CONTENT - International Society of Zoological Sciences

ICZ2008 – Abstracts S20
S20 - Marine organisms and symbiotic systems in extreme environments
Investigation of the intertidal Macrobenthic communities in
the Yangtze estuary, China
Chuanguang An and Yunlong Zhao
School of life science, East China Normal University, Shanghai,
China
The Yangtze River, is a river of medium sediment concentration.
Its length, runoff volume and sediment transporting capacity are
ranked respectively as third, fourth and fifth in the world. The
highly productive tidal flat of the Yangtze estuary serves as habitat
and breeding ground for many commercially valuable fishes and
invertebrates, and migration station for shorebirds. In order to
obtain integrative inshore data, the distribution patterns and faunal
composition of intertidal macrobenthic assemblages were studied
in the Yangtze estuary (30°19′-31°53′N, 121°18′-122°00′E) from
June 2006 to October 2007 as a part of a national project.
According to longitudinal and vertical gradients of the estuary, 116
sites were sampled in the spring and autumn respectively for
qualitative and quantitative investigation. The macrobenthic
species distribution and community structure are related to salinity,
depth, sediment characteristics and artificial activities. The
analyses clearly reveal distinct gradients in diversity, abundance,
and biomass along the vertical and longitudinal gradients.
Compared with the previous data, the species composition and
distribution of macrobenthos of Yangtze estuary have been
remodeled, due to effects of artificial activities and other factors.
Macrobenthos assemble mainly in a less than 100 m wide narrow
strip between the sea dam and seawall, while the sedentary
benthos, which seldom or never existed before in this area,
increased in number and became a boom in seawall. In conclusion,
despite the effects of a boom for some species, the resources of
benthic macrofauna is for the most part reduced.
Vestimentiferan tubeworms from vents and seeps: how
different are they?
Ann C. Andersen 1,2
1 Université Pierre et Marie Curie - Paris 6, Laboratoire Adaptation
et Diversité en Milieu Marin, 2 CNRS, UMR 7144, Equipe
Ecophysiologie: Adaptation et Evolution Moléculaires, Station
Biologique, Place Georges Teissier, BP 74, 29682 Roscoff Cedex,
France
Vestimentiferan tubeworms are polychaete annelids belonging to
the Siboglinidae that have neither mouth nor gut, but live in
symbiosis with chemosynthetic bacteria stored intracellularly in
their trophosome. This symbiotic relationship implies that the worm
gets oxygen, but also carbon dioxide and sulphides from its
surroundings, and brings them through the blood circulation to the
bacteria that in turn use these inorganic elements to build organic
compounds for the benefit of their host. The role of the gill in
assimilating these inorganic molecules depends on the particular
species habitat: vents or seeps. Internal transport of these
molecules relies heavily on the extracellular hemoglobins
dissolved in their blood and coelomic fluid. Till now about 16
vestimentiferan species have been described worlwide in either
hydrothermal vents, cold seeps or even both. Riftia pachyptila,
Jones 1981, lives in the hydrothermal vents from the East Pacific
Ridge, as also Ridgeia piscesae, (Jones 1985) Southward 1995,
the latter having two different morphotypes: one close to
hydrothermal chimneys, and the other in cracks of basaltic fields.
Escarpia southwardae, Andersen 2004, lives in the East Atlantic
cold seeps and Lamellibrachia n. sp. in Mediterranean carbonate
crusts. We compare these four species regarding their morphology,
molecular phylogeny, gill functional anatomy and hemoglobins
structure and function. This synthesis aims to enlight, whether
there could be possible links between the
morphological/physiological characteristics and the habitats
conditions of these tubeworms.
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Multiple new nuclear markers for the exploration of the
adaptative speciations in arctic Nototheniids
Mohamed Berkani 1 , Agnès Dettai 1 , Arnaud Couloux 2 , Corinne
Cruaud 2 , Anne-Claire Lautredou 1 , Sophie Sanchez 1 and Guillaume
Lecointre 1
1 MNHN, UMR7138, Dpt Systématique et Evolution, Paris, France
2 Génoscope, Centre National de Séquençage, Evry, France
It has been proposed that some groups of organisms of the
Antarctic Ocean have diversification patterns characteristic of a
species flock type of adaptive speciation. Nototheniidae (Teleostei)
are endemic to the region, and among the most promising
organisms for this type of study. While recent studies on
nototheniid fishes have resolved most of the relationships within
the group, some nodes of the tree are repeatedly unresolved or
displaying contradictory support depending on the markers used in
the study. We have explored more than ten markers looking for
information to solve the basal nototheniid polytomy and the
interrelationships within the genus Trematomus. Some of these
markers had been previously used for teleost phylogeny (TMO4c4,
rhodopsin retrogene, IRBP gene 1), but several new markers have
been developed for this study and present more variability than the
ones previously available. These show promise for the resolution
of the interrelationships of closely related species and
phylogeographic studies in some other acanthomorph groups,
where the problem of insufficient variability arises repeatedly in
nuclear markers. The comparison of the trees resulting from the
separate analyses of each marker highlights some areas of conflict.
Overall, the new data clarifies the interrelationships of nototheniid
fishes, partially solving the basal part of the nototheniid tree and
allowing to draw some hypotheses on the relationships within the
Trematomus “bush at the top”. The position of several species
never included before in a molecular study could also be clarified.
Comparative study of the lipidic profile of three Atherina
populations of Tunisia: Atherina boyeri (Bizerta sea), Atherina
lagunae (Bizerta lagoon) and Atherina sp. (Kerkannah’s
Islands)
Nawzet Bouriga 1 , Salah Selmi 2 , Eric Faure 3 and Monia Trabelsi 1
1
Unité de Biologie marine. Faculté des Sciences de Tunis, 2092
Campus universitaire, Tunisia
2
Institut National des Sciences et Technologies de la Mer.
Laboratoire de Biotechnologie Marine, La Goulette 2060, Tunisia
3
Laboratoire Systématique Evolutive, case 5, EA 2202
« Biodiversité », place Victor Hugo, Université de Provence, 13331
Marseille cedex 3, France
Atherina are teleostean fish characterised by a capacity to tolerate
enormous variations in temperature and salinity, which allowed
them to occupy seas, lagoons and estuaries. In Tunisia, various
studies based on morphological, morphometric, and genetic
parameters allowed several local populations to be distinguished.
In the present work, we examined possible differences or
variations in the lipidic profiles of Atherina sp. (insular population),
Atherina lagunae (lagoon population) and Atherina boyeri (marine
population) as a means of identifying each population and
investigating the possible existence of new specie that we aim to
characterize. The total lipid content of all examined specimens was
nearly the same, i.e. about 6% of the wet weight. Saturated fatty
acids constitute the majority of the fatty acids pool, reaching
43.54%, 36.96% and 33.64% in marine, lagoon and insular
Atherina respectively. The total polyenes content was 27% in
Atherina boyeri and Atherina sp. In these two populations,
eicosapentaenoic acid, docosahexaenoic acid and linoleic acid are
the predominant fatty acids, while n-6 polyunsaturated fatty acids
of Atherina sp. were significantly higher (14.44%) than in Atherina
boyeri and Atherina lagunae (5.97% and 6.78% respectively). The
index PUFAn-3/PUFAn-6 shows a significant level, indicating a
tendency to accumulate n-3 fatty acids in Atherina boyeri and
Atherina lagunae, and n-6 fatty acids in Atherina sp.