Chariton Chintiroglou

Identification of several cytoplasmic HSP70 genes from the Mediterranean mussel (Mytilus galloprovincialis) and their long-term evolution in Mollusca and Metazoa.

The HSP70 protein family consists one of the most conserved and important systems for cellular homeostasis under both stress and physiological conditions. The genes of this family are poorly studied in Mollusca, which is the second largest metazoan phylum. To study these genes in Mollusca, we have isolated and identified five HSP70 genes from Mytilus galloprovincialis (Mediterranean mussel) and investigated their short-term evolution within Mollusca and their long-term evolution within Metazoa. Both sequence and phylogenetic analyses suggested that the isolated genes belong to the cytoplasmic (CYT) group of the HSP70 genes. Two of these genes probably represent cognates, whereas the remaining probably represent heat-inducible genes. Phylogenetic analysis including several molluscan CYT HSP70s reveals that the cognate genes in two species have very similar sequences and form intraspecies phylogenetic clades, differently from most metazoan cognate genes studied thus far, implying either recent gene duplications or concerted evolution. The M. galloprovincialis heat-inducible genes show intraspecies phylogenetic clustering, which in combination with the higher amino acid than nucleotide identity suggests that both gene conversion and purifying selection should be responsible for their sequence homogenization. Phylogenetic analysis including several metazoan HSP70s suggests that at least two types of CYT genes were present in the common ancestor of vertebrates and invertebrates, the first giving birth to the heat-inducible genes of invertebrates, whereas the other to both the heat-inducible genes of vertebrates and the cognate genes of all metazoans. These analyses also suggest that inducible and cognate genes seem to undergo divergent evolution.

Peracarida populations of hard substrate assemblages in ports of the NW Aegean Sea (eastern Mediterranean)

This study deals with the structure of Peracarida populations in four ports in the NW Aegean Sea, Greece, and with the degree this structure is influenced by the particular biotic and abiotic conditions that prevail in the ports. Quantitative samples were taken during summer and winter in two successive years from artificial hard substrates and were analysed using common biocoenotic methods. The examination of approximately 81,250 specimens revealed the presence of 24 Peracarida species, the most dominant of which were Corophium acutum, Leptochelia savignyi and Elasmopus rapax. All species are very common and have been reported from many sites and assemblages in the N Aegean Sea. The ratios of certain Peracarida genera are discussed as possible indicators of environmental health that may be used in long-term biomonitoring programmes on the impact of pollution in harbours.

Structure of the artificial hard substrate assemblages in ports in Thermaikos Gulf (North Aegean Sea)

Abstract The present study describes the hard substrate assemblages established on the concrete blocks of three ports placed in gradually longer distances from the main source of pollution in Thermaikos Gulf. The samplings were performed on a seasonal basis for a 2-year period. The data analysis indicates a clear separation of the assemblages from each port. Evenness and Shannon–Weaver diversity indices were calculated and their values were found to be quite high. This fact, combined with the seasonal pattern that these assemblages hold, reveals stability and a good adaptation of their faunistic components to local environmental conditions. A change due to the construction of a new block functioning as a surge barrier was detectable at the station of N. Michaniona. Once again, biomonitoring proves to be essential in order to obtain useful information about the water conditions. Emphasis was laid on the taxa of Polychaeta by analyzing their numerical abundance and their feeding guilds separately. The results were very similar, a fact that supports the opinion that a specific taxonomic group can be used for the description and the monitoring in many different cases.

Zoobenthos associated with the invasive red alga Womersleyella setacea (Rhodomelacea) in the northern Aegean Sea

The spatial and temporal structure of the zoobenthos associated with the invasive red alga Womersleyella setacea was studied in the northern Aegean Sea, Greece. Five replicate quadrats (20x20 cm) were collected, seasonally from July 1997 to August 1998, by SCUBA diving at four sites and two depth levels (15 and 30 m) in the Chalkidiki Peninsula. We collected 23,090 specimens representing 278 animal species. Multivariate analysis showed mainly spatial differences in community structure, while the temporal ones were minimal. The ordination of sites showed a clear zonation pattern according to the different algal forms that cover the rocky substrate, with inclination the only environmental factor involved. The epifauna associated with the invasive alga was differently structured compared with three native seaweeds, showing increased species richness and abundance. The filamentous alga W. setacea was dominant in all seasons and depth levels, creating a stable habitat that contributed to the loss of seasonality in zoobenthic community structure.

Anthozoa from a subtidal hydrothermal area of Milos Island (Aegean Sea), with notes on the construction potential of the scleractinian coral Madracis pharensis

Abstract Eleven species of Anthozoa (two Octocorallia and nine Hexa‐corallia) were found on subtidal (2 to 90 m depth) hard substrata off Palaeochori Bay (SE Milos Island), an area characterised by submarine hydrothermalism. For each species, depth distribution and habitat were recorded. Their ecology at Milos was consistent with previous knowledge in other areas of the Mediterranean Sea. The corallites of Caryophyllia inornata (and perhaps other species) were comparatively small‐sized, thus apparently conforming to the so‐called ‘eastern nanism’ (i.e., high occurrence of dwarf individuals in the Aegean as compared to the western Mediterranean) for many Mediterranean benthic species. Madracis pharensis was very common, especially in sites close to vents, locally covering up to 30% of the primary rock with a calcareous crust. Skeletal bulk density (1.95–2.10 g‐cm‐3) was higher, and porosity (29%) lower, than in typical constructional corals. Layering of distinct generations of colonies suggests the significant accretion of a persistent biogenic substratum. It cannot be excluded that the construction potential of the species is enhanced by the hydrothermal activity: impulses of heat from vents maintain water temperature warmer during winter, and emission of Ca and CO2 may favour the biological deposition of carbonates and/or the activity of symbiotic zooxanthellae.

