The demographic histories, genetic relationships and population structure of sedentary fish Pomatoschistus marmoratus (Risso, 1810), which was sampled from the north-eastern basin of the Mediterranean Sea (including the Turkish coasts of the Black Sea, Aegean Sea, Levantine Sea and Sea of Marmara), were investigated by mitochondrial cytochrome c oxidase subunit I (652 bp) and cytochrome b (526 bp) regions. It was found that the population groups had high haplotype diversity while the nucleotide diversity was quite low for both gene regions. Phylogeographic analyses of the haplotypes indicated that the Levantine population (LEV) were genetically different from other populations. Also, the gene flow between LEV and the other populations was very limited. The results of the analyses of neutrality and mismatch distributions that were applied to the population groups were evaluated as a whole. It was determined that the haplogroup that represents the Black Sea and Sea of Marmara populations (BLAMAR) was stable, but the Levantine population (LEV) was under the sudden demographic expansion model following the population bottleneck. The genetic variance indices indicated sudden demographic expansion following population contraction. This was supported by star-shaped haplotype networks. The reason for this limited gene flow and differentiation between the Levantine population (LEV) and the others was linked with wind-driven offshore transport of the larvae and surface currents in these sub-basins. The timing of the differentiation, demographic histories of populations associated with geological and palaeo-climatic events and current ecological conditions were discussed.

Introduction of species is a major driver of global change and loss of biodiversity in ecosystems. The Mediterranean Sea is the most heavily invaded region in the world by introduced seaweeds. The fan mussel Pinna nobilis is the largest Mediterranean bivalve, and a protected species, present at depths from 0.5 m to 60 m. In Cabrera National Park marine protected area (MPA) (Balearic Islands, north-western Mediterranean) the population of P. nobilis is affected by the invasive seaweeds Lophocladia lallemandii and Caulerpa racemosa; however the extent of this colonization on the bivalve is unknown. Therefore, the main aims of the present study were to: (1) determine the extent of invasion of L. lallemandii and C. racemosa on the P. nobilis population; and (2) test if this invasion showed differences with depth. This is the first study assessing invasion by seaweeds on a large bivalve in a high density P. nobilis population. Pinna nobilis was distributed in all seagrass meadows surveyed within the MPA; we found a total of 872 live P. nobilis individuals, 449 and 423 of which were found at 10 and 20 m depth, respectively. High cover of L. lallemandii and low presence of C. racemosa were detected in the P. nobilis population, being quantified in 49.37% and 1.38% of the population of P. nobilis, respectively. Bathymetric differences on Lophocladia epizoism over P. nobilis has been recorded in this study; with increasing values of L. lallemandii cover index, biomass and volume at deeper depths. Pinna nobilis could be a preferential substratum for L. lallemandii in Posidonia oceanica meadows in deeper waters, acting as a stepping-stone for invasive seaweeds and facilitating the invasion throughout seagrass meadows.

Fluorescent proteins (FPs) are reported to play an important role as photoprotectants and antioxidants in corals subjected to stressful conditions. Identifying the various FP genes expressed and FP gene expression patterns under stress in diverse coral species can provide insight into FP function. In this study, we identified 16 putative FP homologues from the transcriptomes of corals with varying susceptibility to elevated temperature, including Acropora digitifera, Favites colemani, Montipora digitata and Seriatopora caliendrum. Each coral expressed a different complement of FP transcripts, which were predicted to have distinct spectral properties. The most diverse and abundant repertoire of FP transcripts, including at least 6 green FPs, were expressed in the temperature-tolerant coral, F. colemani. In comparison, the other corals expressed fewer FP types. Specific FP transcripts exhibited variable expression profiles in coral fragments subjected to 32 ± 1 °C (treatment) or 28 ± 1 °C (control) for up to 72 h, suggesting that distinct FPs may have different roles. Further studies on the expression of the proteins encoded by these FP transcripts, their fluorescence activity, tissue localization, and possible antioxidant properties, are needed to reveal their contribution to thermal stress tolerance in certain species of corals.

