11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 10: Ecological Processes on Today's Reef Ecosystems
10.350
Non-Random Distribution Of Fishes On Two Dominant Habitat Types Within A
Shallow Reef in Northeastern Brazil
Paulo MEDEIROS* 1 , Renato GREMPEL 1 , Allan SOUZA 1 , Martina ILARRI 1
1 Departamento de Sistemática e Ecologia, Centro de Ciências Exatas e da Natureza,
Universidade Federal da Paraíba, João Pessoa, Brazil
Many reef fishes, particularly the site-attached species, show marked habitat selectivity
on reef environments. Therefore, even in patchy reefs, where habitat distinction is often
precluded, fishes tend to show a somewhat corresponding distribution to their favored
environmental variables. The present study aimed at comparing the distribution of fishes
on two dominant habitat types, reef flat (RF) and reef crest (RC), at Picãozinho reef in
Northeastern Brazil. For that purpose, six 20 x 2m belt transect replicates were conducted
haphazardly on each habitat, where fishes and environmental variables data were
collected. On RF and RC, 246 and 214 fishes from 22 and 14 species, respectively, were
recorded. Highly significant differences between the habitats were detected for depth,
encrusting coralline algae, rubble and sand, fish richness, fish diversity and evenness (RF
> RC) and for rugosity, turf algae, living coral and holes (RF < RC). These differences
were crucial for the distribution patterns observed for species such as Coryphopterus
glaucofraenum, Pseudupeneus maculatus and Sparisoma spp., which were significantly
more abundant on RF and Labrissomus nuchipinnis and Stegastes fuscus, which were
significantly more abundant on RC. Further, roving herbivores, planktivores, mobile
invertivores (RF > RC), territorial herbivores and carnivores (RF < RC) also showed
significant differences. The observed differences on fish assemblages emphasize the
distinct distributional patterns of fish on reef environments. Also, our data showed that
RF, once considered a low complexity habitat, sustained a rich and diversified
ichthyofauna, composed mainly of haemulids and scarids, while RC was largely
dominated by territorial damselfishes. Both univariate and multivariate analysis identified
clear segregation patterns among fish species, which reflected their underlying nonrandom
habitat preferences.
Financial Support: CNPq, CAPES
10.352
Recruitment And Resilience On Coral Reefs
Carrie MANFRINO* 1,2 , Elizabeth WHITEMAN 1
1 Central Caribbean Marine Institute, Princeton, NJ, 2 Department of Geology and
Meteorology, Kean University, Union
Marine protected areas have become the most widely used tool to manage reef
ecosystems. Underlying this tool is the assumption that protection of herbivores will
reduce macroalgal cover and increase coral recruitment. Increasing evidence supports the
first half of this assumption but there is little empirical evidence for the latter. In most
locations it is impossible to separate the independent effects of disturbance and
concurrent phase-shift to macroalgae dominance on coral recruitment.
On shallow reefs surrounding Little Cayman, significant loss of live coral cover was
observed between 1999 and 2006. This loss is almost entirely accounted for by loss of
live Montastrea spp. During the same period there was no significant change in the
abundance or density of herbivorous fish species, and no significant change in the size
structure of each species. In addition, there was no increase in the percent cover of fleshy
macroalgae.
The total density of juveniles and the relative proportions of juvenile coral species did not
change following this disturbance to the reef ecosystem. Juvenile coral community
structure displayed significant spatial variation both between and within reefs. In general,
densities of brooding Agaricia spp. and Porites spp. were higher than the spawning
Montastrea spp and Siderastrea spp. Growth and survival of juvenile corals did not differ
between species.
Taken together, our results illustrate that, following a disturbance event causing
significant live coral cover loss, coral recruitment was maintained at levels observed prior
to ecosystem disturbance. Moreover, there was no change in herbivorous fish populations
and no shift to a macroalgae dominated system. Our results confirm the effectiveness of
management strategies focused on herbivorous fish populations but also suggest that in
locations in which grazing is controlled, coral recruitment can rapidly contribute to coral
recovery.
