Effects of freshwater flow on the fish assemblage of the Mondego estuary (Portugal): comparison between drought and non-drought years

2010 ◽  
Vol 61 (4) ◽  
pp. 490 ◽  
Author(s):  
Joana Baptista ◽  
Filipe Martinho ◽  
Marina Dolbeth ◽  
Ivan Viegas ◽  
Henrique Cabral ◽  
...  
Keyword(s):  
Extreme Events ◽  
Fish Assemblage ◽  
Fish Community ◽  
River Flow ◽  
Fish Assemblages ◽  
Freshwater Species ◽  
Freshwater Flow ◽  
Important Species ◽  
Mondego Estuary ◽  
Management Plans

Warming of the planet is indisputable and will lead to more frequent extreme events, such as droughts. From June 2003 to March 2008, the effects of variations in river flow, associated with drought conditions, were studied in the fish assemblage of the Mondego estuary, Portugal. Over this time, two distinct hydrological periods were identified: non-drought years and drought years, with consistent changes in the fish assemblages. In the drought years, salinity increased inside the estuary, displacing the estuarine brackish habitats to more upstream areas. During this period, new marine adventitious species were found mainly in the most downstream areas, while the freshwater species disappeared from the Mondego estuary catchment area. For the marine estuarine-dependent species that use estuaries as nursery areas, a decrease in abundance was observed during the drought years, owing to the decrease in freshwater flow and reduced river plume to the coastal area. In non-drought years, there were higher densities of most species and the more important species of the fish community. Our work shows that extreme events such as droughts, related to climatic changes, influenced the structure and composition of the Mondego estuary fish assemblages, and should be further considered when undertaking management plans for transitional waters.

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.

scholarly journals Assemblage structure and spatial diversity patterns of kelp forest-associated fishes in Southern Patagonia

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0257662
Author(s):  
Mathias Hüne ◽  
Alan M. Friedlander ◽  
Enric Ballesteros ◽  
Jennifer E. Caselle ◽  
Enric Sala
Keyword(s):  
Fish Assemblage ◽  
Fish Assemblages ◽  
Anthropogenic Impacts ◽  
Fish Fauna ◽  
Spatial Diversity ◽  
Assemblage Structure ◽  
Kelp Forests ◽  
Fish Assemblage Structure ◽  
Important Species ◽  
Southern Patagonia

Knowledge of the ecology of the fish fauna associated with kelp (primarily Macrocystis pyrifera) forests in Southern Patagonia is scarce, especially in how abiotic and biotic variables influence their structure, diversity, and distribution. This information is important for the management and conservation of this unique ecosystem, which has minimal anthropogenic impacts at present. We analyzed data from 122 quantitative underwater transects conducted within kelp forests at 61 stations from Chile’s southern Patagonian fjords to the Cape Horn and Diego Ramirez archipelagos and the southern tip of Argentina, including the Mitre Peninsula and Isla de los Estados. In total, 25 fish species belonging to 13 families were observed. Multivariate analysis indicated that there are significant differences in fish assemblage structure among locations and wave exposures, which was driven primarily by Patagonotothen sima and Paranotothenia magellanica, which occurred on exposed and semi-exposed stations. P. cornucola was mainly distributed across sheltered stations of the Kawésqar National Park. Temperature, salinity, depth, and kelp density influenced fish assemblage structure, with the highest diversity in areas with the lowest temperature and greater depth at Isla de los Estados. In contrast, species richness, diversity, abundance, and biomass were all lower in areas with high density of the understory kelp Lessonia spp., which might be driven by the absence of P. tessellata, P. squamiceps and P. cornucola, the most important species in terms of occurrence, abundance, and biomass. Our study provides the first broad-scale description of the fish assemblages associated with kelp forests along the southern cone of South America based on non-invasive visual transects, improving our knowledge of the distribution of fish assemblages across several environmental conditions in this vast and little-studied area.

scholarly journals Colony geometry and structural complexity of the endangered speciesAcropora cervicornispartly explains the structure of their associated fish assemblage

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1861 ◽  
Author(s):  
Esteban A. Agudo-Adriani ◽  
Jose Cappelletto ◽  
Francoise Cavada-Blanco ◽  
Aldo Croquer
Keyword(s):  
Fish Assemblage ◽  
Fish Community ◽  
Fish Assemblages ◽  
Three Dimensional ◽  
Structural Complexity ◽  
Habitat Associations ◽  
Coral Tissue ◽  
Live Coral ◽  
Fish Assemblage Structure ◽  
Acropora Cervicornis

