Fish assemblages associated with natural, transplanted, artificial, and accidental reefs in Puerto Rico

Abstract

When accompanied with well-informed management actions, active restoration strategies such as coral gardening and deployment of artificial reef structures can help mitigate negative effects of human impact on fish assemblages associated to natural reefs. However, ecological patterns of variation of fish assemblages associated with artificial reefs are poorly understood. From mid-April 2018 to mid-June 2019, we compared fish assemblages associated to one of four types of reef structures: natural reefs (NR), transplanted reefs (TR; i.e., Acropora palmata colonies), concrete modules or restoration reefs (RR), and accidental reefs (AC; submerged docks and shipwrecks) across twelve sites around Puerto Rico. Response variables were abundance, biomass, and number of species per sample and these were correlated with environmental factors that could influence the observed patterns of spatial and temporal variation in fish assemblages. Despite natural seasonal fluctuations, differences in fish assemblages between reef types were generally greater than differences among sites, although less obvious between TR and NR. Based on these results, and on the assumption that the general aim of artificial reef deployment is to mimic natural reef function, we highlight the need for management strategies that are tailored to site-specific or reef-specific goals and needs. Our study reinforces the importance of multivariate statistics to recognize patterns of spatial and temporal variation at the smallest spatial scales, understand ecosystem function, and to improve the effectiveness of management actions concerning active restoration strategies like coral gardening and creation of artificial reef habitats.