MEPS 573:25-43 (2017)  -  DOI: https://doi.org/10.3354/meps12159

ABSTRACT: Fragmentation in landscapes may result in a reduction in connectivity among component patches as patch sizes decrease and/or the distance between different patches increases. The movement of nekton into wetlands and intertidal banks during high tide may be influenced by the habitats they traverse. Here, we examined whether the proximity between shallow seagrass beds and mangrove forests affected the utilisation of the seagrass beds by nekton at 2 levels of habitat complexity (dense and sparse seagrass). Fish and epibenthic invertebrates were sampled on multiple occasions in 2 different regions in subtropical Moreton Bay, Queensland, Australia. The nekton assemblages varied considerably with distance between the seagrass and mangroves, although specific effects varied between the 2 regions of the bay. Overwhelmingly, larger numbers of individuals and more species were associated with seagrass beds that were close to the mangroves than those further away. Generally, proximity also had strong effects on the abundance of individual species, but these varied as a function of seagrass complexity and also resulted in some species being more abundant close to mangroves, while others showed the opposite pattern. For many species, the influence of potential connectivity between seagrass and mangroves, i.e. distance of seagrass from mangroves, had a greater influence on nekton than structural complexity of the habitat.

KEY WORDS: Estuarine · Landscape ecology · Habitat fragmentation · Moreton Bay · Subtropical