Seagrass Meadows Provide 3D Habitat for Reef Fish

Abstract

For large fishes, seagrass canopies typically provide a relatively flat habitat on seabeds, but seagrasses in the genus Posidonia can provide additional habitat complexity by forming organic-rich deposits known as mats. Erosional processes can scour channels through the mats, resulting in the formation of escarpments with caves. Here we report that reef fishes, such as groupers, inhabit the caves found within mat escarpments. The characteristics of the cavities are highly variable, ranging from small-elongated holes to deep caves with large entrances. The origin of these caves (biological and/or geological) is unknown, but it is possible that fish behavior enhance their formation. Posidonia seagrass escarpments provide a complex 3D habitat for reef fish that is not provided by typical canopy structure of seagrass. Further studies are required to gain insights into the natural history of seagrass escarpments and their ecological importance.

Non‐linear thresholds characterize the relationship between reef fishes and mangrove habitat

“…) and seagrass (Serrano et al. ) play important roles for species of reef fish, and results of our study highlight the need for both to be considered as important for conservation and management.…”

“…, Serrano et al. ). Specifically, seagrass provides not only feeding grounds for many reef fish species (Zieman ), but also refuge from predators (Orth et al.…”

“…, Serrano et al. ). Results of our study are consistent with the hypothesis that reefs nearby to higher seagrass extent are associated with higher occurrences of the majority (85%) of focal reef fish species.…”

“…, Serrano et al. ), both through functioning as juvenile resident areas (Orth et al. , Verweij et al.…”

“…While doubt has been cast on the generalization of the mangrove-reef fish subsidy effect, there largely has been consensus on the roles that seagrass habitats and anthropogenic influences have on reef fishes. For example, seagrasses have long been thought to substantially contribute to coral reef fish populations (Orth et al 1984, Serrano et al 2017, both through functioning as juvenile resident areas (Orth et al 1984, Verweij et al 2008) and as feeding habitats (Zieman 1982, Verweij et al 2006). In addition, anthropogenic pressures (via higher levels of nearby human population density) have been universally linked to declines in fish populations via fishing pressure, water quality impacts, and habitat degradation (Stallings 2009, Advani et al 2015, Serafy et al 2015.…”