The phytoplankton community structure and abundance in the south-eastern Black Sea was measured from February to December 2009 using and comparing high performance liquid chromatography pigment and microscopy analyses. The phytoplankton community was characterized by diatoms, dinoflagellates and coccolithophores, as revealed by both techniques. Fucoxanthin, diadinoxanthin, peridinin and 19′-hexanoyloxyfucoxanthin were the main accessory pigments showing significant correlation with diatom-C r2 = 0.56–0.71, P < 0.05), diatom-C (r2 = 0.85–0.91, P < 0.001), dinoflagellate-C (r2 = 0.39–0.88, P < 0.05) and coccolithophore-C (r2 = 0.80–0.71, P < 0.05), respectively. Microscopy counts indicated a total of 89 species, 71% of which were dinoflagellates, 23% were diatoms and 6% other species (mainly coccolithophores). Pigment-CHEMTAX analysis also indicated the presence of pico- and nanoplankton. Phytoplankton carbon (phyto-C) concentrations were highest in the upper water column, whereas chlorophyll-a (Chl-a) showed a deep maximum. Average phyto-C was higher at the coastal station (291 ± 66 µg l−1) than at the offshore station (258 ± 35 µg l−1), not statistically different (P > 0.05). The coastal station also had higher Chl-a concentrations (0.52–3.83 µg l−1) compared to the offshore station (0.63–2.55 µg l−1), not significant (P > 0.05). Our results are consistent with other studies and indicate that the southern Black Sea is shifting towards mesotrophy with the increasing prevalence of dinoflagellates compared to diatoms.

One of the most fundamental problems of oceanic ecology is the study of spatial and temporal changes in plankton distribution and the elucidation of the factors that govern them. A prerequisite of such work is that the tech- niques of sampling should be of sufficient accuracy to allow real changes in distribution to be detected and expressed in quantitative terms. The difficul- ties of fulfilling these sampling requirements are formidable even for the smaller plankton organisms, but a number of reliable and accurate quantitative samplers do exist for animals in this size range. For the larger zooplankton and smaller nekton, however, the lack of suitable sampling gear and methods has to a great extent restricted our knowledge. While the use of large conical nets and trawls at all depths over a wide geographic range has produced a vast body of data on the systematics of the major groups of macroplankton, there is little precise data on the depth distribution of even the commonest forms and only the vaguest estimates are available as to their relative abundance. The lack of more precise data can be attributed to two major technical deficiencies, first, the absence of efficient and reliable methods by which large nets can be opened and closed at depth, and secondly, the lack of accurate depth monitoring equipment. This paper describes the preliminary results of work aimed at meeting the first of these requirements but reference will also be made to the use of an instrument that represents a major advance towards serving the second.

It is now well established that natural phytoplankton populations may liberate a substantial proportion of the carbon fixed in photosynthesis directly into the external medium in the form of dissolved organic matter. Glycollate may be an important component of this extracellular organic fraction, both in culture (Hellebust, 1965) and in the natural environment (Watt, 1966). Nevertheless, it has been difficult to investigate the role of glycollate in the environment because of the lack of a convenient and reliable method for determining its concentration in natural waters. Shah & Fogg (1973) and Shah & Wright (1974), however, have developed a procedure for glycollate analysis in sea water, based on adsorption on to alumina and subsequent elution for determination by the Calkins colorimetric technique, which is both sensitive and not too laborious for routine analyses. Fogg (1966) suggested that glycollate excreted by phytoplankton acts as an extracellular reserve which may be utilized for survival under conditions unfavourable for photosynthesis. Wright & Hobbie (1965) showed that some fresh water bacteria take up glycollate at rates of the same order of magnitude as for acetate and glucose. Glycollate would therefore appear to be of importance in the energy flow between different trophic levels. In order to evaluate these hypotheses it seems important to determine the concentrations and turnover rates of glycollate occurring in natural waters.

Patella vulgata gives a positive response to splashing with sea water or water of high salinity, and a negative response to fresh water or water of low salinity. The intensity of the positive response broadly corresponds with the salinity of the water used. There is a greater response to splash and a greater tolerance to reduced salinity in limpets from high-tide than in those from low-tide regions. A positive response is given to NaCl solutions of concentrations approximately equivalent to sea water, while a supra-normal response is given to concentrations somewhat above that of sea water. The perception of salinity is by receptors in the cephalic tentacles and mantle fringe.

The distributions of mackerel eggs and young stages, pilchard eggs, the siphonophore Muggiaea atlantica and the chaetognaths Sagitta elegans, S. setosa, S. serratodentata and 5. lyra in the Celtic Sea in March 1939, April, May-June 1937, 1938 and 1939 and July 1937 and 1938 are described, together with notes on the hydrological conditions in April 1937, 1938 and 1939, May-June 1939 and July 1938.

