Upper and lower mesophotic coral reef fish communities evaluated by underwater visual censuses in two Caribbean locations

Abstract

Despite more than 60 yr of coral reef research using scuba diving, mesophotic coral ecosystems (MCEs) between 30 and 150 m depth remain largely unknown. This study represents the first underwater visual census of reef fish communities in the Greater Caribbean on MCEs at depths up to 80 m in Bermuda and 130 m in Curaçao. Sampling was performed using mixed-gas closed-circuit rebreathers. Quantitative data on reef fish communities were obtained for four habitats: coral reefs (45-80 m), rhodolith beds (45-80 m), ledges (85-130 m) and walls (85-130 m). A total of 38 species were recorded in Bermuda and 66 in Curaçao. Mesophotic reef fish communities varied significantly between the two localities. MCEs in Bermuda had lower richness and abundance, but higher biomass than those in Curaçao. Richness, abundance and biomass increased with depth in Bermuda, but decreased in Curaçao. A high turnover of species was found among depth strata and between Bermuda and other Caribbean upper MCEs (45-80 m), indicating that depth was an important driver of community structure at all localities. However, local and evolutionary factors (habitat and endemism) are likely the main factors shaping communities in isolated locations such as Bermuda. High fishing pressure is evident in both localities, as total biomass of apex predators was generally low, and thus may be driving a ''refugia'' scenario in Bermuda, as the abundance and biomass of macro-carnivores increased with depth and distance from the coast.

First record of forktailed bass Parasphyraenops incisus (Perciformes: Serranidae) in South‐western Atlantic

“…Additionally, the present study also evidenced the depth range expansion of this species. Rarely reported in mesophotic Caribbean reefs (Froese & Pauly, ; Pinheiro et al, ; Smith‐Vaniz & Collette, ), P. incisus was reported here occurring in shallowest waters. Due to the species preference for water temperature of 17.6–27.6 (mean 25.2), it is possible that it can be found in other places including shipwrecks and rocky reefs in the South of Brazil (Kaschner et al, ; Adelir‐Alves, Soeth, Braga, & Spach, ; Bornatowski et al, ).…”

Global community breaks at 60 m on mesophotic coral reefs

“…The changes observed here, using presence/absence data of many diverse taxa, are likely to be indicative of changes in community structure and of changes in community composition, if combined with the observations of changes in abundance with depth (e.g., . Although the generality of the community break at ~ 60 m has been questioned (e.g., Pyle et al, 2016, based on fish assemblages in Hawaii), this evidence is equivocal; many other studies indicate that fish assemblages from Hawaii and elsewhere differ significantly with increasing depth into the mesophotic zone (Asher, Williams, & Harvey, 2017;Baldwin, Tornabene, & Robertson, 2018;Bejarano, Appeldoorn, & Nemeth, 2014;Pinheiro et al, 2016;Rocha et al, 2018). influence the community structure of MCEs (Bridge et al, 2012;Wolanski, Colin, Naithani, Deleersnijder, & Golbuu, 2004).…”

Spatial variability in reef‐fish assemblages in shallow and upper mesophotic coral ecosystems in the Philippines

“…These ecosystems remained relatively unexplored (Kahng et al, ) until the recent technological advancements in remotely operated and autonomous underwater vehicles (Bridge et al, ; Garcia‐Sais, ; Locker et al, ) and in technical diving; e.g. , closed‐circuit breathing apparatus (Pinheiro et al, ; Pyle, , ). Interests in MCEs stem from their potential to function as refugia because of the decreasing risk of disturbances with depth ( e.g.…”