Evidence for habitat-driven segregation of an estuarine fish assemblage

2016 ◽  
Vol 89 (1) ◽  
pp. 804-820 ◽  
Author(s):  
S. N. Loureiro ◽  
J. A. Reis-Filho ◽  
T. Giarrizzo
Keyword(s):  
Fish Assemblage ◽  
Estuarine Fish

scholarly journals Fish Assemblage Structure Comparison between Freshwater and Estuarine Habitats in the Lower Nakdong River, South Korea

2020 ◽  
Vol 8 (7) ◽  
pp. 496
Author(s):  
Joo Myun Park ◽  
Ralf Riedel ◽  
Hyun Hee Ju ◽  
Hee Chan Choi
Keyword(s):  
Fish Assemblage ◽  
Fish Assemblages ◽  
Estuarine Fish ◽  
Freshwater Species ◽  
Fish Assemblage Structure ◽  
Nakdong River ◽  
Structure Comparison ◽  
Significant Difference ◽  
Freshwater Habitats ◽  
The Nakdong River

Variabilities of biological communities in lower reaches of urban river systems are highly influenced by artificial constructions, alterations of flow regimes and episodic weather events. Impacts of estuary weirs on fish assemblages are particularly distinct because the weirs are disturbed in linking between freshwater and estuarine fish communities, and migration successes for regional fish fauna. This study conducted fish sampling at the lower reaches of the Nakdong River to assess spatio-temporal variations in fish assemblages, and effects of estuary weir on structuring fish assemblage between freshwater and estuary habitats. In total, 20,386 specimens comprising 78 species and 41 families were collected. The numerical dominant fish species were Tachysurus nitidus (48.8% in total abundance), Hemibarbus labeo (10.7%) and Chanodichthys erythropterus (3.6%) in the freshwater region, and Engraulis japonicus (10.0%), Nuchequula nuchalis (7.7%) and Clupea pallasii (5.2%) in the estuarine site. The fish sampled were primarily small species or the juveniles of larger species at the estuary region, while all life stages of fishes were observed at the freshwater habitats. The diversity patterns of fish assemblages varied greatly according to study site and season, with higher trends at estuarine sites during the warm-rainy season. No significant difference in diversity between freshwater and estuarine sites during the cold-dry season were found. Multivariate analyses of fish assemblage showed spatial and seasonal differences of assemblage structures. Higher effects of between-site variability but not within seasonal variability at each site were observed. Variations in assemblage structures were due to different contributions of dominant species in each habitat. Common freshwater species characterized the fish assemblage in the freshwater region, while marine juveniles were significantly associated with the estuarine habitat. The results from the ecological guild analyses showed distinct ecological roles for freshwater and marine species, and overlapping roles for fish sampled at the fishways. The lower reaches of the Nakdong River are an important ecosystem for both freshwater and marine juveniles. Nakdong River estuarine residents and migrant fishes, however, have been negatively affected by the construction of the weir (gravity dam), due to the obstruction to migration from and to freshwater habitats. Conservation and management policies aimed at minimizing anthropogenic influences on estuary ecosystems should focus on evaluating ecological functions of estuary weirs.

Temporal variability in fish assemblage structure and recruitment in a freshwater-deprived estuary: The Coorong, Australia

2010 ◽  
Vol 61 (11) ◽  
pp. 1298 ◽  
Author(s):  
Brenton P. Zampatti ◽  
Christopher M. Bice ◽  
Paul R. Jennings
Keyword(s):  
Fish Assemblage ◽  
Fish Assemblages ◽  
Marine Species ◽  
River Regulation ◽  
Assemblage Structure ◽  
Estuarine Fish ◽  
Fish Assemblage Structure ◽  
Murray River ◽  
Eastern Australia ◽  
Freshwater Inflows

River regulation can diminish freshwater flows to estuaries and compromise estuarine functionality. Understanding biotic responses to altered flow regimes is imperative to effectively manage aquatic ecosystems. The present study investigated temporal variation in fish assemblage structure and the recruitment of catadromous fish in the Coorong estuary at the terminus of the Murray River, in south-eastern Australia. Over the three-year study period, freshwater inflows to the estuary diminished and ultimately ceased, disconnecting freshwater and estuarine environments. It was hypothesised that these conditions would lead to (1) increases in estuarine salinities and concomitant changes in fish assemblage structure and abundance, and (2) decreased recruitment of catadromous fish. As freshwater inflow decreased, salinities immediately downstream of a series of tidal barrages increased from brackish to marine–hypersaline, species richness and diversity decreased, freshwater and diadromous species became less abundant and assemblages were increasingly characterised by marine species. Furthermore, the abundance of young-of-year catadromous fish decreased dramatically. Excessive regulation of freshwater inflows is resulting in the Coorong estuary resembling a marine embayment, leading to a loss in species diversity. We suggest, however, that even small volumes of freshwater may promote diversity in estuarine fish assemblages and some recruitment of catadromous species.