Mackerel spawning started in mid-March, rapidly reached a maximum in mid-April, declined gradually through May and June and was very slight at the end of July.

The changes in intensity of spawning are accompanied by a continuous shift eastward and slightly northward of the locus of spawning. In March spawning occurred in a small area at the western edge of the Continental Shelf only. In mid-April it was spread over the greater part of the Celtic Sea, with the main activity concentrated in two centres—to the south of Ireland and to the west of the mouth of the English Channel. By May-June it had shifted farther to the east and occupied the central area of the Celtic Sea. In July there was no spawning to the westward of the Scilly Isles.

The spawning area of the mackerel appears to be confined to the shallow waters over the Continental Shelf.

No mackerel young stages were found in March. Small numbers occurred in April (maximum 174). They were abundant in May-June (maximum 8239), and very scarce in July (maximum 20).

The distribution of young stages closely follows the movement of spawning during the season.

The dynamics and feeding biology of a population of Marthasterias glacialis (Echinodermata: Asteroidea) was examined over a two-year period from 2000–2002 at Lough Hyne Marine Nature Reserve, Co. Cork, Ireland. A multivariate approach was used and both multiple factors and multiple interactions between factors were found to influence population structure. These included time of year, site, individual sea-star size, depth, and predator density. Individuals belonging to the smallest size-classes (0–50 mm and 51–100 mm) were most abundant amongst boulders in shallow water (0–1 m), while larger individuals were primarily found in water below 1 m in depth on finer grade substratum and shell debris. Dietary composition was also found to differ with depth; sea-stars in the immediate subtidal had an opportunistic diet, and fed on a variety of taxa, whilst those M. glacialis from 1–6 m were more selective and restrictive, feeding chiefly on bivalve prey. We propose that spatial partitioning of different size-classes and a generalist feeding strategy may account for the success of M. glacialis at Lough Hyne.

This paper reports, for the first time, the existence of external digestion of decapod larvae by the common octopus, Octopus vulgaris (Mollusca: Cephalopoda), paralarvae. Zoeae of three crab species were externally digested, leaving a whole and empty exoskeleton. The attack sequence on these prey is also described, and divided into the same three phases (attention, positioning and seizure) already known for Sepia hatchlings.

A general formula has been derived for the quantitative treatment of systems involving a number of interdependent equilibria. The formula has been applied specifically to the equilibria set up between metallic cations and their chelates when EDTA is added to sea water. This system involves competition for the fully dissociated quadrivalent anion of EDTA (the principal ion of EDTA which forms complexes) by the metallic cations and by the hydrogenions present. The equilibrium concentration of a metallic cation in any particular case will depend upon the equilibrium concentration of the quadrivalent anion of EDTA, in the sense that the higher the concentration of this ion the lower will be the concentration of the metallic cation. The general formula allows the calculation of the equilibrium concentration of the quadrivalent EDTA anion, and from this the concentrations at equilibrium of each metallic cation can be readily found.

Results are given for measurements of fat, vitamin A and carotenoids in groups of Meganyctiphanes norvegica, Thysanoessa raschii, Crangon allmani, C. vulgaris, Nephrops norvegicus and eyes of Homarus vulgaris, collected at regular intervals for a year or longer.

In both species of euphausiids vitamin A was consistently present mainly in the ester form and concentrated chiefly in the eyes. More than half the total astaxanthin was in the eyes. No other carotenoids were detected.

Astaxanthin and vitamin A were accumulated by the euphausiids more rapidly during the spring and autumn-feeding periods associated with diatom outbursts than at other seasons. There was a delay in Thysanoessa raschii, but not in Meganyctiphanes norvegica, between resumption of more rapid growth during spring and autumn and increase in concentration of vitamin A and astaxanthin. The difference was possibly due to differences in diet of the two species in relation to the seasonal biological composition of the plankton.

In the euphausiids, concentrations of vitamin A and astaxanthin were much higher in larvae and in adults over 30 mm long of M. norvegica, and in larvae and adults over 15 mm of Thysanoessa raschii, than in mature adults of Meganyctiphanes norvegica of 20–30 mm and Thysanoessa raschii of 13–15 mm, respectively. An inverse relationship between fat and vitamin A concentration was noted in both species throughout the year.

In Crangon spp. and Nephrops norvegicus there was no evidence of any seasonal variation of either vitamin A or carotenoids. Differences in the carotenoid metabolism of the two species of Crangon are discussed.

