Endemic and Indo-Pacific plankton in the Mediterranean Sea: a study based on dinoflagellate records

Aim To investigate biogeographical patterns based on published dinoflagellate records from the Mediterranean and Black Seas, and to provide a tentative list of endemic and Indo‐Pacific dinoflagellates in the Mediterranean Sea. Location Mediterranean Sea, Black Sea. Methods Checklists of dinoflagellates of the Mediterranean and Black Seas were compared with worldwide literature records. Only species reported in the Indo‐Pacific Ocean or exclusively known in the Mediterranean Sea were selected for biogeographical analysis. Results Dinoflagellates in the Mediterranean Sea comprised c. 43% of the world marine species and c. 88% of the dinoflagellate genera. Species richness among the Mediterranean sub‐basins showed marked differences due to the less reliable records of unarmoured (athecate) and rare dinoflagellates. These differences disappeared when only the more easily identifiable taxa were considered. Of the 673 dinoflagellates cited in the Mediterranean, 87% were also reported in the Atlantic Ocean. Only 40 taxa (6% of the total) were considered to be potential Indo‐Pacific species. Most were reported from the Ligurian Sea (21), and only two species from the Levantine basin. The other 48 taxa (7% of total) were known exclusively from the Mediterranean Sea, mainly from the Ligurian Sea. Half of these taxa were reported by a single author. Main conclusions Substantial dinoflagellates species richness can be attributed, in part, to the historical tradition of taxonomic studies in the Mediterranean Sea. The list of species of both Indo‐Pacific and exclusively Mediterranean species included taxa of dubious taxonomic validity or that were insufficiently known. The exclusion of these questionable taxa revealed the near absence of endemic dinoflagellates in the Mediterranean Sea compared with macroscopic organisms. This could be related to: (1) continuous replenishment of the plankton populations by the inflow of Atlantic water through the Strait of Gibraltar, (2) the possibility that species introduced during the Pliocenic flooding after the Messinian salinity crisis have not had enough time to diverge from their Atlantic ancestors, and/or (3) the reliance on traditional taxonomy based on morphological characters, which precludes the detection of cryptic speciation.     

Overview on introduced aquatic species in European navigational and adjacent waters

More than 1,000 non-indigenous aquatic species have been recorded, in total, from coastal Europe, i.e. navigational inland waterways for ocean-going vessels and adjacent water bodies in close proximity. Regions considered in this overview range from European Arctic waters to the Mediterranean Sea and Irish waters to the Black Sea. The majority of introduced taxa have been first recorded since the 1950s. Approximately 600 taxa (ranging from unicellular algae to vertebrates) are established with self-sustaining populations. The dominating group of exotic species across all seas is zoobenthos organisms. Introduction vectors are predominantly shipping (ballast water and hull fouling) and species movements for aquaculture or stocking purposes.     

Phylogeography of the planktonic chaetognath Sagitta setosa reveals isolation in European seas