Response of demersal fish assemblages to an extreme flood event in a freshwater-deprived estuary in South Africa

2018 ◽  
Vol 69 (2) ◽  
pp. 253 ◽  
Author(s):  
P. Nodo ◽  
N. C. James ◽  
A.-R. Childs ◽  
M. D. V. Nakin
Keyword(s):  
South Africa ◽  
Fish Assemblage ◽  
Large Scale ◽  
Fish Assemblages ◽  
Salinity Gradient ◽  
Demersal Fish ◽  
Flood Event ◽  
Estuarine Fish ◽  
Water Abstraction ◽  
Extreme Flood

The Kariega Estuary in South Africa, is an example of a freshwater-deprived estuary. Large-scale water abstraction and droughts have resulted in this estuary either being uniformly marine or hypersaline. A major episodic flood event in October 2012, the largest ever recorded in this system, provided us with an opportunity to investigate the prolonged effect of an episodic flood on the demersal fish assemblage of a freshwater-deprived estuary. A beam trawl net was used for sampling the fish assemblages from December 2013 to November 2014. The flood event before the sampling period ‘reset’ the system, such that there was a longitudinal salinity gradient from the head to the mouth, which resulted in ‘normal’ estuarine conditions, typical of most estuaries. There was an increase in the abundance of benthopelagic marine migrant species, particularly early juveniles of important fishery species, in the middle and upper reaches during the present study relative to previous studies conducted in this freshwater-deprived system. This suggests increased recruitment of these species into their estuarine nursery habitat. The present study highlights the importance of understanding the effect of freshwater inflow on the demersal estuarine fish assemblage and the nursery role of this and other estuarine systems and their management.

scholarly journals Fish assemblage structure in a port region of the Amazonic coast

2018 ◽  
Vol 108 (0) ◽  
Author(s):  
Marcelo H. L. Silva ◽  
Audálio R. Torres Júnior ◽  
Antonio C. L. Castro ◽  
James W. J. Azevedo ◽  
Cássia F. C. Ferreira ◽  
...  
Keyword(s):  
Fish Assemblage ◽  
Diversity Index ◽  
Spatial Scales ◽  
Spatial Differentiation ◽  
Assemblage Structure ◽  
Estuarine Fish ◽  
Fish Assemblage Structure ◽  
Spatial And Temporal Distributions ◽  
Port Area ◽  
Conservation Projects

ABSTRACT: The fish assemblage structure in a port area in São Marcos Bay (Amazonic coast) was evaluated based on the spatial and temporal distributions to identify potential changes in response to anthropic pressure increases associated with industrial and port activities in region. The samples were taken between March 2011 and November 2015. The ichthyofauna was represented by a total of 56 species, distributed in 15 orders and 29 families. Captures were dominated by Genyatremus luteus (Bloch, 1790), but Sciades proops (Valenciennes, 1840) was the most representative in terms of biomass. Seasonal distributions of fish assemblage did not reveal significant differences. However, there was a difference between catch sites, abundance, biomass and Shannon diversity index was higher in the Site 1 and evenness in Site 4. The analysis NMDS and the test ANOSIM between months and between sampling sites, based on species composition, revealed a seasonal differentiation associated with the rainy and drought months, as well as spatial differentiation, in function of a depth gradient and hydrodynamics, resulting from greater distance from mangrove areas. The low diversity recorded may be a reflection of port activities that historically occur in the area investigated. However, there was still a maintenance of regional diversity throughout the period under analysis. Thus, temporal and spatial scales become important for the detection and understanding of fish biodiversity in an Amazonian estuary, reflecting, the importance of mangroves for the maintenance of the ichthyofaunistic diversity in the area. In this context, the present study may subsidize possible conservation projects in the area since information of this nature is almost non-existent for estuarine fish from the Maranhão Amazon.