In the past decade, significant efforts have been made to describe fish-habitat associations. However, most studies have oversimplified actual connections between fish assemblages and their habitats by using univariate correlations. The purpose of this study was to identify the features of habitat forming corals that facilitate and influences assemblages of associated species such as fishes. For this we developed three-dimensional models of colonies ofAcropora cervicornisto estimate geometry (length and height), structural complexity (i.e., volume, density of branches, etc.) and biological features of the colonies (i.e., live coral tissue, algae). We then correlated these colony characteristics with the associated fish assemblage using multivariate analyses. We found that geometry and complexity were better predictors of the structure of fish community, compared to other variables such as percentage of live coral tissue or algae. Combined, the geometry of each colony explained 40% of the variability of the fish assemblage structure associated with this coral species; 61% of the abundance and 69% of fish richness, respectively. Our study shows that three-dimensional reconstructions of discrete colonies ofAcropora cervicornisprovides a useful description of the colonial structural complexity and may explain a great deal of the variance in the structure of the associated coral reef fish community. This demonstration of the strongly trait-dependent ecosystem role of this threatened species has important implications for restoration and conservation efforts.

scholarly journals Variation of the ichthyofauna along the Goioerê River: an important tributary of the Piquiri-Paraná basin

2014 ◽  
Vol 104 (1) ◽  
pp. 104-112 ◽  
Author(s):  
Claudenice Dei Tos ◽  
Luiz C. Gomes ◽  
Maria A. Rodrigues
Keyword(s):  
Fish Assemblage ◽  
Fish Community ◽  
Fish Assemblages ◽  
Fish Fauna ◽  
Abundant Species ◽  
Longitudinal Distribution ◽  
Longitudinal Variation ◽  
Community Patterns ◽  
Species Dominance ◽  
Conservation And Management

The construction of reservoirs is considered an important source of impacts on the fish fauna, severely altering the structure of the assemblage. This paper aimed to describe the structure of the fish assemblage of the Goioerê River, determining its longitudinal distribution and patterns of species dominance. The evaluation of its longitudinal variation in the diversity and abundance of the fish assemblage was conducted in July and October 2004 and January and May 2005. The collections were carried out near the headwaters (Gurucaia), middle stretch (Olaria), just above the falls (Paiquerê) and downstream (Foz). Forty-four species were captured. The Gurucaia fish assemblages differed significantly from Olaria, Paiquerê and Foz. The Olaria assemblages differed significantly from the Foz. Gurucaia showed the lowest diversity and abundance of species. Astyanax aff paranae Eigenmann,1914 (78% of the total) was found to be dominant at this site. Almost the same species richness was found at Olaria and Paiquerê, although Olaria had the greatest abundance of individuals. Astyanax aff paranae, Cyphocharax modestus (Fernández-Yépez, 1948) and Astyanax altiparanae Garutti & Britski, 2000 were the top three dominants and comprised over 71% of the total number of fish caught. At Paiquerê, Astyanax altiparanae, Hypostomus aff ancistroides (Ihering, 1911) and Loricariichthys platymetopon Isbrücker & Nijssen, 1979 composed 58% of the catches. Thirty-one species were recorded at Foz, which presented the greatest richness. The most abundant species were Apareiodon affinis (Steindachner, 1879), Galeocharax knerii (Steindachner, 1879) and A.altiparanae, which contributed to 50% of the total catches in this environment.These results record the fish biodiversity and how the community is longitudinally structured in the Goioerê River, and also demonstrate how this type of evaluation is important to understanding the fish community patterns and finding solutions to problems related to the conservation and management of the basin.

scholarly journals Inter-estuarine and temporal patterns of the fish assemblage of subtropical subestuaries along the Río de la Plata coast (Uruguay)

2017 ◽  
Vol 65 (2) ◽  
pp. 173-186 ◽  
Author(s):  
Alicia Acuña ◽  
Nathalie Muñoz ◽  
Rodrigo Gurdek ◽  
Irene Machado ◽  
Veronica Severi
Keyword(s):  
Species Richness ◽  
Fish Assemblage ◽  
Fish Assemblages ◽  
Diversity Indices ◽  
Fish Abundance ◽  
Freshwater Species ◽  
Rio De La Plata ◽  
Río De La Plata ◽  
Southwest Atlantic ◽  
La Plata

