Fish and macroinvertebrate fauna associated with floating or drifting surface water mangrove litter in a shallow coastal area in Trang, southern Thailand

Mangrove litter is continuously supplied to coastal water systems in and around Southeast Asian mangrove forests, often floating or drifting in surface layer water and likely providing ecological benefits for aquatic animals. As a first step toward clarification of possible roles of such litter in coastal ecosystems, associated fish/macroinvertebrate fauna in a shallow coastal area in Trang Province, Thailand, were examined by scoop-netting. During the study period, 398 individual fishes (35 species), 33 macrocrustaceans (8 species) and 30 squid (1 species) were collected. Larval/juvenile Zenarchopterus sp. 1 (cf. Z . dunckeri ) were the most abundant fish (31.4% of total fishes), followed by Butis butis (16.3%) and Terapon jarbua (13.3%). A pygmy squid, Idiosepius sp., was the most abundant macroinvertebrate (47.6% of total). The majority of specimens collected were small-sized individuals. The mangrove litter, which adds a structured microhabitat to the non-structured surface water layer, probably functions (for small animals) in reducing energy costs for movement, including migration to other areas, as well as reducing predation risk and increasing food catchability, resulting in enhanced affinity of small animals for the litter.