11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 11: From Molecules to Moonbeams: How is reproductive timing regulated in coral reef organisms?
11.399
Planula Release, Settlement, Metamorphosis And Growth Of Deep-Sea Soft Corals
ZHAO SUN* 1 , JEAN-FRANÇOIS HAMEL 2 , ANNIE MERCIER 1
1 Ocean Sciences Centre (OSC), Memorial University of Newfoundland, St John's, NL,
Canada, 2 Exploration and Valuing of the Environment (SEVE), St John's, NL, Canada
The life history of deep-sea octocorals has rarely been studied in any detail, mostly owing
to the difficulty of collecting and keeping live specimens. Here we present the
reproductive biology, timing of larval release and settlement, and early growth of three
nephteid species, with a focus on Drifa sp. Specimens collected off the SW Grand Banks
(eastern Canada) were brought back to the laboratory where release of planula larvae was
monitored daily from July to December 2007. Planulae were emitted without any clearly
defined monthly or seasonal patterns. The number of planulae released in a single event
by Drifa sp. varied from 1 to 14 in six colonies from 500 m, and from 1 to 5 in eleven
colonies from 1200 m. The large planulae (ca. 3-6 mm long) were generally expulsed one
at a time from the reproductive polyps in a process that took between 20 min and up to 7
d. They exhibited cycles of contraction and expansion that allowed them to alternately
sink to the bottom and float in the water column. Settlement occurred after 1 to 29 d,
though a small portion of larvae took >2 mo to settle. The type of substratum clearly
influenced the time and rate of settlement: for instance, only 5 of 39 planulae settled on
sterile plates (after 12 to 50 d), whereas 15 of 32 planulae settled on shell fragments (after
2 to 24 d). A few planulae were observed to settle on adult colonies and other planulae.
The eight primary mesenteries typically appeared within 24 h. Polyps developed eight
pinnulated tentacles after 12-75 d; they had a stalk diameter of ca.1 mm and a length of
ca. 5 mm after 140 d of growth.
11.400
Embryogenesis in The Reef-Building acropora Spp.
Nami OKUBO* 1
1 Yokohama National University (present: Kyoto University), Yokohama, Japan
Embryogenesis in the reef building corals Acropora intermedia, A. solitaryensis, A.
hyacinthus, A. digitifera, and A. tenuis was studied in detail at the morphological level,
and the relationships among the animal pole, blastopore, and mouth were investigated for
the first time in coral. These species showed essentially the same sequence of
development. The embryo underwent spiral-like holoblastic cleavage despite the presence
of a dense isolecithal yolk. After the morula stage, the embryo entered the prawn-chip
stage, which consisted of an irregularly shaped cellular bilayer. The embryo began to roll
inward to form the bowl stage; the round shape observed during this stage suggests that it
may be the beginning of gastrulation. However, the blastopore closed and the stomodeum
(mouth and pharynx) was formed via invagination at a site near the closed blastopore.
During the planula stage, a concavity formed in the aboral region in conjunction with
numerous spirocysts, suggesting that spirocysts are used to attach to the substrate before
the onset of metamorphosis.
11.401
Breeding Experiments Of The Hermatypic Coral Galaxea Fascicularis: Partial
Reproductive Isolation Between Colonies Of Different Nematocyst Types, And
Enhancement Of Fertilization Success By The Presence Of Parental Colonies
Mariko ABE* 1,2 , Toshiki WATANABE 3 , Hideki HAYAKAWA 3 , Michio HIDAKA 4
1 Marine and Environmental Science, University of the Ryukyus, Nishihara, Japan, 2 Okinawa
ReefCheck and Research Group, Nishihara, Japan, 3 Ocean Research Institute, The University of
Tokyo, Tokyo, Japan, 4 University of the Ryukyus, Nishihara, Japan
The populations of G. fascicularis in Okinawa, Japan are likely to consist of two cryptic
species. By morphological examination, a nematocyst type macrobasic p-mastigophore (MpM)
in G. fascicularis has been distinguished to two distinct subtypes S and H, named after soft and
hard colonial morphologies, respectively.Type S MpMs had a relatively thick capsule and a
shaft about a half of the capsule length, whereas MpMs of type H had a slender capsule with a
shaft shorter than one third of the capsule length. In the majority of G. fascicularis colonies,
only one of the two MpM types is found in external tentacles. Molecular analyses have shown
that the MpM types are highly correlated to different genotypes in a mitochondrial intergenic
region and at a nuclear microsatellite locus. Thus, this species in Okinawa is suspected to
consist of two reproductive units that occur in sympatry. The present study was to examine the
presence of reproductive isolation in G. fascicularis by performing fertilization experiments
between individuals of the same or different MpM types.
Results of three years breeding experiments showed that fertilization specificity, only a cross
between type H female and type S male, was found to be compatible with the MpM
morphotypes with low frequencies of cross-fertilization, suggesting the presence of permeable
reproductive barrier between the putative cryptic species. In addition we also found an
interesting fertilization mechanism of G.fascicularis, fertilization could only be successful in
the presence of colony fragments.
11.402
Reproductive Effort Of A Brain Coral in The Abrolhos Reef Complex, Brazil
Marcia ALVARENGA* 1 , Clovis CASTRO 1
1 Invertebrates, Museu Nacional - UFRJ, Rio de Janeiro, Brazil
Brazil has the only true coral reefs in the South Atllantic Ocean and Abrolhos is considered the
largest and richest coral reef area in Brazil. Mussismilia hispida is endemic to Brazilian coast.
This specie is very comon and plays an important role as one of the major reef builder along the
Brazilian coast. Five colonies were collected at five sites at the inner reefs of the Abrolhos
Bank, located at different distances from the coast. Reproductive effort was estimated
through fecundity (number of eggs per polyp and per mesenteries). Our data show that the
fecundity is variable. The specie presents a mean of 51,7 (6,0 s.d.) mesenteries per polyp. Mean
fecundity per mesenteries was 28,6 (6,5 s.d.) and the higher number of eggs per mesenteries
was 32. The accuracy of the fecundity per gonad obtained was correlated to sediment deposition
in each site sampled. Sedimentation has previously been considered an important source of
impact in coral reefs. Percentages of fertile mesenteries per polyp were similar among sites.
However, the fecundity per mesenteries varied among colonies and sites, especially on the sites
with high sediment deposition. We suggest that M. hispida can suffer impacts on your
reproductive effort or can also invest a lot of energy in egg production to increase its chance of
survival of the species in more disturb habitats. The study shows data that can be used as a tool
if environment threat in the area.
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