Are non-estuarine mangroves connected to coral reefs through fish migration? : A mini-review

Abstract

Mangroves are an important fish habitat, but little is known of their nursery function and connectivity to other habitats such as coral reefs. Here, the present status of knowledge on connectivity between non-estuarine mangroves and coral reefs by postlarval coral reef fishes is reviewed. Only since the year 2000 has more indirect evidence been obtained for such connectivity, largely based on studies: (1) quantifying juvenile/adult fish abundances in these habitats to deduce ontogenetic migrations, (2) investigating the effect of absence of mangroves on reef fish assemblages, (3) investigating the effect of mangrove forest size on reef fish abundances, and (4) investigating the effect of distance from mangroves on reef fish abundances. Almost all studies have been done in the Caribbean, and they are practically absent for the much larger Indo-Pacific region. So far, it appears that coral reef fish species do not show an obligate dependence on mangroves as a juvenile habitat, except perhaps for the vulnerable Caribbean parrotfish species Scarus guacamaia Cuvier, 1829. Six Caribbean species of Haemulidae and Lutjanidae show high dependence on mangroves/seagrass beds as juvenile habitats, and may be the most vulnerable to loss of these habitats. A study on otolith microchemistry has provided some evidence for one species that mangroves may indeed contribute to coral reef fish populations.