Does water depth influence size composition of estuary-associated fish? Distributions revealed using mobile acoustic-camera transects along the channel of a small shallow estuary

2017 ◽  
Vol 68 (11) ◽  
pp. 2163 ◽  
Author(s):  
Alistair Becker ◽  
Alan K. Whitfield ◽  
Paul D. Cowley ◽  
Victoria J. Cole
Keyword(s):  
South African ◽  
Water Depth ◽  
Fish Assemblages ◽  
Habitat Type ◽  
Size Composition ◽  
Estuarine Fish ◽  
Small Fish ◽  
Shallow Estuary ◽  
Type Water ◽  
Abundance And Distribution

Quantifying the abundance and distribution of fish is fundamental to gaining an understanding of how habitat type, water depth or abiotic conditions influence fish assemblages throughout estuarine systems. Such investigations are inherently difficult because estuaries typically contain a range of habitats across varying depth strata, and data usually consist of replicate samples that cover only a small portion of an entire estuary. We used replicate acoustic-camera (DIDSON) transects along the entire length of a small South African estuary to determine the distributions of different size cohorts of fish. Each size cohort was distributed heterogeneously along the estuary, with abundances peaking in discreet sections of the system. By comparing the abundance of fish to the bathymetry, we found correlations between depth and abundance for two of three size classes. Large fish (>401mm) were more abundant in deep holes (<3m), whereas there were more small fish (100–250mm) in shallow (>1.5m) upper reaches of the estuary. This investigation demonstrated the usefulness of extended DIDSON transects to rapidly collect data on the distributional abundance of estuarine fish from the estuary mouth to the head, showing that bathymetry of a system may be an important factor in determining these patterns.

scholarly journals Relationships between water transparency and abundance of Cynodontidae species in the Bananal floodplain, Mato Grosso, Brazil

2009 ◽  
Vol 7 (2) ◽  
pp. 251-256 ◽  
Author(s):  
Cesar Enrique de Melo ◽  
Jane Dilvana Lima ◽  
Eliete Francisca da Silva
Keyword(s):  
Fish Assemblages ◽  
Water Transparency ◽  
Predatory Fish ◽  
Mato Grosso ◽  
Central Brazil ◽  
Fish Group ◽  
Species Specific ◽  
Abundance And Distribution ◽  
Number Of Individuals ◽  
Habitat Affinities

The Cerrado in the Central Brazil is currently one of the most threatened ecosystems in the world. As a result, the aquatic habitats in this biome also undergo great impacts. Alterations related to land-use change increase sediment loadings in rivers, streams and lakes, resulting in sedimentation and decrease in water transparency. Water transparency determines underwater visibility conditions, and as a consequence fish assemblages respond to spatial and temporal changes in this variable. This work aimed to examine the influence of transparency on the abundance and distribution of Cynodontidae species, a visually oriented predatory fish group. Fish sampling was conducted in 15 sites located between Mortes and Araguaia rivers in the Bananal floodplain, Mato Grosso State. Regression analysis between relative abundance of Cynodontidae (in number of individuals and biomass) and water transparency showed a positive and highly significant correlation, indicating that this group shows species-specific habitat affinities for clearer waters. These results suggest that the increase in water turbidity in this region can affect the patterns of abundance and distribution of the Cynodontidae species, as well as other visually oriented fishes.

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.

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 The contribution of environmental factors to fish assemblages in the Río Acahuapa, a small drainage in Central America

2017 ◽  
Vol 15 (3) ◽  
Author(s):  
Francisco S. Álvarez ◽  
Wilfredo A. Matamoros ◽  
Francisco A. Chicas
Keyword(s):  
Fish Species ◽  
Habitat Structure ◽  
Fish Assemblages ◽  
Species Abundance ◽  
Main Channel ◽  
Estuarine Fish ◽  
Species Origin ◽  
High Temperature Water ◽  
Distribution Of Fish ◽  
Temperature Water

ABSTRACT The ichthyofauna of the Río Acahuapa was analyzed sampling 17 sites that included the basin main channel and its tributaries. Fish were collected using dip-nets, seine-nets and electrofishing. Fish standard length and species abundance were recorded. Species origin and salinity tolerance criteria were used to classify fish species. Water physicochemical variables, habitat structure and sampling sites elevation were recorded. A total of 33 fish species were registered, 12.1% are primary, 45.5% are secondary and 42.4% are of marine derivation. Fish species richness declined with increase of elevation (R2=0.55, p=0.0006). Two assemblages of fishes were identified: the first one associated to sites of low elevations (19-184 masl), composed mainly of secondary and marine-estuarine fish species related with high temperature, water velocity, river width, dissolved oxygen and low sand and silt substrate cover; the second one associated to sites of middle and higher elevations (185-519 masl), composed by primary and secondary freshwater fishes related with high pH, logs and rocks substrate cover. In summary, elevation and environmental variables contributed to the composition and distribution of fish in the Río Acahuapa.

scholarly journals A Comparison of Fishes and Invertebrates Living in the Vicinity of Energized and Unenergized Submarine Power Cables and Natural Sea Floor off Southern California, USA

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Milton S. Love ◽  
Mary M. Nishimoto ◽  
Linda Snook ◽  
Donna M. Schroeder ◽  
Ann Scarborough Bull
Keyword(s):  
Southern California ◽  
Statistical Difference ◽  
Fish Assemblages ◽  
Natural Habitat ◽  
Habitat Type ◽  
Aquatic Organisms ◽  
Power Cables ◽  
Sea Floor ◽  
Total Fish ◽  
Species Groups