Numerous planktonic species have disjunct distribution patterns in the world's oceans. However, it is unclear whether these are truly unconnected by gene flow, or whether they are composed of morphologically cryptic species. The marine planktonic chaetognath Sagitta setosa Müller has a discontinuous geographic distribution over the continental shelf in the northeastern Atlantic, Mediterranean Sea, and Black Sea. Morphological variation between these populations has been described, but overlaps and is therefore unsuitable to determine the degree of isolation between populations. To test whether disjunct populations are also genetically disjunct, we sequenced a 504-bp fragment of mitochondrial DNA comprising the cytochrome oxidase II region of 86 individuals. Sequences were highly variable; each represented a different haplotype. Within S. setosa, sequence divergence ranged from 0.2 to 8.1% and strong phylogeographic structure was found, with four main groups corresponding to the northeastern Atlantic, Mediterranean Sea (including Ligurian Sea, Tyrrhenian Sea and Gulf of Gabes), Adriatic Sea, and Black Sea. Two of these (Atlantic and Black Sea) were resolved as monophyletic clades, thus gene flow between disjunct populations of S. setosa has been extremely limited and lineage sorting has taken place. The deepest divergence was between Atlantic and Mediterranean/Black Sea populations followed by a split between Mediterranean and Black Sea populations. The Mediterranean/Black Sea clade comprised three groups, with the Adriatic Sea as the most likely sister clade of the Black Sea. These data are consistent with a colonization of the Black Sea from the Mediterranean. Furthermore, a possible cryptic species was found in the Black Sea with 23.1% sequence divergence from S. setosa. Two possibilities for the evolutionary origin of this species are proposed, namely, that it represents a relict species from the ancient Paratethys, or that it represents another chaetognath species that colonized the Black Sea more recently. Even though the exact timing of disjunction of S. setosa populations remains unclear, on the basis of the geological and paleoclimatic history of the European basins and our estimates of net nucleotide divergence, we suggest that disjunct populations arose through vicariance resulting from the cyclical changes in temperature and sea levels during the Pleistocene. We conclude that these populations have remained disjunct, not because of limited dispersal ability, but because of the inability to maintain viable populations in suboptimal, geographically intermediate areas.     

Biogeography of the marine birds of a confined sea, the Mediterranean

Aim The Mediterranean sea is a winter productive oligotrophic basin where Atlantic water replaces water lost through evaporation, this influx being a major source of productivity and fertility. The long coastlines and the large number of islands cause high oceanographic heterogeneity. Moreover, during its geological history, it has dried out several times. So we describe the consequences of these particular features on species richness, distribution, and breeding ecology of marine birds. Location The Mediterranean sea (including the Black Sea and the Sea of Azov) communicates with the Atlantic Ocean only through a 14 km wide channel (Straits of Gibraltar), and since 1869, with the Red Sea through the Suez Canal. Methods The Mediterranean was subdivided into different areas, according to physical oceanographic entities and productivity, linked to numbers and distribution of both breeding and wintering marine birds (defined as species strongly dependent on marine resources, breeding only on islands and/or the coastline). Results The total marine bird biomass, and species diversity, are lower in the Mediterranean than in the near Atlantic. The eastern Mediterranean, with lowest primary productivity, contains fewer marine bird taxa than the more productive western part. Taxa which mainly occur in the western and southern parts of the Mediterranean migrate through the Straits of Gibraltar to winter in the southern Atlantic, while those inhabiting the northern and eastern parts are sedentary, as a result of differences in species composition. Northern coastal basin communities (i.e. the Tyrrhenian and the Balearic Seas), are composed of less pelagic, and earlier breeding species, that rear chicks during the productive season. These latter taxa are actually the most typical Mediterranean taxa, in terms of endemism. Main conclusions The Mediterranean marine bird community is not tropical, but rather, shows the highest affinity with the Atlantic temperate community. Its level of endemism is however high and comparable to other confined basins such as the Red Sea.     

Phylogeography of the common ragworm Hediste diversicolor (Polychaeta: Nereididae) reveals cryptic diversity and multiple colonization events across its distribution

Previous studies on the common ragworm Hediste diversicolor (Polychaeta: Nereididae) revealed a marked genetic fragmentation across its distribution and the occurrence of sibling taxa in the Baltic Sea. These results suggested that the phylogeographic patterns of H. diversicolor could reflect interactions between cryptic differentiation and multiple colonization events. This study aims to describe the large-scale genetic structuring of H. diversicolor and to trace the phylogeographic origins of the genetic types described in the Baltic Sea. Samples of H. diversicolor (2 <  n  < 28) were collected at 16 locations across the NE Atlantic coasts of Europe and Morocco and in the Mediterranean, Black and Caspian Seas and sequenced at two mitochondrial gene fragments (COI and cyt b , 345 and 290 bp, respectively). Bayesian analyses revealed deep phylogeographic splits yielding three main clades corresponding to populations (i) from the NE Atlantic coasts (from Germany to Morocco) and from part of the Western Mediterranean, (ii) from the Mediterranean Sea, and (iii) from the Black and Caspian Seas. These clades are further divided in well-supported subclades including populations from different regions of NE Atlantic and Mediterranean (i.e. Portugal/Morocco, Western Mediterranean, Adriatic Sea). The Baltic Sea comprises three sympatric lineages sharing a common evolutionary history with populations from NE Atlantic, Western Mediterranean and Black/Caspian Seas, respectively. Hence, the current patterns of genetic structuring of H. diversicolor appear as the result of allopatric isolation, multiple colonization events and possible adaptation to local environmental conditions.     

