11th ICRS Abstract book - Nova Southeastern University

12-18
Coral Reefs Under The Impact Of Internal Waves, Similan Islands, Andaman Sea:
Primary Production
Carin JANTZEN* 1 , Cornelia RODER 1 , Gertraud SCHMIDT 1 , Christian WILD 2 ,
Claudio RICHTER 1
1 Center for Tropical Marine Ecology (ZMT), Bremen, Germany, 2 Coral Reef Ecology
Work Group (CORE), Center of Geobiology and Biodiversity Research, München,
Germany
Internal waves induced significant small-scale differences in structure and dynamics of
primary producers on the exposed W and sheltered E sides of Similan Islands, Andaman
Sea: Living corals were less abundant on the W side of the islands (49-67 % of total hard
substrate vs. 28-44 % on W sides), with a higher percentage of turf algae (W: 43-46 %;
E: 12-19 %) and higher areal concentrations of chlorophyll a and pheophytin. Chamber
incubations carried out at the same light intensities showed 30-40 % reduced levels of
potential photosynthesis on the W sides, this applies for both, the hermatypic coral
Porites lutea (mg O2 h-1 cm-1 of coral surface) and sediment-associated algae (mg O2 h-
1 mg-1 of Chl a). In-situ rapid lightcurves measured with a submersible pulse amplitude
modulated underwater fluorometer showed lower saturation light intensities along with
higher Chl a content (mg cm-2of coral surface) in W Similan P. lutea, indicating an
adaptation to lower light levels in turbid upwelling waters.
12-20
Coral Reefs Under The Impact Of Internal Waves, Similan Islands, Andaman Sea:
Heterotrophy
Cornelia RODER* 1 , Carin JANTZEN 1 , Gertraud SCHMIDT 1 , Claudio RICHTER 1
1 Center for Tropical Marine Ecology, Bremen, Germany
Coral reefs of the exposed Western sides of the Similan Islands, an offshore island group
in the Andaman Sea, experience strong swell during the SW monsoon and internal wave
induced upwelling, increasing POM concentrations, turbidity and nutrient levels 3 to 4fold
relative to the sheltered E sides of the islands, Here, we test the effect of these
internal bores on the autotrophic vs heterotrophic nutrition of corals.
Measurements on isotopic composition ( 13 C and 15 N) of zooxanthellae as well as coral
host (Porites lutea, Diploastrea heliopora, Pocillopora eydouxi) tissue indicate that the
corals of the W side of the islands are more heterotrophic than on the sheltered E sides,
despite their close geographical distance (200 m), with plankton substituting the reduced
measured photosynthetic activity on the W sides.
Shading experiments suppressing photosynthetic activity revealed a more effective
maintenance of metabolic activity in all three species due to enhanced heterotrophy on
the W side. Cross-transplantation experiments with P. eydouxi showed that corals from
the W side, accustomed to the rough conditions there, show faster adaptability to changes
and enhanced resilience to environmental disturbance. Measurements on fitness
parameters such as RNA/DNA-ratios or protein concentrations further support these
assumptions.
Oral Mini-Symposium 12: Reef Resilience
12-21
Coral Recruitment in The Garden Of Good And Evil: Algae As A Driver Of Coral Reef
Resilience
Robert STENECK* 1 , Suzanne ARNOLD 1 , Peter MUMBY 2 , Valerie PAUL 3 , Raphael
RITSON-WILLIAMS 3
1 School of Marine Sciences, University of Maine, Walpole, ME, 2 Marine Spatial Ecology
Laboratory, University of Exeter, Exeter, United Kingdom, 3 Smithsonian Institution, Fort
Pierce, FL
Coral reefs are globally endangered ecosystems. Their resilience depends on the ecological
success of reef corals. In recent decades, mortality rates of adult corals have increased due to
bleaching and disease. Thus, the ability of reefs to recover depends on the successful
recruitment of corals. We studied the factors driving the recruitment of Caribbean corals at
multiple scales in space and time. Since 2003 we have studied eight regions (Bahamas,
Bonaire, St. Croix, St. John, Mexico, Belize, Honduras, Guatemala) four to six reefs per region
with replicated benthic community structure transects, fish surveys, bite rates, and coral
settlement plates at multiple reefs per region. From this a clear pattern has emerged. Algal
community structure regulates coral recruitment both positively, due to the presence of coralline
algal species that facilitate coral settlement, and negatively, due to the presence of macroalgae
and thick algal turfs that inhibit coral settlement and coralline algal species that kill newly
settled corals (via smothering overgrowth, or the shedding of the coralline’s surface cells).
Increased algal biomass of turfs and macroalgae reduce larval settlement and post-settlement
survival. Since different coralline algal species can affect coral recruitment both positively and
negatively, we conducted laboratory studies to determine if settling corals are selective in
settling on facilitating species and avoiding recruitment inhibiting species. We found that
different coral species show different coralline-specific selectivity. For example, Acropora
palmata metamorphoses and settles near the coralline Hydrolithon boergesenii whereas A.
cervicornis settles onto Titanoderma prototypum. We suspect that settling corals can
determine the right zone, microhabitat (e.g. subcryptic spaces) and ecological state (e.g. high vs.
low algal biomass) based on the coralline flora they detect.
12-22
Algal Effects On Coral Replenishment, And The Resilience Of Coral Reefs
Chico BIRRELL* 1 , Laurence MCCOOK 2 , Bette WILLIS 3 , Guillermo DIAZ-PULIDO 4
1 Australian Institute of Marine Science, Perth, Australia, 2 Pew Fellow in Marine Conservation;
ARC Centre of Excellence for Coral Reef Studies; GBRMPA, Townsville, Australia, 3 ARC
Centre of Excellence for Coral Reef Studies; School of Biological Sciences JCU, Townsville,
Australia, 4 Pew Program in Marine Conservation; ARC Centre of Excellence for Coral Reef
Studies, Brisbane, Australia
The ecological resilience of coral reefs depends critically on the capacity of coral populations to
re-establish in habitats dominated by macroalgae. Coral reefs globally are under rapidly
increasing pressure from human activities, especially from climate change, with serious
environmental, social and economic consequences. Coral mortality is usually followed by
colonisation by benthic algae of various forms, so that algae dominate most degraded and
disturbed reefs. The capacity of coral populations to re-establish in this algal-dominated
environment will depend on direct and indirect impacts of the algae on the supply of coral
larvae from remnant adults, on settlement of coral larvae and on the post-settlement survival
and growth of juvenile corals. This talk summarises a recent review of this topic.
The effects of benthic algae on coral replenishment vary considerably but the thick mats or
large seaweeds typical of degraded reefs have predominantly negative impacts. Some algae,
mostly calcareous red algae, may enhance coral settlement on healthy reefs. Algal effects on
coral replenishment include reduced fecundity and larval survival, pre-emption of space for
settlement, abrasion or overgrowth of recruits, sloughing or dislodgement of recruits settled on
crustose algae, and changes to habitat conditions. There is a serious lack of information about
these effects, which are likely to cause bottlenecks in coral recovery and significantly reduce the
resilience of coral reefs.
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