Mesophotic Coral Ecosystems

MESOPHOTIC CORAL ECOSYSTEMS – A LIFEBOAT FOR CORAL REEFS?

of all fish in abundance. This is in contrast with shallower

reefs, where zooplanktivores represent only 18 per cent of

all fish. Herbivores are scarce at depths ≥ 50 m, reaching

the upper but not the deeper portion of these ecosystems.

In addition, the composition of piscivores changes from

medium-sized species in shallow water to large species in

deeper waters. Fish communities at mesophotic depths

have a more complete trophic structure, with several large

predators, such as black grouper (

Mycteroperca bonaci

Cubera snappers (

Lutjanus cyanopterus

), dog snappers

(

L. jocu

) and Caribbean reef sharks (

Carcharhinus perezii

)

frequently observed, which are now rare at shallower depths.

Deep MCEs also serve as important habitats for these and

other protected species (Figure 6).

In contrast to corals, fish communities within MCEs ≥ 50 m

are well-connected to shallow coral ecosystems. While fish

also show distinct differences in community structure with

depth, there is substantial overlap, with 78 out of 85 species

in MCEs found at both shallow (≤30 m) and mesophotic

(≥40 m) depths. The most common connectivity pattern

for fish (21 species) between shallow and mesophotic

depths, including most commercially-important species

(e.g. surgeonfish, parrotfish, snappers, groupers, grunts and

barracuda) is through ontogenetic migration from nursery

areas in shallow habitats, such as seagrass, mangroves, reefs

and rocky shorelines.

Phototransects show that there is low disease prevalence at

the community level (the mean is 6 per cent). However, in a

one-year period, colonies of

undata

and

lamarcki

have

shown signs of white syndrome (a coral disease resulting in

rapid loss of tissue biomass, caused by an unknown pathogen)

and permanent tissue mortality (see Chapter 4).

Figure 4.

(a) Caribbean reef shark (photo Francisco Pagán), (b) hawksbill turtle (photo Francisco Pagán) and (c) black grouper observed

at depths greater than 50 m (photo Héctor Ruiz).

(a)

(c)

(b)