Spawning of bluefin tuna in the black sea: historical evidence, environmental constraints and population plasticity

The lucrative and highly migratory Atlantic bluefin tuna, Thunnus thynnus (Linnaeus 1758; Scombridae), used to be distributed widely throughout the north Atlantic Ocean, Mediterranean Sea and Black Sea. Its migrations have supported sustainable fisheries and impacted local cultures since antiquity, but its biogeographic range has contracted since the 1950s. Most recently, the species disappeared from the Black Sea in the late 1980s and has not yet recovered. Reasons for the Black Sea disappearance, and the species-wide range contraction, are unclear. However bluefin tuna formerly foraged and possibly spawned in the Black Sea. Loss of a locally-reproducing population would represent a decline in population richness, and an increase in species vulnerability to perturbations such as exploitation and environmental change. Here we identify the main genetic and phenotypic adaptations that the population must have (had) in order to reproduce successfully in the specific hydrographic (estuarine) conditions of the Black Sea. By comparing hydrographic conditions in spawning areas of the three species of bluefin tunas, and applying a mechanistic model of egg buoyancy and sinking rate, we show that reproduction in the Black Sea must have required specific adaptations of egg buoyancy, fertilisation and development for reproductive success. Such adaptations by local populations of marine fish species spawning in estuarine areas are common as is evident from a meta-analysis of egg buoyancy data from 16 species of fish. We conclude that these adaptations would have been necessary for successful local reproduction by bluefin tuna in the Black Sea, and that a locally-adapted reproducing population may have disappeared. Recovery of bluefin tuna in the Black Sea, either for spawning or foraging, will occur fastest if any remaining locally adapted individuals are allowed to survive, and by conservation and recovery of depleted Mediterranean populations which could through time re-establish local Black Sea spawning and foraging.     

Phylogenetic relationships of Ponto-Caspian gobies and their relationship to the Atlantic—Mediterranean Gobiinae

A phylogenetic analysis for five Ponto-Caspian goby species belonging to the two genera Neogobius and Proterorhinus assigned to the sub-family Gobionellinae was conducted, with five Atlantic—Mediterranean species of sub-family Gobiinae, genera Gobius and Zosterisessor , as outgroup taxa. One hundred and two characters (37 continuous cranial osteological, 50 continuous external morphological, five discrete external morphological, four karyological, two vertebral and four external discrete qualitative characters) were studied. Parsimony analysis revealed that the two zoogeographically distinct groups of goby species comprise distinct phyletic lineages that are sister groups. The relation of neogobiids to the sub-family Gobiinae was reconsidered, due to the sharing of the same state for the diagnostic character. The recently proposed classification for the genera Proterorhinus and Zosterisessor was rejected. The status of several of the lower ranked taxa was also considered [e.g. Gobius bucchichi as a member of the genus Zosterisessor and the sub-generic status of Neogobius (Neogobius) fluviatilis and Neogobius ( Apollonia ) melanostomus ]. The paleohistorical data suggest that those lineages, which may both descend from pre-Oligocene Indo-Pacific ancestors, separated at least 12 million years ago, during the early Miocene, after the formation of the Paratethys Sea, and then evolved independently. The Tethyan gobiine species evolved in the marine environment of the Mediterranean Sea and the Atlantic Ocean. The Ponto-Caspian (i.e. Paratethyan) gobies of the genera Neogobiusa and Proterorhinus diverged in the late Miocene or early Pliocene. They probably evolved in the freshwater refuge in the Daccian Basin of the Paratethys Sea (the recent Black Sea basin).     

