11th ICRS Abstract book - Nova Southeastern University

9-17
New Hemiketal Steroid From The Introduced Soft Coral chromonephthea
Braziliensis Ofwegan As Chemical Defense Against Generalist Fishes
Beatriz FLEURY* 1 , Bruno LAGES 1 , Jussara BARBOSA 2 , Carlos KAISER 2 , Angelo C.
PINTO 2
1 Departamento de Ecologia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro,
Brazil, 2 Departamento de Química Orgânica, Universidade Federal do Rio de Janeiro,
Rio de Janeiro, Brazil
Biological invasions in marine environments are one of the lesser understood aspects of
global change (Occhipinti-Ambrogi & Savini, 2003). Recent studies, however,
demonstrated that chemical defensive strategies may facilitate the invasion of the exotic
soft coral Chromonephthea braziliensis Ofwegan (Nephtheidae, Alcyonacea) in the
Brazilian Atlantic coast (Lages et al., 2006). We report for the first time, the detailed
composition of the monohydroxylated sterol fraction, and a new hemiketal steroid, 23keto-cladiellin-A,
isolated from the unpalatable hexane extract from C. braziliensis.
Bioassay-guided fractionation of this extract, incorporated into artificial food, revealed
that this hemiketal steroid exhibits in situ potent feeding deterrent properties against
generalist fishes, at the natural concentration. The major sterol fraction, containing the
monohydroxylated sterols, was inactive in the bioassay. This result supports the enemy
release hypothesis, the most commonly accepted theory to explain the success of invasive
species in their new ranges.
9-18
Uv Protective Sunscreen in Coral Reef Fish Mucus
Maxi ECKES* 1 , Sophie DOVE 2 , Alexandra GRUTTER 3 , Ulrike SIEBECK 4
1 SIB, University of Queensland (UQ), St. Lucia, Queensland, Australia, 2 CMS, UQ, St.
Lucia, Queensland, Australia, 3 SIB, UQ, St. Lucia, Queensland, Australia, 4 SBMS, UQ,
St. Lucia, Queensland, Australia
Coral reefs typically have clear oligotrophic waters with a high UV transmission, which
can damage tissues in marine organisms. The Great Barrier Reef (GBR), Australia has
experienced a significant increase in the number of cloud-free days over the last 10 years
causing an increase in UV-induced DNA damage in reef organisms. Fish were recently
discovered to have sunscreen compounds in their external mucus suspected to be
mycosporine-like amino acids (MAAs). Using High Performance Liquid
Chromatography (HPLC), we examined epithelial mucus from the labrid Thalassoma
lunare and 13 species of Scaridae. For the first time in fish mucus, MAAs were identified
and quantified. In addition, to examine geographical variations, the MAAs from T. lunare
were compared from three different latitudinal locations (Lizard Island, Heron Island, and
North Stradbroke Island, Queensland) and from 13 species of parrotfish along a
longitudinal gradient from inshore reefs (Lizard Island) to the outer edge reefs (GBR) to
oceanic reefs (Osprey Reef). Depending on the species, different combinations and
quantities of the MAAs asterina-330, palythene and mycosporine-N-methylamine serine
were present. MAA levels from T. lunare decreased with distance from the equator.
Thalassoma lunare from North Stradbroke Island had lower MAA levels (mycosporine-
N-methylamine serine) or absent (palythene) compared with mucus from the more
northern locations (Lizard Island and Heron Island). Furthermore, results from our
longitudinal comparison showed that the MAA absorbance increased with distance from
the mainland landmass to the more oligotrophic outer reefs, where UV penetration is
higher. This study shows that the identity and quantity of MAAs in fish mucus not only
varies among species but also within a species sampled in different locations. These
suggest that the ecological role of MAAs in fishes is varied and complex and that several
factors may affect the type and quantity of MAAs found in the mucus of reef fish.
Oral Mini-Symposium 9: Chemical Ecology on Coral Reefs
9-19
The Role Of Chemical Signals in The Feeding Behavior Of Crown-Of-Thorns Seastar,
acanthaster Planci
Ciemon Frank CABALLES* 1 , Peter SCHUPP 1
1 Marine Laboratory, University of Guam, Mangilao, Guam
The crown-of-thorns seastar, Acanthaster planci, is a corallivore known for its capacity to cause
large-scale coral mortality at high population densities and continues to be a reef management
problem despite previous control efforts. There has been no active control of A. planci
populations on Guam since the 1970’s and manta tow surveys confirmed that A. planci
continues to damage large areas of reef around Guam. Large aggregations, ranging from 23 to
336 individuals/ha of reef, were observed to feed mainly on Acroporids, especially encrusting
Montipora. Preferential feeding by A. planci causes differential mortality among coral species,
which can exert a major influence on community structure. However, the role of chemical
signals in A. planci prey selectivity is still poorly understood. In this study, we tested the
effectiveness of organic extracts from preferred coral species and α-linolenic acid, a previously
identified feeding attractant. Feeding assays with A. planci were conducted in a Y-maze, using
crude extracts incorporated into agar-based feeding plates at natural concentrations. A. planci
individuals were attracted to crude extracts of Montipora sp. (n=25; p