Aegean Bath Sponges: Historical Data and Current Status

This study attempts to evaluate the status of the populations of bath sponges (species of the genera Spongia and Hippospongia) in the Aegean, combining historical sources dated before a series of disease outbreaks that occurred from 1986 on, unpublished data obtained during the recovery phase after the first incident, as well as a current survey of the main spongiferous beds in the area. The latter was implemented through an extensive sampling trip assisted by professional sponge fishermen, including 55 stations distributed in 17 Aegean islands. Our analysis of population and morphometric data exhibits regeneration potential for bath sponge stocks, yet highlights the contrast between their present status and that of historical times. Uniformity is not evident, as several populations retain high abundances, while simultaneously areas purportedly rich in bath sponges appear deprived. Small-scale environmental regimes in the Aegean are proposed as the shaping factors of this situation; however, the importance of additional elaborate studies and the implementation of an effective regulation scheme regarding their fisheries are stressed.

Population dynamics, allometric relationships and reproductive status of Microcosmus sabatieri (Tunicata: Ascidiacea) in the Aegean Sea

The Mediterranean ascidian Microcosmus sabatieri is among the conspicuous benthic invertebrates, forming dense populations on moderately inclined cliffs. It is an edible species, commercially harvested at the southern part of the Aegean Sea. Considering that the biology of this species has not been adequately studied, a three-year survey was carried out focusing on population structure, allometric relationships and reproductive status of M. sabatieri stocks in Astypalea Island (Dodecanese, south Aegean). Population density showed insignificant temporal variation and lower values at the steeper station, while the pattern of dispersion was random. All measured biometric characters showed high plasticity, especially those related to siphons. All the examined morphometric relationships follow negative allometry. Ascidian length was a good predictor of biomass, and a strong relation was observed between mantle and tunic characters. Gonad somatic index showed a single spawning season per year, in winter. Length-frequency distribution analysis revealed the presence of one mode of medium sized individuals, implying that M. sabatieri stocks are under moderate fishing pressure in the study area.

Population dynamics and reproductive status of Microcosmus savignyi Monniot, 1962 (Thermaikos Gulf, Eastern Mediterranean): a preliminary assessment

The ascidian Microcosmus savignyi, a suspension‐feeding species, is among the prominent biota of hard substratum benthic communities in Thermaikos Gulf, showing increased population density on biogenic substrata. Considering that the biology of this species is not adequately studied, a one‐year study was carried out to provide information on population structure, growth parameters and reproductive status of M. savignyi stocks in Thessaloniki Bay. Population density showed a steady seasonal trend. Microcosmus savignyi experienced faster axonometric growth and reaches the maximum asymptotic length slowly, having a life span over one year. Length‐frequency distributions analysis revealed the presence of two cohorts. Gonad‐somatic index and gonad histology showed that the species is a protandrous hermaphrodite, with an expanded spawning season, lasting from the end of summer, when the release of spermatozoa begins, to the end of winter, when the release of oocytes is completed. The ecological implications of this reproductive mode are not well understood, however they may prevent self‐fertilization, increasing the fitness of the population to its environment.

First record of the bivalve-inhabiting hydroid Eugymnanthea inquilina in the eastern Mediterranean Sea (Gulf of Thessaloniki, north Aegean Sea, Greece)

The first record of a bivalve-inhabiting hydrozoan Eugymnanthea inquilina was found in Thermaikos Gulf, north Aegean Sea, eastern Mediterranean Sea, associated with Mytilus galloprovincialis . Analyses of biometric data point the same biological differences between the Mediterranean and the Japanese Eugymnanthea , as reported by previous researchers.

Small-scale spatial variability of zoobenthic communities in a commercial Mediterranean port

In the context of the limited information on the ecology of port communities, the present work aims at assessing the small-scale spatial variability of zoobenthos inhabiting hard and soft substrata, in a Mediterranean port with high levels of commercial shipment. Samples were collected in summer from three stations and four depth levels, using core and quadrate samplers. A total of 34,578 individuals were collected, identified to 118 animal species. Soft substratum communities were impoverished and their structure varied spatially according to sediment composition. At a functional level deposit feeders dominated; their abundance decreased at the silty sites. Biotic indices were found inadequate for the assessment of ecological quality, due to the very low abundance of the fauna. Fouling communities varied spatially in vertical scales; diversity indices and the abundance of Bivalvia varied also in horizontal scales. Suspension and deposit feeders dominated showing a decreasing trend with depth. Two animal-dominated communities, serpulid blocks in the lower midlittoral zone and mussel beds in the sublittoral, substituted an algal-dominated community, which has been previously recorded from the same port quays. This substitution may be due to the intensive mussel farming in the nearby area contributing to the rapid expansion of mussels and of their serpulid biofoulers. Despite the existence of biogenic substrata, which enhance habitat complexity, the diversity of the associated fauna decreased and most species were tolerant to organic pollution. Recursive biomonitoring seems necessary to assess the ecological status of communities and to develop integrated management plans for temperate ports.