11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 25: Predicting Reef Futures in the Context of Climate Change
25.1153
Algal Symbiont Communities in Scleractinian Corals in The Galapagos During The
1997-1998 El Niño-Southern Oscillation Bleaching Event
Lauren VANDEPAS* 1 , Andrew BAKER 2 , Peter GLYNN 2 , Josh FEINGOLD 3
1 Marine Biology and Fisheries, Rosenstiel School of Marine and Atmorpheric Science,
University of Miami, Miami, FL, 2 Marine Biology and Fisheries, Rosenstiel School of
Marine and Atmospheric Science, University of Miami, Miami, FL, 3 Division of Math,
Science and Technology, Nova Southeastern University, Ft. Lauderdale, FL
The El Niño-Southern Oscillation (ENSO) bleaching event of 1997-1998 was a severe
disturbance to coral reefs in the Galapagos. Sustained sea surface temperature anomalies
of 3.5–4.5oC resulted in bleaching in a reported 70–90% of all coral species by February
1998, and eventual mortality was approximately 26%. In March 1998, we sampled the
algal symbiont communities (Symbiodinium spp.) from 139 samples of bleached and
healthy corals, and compared them with 20 samples taken from healthy corals in June
1997, before the bleaching event. Algal symbionts were identified using restriction
fragment length polymorphisms (RFLPs) in large subunit ribosomal DNA, and
denaturing gradient gel electrophoresis (DGGE) of the ITS-2 ribosomal region. Samples
taken before the bleaching event (1997) contained a variety of Symbiodinium in clade C,
but no clade D was detected, even in the scleractinian coral Pocillopora, which
commonly hosts D at other sites in the far eastern Pacific (Panama, Mexico). Clade D
was also rare in samples taken during the bleaching event (1998), although they were
found in a few Pocillopora that were unaffected by bleaching, as well as in two almostdead
Pocillopora sampled with the intention of identifying symbionts still remaining in
bleached tissues. These results suggest that the comparative scarcity of heat tolerant
symbionts in the Galapagos may explain why bleaching-related mortality was relatively
higher in the Galapagos in 1997-98 compared to elsewhere in the eastern Pacific. These
findings also indicate that heat tolerant symbionts may have been present in some hosts,
but at levels that were not sufficiently high to affecting survivorship following bleaching.
We hypothesize that the normally cool waters of the Galapagos result in the virtual
absence of heat tolerant symbionts in clade D, resulting in these coral communities being
particularly susceptible to the effects of high temperature bleaching in 1997-98.
25.1154
Coral Reefs Of The Gulf Of Mannar, Southeastern India -Observations On The
Effect Of Elevated Sst During 2005-2007
Edward JK PATTERSON* 1 , G. MATHEWS 1 , K. DIRAVIYARAJ 1 , Jerker
TAMELANDER 2
1 Suganthi Devadason Marine Research Institute, Tuticorin, India, 2 IUCN Global Marine
Programme, Dar es salaam, Tanzania
The effect of elevated sea surface temperature (SST) on the coral reefs of the Gulf of
Mannar, Southeastern India was monitored during 2005-2007 using quadrate and LIT
methods. The pattern of effect was almost similar on the reefs every year except the
modest fluctuations in the temperature levels. The temperature varied between 31.50C
and 33.60C during summer (April–June). The major reef areas in the Gulf of Mannar are
shallow, between 0.5-3.0m depth and in general, comparatively high temperature
prevailed and the reefs seem to be acclimatized to such situation. The average percentage
of bleached corals during 2005, 2006 and 2007 was 14.6, 15.6, and 12.9 respectively. The
bleaching of corals was noticed from mid April and high temperature existed for about a
month from the end of April. Massive corals especially Porites sp. were the first to be
affected and the other dominant coral species partially / fully bleached were Acropora
cytherea, A. formosa, A. intermedia, A. nobilis, Montipora foliosa, M. digitata and
Pocillopora damicornis. The incidence of bleaching was not uniform every year, in terms
of area and depth, but the pattern was same. Depends on rainfall and winds, recovery
began during June-July and completed in 1-4 months. The branching corals recovered
quickly after temperature reduction, but massive corals took longer time. The fastest
recovered coral size groups were 40-80 cm and 80-160 cm. There was no coral mortality
in 3 years due elevated SST, but 80% of the bleached recruits dead in 2007.
25.1155
What Is The Scope For Adaptation And Acclimatization Of Corals – Seeing The Wood
For The Trees
David OBURA* 1
1 CORDIO East Africa, Mombasa, Kenya
Understanding the role of bleaching in corals and therefore its role in corals adapting to change
has been an elusive goal. A rationale is presented here for a primary role of bleaching in
regulation of the coral-zooxanthellae symbiosis. Stress magnifies the differential metabolic
potential between coral and zooxanthellae such that a control mechanism limiting this
differential is necessary for homeostasis; bleaching is induced to minimize damage from stress.
Two general pathways have been demonstrated for bleaching: reduction of the productivity of
individual zooxanthellae by reducing chlorophyll concentrations and reduction in the population
of zooxanthellae. These are mediated through a variety of physiological mechanisms in the
coral and/or zooxanthellae, and these have explicit gene-environment interactions and therefore
also evolutionary implications where a persistent directional selective pressure is applied. The
extreme thermal stress events causing mass coral bleaching worldwide lie outside the reaction
norms for most corals, revealing the limitations of bleaching as a control mechanism. Limits to
the rates and capacity for change in bleaching mechanisms are not yet known in sufficient detail
to predict the scope for adaptation and acclimatization of corals under present scenarios of
climate change.
25.1156
Effects Of Uv Radiation On The Sexual Reproduction Of The Threatened acropora
Cervicornis
Juan TORRES* 1 , Roy ARMSTRONG 2 , Ernesto WEIL 2
1 Biology Department, University of Puerto Rico, San Juan, Puerto Rico, 2 Department of Marine
Sciences, University of Puerto Rico at Mayaguez, Lajas, Puerto Rico
The effects of enhanced ultraviolet radiation (280-400nm: UVR) on the fecundity of Acropora
cervicornis were measured in field-transplanted colonies from 20 m to 1 m depth and vice
versa at La Parguera, Puerto Rico. Fecundity was estimated from histological sections made
from tissue samples obtained at different time intervals during the experimental period (March –
August 2003). All colonies transplanted from 20 m to 1 m showed a 100% reduction in gonads
per mesentery per polyp one month after transplantation, while those transplanted from 1 m to
20 m did not show any significant reduction in fecundity throughout the experimental period.
The latter colonies did show however, a delay in the spawning times by releasing their gamete
bundles approximately two-three weeks after the controls at 1 m and two months after the
controls at 20 m suggesting an induced response as a consequence of changes in their daily light
cycle due to less radiation (PAR and UVR) available at 20 m compared to 1 m. Control colonies
at 20 m spawned after the full moon of June 2003, while the controls at 1 m spawned 5-6 days
after the full moon of July 2003. While a possible reabsorption of the gametes occurred in A.
cervicornis colonies transplanted from 20 m to 1 m, the expulsion of these gametes due to the
sudden stress caused by the transplantation is not discarded. The results suggest that sudden
increases in UVR can completely stop sexual reproduction in ramose broadcasting coral
species, which in turn can affect the dominance of the species and the composition and structure
of shallow reef environments.
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