River-floodplain ecosystems are in delicate balance and are impacted by even minor changes in water availability. In this study, we surveyed fish assemblages and investigated environmental and landscape parameters in ...River-floodplain ecosystems are in delicate balance and are impacted by even minor changes in water availability. In this study, we surveyed fish assemblages and investigated environmental and landscape parameters in a total of 135 floodplain waterbodies (rivers, diversion canals, ponds, irrigation ditches, paddy fields, and wetlands) in the Chao Phraya River Basin in rainy (September 2014) and dry (March 2015) seasons. Factors affecting fish species richness in each type of waterbody were analyzed using generalized linear mixed models. Floodplain area around each surveyed waterbody was a major factor determining fish species richness in rivers, diversion canals, and ponds in the region. The contribution of floodplain area was equivalent to that of hydrology (current velocity, water depth) and water quality (dissolved oxygen, turbidity) in the waterbodies. The population of juvenile fishes was increased in temporarily connected floodplain waterbodies to main rivers compared with isolated waterbodies, and fluvial and lacustrine fishes were observed in the temporary inundated floodplain waterbodies during the rainy season. The high dependence of fish species richness on floodplain area in the region appeared to be a result of the use of inundated floodplains by fish species to forage and breed. Our results highlight the impact of flood control measures that reduces floodplain area. These measures must be reviewed to ensure the conservation of fish biodiversity in the Chao Phraya River Basin, one of the world’s most threatened floodplain systems.展开更多
We investigated the relationship between environmental variables as descriptors of the fish community, in terms of species diversity indices and fish assemblage patterns, in seagrass meadows at Sikao Bay, Trang Provin...We investigated the relationship between environmental variables as descriptors of the fish community, in terms of species diversity indices and fish assemblage patterns, in seagrass meadows at Sikao Bay, Trang Province, Thailand. Fish data and water quality parameters were collected from January to December 2012. A total of 10,596 fish specimens of 97 taxa in 48 families from four stations, Kham Bay (7°30'9.21''N, 99°18'7.67''E), Boonkong Bay (7°31'2.49''N, 99°17'40.09''E), Ban Pak Klong (7°36'17.67''N, 99°16'32.89''E) and Sai Cape (7°38'30.19''N, 99°14'49.85''E), were collected using gillnets of three different mesh sizes. The three most diverse families were Leiognathidae, Carangidae and Tetraodontidae, respectively. The dominant species were Atherinomorus duodecimalis, Sillago sihama and Pelates quadrilineatus. Specimens were highly abundant in July and less so in January and species richness was high in July and less so in March. Fish assemblages were classified into two patterns and the average of the Shannon index was 2.7. The environmental parameters in each month were analyzed by one-way ANOVA which did not show significant difference (P > 0.05) of pH, orthophosphate, wind speed and rainfall. Fish diversity and assemblage, and environmental parameters, were categorized into four groups. These could be promoted to local fisheries so that conservation programs cpuld be set up to ensure the ecological sustainability of seagrass meadows.展开更多
文摘River-floodplain ecosystems are in delicate balance and are impacted by even minor changes in water availability. In this study, we surveyed fish assemblages and investigated environmental and landscape parameters in a total of 135 floodplain waterbodies (rivers, diversion canals, ponds, irrigation ditches, paddy fields, and wetlands) in the Chao Phraya River Basin in rainy (September 2014) and dry (March 2015) seasons. Factors affecting fish species richness in each type of waterbody were analyzed using generalized linear mixed models. Floodplain area around each surveyed waterbody was a major factor determining fish species richness in rivers, diversion canals, and ponds in the region. The contribution of floodplain area was equivalent to that of hydrology (current velocity, water depth) and water quality (dissolved oxygen, turbidity) in the waterbodies. The population of juvenile fishes was increased in temporarily connected floodplain waterbodies to main rivers compared with isolated waterbodies, and fluvial and lacustrine fishes were observed in the temporary inundated floodplain waterbodies during the rainy season. The high dependence of fish species richness on floodplain area in the region appeared to be a result of the use of inundated floodplains by fish species to forage and breed. Our results highlight the impact of flood control measures that reduces floodplain area. These measures must be reviewed to ensure the conservation of fish biodiversity in the Chao Phraya River Basin, one of the world’s most threatened floodplain systems.
文摘We investigated the relationship between environmental variables as descriptors of the fish community, in terms of species diversity indices and fish assemblage patterns, in seagrass meadows at Sikao Bay, Trang Province, Thailand. Fish data and water quality parameters were collected from January to December 2012. A total of 10,596 fish specimens of 97 taxa in 48 families from four stations, Kham Bay (7°30'9.21''N, 99°18'7.67''E), Boonkong Bay (7°31'2.49''N, 99°17'40.09''E), Ban Pak Klong (7°36'17.67''N, 99°16'32.89''E) and Sai Cape (7°38'30.19''N, 99°14'49.85''E), were collected using gillnets of three different mesh sizes. The three most diverse families were Leiognathidae, Carangidae and Tetraodontidae, respectively. The dominant species were Atherinomorus duodecimalis, Sillago sihama and Pelates quadrilineatus. Specimens were highly abundant in July and less so in January and species richness was high in July and less so in March. Fish assemblages were classified into two patterns and the average of the Shannon index was 2.7. The environmental parameters in each month were analyzed by one-way ANOVA which did not show significant difference (P > 0.05) of pH, orthophosphate, wind speed and rainfall. Fish diversity and assemblage, and environmental parameters, were categorized into four groups. These could be promoted to local fisheries so that conservation programs cpuld be set up to ensure the ecological sustainability of seagrass meadows.
