Short-term accumulation of fauna colonising natural versus artificial seagrass floating near to shore

Detached and floating macrophytes are commonly found along beaches in Southern Australia, but few studies have investigated their associations with animals along the drift pathway, particularly in the southern hemisphere. This study investigated the colonisation by macroinvertebrates and fish of natural and artificial tagged seagrass within 6 h of release and compared this to fauna found with in situ floating macrophyte clumps netted at different distances from shore in Southern Australia. We found some evidence that more macroinvertebrates may colonise floating macrophytes at distances closer to shore (i.e., 0.25 km) potentially due to shallower depths and increased proximity of source habitats. Particular fauna may stay with macrophytes as they arrive and accumulate as wrack in the surf-zone, while others may leave for more suitable habitats. Colonisation by fish to floating macrophytes was judged more likely to be for habitat and shelter rather than food resources. This study provides some further evidence for rapid colonisation of fauna and hence an important habitat function of detached and floating macrophytes along nearshore coastlines in Southern Australia.