Tropical intertidal seagrass beds: An overlooked foraging habitat for fishes revealed by underwater videos

Abstract

Intertidal seagrass beds occur throughout the tropical Indo-Pacific region and several studies have shown that small fishes inhabit them when inundated during the tidal regime. However, there is a lack of evidence regarding the trophic importance of these habitats to different fish populations at such times. In this study, we examined the feeding behavior of the juvenile fish communities during an incoming tide at two intertidal seagrass bed sites in northern Mindanao, Philippines, during both wet and dry seasons, by deploying remote underwater video cameras. The video footages (3 h) revealed that nearly half of all fish species arrived within 30 min from the start of recording (ca. 30–40 cm water depth, 10–20 cm above the seagrass canopy), and that species richness gradually increased with rising tide, reaching 80% of recorded species within 120 min at both sites in both seasons. Small juvenile (<10 cm total length) labrids, lethrinids, lutjanids, and siganids were most abundant in all video recordings. Large juveniles (>10 cm total length) of the latter three families were first to invade intertidal seagrass beds with incoming tides, whereas those of Labridae were more abundant in later stages of the tidal cycle. The fishery target families Labridae, Lethrinidae, Siganidae, and Lutjanidae foraged during the rising tide, pointing to the importance of intertidal seagrass beds as a foraging habitat for at least 17 species. Because these habitats are disappearing due to expanding coastal developments for human use, the results highlight the ecological importance as a foraging area for multiple fish species to which it may help support developing conservation and management policies in coastal zones.