Increasing reliance on deep-water renewable energy has increased concerns about the effects of the electromagnetic fields (EMFs) generated by submarine power cables on aquatic organisms. Off southern California, we conducted surveys of marine organisms living around energized and unenergized submarine power cables and nearby sea floor during 2012–2014 at depths between 76 and 213 m. In general, EMFs declined to background levels about one meter from the cable. We found no statistical difference in species composition between the fish assemblages along the energized and unenergized cables. The natural habitat community statistically differed from both energized and unenergized cable communities. Within species (or species groups), we found no differences in densities between energized and unenergized cables. Total fish densities were significantly higher around the cables than over the natural habitat. We found that invertebrate communities were structured by habitat type and depth and, similar to the fishes, there was no statistical difference between the energized and unenergized cables. Individually, the densities of four invertebrate species or species groups (Metridium farcimen, Luidia spp., unidentified black Crinoidea, and Urticina spp.) differed between energized and unenergized cables, but this difference was not significant across all depth strata. The invertebrate community inhabiting the natural habitat strongly differed from the energized and unenergized cable community exhibiting the fewest species and individuals.

Historical Changes in Large River Fish Assemblages of the Americas

2005 ◽  
Keyword(s):  
Relative Abundance ◽  
Mississippi River ◽  
Largemouth Bass ◽  
Fish Assemblage ◽  
Fish Assemblages ◽  
Micropterus Salmoides ◽  
Lepomis Macrochirus ◽  
Large River ◽  
Frequency Of Occurrence ◽  
Abundance And Distribution

<em>Abstract.</em>—An investigation of historical fisheries information for pools 4–13 of the upper Mississippi River (UMR) was conducted to 1) determine the pre-1938 relative abundance and distribution of bluegill <em>Lepomis macrochirus </em>and largemouth bass <em>Micropterus salmoides, </em>2) determine the composition and relative abundance of the preimpoundment fish assemblage, and 3) determine if a shift in frequency of occurrence and relative abundance has occurred due to impoundment.

scholarly journals Trends in numbers of Cape gannets (Morus capensis), 1956/1957–2005/2006, with a consideration of the influence of food and other factors

2006 ◽  
Vol 64 (1) ◽  
pp. 169-177 ◽  
Author(s):  
Robert J. M. Crawford ◽  
Benedict L. Dundee ◽  
Bruce M. Dyer ◽  
Norbert T. W. Klages ◽  
Michael A. Meÿer ◽  
...  
Keyword(s):  
South Africa ◽  
South African ◽  
Conservation Status ◽  
Fish Prey ◽  
Management Measures ◽  
Fur Seals ◽  
Long Term Changes ◽  
Influence Of Food ◽  
Abundance And Distribution

Abstract Crawford, R. J. M., Dundee, B. L., Dyer, B. M., Klages, N. T., Meÿer, M. A., and Upfold, L. 2007. Trends in numbers of Cape gannets (Morus capensis), 1956/57–2005/06, with a consideration of the influence of food and other factors – ICES Journal of Marine Science, 64, 169–177. Cape gannets (Morus capensis) breed at six colonies in Namibia and South Africa. Population size averaged about 250 000 pairs over the period 1956/1957–1968/1969 and about 150 000 pairs from 1978/1979 to 2005/2006. Over the whole 50-y period, numbers at the three Namibian colonies fell by 85–98%, with greater proportional decreases in the south. There were increases at two South African colonies between 1956/1957 and 2005/2006. The colony at Lambert's Bay increased between 1956/1957 and 2003/2004, but attacks by Cape fur seals (Arctocephalus pusillus) on birds at nests caused abandonment of the entire colony in 2005/2006. Long-term changes at colonies are thought to be largely attributable to an altered abundance and distribution of prey, especially sardine (Sardinops sagax) and anchovy (Engraulis encrasicolus). In both Namibia and South Africa, the numbers of Cape gannets breeding were significantly related to the biomass of epipelagic fish prey. Over the 50-y period, there was also a marked similarity in the proportions of gannets and epipelagic fish in the Benguela system, which were present in Namibia and South Africa. In the 2000s, there was an eastward shift in the distribution of sardine off South Africa and a large increase in the number of gannets breeding at South Africa's easternmost colony. When sardine were scarce off South Africa, gannets fed on anchovy, but off Namibia anchovy only temporarily and partially replaced sardine. Ecosystem management measures that might improve the conservation status of Cape gannets are considered.

Spatial patterns in estuarine fish faunas in tropical Queensland: a reflection of interaction between long-term physical and biological processes?

1998 ◽  
Vol 49 (1) ◽  
pp. 31 ◽  
Author(s):  
Marcus Sheaves
Keyword(s):  
Fish Assemblages ◽  
Abundant Species ◽  
Common Species ◽  
Estuarine Fish ◽  
Maximum Deviation ◽  
Seawater Salinity ◽  
Spatial Differences ◽  
Upstream Direction ◽  
Catch Rates

Spatial differences in the distribution and abundance of fish faunas of structurally complex habitats in subtidal areas of three tropical estuaries were investigated by using modified Antillean-Z fish traps. The overall species compositions of the three estuaries were similar; however, the distribution and abundance of species differed substantially both within and among estuaries. Although the abundance of most species declined in an upstream direction, the fish assemblages of upstream areas of different estuaries were similar. In contrast, assemblages in seaward regions were quite distinct. Neither temperature nor turbidity were correlated with catch rates of the most abundant species. Although catch rates of some species were significantly correlated with deviation away from normal seawater salinity, in most cases the correlation with maximum deviation in salinity was much stronger. Thus, decreased catches and the absence of some common species from upstream areas may be related to the influence of long-term (months and years) patterns of salinity. Some species were abundant only in one region of a single creek. This may reflect the close proximity of nearby habitats from which recruits may come.

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