scholarly journals Effects of forest width on fish use of fringing mangroves in a highly urbanised tropical estuary

2017 ◽  
Vol 68 (9) ◽  
pp. 1764 ◽  
Author(s):  
Kimberley Dunbar ◽  
Ronald Baker ◽  
Marcus Sheaves
Keyword(s):  
Fish Assemblage ◽  
Field Of View ◽  
Estuarine Fish ◽  
Tropical Estuary ◽  
Use Patterns ◽  
Patterns Of Use ◽  
Underwater Cameras ◽  
The Mean ◽  
Number Of Individuals ◽  
Over Time

The size and shape of a habitat patch can influence patterns of species utilisation. The present study examined how the width of fringing mangrove habitats affects the composition and use patterns of the fish assemblage using mangrove edge habitats on the flooding tide. Underwater cameras surveyed fish approaching mangrove habitats, ranging from a thin fringe 5m wide to forests over 75m wide, in a highly modified tropical estuary. The fish assemblage composition was similar across all mangrove widths, although the temporal patterns of use varied among mangrove widths for some species. The mean maximum number of individuals in the field of view was similar among mangrove widths, but fish were visible for a significantly greater proportion of time in videos from narrow (<20m) than wide (≥20m) mangrove stands (15v. 3% respectively). At least some fish were visible in the field of view in narrow mangrove fringes throughout the first hour of the flood tide, whereas in wide mangroves areas the presence of fish declined over time. The findings suggest that estuarine fish are using mangrove edge habitat regardless of width, making narrow mangroves viable habitats for estuarine fish.

scholarly journals Seasonal composition, abundance and biomass of the subestuarine fish assemblage in Solís Chico (Río de la Plata estuary, Uruguay)

2016 ◽  
Vol 77 (3) ◽  
pp. 622-631 ◽  
Author(s):  
A. Acuña Plavan ◽  
R. Gurdek ◽  
N. Muñoz ◽  
J. M. Gutierrez ◽  
M. Spósito ◽  
...  
Keyword(s):  
Fish Assemblage ◽  
Fish Community ◽  
Abundant Species ◽  
Estuarine Fish ◽  
Rio De La Plata ◽  
Río De La Plata ◽  
La Plata ◽  
Juvenile Stages ◽  
Micropogonias Furnieri ◽  
First Time

Abstract The large estuaries can present long narrow branches called subestuaries or tidal creeks. These types of subsystems are distributed along the Uruguayan coast of the Río de la Plata estuary and are very important as nursery and refuge areas for fish. For the first time, the seasonal composition and abundance of the fish community of the Solís Chico subestuary was studied by using beach and gill nets. Fourteen species, mainly euryhaline (86%) presented a significant representation of juvenile stages. The fish community was dominated by Odontesthes argentinensis, Platanichthys platana, Mugil liza, Brevoortia aurea, Micropogonias furnieri and Paralichthys orbignyanus, similar to adjacent subestuaries. While Micropogonias furnieri and B. aurea were the most abundant species, some other species were rarely caught. A seasonal variation of the fish assemblage abundance was detected, with higher values in autumn showing a positive correlation with temperature. Species that complete their life cycle in the Río de la Plata estuary, some of which are relevant to fisheries (64% of the analyzed species) were captured in the Solís Chico subestuary. The importance of this environment as a transitional system for some estuarine fish species is advised.

Inter- and intra-estuarine fish assemblage variability patterns along the Portuguese coast

2011 ◽  
Vol 91 (2) ◽  
pp. 262-271 ◽  
Author(s):  
Susana França ◽  
Maria José Costa ◽  
Henrique N. Cabral
Keyword(s):  
Fish Assemblage ◽  
Estuarine Fish ◽  
Portuguese Coast

Spatio-temporal and interspecific variation in otolith trace-elemental fingerprints in a temperate estuarine fish assemblage

2003 ◽  
Vol 56 (5-6) ◽  
pp. 1111-1123 ◽  
Author(s):  
Stephen E Swearer ◽  
Graham E Forrester ◽  
Mark A Steele ◽  
Andrew J Brooks ◽  
David W Lea
Keyword(s):  
Fish Assemblage ◽  
Interspecific Variation ◽  
Estuarine Fish ◽  
Trace Elemental ◽  
Spatio Temporal
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