This study investigates the catch components of a commercially used demersal trawl cod end in Izmir Bay, and reveals some of the morphological characteristics of nine commercial fish species; red mullet (Mullus barbatus), hake (Merluccius merluccius), whiting (Merlangius merlangus euxinus), poor cod (Trisopterus minutus capelanus), tub gurnard (Trigla lucerna), common pandora (Pagellus erythrinus), axillary sea bream (Pagellus acarne), picarel (Spicara smaris) and annular sea bream (Diplodus annularis) in relation to mesh size and shapes. Furthermore selectivity of 40-mm polyethylene netting cod end for red mullet, hake, common pandora, axillary sea bream, picarel and annular sea bream is presented. The results are discussed in a way to understand the probable effects of fish body shape on mesh selectivity.

Phytoplankton and microzooplankton community structure and the impact of microzooplankton grazing were investigated during a one-day study of an Emiliania huxleyi bloom off the coast of Devon during July 1999. Vertical profiles were undertaken at four stations, along a transect which crossed from a low reflectance to a high reflectance area as seen by satellite imagery. Microzooplankton dilution grazing experiments, coupled with pigment analysis to determine class specific grazing rates, were performed at two of these stations.

Highest concentrations of chlorophyll-a (5·3 mg m−3) and accessory pigments were measured inside the area of high reflectance. Phytoplankton standing stocks ranged between 1588 and 5460 mg C m−2 and were also highest in the area of high reflectance. The phytoplankton community was dominated by coccolithophores and diatoms in low reflectance waters and by photosynthetic dinoflagellates in high reflectance areas. Microzooplankton standing stocks ranged between 905 and 2498 mg C m−2. Protozoa dominated the microzooplankton community. The protozoan community comprised a relatively even mixture of heterotrophic dinoflagellates, non-choreotrich and choreotrich ciliates in low reflectance waters. However, non-choreotrich ciliates dominated the communities inside the high reflectance area. Of the heterotrophic ciliates, a predatory ciliate Askenasia sp. dominated both non-choreotrich abundance and biomass.

Results from grazing experiments showed that 60–64% of the chlorophyll-a biomass was consumed daily by the microzooplankton. Highest grazing mortality was associated with peridinin (dinoflagellates) and alloxanthin (cryptophytes). Lower grazing rates were found on fucoxanthin (diatoms and prymnesiophytes). Our results indicate that grazing on E. huxleyi in the area of remotely sensed high reflectance was low and highest grazing was on photosynthetic dinoflagellates and cryptophytes.

Field observations and laboratory experiments were made on Cyclope neritea, a small (~10 mm diameter) burrowing stenoglossan gastropod with a flattened shell found in very high densities (>200 m2) in Paleohori Bay on the south coast of Milos (Aegean Sea). Cyclope neritea forms a high proportion of the biomass at seeps in this bay, where the medium to fine sand overlies hot, sulphidic brines. About half the animals were found on the surface in the daytime, an exception to the normal habit of this species which usually emerges from the sediment only at night. The C. neritea were aggregated on the thinner bacterial mats over the seeps. In the laboratory, C. neritea remained active for 3 h at sulphide concentrations up to 1 mM, the highest concentration in the interstitial water in the upper 25 mm of sediment at the seeps. Although the species can tolerate elevated salinity and temperature, it shows little adaptation for sulphide detoxification by oxidative pathways. It may survive at the seeps by its behaviour pattern, especially the use of the extensible siphon to access oxic water above the sediment boundary layer, and perhaps by exclusion of sulphide from the tissues. Cyclope neritea ingests large quantities of sand together with adhering bacteria and diatoms, but also scavenges on other animals killed by the extreme conditions of the seeps.

The spatial pattern of the ostracod Cyprideis torosa (Jones, 1850) is aggregated and can be described by the negative binomial distribution. The fit of the observed distribution to the negative binomial is less well for the total number of females because females that are not carrying eggs tend to be independently distributed from both females carrying eggs and males. The aggregations are roughly circular with a radius of about 13 cm and may be themselves aggregated. A method to picture the aggregations is described.

Modifications are described to the penetrometer originally designed by Chapman & Newell (1947) for the measurement of the resistance to penetration of marine soils.

An account is given of qualitative and quantitative tests made during the study of the thixotropy and dilatancy of the muddy sand of the Arenicola region of the shore at Whitstable. The results of tests made with the dilatancy viscometer originally used by Freundlich & Röder are shown not to be in clear agreement with the observed behaviour of the soil.

The electrophoretic mobilities of 13 enzymes in two species of Chthamalus, C. stellatus Poli and C. montagui Southward, were compared. These species differed absolutely for eight of the enzymes and exhibited some species-specific allozymes for a further four enzymes. No evidence of hybridization was found. The observed mean heterozygosity was 0087 for C. stellatus and 0179 for C. montagui.

