11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 10: Ecological Processes on Today's Reef Ecosystems
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Factors Influencing Coral Recruitment Patterns in The Sulu Sea Marine Corridors
Jeneen GARCIA* 1 , Porfirio ALINO 2
1 Institute of Environmental & Marine Sciences, Silliman University, Dumaguete City,
Philippines, 2 Marine Science Institute, University of the Philippines, Quezon City,
Philippines
Coral recruitment studies provide crucial information on a reef’s capacity to recover from
disturbances in the form of catastrophic events, such as storms and mass mortality from
coral bleaching, or destructive fishing. The Sulu Sea has been identified as the apex of a
“coral triangle”, yet little is known on coral recruitment in this area. This study aimed to
determine the abundance and composition of coral recruits in the three major marine
corridors of the Sulu Sea, and determine patterns in coral recruitment in relation to each
corridor’s physical and biological features. Terracotta tiles were deployed along 50-m
transects in the Cagayan Ridge (Jessie Beazley reefs, Tubbataha atolls, Cagayancillo
islands), Balabac Strait, and Verde Island Passage in October 2006. The tiles were
retrieved in April and May 2007 and subjected to stereoscopic analysis. Initial results
show high recruit density in embayments and island fronts, while diversity is greater in
the Balabac Strait, which is a convergence point of the Sulu and South China Seas. These
results, however, varied with the density and composition of corresponding adult coral
communities. This shows that currents greatly determine recruitment patterns, but other
factors may come into play to alter the composition and density of corresponding adult
communities. These insights are significant to the Sulu Sulawesi Seascape marine
conservation strategy in the design of a marine protected areas network.
Recommendations on how to maintain and improve the connectedness of these corridors
are derived.
10.275
Herbivory Is The Primary Promoter Of Coral Health On Bonaire, Netherlands
Antilles
Joost DEN HAAN* 1 , Ramon DE LEON 2 , Emily MCGRATH 3 , Rudi ROIJACKERS 4 ,
Marten SCHEFFER 4 , Robert STENECK 5
1 Earth System Science & Climate Change, Wageningen University, Wageningen,
Netherlands, 2 Bonaire National Marine Park, Kralendijk, Netherlands Antilles, 3 CIEE,
Benton, PA, 4 Wageningen University, Wageningen, Netherlands, 5 University of Maine,
Walpole, MA
A massive region-wide decline of corals across almost the entire Caribbean basin has
been reported, with the average hard coral cover of reefs being reduced by 80%, from
approximately 50% to 10% cover in only three decades. The amount of substratum
currently occupied by macroalgae apparently exceeds the amount that can be controlled
by herbivores, with the result that substantial stands of macroalgae developed and
persisted. Many coral reefs in the Caribbean seem to have turned into this alternative
equilibrium, however, there are still some locations in the Caribbean where the coral
reefs are not algal-dominated. The island of Bonaire (Netherlands Antilles) has the
highest abundance of live coral and the lowest abundance of macroalgae resulting in the
highest index of reef health in the Caribbean. From September 2007 until January 2008
the western coast of Bonaire was studied for coral cover, algal biomass, juvenile coral
recruitment and herbivore biomass to study the interrelationships between coral health –
macroalgae – herbivores. There seems to be a strong negative correlation between the
biomass of macroalgae and the biomass of herbivores (parrotfishes and surgeonfishes)
resulting in increased recruitment possibilities for young corals increasing the reef’s
resilience. This makes reefs less susceptible to both man-made and natural disturbances,
e.g. the impact of hurricanes. It is recommended that parrotfishes and surgeonfishes
remain highly protected as they serve a major purpose in maintaining the coral reefs as
healthy as they are today. For other regions in the Caribbean, to increase their reef’s
resilience it is recommended management plans are made to protect herbivory, especially
parrotfishes and surgeonfishes.
10.276
Anthropogenic Influence On Macroalgal Nutrient Dynamics -Implications For Potential
Bottom-Up Effects On Secondary Production in The Western Indian Ocean
Gustaf LILLIESKÖLD SJÖÖ* 1 , Erik MÖRK 1
1 Systems Ecology, Stockholm University, Stockholm, Sweden
The circulation and retention of nutrients determine the trophic status in coastal ecosystems.
Benthic producers, such as macroalgae, greatly influence these processes, as they bind nutrients
and transfer energy to higher levels in the food web. Due to different morphological properties,
different macroalgal types have different uptake and binding potential. Furthermore,
morphological and physiological traits determine nutritional value and susceptibility to grazing
by herbivores, thus controlling subsequent bottom-up transfer in the system. Temporal changes
in composition and nutritional status of the macroalgal communities can therefore indicate the
amount of energy bound within the system, as well as the rate of nutrient turnover and
production potential at higher trophic levels. The present study investigates changes in
macroalgal biomass, diversity, composition of functional groups and gross nutrient binding,
within and between seasons. The study was conducted in Kenya, during two dry seasons
2006/2007, at sites with varying levels of nutrient loading and herbivore abundance. Both
grazing and available nutrients proved to affect the properties of the macroalgal community,
with the highest nutrient turnover at a fished site where both herbivore abundance and nutrient
loading is relatively low. The reduced grazing pressure increased biomass of ephemeral
macroalgae, with a high growth-rate and tissue turnover. At sites where herbivores are more
abundant, the algal community is dominated by fleshy brown macroalgae with lower nutrient
capture ability and tissue turnover. Overall it seems that sites under moderate anthropogenic
influence have the highest macroalgal productivity and nutrient circulation, resulting in a
possibly higher energy transfer between trophic levels. In turn, such areas may sustain a larger
production of macroalgal grazers and subsequent extraction over time.
10.277
Top-Down And Bottom-Up Regulation Of Coral Reef Macroalgal Communities in A
Gradient Of Anthropogenic Influence Off The Kenyan Coast
Erik MÖRK* 1 , Gustaf LILLIESKÖLD SJÖÖ 1 , Nils KAUTSKY 1 , Tim MCCLANAHAN 2
1 Systems Ecology, Stockholm University, Stockholm, Sweden, 2 Marine Programs, Wildlife
Conservation Society, Mombasa, Kenya
Humans affect the herbivore abundances and nutrient loading in coral reef communities through
artisanal fisheries and effluents from populated areas. Such anthropogenic activities influence
the top-down and bottom-up forces regulating macroalgal community structure and function. In
turn, an altered community structure can result in trophic cascades, as macroalgae are the most
important benthic producers in the coral reef ecosystem. In areas where traditional fishing
methods are common and still practiced by the majority of the local coastal communities,
anthropogenic influences have been observed to decrease with increasing distance from
settlements. This is mainly due to limitation of travel as regular visits to remote fishing grounds
is time consuming and sometimes dangerous. This case study was conducted in the
southernmost part of Kenya, where a chain of islands with increasing distance (up to 10 km)
from a fishing community was used as a model system. Increasing herbivore abundance, and
decreasing nutrient loading, has been established along the gradient, making the system a
suitable area for testing distance related effects on macroalgal community structure. In general,
the study showed a decrease in macroalgal cover, diversity and biomass, with increasing
distance from the fishing community. Composition and relative abundance of algal functional
groups also changed along the island chain. Furthermore, the dominant type of grazers (i.e. fish
or sea urchins) proved to influence macroalgal abundance and composition. In conclusion, even
a traditional fishing community can greatly influence coral/macroalgal dominance regimes,
within accessible distance.
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