11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 10: Ecological Processes on Today's Reef Ecosystems
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Some sponges don’t bleach
Christine SCHÖNBERG* 1 , Ryota SUWA 2 , Michio HIDAKA 2 , William Kok Weng
LOH 3
1 Dept. of Animal Biodiversity and Evolution, Carl von Ossietzky University, Faculty 5,
Biology and Environmental Sciences, Oldenburg, Germany, 2 Department of Marine and
Environmental Science, University of the Ryukyus, Graduate School of Engineering and
Science, Okinawa, Japan, 3 Marine Biology Australia, PO Box 6112, St. Lucia, QLD
4067, Australia; and CMS, QLD Uni, Australia, St. Lucia, Brisbane, Australia
Symbiotic coral reef organisms are under increasing environmntal pressure. Related
studies are mostly concerned with reef builders. That bioeroding sponges contain
dinoflagellate symbionts (zooxanthellae) is less well known. However, it may be possible
to learn from this symbiosis, which appears to be comparatively robust and has never
been observed to fail in nature. In this context Cliona orientalis Thiele, 1900 was studied.
It is a common Indo-Pacific bioeroding sponge, which can attack live coral, is a
representative of the Cliona viridis (Schmidt, 1870) species complex, which occurs in all
warm and temperate seas, and plays an important role in benthic calcium carbonate
cycling. Our data showed that the sponge-zooxanthella symbiosis is younger than other
known invertebrate-zooxanthella associations. Only subclade G-type Symbiodinium was
found in these bioeroding sponges taken from locations thousands of kilometers apart.
The symbionts appear to be transferred maternally to form a very close relationship with
the sponge, e.g. supporting its growth. Approaches to experimentally bleach C. orientalis
failed, and we could not detect clear evidence of heat or light stress during experiments.
The stability of the symbiosis is partly related to the stress resistance of G-type
Symbiodinium, and partly to protection by the host. The symbionts can be shifted within
the sponge and are transported away from the source of stress. This behaviour, the
sponge’s endolithic life style and its three-dimensionality provide very efficient shelter.
Additional protection may be obtained from a bright yellow pigment that appears when
the sponge is exposed to adverse conditions. Overall, the sponge-zooxanthella symbiosis
is extraordinarily strong, and we have noted significant increases in sponge abundances
in disturbed habitats where coral mortality was high.
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Probing Into Hard Substrates – Growth Habits Of Bioeroding Sponges
Christine SCHÖNBERG* 1 , Lydia BEUCK 2
1 Animal Biodiversity and Evolution, Carl von Ossietzky University, Faculty 5, Biology
and Environmental Science, Oldenburg, Germany, 2 Institute for Palaeontology,
University of Erlangen, Erlangen, Germany
Traditionally, bioeroders have been studied by medical radiographic and cast techniques.
These methods have significantly improved over the last 10 years and presently allow
viewing in three dimensions and as animation, thus enabling studies in unprecedented
detail. The application of anaglyph technique on three-dimensional images and
animations further enhances the spatial visualisation, permitting even the interpretation of
dense and interwoven trace assemblages often present in long-term exposed calcareous
substrates. We show a few examples of erosion caused by bioeroding sponges in various
samples from the Australian Great Barrier Reef and Atlantic and Mediterranean coldwater
corals. While cast techniques display features ‘in negative’, micro-computed
tomography allows the investigator to view the material as if the substrate were
transparent. Traces of different species can easily be recognised, precisely pictured and
displayed, especially supported by the application of the anaglyph technique. As an
example, the two bioeroding sponges Cliona orientalis Thiele, 1900 and Cliona celata
Grant, 1826 develop very different patterns of destruction, with the former eroding very
uniformly and densely, while the latter has larger canal diameters in the centre and thins
out towards the margins. We further show images of erosion obtained from cold-water
reefs, with sponges such as Aka, Pione and Alectona displaying aspects of their coexistence
and interspecific interactions.
10.272
Impact of the invasive native algae Caulerpa sertularioides on coral reef communities in
Culebra Bay, Costa Rica (Eastern Pacific)
Cindy FERNÁNDEZ* 1 , Juan José ALVARADO 1 , Jorge CORTÉS 1
1 Centro de Investigación en Ciencias del Mar y Limnología (CIMAR), Universidad de Costa
Rica, San José, Costa Rica
The green algae Caulerpa sertularioides is spreading in the seasonal upwelling region of the
northern Pacific coast of Costa Rica (Culebra Bay). It seems that this macroalgae is the cause,
and not the consequence, of coral degradation of the reef ecosystem. The spread of C.
sertularioides negatively affected the growth rate of the branching corals such as Pocillopora
elegans and Psammocora stellata. Coral growth declined mainly due to accumulation of
sediments, abrasion and overgrowth of the algal fronds. This last impact did not seem to effect
the survival of P. elegans due to the presence of symbiont crabs (Trapezia spp.) that constantly
cropped the algae. Intensity of the algal impact on the corals varied with areal cover and density
of the algal fronds, which were dependent on the amount of nutrients and the water temperature.
Algal cover and frond density were highest during seasonal upwelling, while coral growth was
highest in the non-upwelling season when algal cover and frond density decreased. The
propagation of C. sertularioides also caused modifications in the structure of other components
of the benthic community as its presence affected the abundances of invertebrates such as
nudibranchs and polychaetes and displaced other algal species.
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Effect Of Hurricane John (2006) On Invertebrates Associated With Coral in Bahía De La
Paz, Gulf Of California
Luis HERNANDEZ 1 , Eduardo BALART* 1
1 CIBNOR, La Paz, Mexico
Every quarter for the past four years, surveys of 10 m × 1 m sample areas at six sites at a coral
reef community, with five replicates, were undertaken near Bahía de La Paz. This study
describes the effect of Hurricane John (level II, 216 km/h winds) on the assemblage of
invertebrates on the reef and documents the conditions prior and previous to the hurricane.
Physical damage to the coral reef included fragmentation of coral branches and changing the
sandy gravel bottom with surviving coral fragments. Prior to the hurricane (July 2006), the
surveys averaged 50 species (3093 specimens). After the hurricane (October 2006), the surveys
located only 39 species (2018 specimens). Similarity Index for these two months was 83.1%.
After the hurricane, 13 species were lost, but three species were new for this area. The most
affected group was echinoderms, with the disappearance of six species. Two of the new species
were crabs. One year after Hurricane John (October 2007), the community had recovered 38%
(five) of its lost species. These were three echinoderms and two mollusks.
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