The influence of canopy structure and tidal level on fish assemblages in tropical Southeast Asian seagrass meadows

Lunar, diel, and tidal changes in fish assemblages in an East African marine reserve

“…Again, mobile species like S. sutor, S. flavicauda, C. viridis, and C. sordidus contributed most to the observed differences (Table 2(E)) and were more abundant during high compared to low tides. Our results are consistent with previous studies (Pogoreutz et al, 2012;Sogard et al, 1989;Unsworth et al, 2007) and support the hypothesis that fish utilization of seagrass habitats are related to both availability of prey (diel patterns) and water levels (tidal patterns). In particular, patterns for planktivorous fish species like C. viridis, whose feeding strategy is strongly related to water currents and which were at the same time less abundant in the coral reef, indicate foraging movements from adjacent habitat types to the seagrass bed.…”

“…Similar habitat effects were also found in studies at comparable locations in the Indo-Pacific (Unsworth et al, 2007). Species richness and diversity (H ′ ) in the seagrass beds were similar to those reported for other seagrass meadows in Zanzibar (Lugendo et al, 2007) with a dominance of similar species and fish families like the ones found in seagrass beds in Mozambique (Gell and Whittington, 2002) or Indonesia (Pogoreutz et al, 2012). Further, the seagrass beds at Chumbe Island showed a common feature for inshore fish assemblages, where less than six species comprised about 70% of the total abundance, even though many more species were present (Quinn, 1980).…”

Tidal variation in fish assemblages and trophic structures in tropical Indo-Pacific seagrass beds

“…Indeed, numerous studies have documented increases in fish densities during flood tides (Kneib and Wagner 1994;Unsworth et al 2007a). Generally, the deeper water can support more fish abundance by both retaining more space and serving as a more stable environment for larger sized or pelagic fish (Pogoreutz et al 2012). Lower water levels may also restrict movements, or cause stranding, both of which could affect predation (Sogard et al 1989).…”

“…However, S. spinus and H. far showed more transient usage patterns and were never present in intertidal seagrass beds during ebb tides. A previous study in Indonesia found that Siganus species were present at higher densities in deeper meadows (Pogoreutz et al 2012). The transient movement of H. far into seagrass meadows was also observed in the Hoga Island, Indonesia (Unsworth et al 2007a).…”

“…Fish assemblages here can be both species-rich and functionally diverse and can demonstrate a complex trophic and habitat structure (Bellwood et al 2004). The variation in fish abundance in seagrass beds may be driven by both hydrology and landscape structure, especially depth (Dorenbosch et al 2004;Unsworth et al 2007a;Pogoreutz et al 2012). In general, such studies found that the depth changes in the water column that occur in response to the tidal cycle may influence the distribution of different fish.…”