A sample of ‘C. montagui’ from Venice differed from two samples from south-west England in external shell characters and in allozyme frequency for two enzymes. These differences are thought to be the result of a geographical cline rather than a distinct separation of subspecies.

Calyptogena gallardoi sp. nov. is described from eight articulated and 15 separated valves collected by dredge at ∼760 m depth off the Bay of Concepción, central Chile (∼36°S). In general outline, C.gallardoi sp. nov. is close to C. pacifica and to a new species of Calyptogena from Peru, from which it differs in details of the shell shape and hinge margin. Bivalves of the genus Calyptogena are typical constituents of marine chemosynthesis-based communities, and are therefore indicators of reducing environments. In the area of occurrence, the presence of C. gallardoi sp. nov. is related to methane seepage, associated in turn with the extensive gas–hydrate fields recently reported for the Chilean margin along 35°S to 45°S. Gas-saturated sediments as well as fragments of other chemosynthetic endosymbiont-containing clams of the families Vesicomyidae, Lucinidae, Thyasiridae and Solemyidae were also retrieved in the area.

Calyptogena gallardoi sp. nov. is the first species of Calyptogena s.s. and the second species of the family Vesicomyidae so far described for the south-eastern Pacific area.

During the last decades, the Mediterranean shallow-water benthic communities have experienced significant changes in taxa composition and distribution. These variations were related to a complex set of anthropogenic stressors as well as to mass mortality events starting from 1999 and related to the current climatic changes. To evaluate the effect of these changes on long-living species with a limited larval dispersal capacity, a quantitative and qualitative monitoring of the shallow-water hard bottom community structure was performed over a pluri-decennial interval of time. The aim of this work was the comparison of the quali-quantitative occurrence and seasonal cycles of several benthic taxa living on a rocky cliff of the Portofino Promontory (eastern Liguria, Mediterranean Sea), from 15 to 20 m depth. The studied community, within a Lithophyllo–Halimedetum tunae association, was analysed by sets of photographs repeated, exactly in the same site, at 25 years of distance (1987/88 and 2012/13). The results suggest that the macroalgal coverage of the surveyed cliff suffered, during the monitored span of time, a significant depletion in quali-quantitative terms, while the overall sponge coverage remained almost unvaried. Nevertheless, a discrete analysis of the most common sponge species present in the study area showed significant variations, with some taxa now more abundant (Axinella spp. and Agelas oroides), some virtually stable (Cliona viridis and the complex of red encrusting sponges), and others drastically depleted (Chondrosia reniformis, Phorbas tenacior, Acanthella acuta, Ircinia spp., Dysidea avara and Petrosia ficiformis). Finally, some sponge species showed clear seasonal cycles indicating recruitment periods and post-recruit mortalities.

A new member of the Chrysophyceae, Rhizochromulina marina gen. et sp.nov. is described by means of both light and electron microscopy of cultured material. Vegetative cells are non-flagellate and amoeboid with many fine beaded filipodia and a single golden-brown chloroplast. Zoospores are fusiform in shape and genuinely uniflagellate with no emergent vestigial second flagellum. They appear to possess the most reduced and phylogenetically advanced type of motile cell organization yet found in the Chrysophyceae.

During January 2003 the bathymetric distribution of the cephalopod fauna of the South Georgia and Shag Rocks slope (100–900 m) was investigated using a commercial bottom trawl. Forty-four trawl stations caught 193 cephalopod specimens including six species of octopod and seven of squid. The benthic octopods Pareledone turqueti and Adelieledone polymorpha were abundant in shallow water at South Georgia, being replaced by Thaumeledone gunteri in greater depths. However, neither A. polymorpha nor T. gunteri were caught on the adjacent Shag Rocks area. Two specimens of the deep-sea genus Graneledone were caught on the South Georgia slope. The most abundant squid species caught were Moroteuthis knipovitchi, Psychroteuthis glacialis and Slosarczykovia circumantarctica, which are primarily pelagic and may have been taken when their vertical migrations impinged on the slope.

The swimming methods and habits of certain Decapod larvse have been observed. The first larva of Munida bamffica was chosen for special attention. Such a study shows the importance of (1) orientation, (2) the presence of a reversal mechanism.

Observations on other types show these factors to be of great importance and also show that there are a great variety of attitudes in which larvæ swim.

Points in the relation of the larvæ to their environment were next considered; orientation is again important here, but whereas in Munida larvæ a “resting” orientation is found no such attitude is seen in Brachyurous zoeas.