Archipelago Los Roques: A potential baseline for reef fish assemblages in the southern Caribbean

Abstract

1. Despite increasing policies of protection, few localities in the Caribbean remain spared from human impacts. These lightly affected areas can better reflect the past composition of reef fish assemblages and provide baseline information about the natural factors driving fish distributions in the region. 2. Reef fish assemblage structures were analysed in 21 Caribbean fished areas and marine protected areas (MPAs) along a gradient of distance to the nearest major market place. Assemblage structures by size and by trophic group were significantly related to the distance to market. 3. Relationships of reef fish life‐history traits, families, and vulnerability indicators were examined with the seascape and the benthic composition at Los Roques Archipelago, the most isolated MPA in the analysis. Factors linked to seascape features were more important than benthic composition or human activities in explaining fish assemblage structure. 4. Wave exposure was the most influential seascape metric. Exposed habitats were dominated by octocorals and sponges. More sheltered habitats were characterized by high coral cover, while leeward sites were characterized by steep slopes with close proximity to deeper water. 5. Exposed habitats were mostly occupied by unspecialized fish species. Piscivore densities were high at south and south‐west sites, and were likely related to the large concentrations of planktivorous fishes found there. South and south‐west sites experience full oceanic conditions, and supported the highest species richness and densities within the archipelago. 6. Los Roques National Park is one of the oldest and most remote Caribbean MPAs. Its fish assemblage structure is healthier than other fished or protected areas, with higher species richness, higher density of piscivores, and an abundance of large species. Predator–prey relationships provided additional evidence that Los Roques reef fish assemblage presented specific characteristics. 7. The main patterns observed in this study represent a baseline for assessing reef fish assemblages elsewhere in the southern Caribbean.

Structural Complexity and Benthic Cover Explain Reef-Scale Variability of Fish Assemblages in Los Roques National Park, Venezuela

“…We found that sites such as DMS and FAR supported 4-6 times more fish biomass and 1.5-fold higher species richness compared to CAY, where the habitat was flatter and less structurally complex and the fish assemblage comprised mostly small demersal species like Stegastes partitus and Thallassoma bifasciatum. These species are considered omnivorous and generalist, often associated with degraded sites with low complexity and where competition with other species of damselfish is limited (Dominici-Arosemena and Wolff, 2006;Elise et al, 2017). Our results also indicated that only a few massive coral species (e.g., Orbicella faveolata, O. annularis, and Colpophyllia natans) contributed to live coral cover while increasing habitat structural complexity.…”

“…Severe bleaching events leading to rapid loss of coral cover have impacted several coral populations in Los Roques (Villamizar et al, 2008;Bastidas et al, 2012), and Los Roques also suffered the loss of most of the reef building Acropora palmata populations in past years (Croquer et al, 2016). Nevertheless, coral reefs in this MPA still support fish abundance that is above the Caribbean average (Elise et al, 2017). This finding highlights the ecological importance of this MPA at the regional scale for there is increasing evidence indicating that Caribbean reefs are losing most of their structural complexity (Alvarez-Filip et al, 2009) and concomitantly fish communities have changed rapidly (Alvarez-Filip et al, 2009, 2015.…”

“…Recent studies have pinpointed Los Roques as a potential refuge for corals and fish because the MPA possesses higher coral cover than typical in the region and populations of important reef builders that provide highly heterogeneous reefs (Villamizar et al, 2003;Jackson et al, 2014;Elise et al, 2017). Severe bleaching events leading to rapid loss of coral cover have impacted several coral populations in Los Roques (Villamizar et al, 2008;Bastidas et al, 2012), and Los Roques also suffered the loss of most of the reef building Acropora palmata populations in past years (Croquer et al, 2016).…”