ABSTRACT Fish assemblages in subestuaries have been poorly studied worldwide. In order to evaluate the inter-estuarine and temporal variability of the ichthyofauna of subestuaries along the Uruguayan coast of the Río de la Plata (RdlP), the Pando, Solís Chico and Solís Grande systems were sampled between 2011 and 2013. Fish biomass, abundance, species richness and diversity indices were analysed, defining fish assemblages characterised by a few species and great abundance. Estuarine resident and freshwater species represented 55.5% of the fish assemblage according to estuarine use guilds. Species occurrence was similar in the three subestuaries, but the relative abundances differed among them. The analysed community parameters showed a decreasing trend from west to east along the Uruguayan coast. Highest diversity and fish abundance were recorded in the Pando system located in the proximities of an important spawning area in the inner RdlP estuary. In the Solís Grande subestuary occurred the lowest species richness and fish abundance. The Solís Chico was characterised as a transitional subsystem. All three subestuaries showed an increase in species richness and abundance during high temperature periods, probably related to the life cycle of the species sharing habitats between the RdlP and the coastal subestuaries. This study constitutes the first step in assessing the fish assemblage patterns in coastal ecosystems of the RdlP and an approach about the ecological role of the subestuaries in the southwest Atlantic Ocean.

scholarly journals Predicting spatial distribution patterns and hotspots of fish assemblage in a coastal basin of the central-south of Chile, by geostatistical techniques

2019 ◽  
Vol 78 (2) ◽  
Author(s):  
Sam Catchpole ◽  
Reinaldo Rivera ◽  
Cristián E. Hernández ◽  
Javiera De La Peña ◽  
Pablo González
Keyword(s):  
Fish Assemblage ◽  
Fish Assemblages ◽  
Conservation Status ◽  
Distribution Patterns ◽  
Freshwater Ecosystems ◽  
Freshwater Species ◽  
Simple Kriging ◽  
Geostatistical Techniques ◽  
Central South

Currently the application of geographic information systems in the subjects of biology and ecology has facilitated the study patterns of distribution, richness y diversity of species. However, in freshwater ecosystems the application of geostatistical analysis are scarcely used in the worldwide, including Chile. Therefore, in our study we developed predictive maps using simple Kriging (resolution 12.5 x 12.5 m), based on richness and Shannon-Weaver diversity, and we analyzed spatial autocorrelation of fish assemblages (Moran and Getis-Ord index) present in the Andalién River basin. Our results established a fish assemblage composition of 24 species, most of them native (79%) and with endanger conservation status. Predictive maps showed highest values of richness and diversity of fish species in the potamon zone of the Andalién and Nonguén streams, while the low values were described in the Chaimavida sub-basin and the transition zone of Andalién River. The Moran and Getis-Ord index determined a cluster pattern of the data and define hotspot and coldspot zones, concordant with the predictive maps of richness and Shannon-Weaver diversity. The geostatistical and spatial techniques showed to be relevant tools for the determination of distribution patterns of freshwater species and conservation issues.

scholarly journals Assessing Spatial and Temporal Trends in a Mediterranean Fish Assemblage Structure

Diversity ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 368
Author(s):  
Michel Marengo ◽  
Laura Iborra ◽  
Michèle Leduc ◽  
Pierre Lejeune ◽  
Pierre Boissery ◽  
...  
Keyword(s):  
Fish Assemblage ◽  
Fish Community ◽  
Fish Assemblages ◽  
Fish Communities ◽  
Assemblage Structure ◽  
Marine Biodiversity ◽  
Significant Shift ◽  
Fish Assemblage Structure ◽  
Data Set ◽  
General Decline

Coastal fishes are not only valuable elements of marine biodiversity, but they also play an important ecological role in the functioning of coastal ecosystems: food resource, transfer of nutrients, predators. Therefore, data on the compositions of fish assemblages are of great importance. The objectives of the present study were to (i) define the faunistic characteristics of a typical fish community on the Mediterranean coast; (ii) investigate spatiotemporal changes in fish assemblages. Based on a set of indices (Fast protocol) and a long-term data set (6 years, 612 visual counts, 154 h of diving), changes in coastal fish communities were analyzed. Our results indicated that there was a significant shift in fish community structure, with a general decline of the calculated indices. In our study, part of the observed variability in fish assemblage structure could be due to different factors as site location and sampled year. The changes in the fish assemblages associated with inter-annual fluctuations observed in this study also provide important insights into how fish communities may change under environmental and anthropogenic influences.

