Reef Structural Complexity Influences Fish Community Metrics on a Remote Oceanic Island: Serranilla Island, Seaflower Biosphere Reserve, Colombia

Abstract

Serranilla is a protected island of the Seaflower Biosphere Reserve, far from dense human population. These characteristics could help sustain structurally complex coral reefs, often associated with higher biodiversity, abundance, and biomass of reef-associated organisms, including reef fish. However, the multiple threats present in Serranilla, including intense illegal fishing, can impact coral ecosystems generally and also specific key groups, such as the parrotfish, in particular. During the “Seaflower Research Expedition 2017”, we assessed how structural habitat complexity influences reef fish assemblages. In addition, we explored differences in parrotfish species (family: Scaridae) between Serranilla and San Andrés, the most populated island in the Archipelago. On Serranilla, we found that habitat structure, rugosity, and coral cover accounted for up to 66% of variation in reef fish diversity, abundance, and biomass, with values being higher on more complex reefs. Parrotfish species differed between the islands, with larger species supporting higher biomasses at Serranilla, by comparison with San Andrés; however, the abundance, biomass, and lengths of parrotfish species were low in both areas compared with those reported from other protected Caribbean reefs. Our study indicates that despite the evident relationship between structurally complex habitats and reef fish, other threats in Serranilla could be affecting parrotfish populations, such as illegal fishing, a widespread activity in the area.

Haven or hell? A perspective on the ecology of offshore oil and gas platforms

“…The three-dimensional arrangement of structural features over the seafloor surface is a fundamental property of coral reefs [16]. This complexity is positively linked to biodiversity and carrying capacity of habitats in both temperate and tropical ecosystems [17][18][19], with a possible relationship with their ability to recover from degraded states [20]. The ecological importance of complexity is often related to sheltered spaces and physical niches.…”

Bloom of Trichogloeopsis pedicellata (Rhodophyta, Nemaliales) following hurricane Iota in San Andrés, Southwestern Caribbean Sea

“…The eastern coast of the island was also surveyed, but no bloom was present. At each site, three 10-mlong video transects were realized with a GoPro Hero8 Black to determine the cover of the main categories of benthos, as well as the blooming alga (methodology modified from Castaño et al, 2021). The camera was mounted on a holder for greater stability, and the video was filmed at a constant distance (50 cm) from the bottom.…”