How is Pelagic Sargassum-Associated Biodiversity Assessed? Insights from the Literature

Abstract

Over the past decade unprecedented blooming of pelagic Sargassum has occurred across the Equatorial Atlantic from West Africa to the Caribbean. Although pelagic Sargassum mats are considered beneficial in the open ocean, providing valuable habitat for a diverse array of endemic and associated species, they also inundate coastal areas and cause a plethora of management challenges for fisheries, tourism, nearshore coastal ecosystems, public health and the socioeconomic welfare of coastal communities. In—water harvesting has been suggested as a desirable management solution to prevent shoreline inundation, but destruction of the associated biodiversity is a concern with this approach and has not been adequately examined. Furthermore, in—water harvesting methods within the Tropical Atlantic and Caribbean have been ad hoc and highly variable with no established sampling protocol. Here we review 30 published studies detailing methods to collect information on the biodiversity associated with pelagic Sargassum. Nets, hook and line, video recordings, bare—hands and plastic bags have all been used to collect epiphytic, clinging and free—swimming fauna associated with Sargassum. Net sampling was the predominant method; however, in the absence of a standardized approach a wide range of net types and sizes were used. Similarly, separation, identification and preservation methods were all unstandardized. This review highlights the need for standardization and provides the first set of guidelines for the collection and assessment of Sargassum—associated biodiversity. Nevertheless, these approaches are labor intensive and require extensive replication in time and space to produce a reasonable assessment of the biodiversity associated with the Sargassum community.