Phosphate in the sediments of the Gulf of Lions (NW Mediterranean Sea), relationship with input by the river Rhone

We investigated P-input by the Rhone river into the Mediterranean Sea taking into account P trapped in the surface sediment of the Gulf of Lions. Total phosphate concentration was determined every cm in the upper 10 cm-layer of sediments sampled at 11 stations in the Gulf of Lions during two cruises (March 1998 and January 1999). Two low downward gradients, one East–West and another North–South, with distance to the Rhone river mouth were found. Except at one station, total phosphate concentration in surface sediments was found to be constant with depth down to 10 cm. Values for individual stations ranged between 400 and 700 g g^–1 with an average value of 547 g g^–1 (st. dev. = 63 g g^–1) for the whole gulf. The low variability in total-P concentration in sediments is in contrast to the large variability in suspended matter load of the river Rhone and suggests the dominance of authigenic P removal mechanisms in P burial. The total P-pool in the upper 10 cm-layer of the sediments in the gulf was estimated at 562 kt, with about 80% trapped into the shelf and 20% into the slope. Annual P-deposition was estimated as 7.2–12.4 kt y^–1, from the P-pool in the sediment and the sedimentation rates. This is equivalent to a previous estimation of the river Rhone input, estimated to be about 6.5–12.2 kt y^–1. As the Rhone is the major river flowing into the Mediterranean Sea, total P in surface sediments of the Gulf of Lions should be taken into account in P-budgets at the scale of the Mediterranean Sea.     

Airborne pollen, spores, and dust across the East Mediterranean Sea

Airborne pollen and spores, as well as airflow directions, were continuously monitored during a cruise across the East Mediterranean from Tel Aviv, Israel, to Istanbul, Turkey. In spite of the fact that a high-altitude dust cloud moved, at that, time from North Africa, across the East Mediterranean, only a few dust particles were monitored on the boat. The numbers of counted airborne pollen along the cruise path were rather small. This is, in part, because the trip was taken after the main flowering season in the East Mediterranean region. Nevertheless, airborne pollen grains were still found, either as a result of remnant pollen releases by late-flowering plants or because of secondary lift-up of previously settled pollen. The presented pollen counts are average pollen counts /m³ air /6 h. The counts ranged between ∼5 pollen/m³ of air in mid-sea (July 16th–July 17th) or ∼6 pollen/m³ of air on the Israeli coast (July 16–July 17th), and 30 pollen/m³ of air near the coasts of Turkey and of the Greek Islands (July 18th–July 19th) and some 18 taxa of pollen were identified, most of them at the family level. Some 30 taxa of different spores were recorded. The numbers of airborne spores were relatively low in mid-sea (300–750 spores/m³ air), but were high near the coasts of Turkey (1,200–2,400 spores/m³ air) and of Israel (340–1,695 spores/m³ air).     

Calcareous nannofossil surface sediment assemblages from the Sicily Channel (central Mediterranean Sea): Palaeoceanographic implications

Quantitative analysis of 67 calcareous nannofossil assemblages from surface sediments recovered in a wide area across the Sicily Channel has been carried out in order to improve the interpretation of palaeontological data based on this planktonic group in a key area for Mediterranean palaeoceanographic studies. The investigation focused on three case studies that demonstrate the high potentiality of such a combined approach, taking into account the recent distribution of taxa or groups of taxa on the sea floor and the palaeontological record. The distribution of reworked specimens over the northern Sicily Channel sea floor validates the role of southern Sicily as a source region for reworked nannofossils and the role of rivers as their carrier. Eustatic sea-level fluctuations can be considered to be the main factor that influenced the abundance variations in sedimentary sequences of this area. The distribution of Florisphaera profunda can be explained in terms of topography (positive correlation) and mesoscale oceanographic circulation. In particular, its significant anti-correlation to the amount of chlorophyll-A deduced by satellite imagery validates the use of this species as a proxy for palaeoproductivity reconstructions. Finally, high abundance values of G. oceanica are confined to the westernmost part of the Sicily Channel, coinciding with a water mass salinity minimum. In particular, abundances of up to about 10% were observed in the westernmost part of the African Margin, suggesting the importance of the Atlantic Tunisian Current, whose activity is more pronounced in winter. The comparison of data of this species between 135 and 110 kyr BP, inside and outside the Channel, led us to deduce that the physical transport in almost unmodified waters of Atlantic origin might be the most important factor for its significant occurrence.     