Currently, there is little comparative data on ‘efficiency’ of different engineering species, i.e. species richness, density and biomass of the associated organisms that have been supported by engineering species. The use of fouling communities makes it possible to compare the efficiency of different engineering species under the same conditions, which is necessary to obtain correct estimates and difficult to do when studying natural bottom communities. In this study, we have analysed the fouling communities in four different mussel culture farms in the White Sea to test the following hypotheses. (1) Different engineering species (mussel Mytilus edulis, solitary ascidian Styela rustica, sponge Halichondria panicea) have different assemblages of the associated vagile fauna. (2) Mytilus edulis is the most efficient engineering species, i.e. species richness, species diversity, density and biomass of the associated vagile fauna is higher in the mussel communities than in those dominated by Styela rustica or Halichondria panicea. The first hypothesis was confirmed, while the second was rejected. In all the culture farms studied, all parameters of the mussel-associated vagile fauna were not higher and in most cases were even lower than those of the fauna associated with ascidians or sponges. The reason for this seems to be the very dense packing of mussels in patches. Therefore, Mytilus edulis is not the most efficient engineering species among fouling organisms, at least in the conditions of the subarctic White Sea. The data obtained are particularly important in view of the ever-increasing volume of anthropogenic substrate and fouling communities in coastal marine ecosystems.

The alpha taxonomy of scaphopods is based mainly on the shell morphology, as it is for most molluscs. In the last three decades, the employment of morphometric variables of the shell in combination with statistics has considerably increased to aid species discrimination, but this has not been used above species level. In this study, a traditional morphometric approach was used to distinguish congeners, genera and families within the orders Dentallida and Gadilida. We studied 28 species of scaphopods from Brazil, belonging to 12 genera and five families. Twelve morphometric variables were measured, and a correlation test was done to select a set of variables without correlation as input data to perform a discriminant analysis. In the analysis of congeners, the discrimination power was high in both orders. Among the genera studied, the robustness of the analysis was drastically reduced in Dentaliida, while Gadilida maintained a high percentage of correct classifications. At the family level, both orders presented high percentages of correct classification, but the imbalance of cases for each taxon masks an inconsistent result. Based on our results, the morphometric approach was a useful tool to discriminate congeneric species of both orders and to discriminate the genera of Gadilida.

Concentrations of iron in embryos and yolk sacs of dogfish Scyliorhinuscanicula (Elasmobranchii: Squaliformes) reared in natural and artificial (iron-free and iron-augmented) seawater were measured and compared with the iron content of adult dogfish tissues in order to investigate the iron budget of dogfish embryos. No difference in iron concentration between sexes was observed in adult dogfish. Liver iron concentration (89.6±5.8 μg g−1) showed the highest value among the three tissues investigated and was significantly higher than that measured in muscle (22.6±2.1 μg g−1), or developing eggs from females (40.5±2.5 μg g−1). The iron concentration in the entire contents of early eggcases (27.1±4.8 μg g−1) was lower, but not significantly different from that of eggs taken from the females. Dogfish yolk sacs from eggcases maintained in (a) natural seawater, (b) artificial seawater, and (c) artificial seawater with supplementary iron, for periods of up to six months, did not show any differences in iron content. Developing embryos from the artificial seawater with supplementary iron treatment demonstrated elevated iron concentrations (62.4±12.0 μg g−1) when compared with those from the remaining two treatments (35.8±5.8 and 35.1±2.7 μg g−1 respectively). The results identify maternal investment as the primary contributor to the iron burden of juvenile dogfish, and demonstrate the ability of the embryos to supplement this supply from their environment.

