11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 15: Progress in Understanding the Hydrodynamics of Coral Reef Systems
15.527
Environmental Vs. Intrinsic Determination Of Colony Symmetry in The Coral
Pocillopora Verrucosa
Tali MASS* 1 , Amazia GENIN 1
1 ESE department, Life Sciences Institute, Heberw University,Jerusalem, Eilat, Israel
The morphology of corals is strongly dependent on environmental conditions.
Different morphologies can be induced by flow and light due to their remarkable effects
on the rates of respiration, production, calcification and prey capture of corals.
Yet, colonies of many branching corals exhibit a remarkable radial symmetry, possibly
indicating an intrinsic determination of colony morphology.
The scleractinian coral Pocil1lopora verrucosa (Ellis and Solander, 1786) is a common
species in a variety of reef environments of the Red Sea and displays a striking
morphological variation in colony shape depending on the flow regime in their habitat.
Branches are thick and compact in habitats exposed to high flow conditions, becoming
open and thinner in protected habitat
The objective of this study was to experimentally examine whether flow conditions can
affect the radial symmetry in colonies of the branching coral Pocillopora verrucosa. Eight
colonies of P. verrucosa were transplanted to transparent, flow-manipulation chambers
which were effectively shielding the coral from the ambient flow. Thereby, the coral was
exposed to a unidirectional flow, creating asymmetric flow conditions with stronger
current at the up- than down-flow side. Within 4 months, the up-current side of the corals
had higher concentration of chlorophyll and proteins, greater density of zooxanthellae,
and more compact morphology. While asymmetry in photosynthesis and
photosynthetates may disappear due to within-colony translocation, our findings on
asymmetry in proteins and, in particular, skeletal morphology indicates that asymmetry in
environmental conditions generates permanent asymmetry in corals. The ubiquitous
symmetry observed in branching corals in many reefs is apparently determined by
corresponding symmetry in the flow, rather than intrinsic mechanisms in the colony.
15.528
Pumping Rates Of The Giant Barrel Sponge xestospongia Muta On Caribbean
Reefs: Size Scaling, Environmental Controls, And Bleaching Effects.
Christopher FINELLI* 1
1
Biology and Marine Biology, University of North Carolina Wilmington, Wilmington,
NC
Sponges are among the most diverse and abundant taxa on Caribbean coral reefs, with
numbers of species and biomass equaling or exceeding that of corals and algae. Their
success on reefs can be partially attributed to the ability remove very small particles
(bacteria and viruses) from the water column and their ability to permeate the entire three
dimensional structure of the reef. Because bacterioplankton are likely to be a significant
fraction of the planktonic community (including as primary producers) in oligotrophic
waters, sponges represent a major pathway of carbon flux from the water column to the
benthos and a mechanistic understanding of sponge filtration rates is needed. The giant
barrel sponge, Xestospongia muta, comprises up to 60% of sponge biomass on Caribbean
reefs with a size range (diameter) that spans three orders of magnitude. Moreover, this
species exhibits two types of bleaching (‘cyclic’ and ‘fatal’) that may affect both
individual (via decreased vigor) and population (via size specific mortality) filtration
rates. To address the effects of sponge size and bleaching on filtration rates, I measured
pumping rates of bleached and healthy X. muta across wide range of sizes on Bahamian
reefs in June 2007. Velocity distributions across the oscula were uneven, with maximal
centerline velocities 3 to 4 times greater than the average. Resulting volumetric pumping
rates scaled linearly with tissue volume and averaged 40 ml-H2O h-1 ml-tissue-1.
Pumping rates were constant over periods up to 24 hrs, although some specimens
decreased pumping during rapid fluctuations in water temperature. Cyclic (non-fatal)
bleaching did not affect filtration rates.
15.529
Physical Processes Influencing The Locations Of Nassau Grouper (Epinephelus Striatus)
Spawning Areas And Implications For Reef Fishery Management
Mandy KARNAUSKAS* 1 , Laurent CHERUBIN 2,3 , Vera AGOSTINI 4 , Claire PARIS 2
1 Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, Miami,
FL, 2 Meteorology and Physical Oceanography, Rosenstiel School of Marine and Atmospheric
Science, Miami, FL, 3 Meteorology and Physical Oceanography, Rosenstiel School of Marine
and Atmospheric Science, Miami, 4 The Nature Conservancy, Seattle, WA
Spawning aggregations (SPAGs) of Nassau groupers (Epinephelus striatus) have been observed
along the Mesoamerican Reef and offshore atolls of Belize. SPAGs are consistently located on
the seaward side of reefs adjacent to submerged capes with steep walls. In order to elucidate
the factors underlying preference of these spawning areas by groupers, characteristics of known
SPAG locations were compared to similar locations where spawning does not occur. Modeling
experiments of current flows around capes have shown that the main controlling parameter
affecting flow patterns is the equivalent Reynolds number (Ref), which gives the ratio between
advection and bottom friction terms. When Ref is small (Ref values