Genetic differentiation of white sea bream within the Lion's Gulf and the Ligurian Sea (Mediterranean Sea)

An allozymic study was conducted on 190 individuals of white sea bream, Diplodus sargus sampled on five locations throughout the Lion's Gulf and the Ligurian Sea (Mediterranean Sea), in order to identify genetic structure. Electrophoretic surveys carried out on muscle and liver tissues identified 25 loci of which 12 were polymorphic ( P 0.95). G -test analysis shows significant differences on allelic frequencies between the five stations at six loci. Examination of the spatial structure was performed using Nei's distances and F statistics, and indicated significant genetic differences between three groups. A group which clustered Blanes (Spain), Marseille (France) and Livorno (Italy) where the absence of genetic difference can be explained by migration of larvae and adults along a coastal 'continuum'. The Elba sample (Italy) shows genetic divergence from other samples and this difference may result from isolation due to limited migration of larvae and adults. Banyuls (France), differs from all other stations. Several hypotheses are proposed to explain genetic patterns including local current systems, larval dispersal, geographic isolation and historical effects, and variation in the size classes of sampled individuals between sites.     

On three interesting marine red algae (Ceramiales,Rhodophyta) from the Mediterranean Sea

Abstract

Observations on three interesting Ceramiales from the Mediterranean Sea are reported; Ceramium incospicuum Zanardini, Polysiphonia setacea Hollenberg and Rodriguezella pinnata (Kützing) Schmitz ex Falkenberg. The male reproductive structures on the genus Rodriguezella are described for the first time.     

Reproductive biology of the smooth-hound shark Mustelus mustelus (L.) in the Gulf of Gabès (south-central Mediterranean Sea)

The reproductive biology of the smooth-hound shark Mustelus mustelus was studied in the Gulf of Gabès (southern Tunisia). Females were found to mature between 1075 and 1230 mm total length ( L _T) whereas males matured between 880 and 1120 mm L _T. The L _T at which 50% of the population reached maturity was 971 and 1172 mm for males and females, respectively. Male gonads were symmetrical in terms of mass and both functional, whereas in females only the right ovary was functional. The seasonal changes in the oocytes and testes development, embryo length and the occurrence of near-term and post-partum females showed that this species displayed a clearly defined annual reproductive cycle with parturition occurring during late April and early May, after a gestation period of 10–11 months. Mating took place during May and early June and fertilization occurred from early June to early July. The embryo sex ratio was not significantly different from unity. Litter size varied from four to 18 embryos and was positively correlated with maternal L _T. The young were born with a L _T of 340–420 mm.     

Chorotypes of seaweeds from the western Mediterranean Sea and the Adriatic Sea: An analysis based on the genera Audouinella (Rhodophyta), Cystoseira (Phaeophyceae) and Cladophora (Chlorophyta)

The aim of the present paper is to identify the possible existence of groups of species in the genera Audouinella (Rhodophyta), Cystoseira (Phaeophyceae) and Cladophora (Chloropyta) with significantly similar distribution patterns (chorotypes), in the western Mediterranean Sea and the Adriatic Sea. Of the 98 species studied, 59 were grouped into 11 chorotypes, whereas 39 species remained ungrouped. Thirty‐eight species were included in a generalist chorotype, whereas 6 chorotypes were monospecific. The relationships with the environmental factors that could explain the chorotypes are discussed.     

First record of Cephalopholis taeniops (Valenciennes) in the Mediterranean Sea

Two specimens of African hind Cephalopholis taeniops (Valenciennes, 1828) are recorded for the first time in the Mediterranean Sea, in the coastal area of Gulf of Syrte, Libya. This finding represents an additional case of a tropical species of fish of West African origin in the Mediterranean Sea.     

Entrapment, preservation and incipient fossilization of benthic predatory molluscs within deep-water coral frames in the Mediterranean Sea

Holocene Madrepora-Lophelia subfossil frames recovered at ca. 690 m from deep-water coral grounds south of Malta (Strait of Sicily, Central Mediterranean Sea) were found to entrap shells of cnidarian predatory gastropods such as Babelomurex sentix, “Coralliophila” squamosa (morphotype ruderatus) and architectonicids. This finding documents the capability of deep-water coral reefs to serve as taphonomic traps eventually promoting the preservation of rare components of their original biota.     

