CONTENT - International Society of Zoological Sciences

ICZ2008 – Abstracts S20
Fat reserves and moisture content in relation to sexual cycle
of sardine, Sardina pilchardus (Walbaum., 1792), in the
eastern middle adriatic fishery grounds
Gorenka Sinovčić and Bosiljka Mustać
Institute of oceanography and Fisheries, Split, Croatia
The fat reserves, moisture and sexual cycle of sardine, Sardina
pilchardus (Walbaum, 1792), were studied from monthly random
samples of purse seine catches from March 2004 to February
2005. Catches were realised in offshore (Dugi Otok) and inshore
waters (Virsko more) of the Mid Adriatic Sea. A total of 1,219
sardine specimens were collected, out of which 668 were males
and 541 females. Fish were measured, weighed and sexed. The
sexual cycle analysis was based on the temporal evolution of
gonadosomatic index and gonad mass. Gonadosomatic index
(GSI) was calculated by expressing the monthly gonad weight as a
proportion of the total body weight. The fat content was examined
on the basis of monthly analyses of mesenteric fat in the visceral
cavity and by determining the amount of lipid content in sardine
tissues using Soxhlet’s s method. The total length of sardine
ranged from 13.0 to 19.0 cm and the mass ranged from 16.72 to
51.45 g. The reproductive period was from October to May,
coinciding with the highest gonad weights and gonadosomatic
indices. The mean percentage of mesenteric fat grades in visceral
cavity points to the greatest fat quantities in August, when grade 4
(fattest fish) presence amounted to 72%. The value is the result of
an increase of mesenteric fat started in June and proceeding in the
successive months until October. During autumn, a decrease trend
is evident and it becomes pronounced in winter and spring when
the lowest mesenteric fat quantities are recorded. Thereafter an
increase in mesenteric fat for sardine was recorded, indicated by
the records of grades 3 and 4. Due to such variations in
mesenteric fat and tissue lipid during year, i.e. its greatest levels in
summer (out of spawning) and lowest levels in the colder part of
the year (during sardine spawning), it was assumed that quantity
of sardine fat was affected by its sexual cycle. Lipid content in
terms of sardine tissue dry weight showed the same trends as
mesenteric fat - highest amounts during resting phase of
reproduction (41.1%) and lowest during the peak of spawning (1.0-
2.2%). Amounts of total lipids and moisture in sardine tissues
showed that females had more fat content and less moisture than
males. An inverse correlation between fat content and sexual
cycle on one side and lipid content and moisture on the other has
been noted.
Nutritional strategies of Pectinodonta sp., a gastropod
associated with sunken woods
Magali Zbinden 1,2 , Marie Pailleret 1,2,3 , Juliette Ravaux 1,2 , Sébastien
Halary 1,2 , Françoise Gaill 1,2 and Sébastien Duperron 1,2
1 UPMC, Laboratoire Systématique Adaptation et Evolution, 7 Quai
St Bernard, 75252 Paris, France;
2 CNRS, UMR7138, Systématique, Adaptations, Evolution, AMEX,
7 Quai St Bernard, 75252 Paris, France;
3 CNRS UMR 5143 Paléodiversité et Paléoenvironnements,
Laboratoire de Paléobotanique, UPMC, 12 rue Cuvier, 75005 Paris,
France
The occurrence of sunken wood and vegetal debris in deep
oceanic environments has been known for a long time (Murray
1895; Wolff 1979).
Sunken woods are abundant in the deep sea, at all depths, with
higher densities near estuaries, and in sedimentary accumulation
basins. Wood reaches abyssal depths in sufficient quantity to
support locally the development of long-lasting ecosystems,
playing a key role in the deep sea (Cayré & Richer de Forges
2002).
The faunal diversity that colonize sunken woods is widespread,
comprising gastropod, polyplacophoran and bivalve molluscs,
decapod and peracarid crustaceans, polychaetes, and
echinoderms (Turner 1973, 1977, Cayré & Richer de Forges 2002).
Until now, the only well known organisms able to degrade wood
(thanks to symbiotic association with cellulolytic bacteria) and to
use it as a food source are wood boring mollusca (Teredinidae and
Xylophagainae) and isopodes crustacea (Limnoridae) (Gareth
Jones et al. 2001).
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During several cruises dedicated to sample sunken woods around
Vanuatu, some species were observed stuck in hollows that they
seem to dig at the surface of dregded woods. The most numerous
species observed is a true limpet (Patellogastropoda) of the genus
Pectinodonta, the species being still undescribed.
The present work combine various approaches (microscopic
observations of the radula, gills, and gut content; molecular
methods to determine occurrence, localisation and phylogenetic
position of associated microorganisms, and enzymatic assays to
look for cellulolytic activity) to determine wether wood is a food
source for this species and what are the terms and conditions of its
degradation.
New insigths on the metabolic diversity among the epibiotic
microbial communitiy of the hydrothermal shrimp Rimicaris
exoculata
Magali Zbinden 1 , Bruce Shillito 1 , Nadine Le Bris 2 , C. de Villardi de
Montlaur 1 , E. Roussel 3 , F. Guyot 4 , Françoise Gaill 1 and Marie-
Anne Cambon-Bonavita 3
1
UMR CNRS 7138, Systématique, Adaptations et Evolution,
UPMC, 7 Quai Saint Bernard, 75252 Paris cedex 05, France:
2
Département Environnement Profond, Ifremer DRO, BP 70,
29280 Plouzané, France;
3 Laboratory of Microbiology of Extreme Environments, Ifremer
Brest, LM2E, UMR 6197, BP 70, 29280 Plouzané, France;
4
Institut de Physique du Globe de Paris, Laboratoire de
Minéralogie-Cristallographie, Université Paris-Jussieu, Tour 16,
Case 115, 4, place Jussieu, 75 252 Paris Cedex 05, France
The shrimp Rimicaris exoculata (Williams and Rona, 1986)
dominates the megafauna of some of the Mid Atlantic ridge
hydrothermal vent sites. This species harbors a rich community of
bacterial epibionts inside its gill chamber. Literature data indicate
that a single 16S rRNA phylotype dominates this epibiotic
community, and is assumed to be a sulfide-oxidizing bacteria.
However attempts of cultivation were not successful and did not
allow to confirm it. The aim of our study was to test the hypothesis
of sulfide oxidation in the gill chamber, by a multidisciplinary
approach, using in vivo experiments at in situ pressure in the
presence of sulfide, microscopic observations and a molecular
survey. Morphology of microorganisms, before and after treatment,
was analyzed to test the effect of sulfide depletion and re-exposure.
Our observations, as well as molecular data indicate a wider
diversity than previously described for this shrimp’s epibiotic
community. We observed occurrence of bacterial intracellular
sulfur- and iron-enriched granules and some methanotrophic-like
bacteria cells for the first time. Genes that are characteristic of
methane-oxidizing (pmoA) and sulfide-oxidizing (APS) bacteria
were identified. These results suggest that three metabolic types
(iron, sulfide and methane oxidation) may co-occur within the
epibiont community associated with Rimicaris exoculata. As this
shrimp colonizes chemically contrasted environments, the relative
abundance of each metabolic type could vary according to the
local availability of reduced compounds.