Abstract
To understand the spatial species diversity of demersal fish assemblages in Taijiang National Park (TJNP) of Taiwan, fishes from 44 demersal trawl hauls and environmental data were collected in the nearshore and offshore areas of TJNP from April 2016 to May 2019. In total, fishes of 47 families, 84 genera, and 113 species were recorded. The nearshore and offshore demersal fish assemblages in TJNP exhibited significant variability in species composition assessed via beta diversity. Using distance-based redundancy analysis, we demonstrated that bottom depth and substrate type were significant explanatory variables of spatial species diversity and identified three habitat types (I: shallow soft bottom; II: deeper soft bottom; III: deeper bottom with mixed sand and gravel substrates). The nearshore assemblage was characterized by type I, where Tarphops oligolepis (flounder), Trachinocephalus myops (snakefish), and Liachirus melanospilos (carpet sole) dominated in terms of abundance. The offshore assemblage was characterized by either type II or type III because differences in substrate types among sampling sites were noticeable. At the offshore sites characterized by a deeper soft bottom (type II), Johnius distinctus (croaker), Cynoglossus kopsii (shortheaded tonguesole), and Coelorinchus formosanus (Formosa grenadier) predominated. In contrast, the westernmost sampling site, characterized by type III habitat, exhibited relatively high Shannon indices, and Scorpaena miostoma (scorpionfish), Urolophus aurantiacus (sepia stingray), and Parabothus taiwanensis (lefteye flounder) predominated. Our results provide the first baseline information on the environmental characteristics and spatial species diversity of demersal fish assemblages in TJNP and have implications for biodiversity conservation in existing spatial management areas.
Highlights
Demersal fish assemblages are formed as a result of the environmental preferences of species; that is, gatherings of species dependably co-occur in constrained subareas and in habitually expansive zoogeographical areas
Cynoglossus kopsii (#39) contributed conspicuously to the group of offshore sites characterized by a soft bottom
The sepia stingray Urolophus aurantiacus (#1), the scorpionfish Scorpaena miostoma (#7), the stonefish Scorpaenodes crossotus (#8), Whitehead’s basslet Plectranthias whiteheadi (#15), the grub fish Parapercis sexfasciata (#25), and the lefteye flounder Parabothus taiwanensis (#32) predominated in the group of offshore sites characterized by a substrate type of mixed sand and gravel
Summary
Demersal fish assemblages are formed as a result of the environmental preferences of species; that is, gatherings of species dependably co-occur in constrained subareas and in habitually expansive zoogeographical areas. For the spatial heterogeneity and habitat use of coastal-offshore demersal fishes, water depth, substrate. Understanding the spatial patterns of demersal fish biodiversity across regional gradients, such as depth, is one of the major goals in marine ecosystem studies (Zintzen et al 2012, 2017). Only a few studies on beta diversity patterns in marine demersal fish assemblages have been conducted (e.g., Anderson et al 2013; Zintzen et al 2017; VegaCendejas and Santillana 2019). Knowledge of the small-scale spatial heterogeneity of demersal fish assemblages and environmental settings in coastal-offshore environments is important for creating management and conservation strategies operating at a range of scales (Chang et al 2012; Hewitt et al 2015; Amezcua et al 2019)
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