The biological production of marine suspended barite and the barium cycle in the Western Mediterranean Sea

Suspended particulate barium was measured in the Western Mediterranean along 4 profiles sampled during the PHYCEMED 1 cruise in 1981. The non-terrigenous fraction of particulate barium (i.e. excess Ba; Ba_xs) can account for up to 96% of total barium. This fraction follows the barite settling and dissolution rate model we described earlier for the Atlantic Ocean, confirming barite as the carrier of excess barium. We propose that these Ba_xs concentrations, which are higher in the Western Mediterranean than in the overall Atlantic, may represent an adaptation of the microplankton to the high densities and density gradients of surface Mediterranean waters.A mass-balance for Ba in the Mediterranean Sea shows: (1) that the atmospheric source must be much more important than previously reported: (2) that contrary to the Atlantic situation, the internal recycling of barium is of little importance compared to the flow of barium through the system.     

Calcareous dinoflagellate cysts in surface sediments from the Mediterranean Sea: distribution patterns and influence of main environmental gradients

The distribution of calcareous dinoflagellate cysts in surface sediments from the Mediterranean Sea was quantitatively analysed. The samples contain 11 cyst species and the vegetative coccoid Thoracosphaera heimii. Cyst abundance increases towards the deeper parts of the basins and is generally higher in the eastern Mediterranean Sea. Three major distribution characteristics exist: (1) different assemblages in oceanic and neritic regions, (2) little agreement with the associations of areas studied so far like the Atlantic Ocean, and (3) a unique oceanic assemblage in the eastern Mediterranean Sea. A gradual change in cyst assemblages from the western to the eastern Mediterranean Sea was observed and statistically compared with the main environmental gradients in the upper water column. Temperature, nitrate concentration and possibly salinity appear to be the most important factors controlling cyst production. Three groups containing cysts with similar environmental preferences can be distinguished: (1) an eastern Mediterranean group related to relatively high temperature and salinity but low nitrate concentration, (2) a group of more or less consistently abundant cosmopolitan species tolerating or even preferring relatively low temperature and salinity but high nitrate concentration, and (3) a group containing species that are possibly adapted to neritic environments and have probably been transported from coastal areas into the studied regions. In contrast to other calcareous plankton, calcareous dinoflagellate cysts correlate strongly with the main environmental gradients in the Mediterranean Sea, bearing a high potential for palaeoenvironmental reconstructions.     

Seasonal variations of microphytoplankton assemblages and environmental variables in the coastal zone of Bozcaada Island in the Aegean Sea (NE Mediterranean Sea)

Seasonal changes in the microphytoplankton assemblages were examined in the coastal zone of Bozcaada Island with regard to some major physical and chemical variables. Samples were collected from May 2000 to December 2001 at four stations. A total of 108 dinoflagellates, 102 diatoms, 1 chrysophycean, 3 dictyochophycean, and 1 prasinophycean species were identified and quantified during the study period. Diatoms and dinoflagellates were the most important in terms of species number and abundance. The maximum values of total microphytoplankton were observed at 0.5 m depth (46.2 × 10³ cells l⁻¹ at st. 3) in May as this was the month when the diatom Pseudo-nitzschia pungens bloomed. Chlorophyll (chl) a concentration ranged between 0.08 (August) and 0.78 μg l⁻¹ (February). May was another important month in which chlorophyll a increased (0.41–0.47 μg l⁻¹). Species diversity values (H′_log2) ranged from 1.66 bits (June, 20 m) to 4.11 bits (November, 0.5 m). The increase was attributed to a more balanced distribution of abundance among species. The amounts of nitrate + nitrite (0.6−3.7 μg-at N l⁻¹), phosphate (0.2−0.6 μg-at P l⁻¹) and silicate (0.7−2.5 μg-at Si l⁻¹) were recorded on each sampling occasion. Nutrient concentrations and chl a values of the research area were found to be poorer than those of the many other coastal areas in the northeastern Mediterranean. The mean atomic ratio of nitrogen to phosphorus varied from 1.3 (June) to 12.9 (February). This ratio was lower than the Redfield ratio of 16 for ocean phytoplankton, and phytoplankton was potentially limited by nitrogen for most of the months. The result of this study confirms and emphasizes the oligotrophic nature of the eastern Mediterranean.     

Presence of the Guinean puffer Sphoeroides marmoratus (Lowe, 1838) in the Mediterranean Sea

The collection of a single specimen of the Guinean puffer Sphoeroides marmoratus from the Ionian Sea in September 1977, misidentified at that time as Lagocephalus lagocephalus , shows that this subtropical species of fish has occurred in the Mediterranean Sea from 30 years ago.     

