 (1) ◽  
pp. 264 ◽  
Author(s):  
E. J. OLAYA-MARIN ◽  
F. MARTÍNEZ-CAPEL ◽  
R. GARCÍA-BARTUAL ◽  
P. VEZZA
Keyword(s):  
River Basin ◽  
Fish Species ◽  
Model Parameters ◽  
Physical Habitat ◽  
Mediterranean Rivers ◽  
Exotic Fish ◽  
Gradient Descent Algorithm ◽  
River Basin District ◽  
Endemic Fish ◽  
Exotic Fish Species

Luciobarbus guiraonis (Eastern Iberian barbel) is an endemic fish species restricted to Spain, mainly distributed in the Júcar River Basin District. Its study is important because there is little knowledge about its biology and ecology. To improve the knowledge about the species distribution and habitat requirements, nonlinear modelling was carried out to predict the presence/absence and density of the Eastern Iberian barbel, based on 155 sampling sites distributed throughout the Júcar River Basin District (Eastern Iberian Peninsula). We used multilayer feed-forward artificial neural networks (ANN) to represent nonlinear relationships between L. guiraonis descriptors and variables regarding the physical habitat and biological components (macroinvertebrates, fish, riparian forest). The gradient descent algorithm was implemented to find the optimal model parameters; the importance of the ANN’s input variables was determined by the partial derivatives method. The predictive power of the model was evaluated with the Cohen’s kappa (k), the correctly classified instances (CCI), and the area under the curve (AUC) of the receiver operator characteristic (ROC) plots. The best model predicted presence/absence with a high performance (k= 0.66, CCI= 87% and AUC= 0.85); the prediction of density was moderate (CCI = 62%, AUC=0.71 and k= 0.43). The fundamental variables describing the presence/absence were; solar radiation (the highest contribution was observed between 2000 and 4200 WH/m2), drainage area (with the strongest influence between 3000 and 5.000 km2), and the proportion of exotic fish species (with relevant contribution between 50 and 100%). In the density model, the most important variables were the coefficient of variation of mean annual flows (relative importance of 50.5%) and the proportion of exotic fish species (24.4%). The models provide important information about the relation of L. guiraonis with biotic and abiotic variables, this new knowledge can help develop future studies and management plans for the conservation of this species in the Júcar River Basin District and, potentially, for the conservation of other endemic fish species of Barbus and Luciobarbus in Mediterranean rivers.

The Role of the Neighbourhood in Rehabilitation of an Urban Aquatic Ecosystem

1997 ◽  
Vol 32 (2) ◽  
pp. 245-256 ◽  
Author(s):  
K.W. Dance
Keyword(s):  
Fish Species ◽  
Exotic Fish ◽  
Positive Role ◽  
Management Intervention ◽  
Rehabilitation Plan ◽  
Management Interventions ◽  
Periodic Monitoring ◽  
Exotic Fish Species

Abstract For the first 10 to 15 years following rehabilitation, the original goals at West Heights Pond, Kitchener, were attained. Monitoring over a 16-year period revealed that if ecosystem health and aesthetics goals are to be sustained in the future, management intervention is required. Required management includes on-going control of aggressive wetland plant pests; efforts to discourage waterfowl feeding so that numbers decline and water quality improves; and potential future control of exotic fish species goldfish and carp. The study has concluded that (1) periodic monitoring over the long term is required to determine whether rehabilitation plan goals are being met and to identify the nature of required management interventions; (2) human neighbours are a critical species in the ecosystem management process since they can be the agents of significant positive and negative actions which affect attainment of rehabilitation plan goals; and (3) the lead agency in rehabilitation implementation should ensure that a long-term dialogue with site neighbours capitalizes on the positive role neighbours can play and avoids negative actions such as feeding waterfowl, trampling banks and vegetation, and introducing exotic fish species.

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