The morphology and stomatogenesis of the marine scuticociliate Pseudocohnilembus hargisi collected from a shrimp culturing pond in Qingdao, China, were studied using pyridinated silver carbonate and Chatton–Lwoff silver impregnation techniques. The result shows that the Qingdao population of this species possesses typical characteristics of the genus Pseudocohnilembus: the buccal apparatus consists of three highly specialized membranelles; membranelle 1 comprises a single row of kinetosomes, is parallel to membranelle 2, and lies anterior to the paroral membrane; membranelle 2 is longer than membranelle 1 and also comprises one row of kinetosomes; membranelle 3 is located near the middle of the paroral membrane and comprises three rows of kinetosomes. The silverline system is similar to that of P. persalinus. During stomatogenesis, the parental scutica proliferates and becomes the primordial field. This subsequently develops in two separate parts, the anterior part eventually disappears while the posterior part forms membranelle 3 of the opisthe. The secondary proliferated field, which derives from the zigzag configuration of parental paroral membrane, also develops in two parts, with the anterior becoming the paroral membrane and scutica of the opisthe and the posterior part developing into membranelles 1 and 2 of the opisthe. The remnants of the parental paroral membrane give rise to the paroral membrane and scutica of the proter.

An account is given of the effects of changes of concentration of salts in the ambient medium on the colours reflected by the scales of herring and salmon. These lead to the conclusions (1) that in the herring in life the reflecting cells which lie under the scales and outside the scale pocket are in osmotic equilibrium with the external medium and not with the fish's body fluid (2) that the corresponding cells which lie inside the scale pocket of herring are always in equilibrium with these body fluids (3) that in the salmon all parts of the scale, including the parts outside the scale pocket, are in equilibrium with the internal body fluid and osmotically protected from the external medium.

Two female snapper-choking isopods Cymothoa excisa (body length 11 and 14 mm) were in the buccal cavity of two invasive lionfish Pterois volitans (total length 294 and 301 mm) collected in Alacranes Reef, southern Gulf of Mexico. This is the first record of C. excisa parasitizing invasive lionfish P. volitans in coral reefs of the Western Atlantic, where these isopods appear to have infected the host through adult prey-predator transfer.

Nectonema species are parasites of decapod crustaceans and the only known representatives of the otherwise freshwater/terrestrial taxon Nematomorpha. We report the American lobster, Homarus americanus, as a new host for Nectonema agile, a first record among astacidean decapods. A female, about 590 mm long, was found in the body cavity of one female lobster specimen. We assume lobster to be a very rare host for Nectonema.

The origin and development of the Journal of the Marine Biological Association of the United Kingdom is described on the occasion of the publication of the 100th volume. Papers in the Journal demonstrate how the techniques and approaches to the study of the marine environment have evolved over the 120 years of publication. The early papers provided a baseline description of the marine environment and of marine communities that allowed the effects of later perturbations of the environment to be determined. Both the early papers and the long time series of records have proved to be particularly relevant as marine scientists try to predict the long-term results of climatic and anthropogenic effects on the marine ecosystem. The Journal has now become increasingly international, with most papers coming from outside Europe.

Karyotypes for several East Pacific Rise hydrothermal vent invertebrates are described here for the first time: the vestimentiferans Riftia pachyptila and Oasisia alvinae, the alvinellid polychaetes Alvinella pompejana, A. caudata and Paralvinella grasslei, the polynoid polychaetes Branchinotogluma grasslei and Branchipolynoe symmytilida, the serpulid Laminatubus alvini and the mytilid bivalve Bathymodiolus thermophilus. For comparative purposes, the karyotype of the Atlantic vent mussel Bathymodiolus azoricus is also described here for the first time. Each species has its own unique chromosomal characteristics which can be interpreted both in terms of group characteristics and species divergence. From comparisons with published results on other vent species and closely-related coastal species, we identified a positive correlation between chromosome number variation and molecular divergence at two ribosomal ribonucleic acid gene loci (the 18S and 28S rRNA). Whilst the patterns of chromosome divergence we found were generally within the ranges previously reported for these taxonomic groupings, there was an apparent inconsistency in the case of Branchipolynoe symmytilida (EPR) and Branchipolynoe seepensis (MAR), which show a greater degree of divergence at the chromosome level compared with other members of the same genus. Moreover, polychaetes as a whole showed greater variation in the number and structural divergence of chromosomes compared to Mytilids (structural information only). Our findings highlight the great potential for chromosome analysis in future taxonomic and evolutionary studies of the deep-sea vent fauna.