10.353
Testing Inorganic Nutrient Addition Effects On The Stability Of Coral-Algae Interactions
in Coral Reefs
Andreas HAAS* 1 , Malik NAUMANN 1 , Florian MAYER 1 , Mohammed AL-ZIBDAH 2 ,
Mohammed RASHEED 2 , Christian WILD 1
1 Coral Reef Ecology Work Group (CORE), GeoBio-Center LMU München, Munich, Germany,
2 Marine Science Station, Yarmouk University, Aqaba, Jordan
Recent studies in fringing reefs of the Northern Red Sea revealed that the in-situ stability of
coral-algae interactions in coral reefs was highly variable with fast overgrowth of coral by algae
in fall and close to equilibrium between both groups of organisms in summer. This may be
caused by measured 3 fold higher concentrations of inorganic nutrients in fall and winter,
thereby promoting algae growth with concomitant equilibrium shift. A long term experiment
was conducted in order to study the effect of different kinds of inorganic (ammonium,
phosphate, nitrate) and organic (monosaccharides) nutrients onto the stability of one of the most
dominant coral-algae interaction of the Northern Red Sea involving branching corals of the
genus Acropora and a typical consortium of benthic turf algae. Nutrients were added in
concentrations 5 fold higher compared to the annual average concentrations and the areas of
living and dead coral tissue were measured in regular intervals. This confirmed that increased
inorganic nutrients concentrations can strongly affect the stability of interactions between corals
and algae either via direct stimulation of algae growth or via facilitation of organic matter
release by benthic algae triggering microbial oxygen consumption with associated coral
mortality.
10.354
Localized Fish Community Response To A Rapid Habitat Phase Shift From Coral Rubble
To Overgrowth By Caulerpa Sp. At Aldabra Atoll, Southern Seychelles Islands
Raymond BUCKLEY 1,2 , Ben STOBART 3 , Nigel DOWNING 4 , Kristian TELEKI* 5
1 College of Ocean and Fishery Sciences, School of Aquatic and Fishery Sciences, University of
Washington, Seattle, WA, 2 Fish Program/Marine Resources, Washington Department of Fish
and Wildlife, Seattle, 3 Marine Reserves, Spanish Institute of Oceanography, Mallorca, Spain,
4 Cambridge Coastal Research Unit, Cambridge University, Cambridge, United Kingdom,
5 International Coral Reef Action Network (ICRAN), Cambridge, United Kingdom
The value and utility of coral reef habitats to reef fish assemblages are often greatly degraded
by algal invasion, possibly resulting in significant loss of reef fish diversity. However, reef fish
community responses to rapid overgrowth of low relief, spatially heterogeneous coral rubble
habitat by spatially heterogeneous macro-algae habitat have not been documented. We examine
changes in the predominantly juvenile fish communities at 10m and 20m depths at a mixed
coral rubble (70%) and Halimeda (30%) site off the northeast coast of Aldabra Atoll, from 1999
through 2006. Caulerpa was detected at the site in May 2003 at 20m, and remained scarce
through April 2005. This Caulerpa habitat proliferated dramatically by December 2006 to cover
completely the 20m depth transect. No Caulerpa has been detected at 10m. Multivariate
analyses of fish assemblages showed no directional change over time at either 10m or 20m,
although there are consistently higher counts of fish species and abundances at 10m. The 2006
surveys at both 10m and 20m are similar to low counts in 2003, but there is no indication of any
dramatic changes in fish community structure in response to the phase shift to Caulerpa habitat.
We conclude that in this low profile coral rubble dominated area, it is likely that the spatial
heterogeneity of the Caulerpa habitat is either a sufficient substitute habitat for the juvenile
fishes, or it does not prevent fish from accessing the buried coral rubble habitat. The combined
coral-algal habitat may enhance settlement, survival, and ontogenetic habitat shifts for juvenile
fishes at the site. Future monitoring should reveal any long-term changes to the fish community,
and the residence time of the Caulerpa invasion.
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