Journal of the Marine Biological Association of the United Kingdom

Tidal fish connectivity of reef and sea grass habitats in the Indo-Pacific

Richard K.F.  Unsworth a1, James J.  Bell a2 and David J.  Smith a1c1
a1 Coral Reef Research Unit, Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK
a2 School of Biological Sciences, Victoria, University of Wellington, PO Box 600, Wellington, New Zealand

Article author query
unsworth rkf   [PubMed][Google Scholar] 
bell jj   [PubMed][Google Scholar] 
smith dj   [PubMed][Google Scholar] 


The present study considered the influence of the tide on shallow water fish assemblages within the Wakatobi Marine National Park, Indonesia. Timed underwater visual observations were made across a gradient of intertidal to subtidal habitats from near-shore to reef crest at different tidal heights. Transient fish were found to dominate shallow water fish assemblages and the assemblage composition varied with tidal state. Fish assemblages were more diverse and abundant at higher tides in both coral and sea grass habitats, however, this was more pronounced within sea grass habitats. A tidal reduction from [approximate]2.0m to [approximate]0.8m (above chart datum) corresponded to a 30% reduction in fish abundance, while species richness also significantly decreased from 13.5 to 10.8 species per standardized timed observation. Fifty fish groups were reported from sea grass habitats with the most abundant being from the Engraulidae family and Lethrinus harak, which form important local subsistence fisheries. This research confirms the importance of tidal changes in structuring the fish fauna of Indonesian sea grass habitats and underlines the connectivity that exists between these habitats and nearby coral reefs.

(Published Online October 18 2007)
(Received November 2 2006)
(Accepted July 26 2007)

c1 Corresponding author, e-mail: