Laverick et al. 2017

scientific article | PLoS ONE | open access Open access small aa108fa7f478951c693af64a05bc4b46e6711dbb69a20809512a129d4d6b870f

Using light-dependent scleractinia to define the upper boundary of mesophotic coral ecosystems on the reefs of Utila, Honduras

Laverick JH, Andradi-Brown DA, Rogers AD

Adobe pdf ff6e8bea21f0598930b59d2452bacbad49a13eb0fa773865059b4c2ed088a358
Www fec836ca290318f37dc3ecd481f22b98faf488d5ddef687807ca6b76d8e893ed
Gscholar 58dd9f05df3b8d1811d087e8507325500777053d6677b471fd75373a30a4cee1

Shallow water zooxanthellate coral reefs grade into ecologically distinct mesophotic coral ecosystems (MCEs) deeper in the euphotic zone. MCEs are widely considered to start at an absolute depth limit of 30m deep, possibly failing to recognise that these are distinct ecological communities that may shift shallower or deeper depending on local environmental conditions. This study aimed to explore whether MCEs represent distinct biological communities, the upper boundary of which can be defined and whether the depth at which they occur may vary above or below 30m. Mixed-gas diving and closed-circuit rebreathers were used to quantitatively survey benthic communities across shallow to mesophotic reef gradients around the island of Utila, Honduras. Depths of up to 85m were sampled, covering the vertical range of the zooxanthellate corals around Utila. We investigate vertical reef zonation using a variety of ecological metrics to identify community shifts with depth, and the appropriateness of different metrics to define the upper MCE boundary. Patterns observed in scleractinian community composition varied between ordination analyses and approaches utilising biodiversity indices. Indices and richness approaches revealed vertical community transition was a gradation. Ordination approaches suggest the possibility of recognising two scleractinian assemblages. We could detect a mesophotic and shallow community while illustrating that belief in a static depth limit is biologically unjustified. The switch between these two communities occurred across bathymetric gradients as small as 10m and as large as 50m in depth. The difference between communities appears to be a loss of shallow specialists and increase in depth-generalist taxa. Therefore, it may be possible to define MCEs by a loss of shallow specialist species. To support a biological definition of mesophotic reefs, we advocate this analytical framework should be applied around the Caribbean and extended into other ocean basins where MCEs are present.

Depth range
5- 85 m

Mesophotic “mentions”
46 x (total of 5633 words)

Community structure Connectivity

Research focus
Overall benthic (groups) Scleractinia (Hard Corals)

Honduras - Bay Islands

Research platforms
Diving - Technical Rebreather
Author profiles
Jack Laverick ( 3 pubs)
Dominic Andradi-Brown ( 8 pubs)