SEMINAR: MGG Student Seminar - Tuesday, April 26 at 12 pm, CIMAS Conference Room

[Thiago Correa <TCorrea@rsmas.miami.edu>]

MGG Student Seminar

Tuesday, April 26

12:00 pm - 1:00 pm

CIMAS Conference Room, 3rd floor

Bioerosion in the ‘Twilight Zone’:  Spatial variability of alteration in mesophotic reefs

David Weinstein           

Continued decline of shallow water coral reef health and the mesophotic refugia hypothesis have rejuvenated interest in deeper (30-150 m) mesophotic coral ecosystems (MCEs).  Like their shallow water counterparts, mesophotic reefs build complex geomorphic structures that create vital ecosystems.  Much research has shown that bioerosion fundamentally impacts the development, destruction, and sustainability of complex shallow reef structures.  Consequently, a solid understanding of mesophotic bioerosion is essential for effectively managing MCEs, sustainably utilizing their resources, and preventing habitat degradation.  Recent advances in SCUBA technological have stimulated various biological and ecological MCE studies.  However, there exists a critical gap in knowledge regarding the relative importance of bioerosion and the control it exerts in varying mesophotic geomorphic habitats, especially near-horizontal banks and basins. 

The Hind Bank Marine Conservation District and Grammanik Bank, 11 km south of St. Thomas (USVI), contain diagnostic geomorphic deep-reef habitats ideal for studying MCE bioerosion variability. Coral rubble was randomly collected from four distinct MCE habitats, as well as three shallower sites for comparison.  Point-count analysis reveals that mesophotic coral rubble experiences more macroboring (43.8%) than shallow reef rubble (28%), but has less macroboring diversity.  Mesophotic macroboring density averages 45.8% at the high bank habitats, 37.1% at the hillock basin habitat, and 19.7% at the deep patch habitat.  These results indicate significant variation of macroboring patterns in nearby, but structurally different mesophotic habitats.  Varying patterns are postulated to be responsible for maintaining distinct mesophotic habitat geomorphology.  Comparing macroboring results with water column profiles and ecological trends indicates that MCE macroboring variability is likely controlled by differences in environmental conditions and localized mortality events.  Therefore, monitoring mesophotic bioerosion proves a potentially useful method for predicting mesophotic ecological responses to changing environmental conditions and interpreting the paleoenvironments of deep fossil reefs.

Kenny Zhao

TBA