The study of living Halecium halecinum colonies revealed a new case of zooid polymorphism. Besides the ordinary hydranth, the polyp devoted to feeding, this species is provided with a second kind of polyp, differing only slightly in structure and morphology but most conspicuously in its behaviour. It is named ‘extensible polyp’ in reference to its great extensibility and the resulting filiform shape. There are slight differences in the tentacles: lower number, shorter length, thicker diameter, and the tip slightly swollen and rounded instead of tapering. Their large microbasic mastigophores are abundant and evenly distributed, while the hydranth has a few large ones only on the oral side but has otherwise numerous small ones. When extended and at rest, the tubular column is much longer than that of the hydranth and not delimited from the head of the polyp by a bulge followed by a constriction. Behavioural differences are its capacity to coil and bend during extension and thus being able to move in all directions and exploring a large volume of seawater, and also its ability to produce regional swellings (peristalsis) and to contract by folding and bulging though still extended. Besides a probable role in defence, the extensible polyp exhibits an excretory function and it could also have sensory functions. The extensible polyp type is not classified as a nematophore because it has a functional gastrovascular cavity and a mouth. Polyp dimorphism (hydranth/extensible polyp) is reported in one more halecid and two sertularids.

Grey seals (Halichoerus grypus) are a species of conservation concern that require Marine Protected Area management and population status assessment under the EU Habitats Directive. Aerial surveys are commonly used to monitor grey seal pup production at their globally important UK colonies. However, in Wales more than half of pups are born in cryptic breeding habitats such as sea caves. These cryptic habitats preclude the use of aerial monitoring methods and necessitate ground-based counts, which are costly in resources. In this study, we compare a ground-based pup production census with a reduced effort plot-sampling survey to estimate pup production, derive a total population size and assess cost effectiveness. Pup production in North Wales was estimated at 91 (95% confidence interval: 70–112) by the plot-sampling design and was a good approximation of the ‘true’ value of 96 derived from the census. The total population size in North Wales was estimated at between 242 and 307 grey seals. The plot-sampling design reduced survey effort by 46% and saved 30% on logistical costs compared to the full census. We outline the suitability of this method as part of a monitoring programme for grey seal pup production and suggest our approach may be applicable to other regions where grey seals use cryptic breeding habitat.

The taxonomy of marine worms belonging to family Nereidae is still in an uncertain state. There are many species, like Nereis diversicolor Müller, N. japonica Izuka and N. limnicola Johnson, which are morphologically similar but have different reproductive habits. Clark (1977) reviewed many examples of reproductive isolation without morphological differentiation in polychaetes including members of the family Nereidae. He also stressed the need for detailed study in such polychaetes where taxonomic confusion exists.

Electrophoretic techniques have contributed a great deal in solving taxonomic problems (see Avise, 1975 and Burton, 1983). All electrophoretic methods have proved useful to varying degrees in characterizing specific organisms. In particular, acrylamide gel electrophoresis has seen extensive use because it has excellent resolving power (Brewer, 1970). Studies of the electrophoretic variation of nereid isozymes have not been reported, except by Jones (1970), who examined various polychaetous annelids for the presence of certain dehydrogenases. This present report contains preliminary observations concerning the applicability of isozyme electrophoresis to the study of nereid worms.