The morphology and ecology of Dipolydora armata (Polychaeta, Spionidae) from the western Mediterranean Sea

Bick. A. 2001. The morphology and ecology of Dipolydora armata (Polychaeta, Spionidae) from the western Mediterranean Sea. — Acta Zoologica (Stockholm) 82 : 177–187
The cosmopolitan spionid Dipolydora armata is a dominant species of epifauna on Thais haemastoma shells in the western Mediterranean Sea. Some characters, particularly number, thickness and arrangement of notopodial spines, were extremely variable among specimens. Three morphological forms were distinguished based on the general appearance of the bundles of spines; one form possesses at least one bundle of stout spines, whereas bundles of medium spines or thinner acicular spines characterise the other forms. Differences in prostomial shape, as well as in the extension and form of the caruncle, were artefacts (preservation or angle of observation). The present study supports D. rogeri as a junior synonym of D. armata. D. armata was regularly found on shells inhabited by hermit crabs ( Calcinus tubularis , Clibanarius erythropus ) and on damaged, empty shells. Abundance, dominance, size frequency, occurrence of larvae and occurrence of regenerated specimens varied, possibly as a result of fouling strategy and recurrent settlements.     

Diatom assemblages in superficial sediments from the Gulf of Riga,eastern Baltic Sea

Twenty one superficial sediment samples from areas of high and moderate eutrophication in the Gulf of Riga were studied with respect to siliceous microfossils, mainly diatoms.The results seem to imply that the number of taxa and the abundance of the frustules are affected by runoff from rivers and the degree of eutrophication in different parts of the Gulf. Areas with high eutrophication, e.g. the river estuaries, have diatom assemblages of varying composition, while in areas with moderate eutrophication the composition is almost constant and the influx of freshwater diatoms and littoral periphyton small. The high abundance and low diversity of brackish-marine and brackish, planktonic diatoms seem to be a result of an influx of nutrients and pollutants in the water and bottom sediments. The sea ice diatoms occurring in the Baltic waters and also in the Gulf of Riga tend to be resistant to eutrophication or are even favoured by it.     

Parmales species (siliceous marine nanoplankton) in surface sediments of the Weddell Sea, Southern Ocean: indicators for sea ice environment?

The distribution pattern of the Parmales, a recently described order of siliceous marine nanophytoplankton, is described and quantified in surface sediments of the Atlantic sector of the Southern Ocean. Additional samples were investigated from the Bransfield Strait and the eastern Bellingshausen Sea. Highest abundances occurred in nearshore areas of the southern and southeastern Weddell Sea. Due to the distribution of Parmales species, which is strictly linked to these neritic areas, influenced most of the year by sea ice, it is suggested that the presence of Parmales species may be an indicator of sea ice influence probably useful in later down core studies.     

First record of Cyclopterus lumpus L., 1758 (Osteichthyes: Cyclopteridae) in the Mediterranean Sea

The Atlantic lumpsucker Cyclopterus lumpus (343 mm total length) is recorded for the first time from the Mediterranean Sea. The specimen was collected in the night between 16 and 17 September 2004 off Molunat Bay, Croatia, southern Adriatic Sea. This record may present a case of a vagrant specimen.     

Thaliacean distribution and abundance in the northern part of the Levantine Sea (Crete and Cyprus) during the eastern Mediterranean climatic transient, and a comparison with the western Mediterranean basin

First results are presented on the composition, abundance and vertical distribution of the thaliacean fauna in the Levantine basin obtained from stratified tows at three deep-sea sites in 1993: SE off Crete, and SW and NE off Cyprus. Samples with a 10 m²-MOCNESS (mesh size 1.67 mm) were poor in species and specimens as compared to samples with a 1 m²-double-MOCNESS (0.333 mm). Of the 12 species identified, six species belonged to the most abundant Doliolida, predominated by the phorozooids of Doliolum nationalis, five species belonged to the Salpida and one to the Pyrosomatida. Thaliaceans, most abundant by species and numbers SE off Crete, comprised ≤0.2% of the local mesozooplankton standing stocks. Presumably, they did not contribute substantially to the vertical flux generating the locally increased biomass and activity of the microbial benthos at the 4,300 m deep Cretean site. Most doliolids and salps were collected from the epipelagic and upper mesopelagic layers, and appeared to be most abundant close to the deep maximum of chlorophyll-a. Samples below 150 m were rarely rich in specimens, although two species performed diel migrations from the mesopelagic zone into the surface layers where some vertical segregation was evidenced. The aspect of niche separation is discussed.     

The Sperm Whale,Physeter macrocephalus,in the Eastern Mediterranean Sea

Abstract

After the successful establishment of free–living populations of Rose–ringed Parakeets (Psittacula krameri) and Common Mynas (Acridotheres tristis) in Jeddah, an overview of all exotic birds imported into Jeddah in the first three months of 1990 is given.