New records of Malaysian marine algae

Checklists of the marine algae of Malaysia have been published. The last checklist included the marine algae of Singapore. The checklist recorded 212 taxa for the region. This paper lists an additional 7 taxa of Chlorophyta, 18 taxa of Rhodophyta and 5 taxa of Phaeophyta, which had been left out of the last checklist. These include marine algae from Pulau Pinang, Pulau Redang and Pulau Sibu. In addition, new records of Cyanophyta (2 species), Chlorophyta (4 species), Rhodophyta (10 species) and Phaeophyta (3 species) are reported.     

The Mediterranean and Black Sea Fisheries at Risk from Overexploitation

The status of the Mediterranean and Black Sea fisheries was evaluated for the period 1970-2010 on a subarea basis, using various indicators including the temporal variability of total landings, the number of recorded stocks, the mean trophic level of the catch, the fishing-in-balance index and the catch-based method of stock classification. All indicators confirmed that the fisheries resources of the Mediterranean and Black Sea are at risk from overexploitation. The pattern of exploitation and the state of stocks differed among the western (W), central (C) and eastern (E) Mediterranean subareas and the Black Sea (BS), with the E Mediterranean and BS fisheries being in a worst shape. Indeed, in the E Mediterranean and the BS, total landings, mean trophic level of the catch and fishing-in-balance index were declining, the cumulative percentage of overexploited and collapsed stocks was higher, and the percentage of developing stocks was lower, compared to the W and C Mediterranean. Our results confirm the need for detailed and extensive stock assessments across species that will eventually lead to stocks recovering through conservation and management measures.     

First record of shape Saturnius papernai Overstreet, 1977 in the Black Sea,with a review of the genus shape Saturnius Manter, 1969 (Digenea,Bunocotylidae)

Saturnius papernai Overstreet, 1977 is recorded from the stomach of Mugil cephalus L. (Osteichthyes, Mugilidae) in the Black Sea (a new geographical record) off the southern part of the Bulgarian coast. The species is redescribed and figured on the basis of the Black Sea specimens. Some amendments to the generic diagnosis are proposed concerning the presence of a uterine seminal receptacle and a posterior (third) circular flange. It is proposed that the occurrence of S. papernai is a feature of one of the three shoals of M. cephalus in the Black Sea, i.e. the Balkan shoal. In a zoogeographical analysis, S. papernai is regarded as a Mediterranean immigrant, probably a characteristic element of only the South-Western Faunistic Region of the Black Sea. A review of the genus Saturnius Manter, 1969 is presented.     

Biogeographic zonation of the Black Sea and Caspian Sea basin based on Mysid fauna (Crustacea: Mysidacea)

A biogeographic analysis of the Black Sea and Caspian Sea basin and adjacent Aegean Sea and the Sea of Marmara was conducted based on the distribution of 55 mysid species. The Black and Caspian Sea basin proper is inhabited by 35 mysid species belonging to 12 genera, among them 26 species and 3 genera are endemic to the region. Ponto-Caspian and Caspian species are predominant. The explored areas were included into two provinces of the Mediterranean subrealm of the East-Atlantic Subtropical realm and three provinces of the Ponto-Caspian realm.     

