Effects of salinity on fish assemblage structure: An evaluation based on taxonomic and functional approaches in the Casamance estuary (Senegal, West Africa)

Kantoussan, Justin; Écoutin, Jean-Marc; Simier, Monique; Morais, Luis Tito de; Laë, Raymond

doi:10.1016/j.ecss.2012.07.018

Cited by 24 publications

(34 citation statements)

References 63 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…There were spatial and temporal variations in the structure and composition of ichthyofauna across the zones of the estuary, and depth and transparency emerged as the principal environmental influences on the distribution of fish assemblages. Similar results have been reported for temperate (Eick & Thiel, ; Pritchett & Pyron, ), subtropical (Whitfield, Taylor, Fox, & Cyrus, ) and tropical estuaries (Kantoussan, Ecoutin, Simier, Morais, & Laë, ).…”

Section: Discussionsupporting

confidence: 85%

Do the shallow‐water habitats of a hypersaline tropical estuary act as nursery grounds for fishes?

et al. 2018

View full text Add to dashboard Cite

Fish assemblages were studied in a hypersaline tropical estuary in Northeastern Brazil. A total of 104 species were collected by beach seine during the dry and rainy seasons of 2012. Two families, Atherinopsidae and Gerreidae, were numerically dominant in all zones of the estuary; juveniles of Atherinella brasiliensis, Eucinostomus argenteus, Lile piquitinga, Ulaema lefroyi, Lutjanus analis and Sphoeroides greeleyi contributed 77% of the total catch. The factors that best explained the fish abundance pattern were salinity and depth, which were related to spatial segregation. Species richness was lowest in the upper zone, an area with high salinity and shallow depth. The distinct roles of structurally different habitats (submerged macrophyte beds and mangrove prop‐roots) and the influence of physicochemical conditions in the middle zone of the estuary may influence taxonomic diversity. The middle zone of the estuary is the one most attractive to juveniles of reef species (Lutjanidae and Serranidae). The fish assemblages are clearly dominated by marine estuarine dependent species, highlighting the importance of the ecosystem as a nursery ground for marine species of the Brazilian coast.

show abstract

Section: Discussionsupporting

confidence: 85%

Do the shallow‐water habitats of a hypersaline tropical estuary act as nursery grounds for fishes?

et al. 2018

View full text Add to dashboard Cite

show abstract

“…One of the suggestions as to why euryhaline freshwater cichlids are so successful in the hyperhaline upper reaches of some estuarine systems is that most marine piscivorous fishes are absent from these areas during such times. The piscivorous West African ladyfish Elops lacerta Valenciennes 1847, however, is present in the hyperhaline upper reaches of the Casamance Estuary (Senegal; Kantoussan et al ., ) and E . machnata in the hyperhaline upper lakes of the St Lucia system (Wallace, ), together with S .…”

Section: Predationmentioning

confidence: 97%

Why are there so few freshwater fish species in most estuaries?

Whitfield

2015

Journal of Fish Biology

View full text Add to dashboard Cite

The freshwater fish assemblage in most estuaries is not as species rich as the marine assemblage in the same systems. Coupled with this differential richness is an apparent inability by most freshwater fish species to penetrate estuarine zones that are mesohaline (salinity: 5·0-17·9), polyhaline (salinity: 18·0-29·9) or euhaline (salinity: 30·0-39·9). The reason why mesohaline waters are avoided by most freshwater fishes is difficult to explain from a physiological perspective as many of these species would be isosmotic within this salinity range. Perhaps, a key to the poor penetration of estuarine waters by freshwater taxa is an inability to develop chloride cells in gill filament epithelia, as well as a lack of other osmoregulatory adaptations present in euryhaline fishes. Only a few freshwater fish species, especially some of those belonging to the family Cichlidae, have become fully euryhaline and have successfully occupied a wide range of estuaries, sometimes even dominating in hyperhaline systems (salinity 40+). Indeed, this review found that there are few fish species that can be termed holohaline (i.e. capable of occupying waters with a salinity range of 0-100+) and, of these taxa, there is a disproportionally high number of freshwater species (e.g. Cyprinodon variegatus, Oreochromis mossambicus and Sarotherodon melanotheron). Factors such as increased competition for food and higher predation rates by piscivorous fishes and birds may also play an important role in the low species richness and abundance of freshwater taxa in estuaries. Added to this is the relatively low species richness of freshwater fishes in river catchments when compared with the normally higher diversity of marine fish species for potential estuarine colonization from the adjacent coastal waters. The almost complete absence of freshwater fish larvae from the estuarine ichthyoplankton further reinforces the poor representation of this guild within these systems. An explanation as to why more freshwater fish species have not become euryhaline and occupied a wide range of estuaries similar to their marine counterparts is probably due to a combination of the above described factors, with physiological restrictions pertaining to limited salinity tolerances probably playing the most important role.

show abstract

“…; Kantoussan et al . ), a positive tropical estuary (Teixeira & Helmer ; Franco et al . ) and in coastal lagoons (Andreata et al .…”

Section: Discussionmentioning

confidence: 99%

“…Hypersaline environments are habitats of great conservation importance, supporting unique communities in terms of composition and structure (Kantoussan et al . ). Regarding the ichthyofauna, the assemblage shall be determined according to the osmoregulatory capacity of the fish, as the intensity of this process varies according to the species (Harrison & Whitfield ).…”

Section: Introductionmentioning

confidence: 99%

Distribution and feeding ecology of three juvenile mojarras in a hypersaline tropical estuary in Northeastern Brazil

2016

View full text Add to dashboard Cite

Although mojarra species usually demonstrate a wide distribution in tropical and subtropical estuaries, relatively little is known about the process influencing the spatial resource partitioning to nearshore habitats. Therefore, the aim of this study was check the existence of habitat and food partitioning among confamiliar species in a hypersaline estuary. The dietary compositions of three co‐occurring species of mojarras were determined, using samples collected with a beach seine from an inverse tropical estuary in Northeastern Brazil, during the rainy and the dry seasons of 2012. Eucinostomus argenteus and Ulaema lefroyi were abundant throughout the year, while Eugerres brasilianus was most abundant during the rainy season. Although these mojarras were found together in all areas of the estuary, there was evidence of habitat partitioning: E. argenteus and E. brasilianus were dominant in areas with submerged vegetation, while U. lefroyi was most abundant in areas with little habitat complexity and minimal shelter. All mojarras consumed, to different degrees, zooplankton, Bivalvia and Polychaeta. However, E. brasilanus also consumed a considerable amount of algae. Although the niches of the mojarra species appeared to significantly overlap, some resource partitioning patterns were apparent. While E. brasilanus was clearly different along the trophic niche, segregation of the other species was more important with respect to the spatial dimension. The different feeding strategies appear to minimize inter‐specific overlap and allow the co‐occurrence of these species in this hypersaline tropical estuary.

show abstract

Effects of salinity on fish assemblage structure: An evaluation based on taxonomic and functional approaches in the Casamance estuary (Senegal, West Africa)

Cited by 24 publications

References 63 publications

Do the shallow‐water habitats of a hypersaline tropical estuary act as nursery grounds for fishes?

Do the shallow‐water habitats of a hypersaline tropical estuary act as nursery grounds for fishes?

Why are there so few freshwater fish species in most estuaries?

Distribution and feeding ecology of three juvenile mojarras in a hypersaline tropical estuary in Northeastern Brazil

Contact Info

Product

Resources

About