RIMurban – A generalized GPU-based model for urban pluvial flood risk modelling and forecasting

2021 ◽  
Author(s):  
Heiko Apel ◽  
Sergiy Vorogushyn ◽  
Mostafa Farrag ◽  
Nguyen Viet Dung ◽  
Melanie Karremann ◽  
...  
Keyword(s):  
Risk Management ◽  
Extreme Events ◽  
Flood Risk ◽  
Convective Precipitation ◽  
Sewer System ◽  
Urban Flood ◽  
The Core ◽  
Model Based ◽  
Management Plans ◽  
Model Setup

<p>Urban flash floods caused by heavy convective precipitation pose an increasing threat to communes world-wide due to the increasing intensity and frequency of convective precipitation caused by a warming atmosphere. Thus, flood risk management plans adapted to the current flood risk but also capable of managing future risks are of high importance. These plans necessarily need model based pluvial flood risk simulations. In an urban environment these simulations have to have a high spatial and temporal resolution in order to site-specific management solutions. Moreover, the effect of the sewer systems needs to be included to achieve realistic inundation simulations, but also to assess the effectiveness of the sewer system and its fitness to future changes in the pluvial hazard. The setup of these models, however, typically requires a large amount of input data, a high degree of modelling expertise, a long time for setting up the model setup and to finally run the simulations. Therefor most communes cannot perform this task.</p><p> In order to provide model-based pluvial urban flood hazard and finally risk assessments for a large number of communes, the model system RIM<em>urban</em> was developed. The core of the system consists of a simplified raster-based 2D hydraulic model simulating the urban surface inundation in high spatial resolution. The model is implemented on GPUs for massive parallelization. The specific urban hydrology is considered by a capacity-based simulation of the sewer system and infiltration on non-sealed surfaces, and flow routing around buildings. The model thus considers the specific urban hydrological features, but with simplified approaches. Due to these simplifications the model setup can be performed with comparatively low data requirements, which can be covered with open data in most cases. The core data required are a high-resolution DEM, a layer of showing the buildings, and a land use map.</p><p>The spatially distributed rainfall input can be derived local precipitation records, or from an analysis of weather radar records of heavy precipitation events. A catalogue of heavy rain storms all over Germany is derived based on radar observations of the past 19 years. This catalogue serves as input for pluvial risk simulations for individual communes in Germany, as well as a catalogue of possible extreme events for the current climate. Future changes in these extreme events will be estimated based on regional climate simulations of a ΔT (1.5°C, 2°C) warmer world.</p><p>RIM<em>urban</em> simulates the urban inundation caused by these events, as well as the stress on the sewer system. Based on the inundation maps the damage to residential buildings will be estimated and further developed to a pluvial urban flood risk assessment. Because of the comparatively simple model structure and low data demand, the model setup can be easily automatized and transferred to most small to medium sized communes in Europe and even beyond, if the damage estimation is modified. RIM<em>urban</em> is thus seen as a generally appölicable screening tool for urban pluvial flood risk and a starting point for adapted risk management plans.</p>

scholarly journals Freshwater fishes of Bontebok National Park

Koedoe ◽  
2001 ◽  
Vol 44 (2) ◽  
Author(s):  
I.A. Russell
Keyword(s):  
South African ◽  
National Park ◽  
Fish Assemblages ◽  
Micropterus Salmoides ◽  
Clarias Gariepinus ◽  
Lepomis Macrochirus ◽  
River System ◽  
Indigenous Species ◽  
Freshwater Species ◽  
Micropterus Dolomieu

Fish assemblages were sampled at six sites in the Breede River in the Bontebok National Park during 1999 and 2000. A total of 380 fish from 12 species was recorded. Indigenous fish collected included one freshwater species (Barbus andrewi), two catodromous species (Anguilla mossambica, Myxus capensis). and three estuarine species (Gilchris- tella aestuaria, Monodactylusfalciformis, Mugil cephalus). Four of the species recorded were aliens (Tinea tinea, Lepomis macrochirus, Micropterus salmoides, Micropterus dolomieu) and two species translocated from other South African rivers (Tilapia sparrmanii, Clarias gariepinus). A further two indigenous species (Sandelia capensis, Pseudobarbus biirchelli) could potentially occur within the park, though the high abundance of alien predators means that there is little chance for recolonisation from tributaries higher in the Breede River system. There is little opportunity to meaningfully conserve most indigenous freshwater fish in Bontebok National Park.

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