Chemical composition of Corallina mediterranea Areschoug and Corallina granifera Ell. et Soland

The composition of sterols, volatiles and some polar compounds from three Corallina samples (C. granifera and C. mediterranea from the Black Sea and C. mediterranea from the Mediterranean Sea) was established. The sterol composition of the Black Sea samples was similar but it differs from that of the Mediterranean sample. The composition of the volatiles was very complex. The main groups of constituent were hydrocarbons, alcohols, carbonyl compounds, acids and their esters, terpenes. The composition of the polar components, soluble in n-butanol, was also established. There were some differences in the chemical composition of the two Black Sea species, which may be due to the biodiversity between them, while the differences in the composition of the two C. mediterranea samples could be due to the differences in the environment (salinity, temperature, pollution, etc.).     

Free-living marine Rhabdocoela (Platyhelminthes) from the N. American Pacific coast. With remarks on species from other areas

From the N. American Pacific coast the following taxa are described: Coronopharynx pusillus Luther, Pogaina bicornk sp.n., P. paranygulgus sp.n. (Provorticidae); Brinkmanniella palmata sp.n., Tvaerminnea karlingi pucifica subsp.n. (Promesostomidae); Trigonostomum setigerum O. Schmidt, Messoplana pacifica sp.n., Ceratopera axi (Riedl), C. ehlersi sp.n., C. pilifera sp.n. (Trigonostomidae); Polycystis ali Schockaert, P. hamata sp.n. (Polycystididae). From other areas: Brinkmanniella palmata from the Skagerrak, Black Sea and Mediterranean Sea; Ceratopera axi from the Falkland Islands; Polycystis ali from Galapagos Islands; Ceratopera bermudensis sp.n. from Bermuda. Polycystis ali is considered to be a polytypic species with the forms 'Somali', 'California' and 'Galapagos'. Brinkmanniella augusti Marcus and B. falklandica Westblad are considered to be species incertae sedis. Problems in penetrating the world-wide marine turbellarian fauna are discussed.     

The distribution and molecular diversity of the Eastern Atlantic and Mediterranean chthamalids (Crustacea, Cirripedia)

The three chthamalids Chthamalus stellatus , C. montagui and Euraphia depressa are common inhabitants of the intertidal zone in the Eastern Atlantic, Mediterranean Sea and Black Sea. In this study, we investigated the occurrence of these barnacles in a wide range of their distribution. Population divergences of these two species have been inferred using three molecular markers — internal transcribed spacer (ITS), elongation factor 1α (EF-1α) and cytochrome oxidase subunit I (COI). ITS sequences of C. stellatus were identical throughout the species range, whereas ITS sequences of C. montagui indicated that the Black Sea and Mediterranean populations are isolated from the Atlantic population. The COI and EF-1α sequences were the most variable and informative. They indicated a high genetic divergence between Atlantic, Mediterranean and Black Sea populations for C. montagui . In addition significant genetic structure was found among the populations of C. stellatus based on EF-1α but not COI. Interestingly, our molecular dating analysis correlated the pattern of diversification in C. montagui to major geological changes that occurred in the Mediterranean during the end of the Messinian and Pleiocene periods. We suggest that palaeohistory shaped the divergences between Chthamalus populations that have probably been maintained by current hydrographic conditions. Finally, COI phylogenetic analysis placed the genus Euraphia within the Chthamalus clade, suggesting the need for a taxonomic revision of Euraphia . This study represents the most detailed phylogeographical analysis of intertidal Mediterranean species to date, and shows that geological events have strongly shaped the current diversity pattern of this fauna.     

New records of deep-sea decapod crustaceans in the Turkish Mediterranean Sea (North Levant Sea)

A survey of the bathyal trawling grounds in the Gulf of Antalya (Turkish Mediterranean Sea) yielded 34 species of decapod crustaceans. Four species (Funchalia villosa, Plesionika acanthonotus, P. gigliolii, Monodaeus couchii) are recorded for the first time from the Levant Sea. The number of marine decapod species reported for Turkey rises to 265 and the number reported from the Turkish Mediterranean Sea to 211.     