The temporal and spatial variation of Paralonchurus brasiliensis density (fish per m2) in relation to environmental factors was studied on the coasts of Ubatuba and Caraguatatuba, south-eastern Brazil. The fish were collected by shrimp fishery trawl on a monthly basis from January to December, 2002. Seven depths were previously established and for each one the temperature, salinity, organic matter content and grain size of the sediment (φ) was measured. The seasonal analysis of temperature and salinity indicated the presence of the water masses South Atlantic Central Water (SACW) and Coastal Waters (CW) acting in the study area. A total of 29,808 fish were collected during the study period. The highest densities were registered during the summer and autumn indicating an association with CW. The fish population moved to shallow depths during the intrusion of the cold water mass, SACW. The highest densities were registered in depths where the sediment composition ranged from fine sand to silt–clay. Thus, the temperature and type of the sediment are the main environmental factors which affect the spatial–temporal variation of P. brasiliensis density in south-eastern Brazil.

Diel vertical migration (DVM) and distributional patterns of copepods collected in the water column at shallow water site (Station M) in Tanabe Bay, Japan were investigated. Twenty-one taxa of zooplankton and 48 species of copepods at Station M had positive ΔZ values (subtraction of night-time weighted mean depth from daytime value) and performed normal DVM. The highest ΔZ value was 4·3 observed in Ambunguipes rufocincta. Three taxa and 39 species collected only at night also had high WMD (weighted mean depth) values (4·0∼7·5), which were previously considered hyperbenthic species. Statistically significant differences were found only in Myodocopina spp., Calocalanus plumulosus and Clausocalanus spp. Myodocopina spp. and Clausocalanus spp. showed downward migration at low to high and high tidal phases. Calocalanus plumulosus and some copepods performed downward migration during high and high to low tidal phases. Four distributional patterns of copepod species in Tanabe Bay were found. The groups are as follows: (A) true planktonic group; (B) swarming and night emerging group; (C) night emerging meiobenthic and hyperbenthic group; (D) symbiotic and night emerging group.

Respiration in marine bacteria (fraction <0.6 µm) was investigated in 5 distinct coastal ecosystems. Respiration rates were estimated from the decrease of dissolved oxygen (O2) concentrations measured with a fibre-optic oxygen sensor (optode) during short-term incubations (5 to 6 hours) in the dark. Sub-populations of heterotrophic bacteria were defined and enumerated by flow cytometric analysis. Respiration rates ranged from 0.04 to 0.14 µmol O2 l−1 h−1 and were not correlated to total bacteria abundances. In contrast, they significantly increased with the relative proportion of HDNA cells (i.e. high deoxyribonucleic acid content) within the bacterioplankton community. These results stress the need to relate bacterial respiration rates to the absolute and relative abundance of the different cytometrically defined sub-populations found in bacterial assemblages, rather than to total cell counts. This result indicates that only a fraction of bacterial cells may contribute to bacterial respiration, which indicates a reconsideration of the relevance of some previous estimates of bulk bacterial respiration and the related biogeochemical fluxes may be required.

1. Twenty-one thousand, five hundred and fourteen (21,514) amphipods of the species Gammarus chevreuxi Sexton have been examined for eyecolour, 21.302 referred to in this paper, and 212 in other experiments, not included.

2. The normal eye-colour of this species is black, with a superficial reticulation of opaque white pigment.

3. The pigmentation of the eye is very variable within limits. Eyes have been observed either partially or entirely lacking in the coloured pigment of the retinular cells, or with either a partial or entire lack, or else an excess of the opaque white pigment.

4. The red strain appears to have arisen as a “sport” in the second generation of offspring of the first animals captured. No red-eyed animals have yet been found in natural conditions, although many thousands have been brought in from time to time and examined. Those counted for the purpose while the work for this paper was in progress numbered 8697, but this figure does not include the many thousands previously observed. Experiments have been made repeatedly with a view of getting the Red strain again from the Pure Black, but with no success.

In his paper on “Plankton Studies in Eelation to the Western Mackerel Fishery,” in the last number of this Journal (Vol. VIII., p. 269), G. E. Bullen shows that for the years 1903–1907 there appears to be a correlation between the number of mackerel taken during May and the amount of Copepod plankton, upon which the mackerel feed, taken in the neighbourhood of the mackerel fishing grounds during the same month.