Coastal environments comprise a variety of ecosystems that are linked by the flow of water and the movement of organisms. The spatial context and configuration of ecosystems can shape many properties of animal assemblages and modify the ecological functions that animals provide. Urbanisation can, however, fundamentally transform the diversity and configuration of ecosystems, while also introducing new complex structures that provide habitat for animals in coastal seascapes.
In this paper, the authors surveyed fish from mangroves, rock bars, log snags, unvegetated sediments, and armoured shorelines, and assessed how the spatial context of natural and artificial habitats interacted to structure the composition of fish assemblage across estuarine seascapes.
The spatial context of mangroves and armoured shorelines combined to modify the composition of fish assemblages in most estuarine habitats. Fish diversity and abundance was positively linked to the proximity of mangroves and decreased with proximity to armoured shorelines.
The authors findings suggest that when mangroves are replaced by armoured shorelines, the ecological effects of this habitat transformation can extend to fish assemblages in most estuarine habitats.
Many estuarine seascapes are comprised of spatially linked fragments of natural and artificial habitat, and the authors suggest that conserving patches of high-quality mangroves, which are functionally connected across coastal seascapes, both to each other and to other ecosystems, will be critical for maintaining diverse and abundant fish assemblages in urban estuaries.
"Many cities are centred on estuaries, and urban expansion is often associated with the fragmentation of mangrove forests. Our findings emphasize that these transformations of urban estuarine landscapes are likely to propagate to broader ecological impacts detectable in multiple habitats beyond mangrove forests" (Henderson et al., 2019).
"Fish diversity and abundance were typically highest in structurally complex habitats, such as mangrove forests, rock bars, log snags, and armoured shorelines, which provide diverse feeding and sheltering opportunities for fish assemblages."
Contrasting effects of mangroves and armoured shorelines on fish assemblages in tropical estuarine seascapes
Authors: Christopher J. Henderson, Ben L. Gilby, Thomas A. Schlacher, Rod M. Connolly, Marcus Sheaves, Nicole Flint, Hayden P. Borland, Andrew D. Olds