Saturnius minutus n. sp. and S. dimitrovi n. sp. (Digenea: Hemiuridae) from Mugil cephalus L. (Teleostei: Mugilidae), with a multivariate morphological analysis of the Mediterranean species of Saturnius Manter, 1969

Three species of the bunocotyline genus Saturnius Manter, 1969 are described from the stomach lining of mugilid fishes of the Mediterranean and Black Seas. Two of the species are new: S. minutus n. sp. occurs in Mugil cephalus off the Mediterranean coast of Spain; and S. dimitrovi n. sp., a parasite of M. cephalus off the Bulgarian Black Sea coast and the Spanish Mediterranean coast, was originally described as S. papernai by Dimitrov et al. (1998). In addition, S. papernai Overstreet, 1977 is redescribed from M. cephalus off the Spanish Mediterranean coast and from Liza aurata and L. saliens off the Bulgarian Black Sea coast. The three species are distinguished morphometrically using univariate and multivariate analyses. These results were verified using Linear Discriminant Analysis which correctly allocated all specimens to their species designations based on morphology (i.e. 100% successful classification rate) and assigned almost all specimens to the correct population (locality). The following variables were selected for optimal separation between samples: the length of the forebody, ventral sucker and posterior testis, the length and width of the posteriormost pseudosegment, and the width of the muscular flange at ventral sucker level.     

Mediterranean non-indigenous bryozoans: an update and knowledge gaps

This paper provides an inventory of non-indigenous bryozoan species (NIB) recorded in the Mediterranean Sea. Taking into account previous NIB lists and updated non-indigenous concept, a careful literature review was carried out, reporting data on 33 NIB from 14 Mediterranean countries (Algeria, Croatia, Cyprus, Egypt, France, Greece, Israel, Italy, Lebanon, Malta, Spain, Syria, Tunisia and Turkey). A total of 296 valid records were listed, including 6 yet unpublished. Other 62 records were labelled as uncertain and listed separately, until further analyses on taxonomic identity, non-indigenous status and distribution patterns of the species involved will clarify their status. The countries with the higher numbers of NIB and single records are Lebanon (20 and 78, respectively) and Italy (12 and 112, respectively). The distribution of NIB in the Mediterranean Sea appears scattered and no data are available at all for eight countries. Studies and monitoring efforts on bryozoans in the Mediterranean Sea are not evenly distributed, probably as a consequence of the decrease in number of expert taxonomists and the poor allocation of funds on biodiversity studies. The coordination among Mediterranean countries on standardised sampling methods is needed in order to create a comprehensive baseline knowledge on NIB distribution in the Mediterranean Sea and prioritise taxa and countries that are still poorly investigated.     

Genetic and morphological analyses of tub gurnard Chelidonichthys lucerna populations in Turkish marine waters

Genetic and morphological structure of tub gurnard Chelidonichthys lucerna populations in Turkish marine waters were investigated with mtDNA sequencing of 16S rRNA and morphological characters. C. lucerna samples were collected from the Black Sea, Marmara, Aegean and northeastern Mediterranean coasts of Turkey. The lowest genetic diversity was found in the northeastern Mediterranean (Iskenderun Bay) population, while the highest was in the Marmara population with overall average value of genetic diversity within populations. A total of 14 haplotypes was found, and the highest haplotype diversity was in the Black Sea whereas the lowest was in the northeastern Mediterranean population (Iskenderun Bay). The Black Sea and Iskenderun Bay populations showed the least genetic divergence (0.001081), while the highest was between the Marmara Sea and northeastern Mediterranean (Antalya Bay) populations (0.002067). Pairwise comparisons of genetic distance revealed statistically significant differences (P < 0.05) between the Marmara and both the Aegean and northeastern Mediterranean (Antalya Bay) samples. Neighbour joining tree analyses clustered the northeastern Mediterranean populations (Antalya Bay and Iskenderun Bay) as genetically more interrelated populations, whereas the Aegean Sea population was clustered as most isolated one. Discriminant function analysis of morphological characters showed that only the Black Sea population is differentiated from the other populations.