The light energy emitted in a flash by single elytra of two polynoid worms has been measured, viz. Acholoë astericola and Lagisca extenuata. Maximal emission occurs at 515 mμ. Mean values for light intensity per flash from 1 elytrum are: Lagisca, 1·8 × 10−10 μJ/cm2 receptor surface at I m ; Acholoë, I·II × 10−8 μJ/cm2 receptor surface at I m. The light emitted in I flash by a single photocyte of Lagisca is 0·12 × 10−12 μJ/cm2 receptor surface at I m. It is estimated that the light from I elytrum of Lagisca could be seen by the dark-adapted human eye at 1·2 m in air.

Two new species of zoarcid fish, Ophthalmolycus eastmani sp. nov., and Ophthalmolycus polylepis sp. nov. are described from specimens collected from the Bellingshausen Sea and Gerlache Strait, Southern Ocean, at depths of 1837 and 1056 m. Ophthalmolycus eastmani can be distinguished from its congeners by the following combination of characters: two posterior nasal pores; epidermal prickles on lips and snout; gill slit extending ventrally to the lower margin of the pectoral fin base; vertebrae asymmetrical 26 − 27 + 91 − 92 = 117 − 118; dorsal fin rays 111–113; dorsal fin origin associated with vertebra 6, with no free pterygiophores; pectoral fin rays 17–18; two postorbital pores; lateral line with ventral and mediolateral branches; scales extending anteriorly to just anterior to the anal fin origin; six branchiostegal rays; oral valve nearly reaching the anterior edge of vomer; palatine teeth in two rows anteriorly; 3–5 pseudobranch filaments; two well developed pyloric caeca; pelvic fin and vomerine teeth present. Ophthalmolycus polylepis can be distinguished from its congeners by the following combination of characters: two posterior nasal pores; epidermal prickles on lips; gill slit extending ventrally just to below mid-pectoral fin base; interorbital pore present; two postorbital pores; lateral line triple with ventral, mediolateral and dorsolateral branches; scales extending anteriorly to predorsal area, abdomen, pelvic fins base, and pectoral fins base and axil; vertebrae asymmetrical 22 + 76; dorsal fin origin associated with vertebra 5; pectoral fin rays 18; six branchiostegal rays; oral valve overlapping the anterior edge of vomer; two rows of palatine teeth anteriorly; two vestigial pyloric caeca and 2 pseudobranch filaments; pelvic fin and vomerine teeth present. A key to the species of Ophthalmolycus is provided.

The present study investigates the potential of algal oil (extracted from Nannochloropsis salina), cod liver oil, olive oil and yeast for live prey enrichments in A. percula larviculture. After hatching, larvae were divided into six experimental groups as follows. Larvae fed on non-enriched (control), cod liver oil enriched, olive oil enriched, algal oil enriched, yeast enriched live prey and wild collected mixed plankton. Growth (total length, standard length, body depth, head depth and weight), survival, carotenoid and PUFAs content were observed at higher levels in juveniles fed on wild plankton and algal oil enriched diets. Thyroid hormones (T3, T4 and TSH) levels were also higher in the juveniles fed on wild plankton followed by algal oil enriched diet. Based on the present study, it can be concluded that mixed zooplankton and algal oil enriched rotifers Brachionus plicatilis and Artemia nauplii may be considered suitable live prey for clownfish larviculture.

The reproductive cycle, development and spatial organization of the gonads of an exotic ascidian, Styela clava, were studied in Cork Harbour, Ireland. Monthly histological samples enabled the division of gonad development into six main stages, ranging from `inactive' to `regression'. Gonad development was asynchronous in the population, with more than one stage being found within some months. Gametogenesis was observed from February–November, but peaked between August–October. Spawning took place in September–October, followed by gonad regression in November–December.

This study focused on the breeding period of Stenorhynchus seticornis (Brachyura, Majidae, Inachinae) in the south-eastern Brazilian coast. Monthly collections were accomplished from January to December of 2000. A catch effort of approximately 4 h was allocated to each monthly survey. The breeding intensity was determined as the percentage of ovigerous crabs within the whole adult female population. A total of 204 adult females were obtained, from which 74·5% presented eggs attached to their pleopods. Ovigerous females were observed year-round, usually comprising more than 60% of sampled adult females. The ovigerous frequency was not found to be correlated with either temperature or salinity.

A new species, T. strongylata sp. nov. is described on the basis of material collected from the Pacific Ocean. The new species is characterized by the presence of sinuous strongyles. Moreover the incomplete description of T. simplex (Sarà, 1959) is implemented on the basis of new abundant material allowing, for the first time, the complete description of the skeleton of a Triptolemma species and the detecting of the presence of monaxonic spicules in the spicular complement of the genus. The skeleton is composed of a thick crust of disorderly arranged mesotriaenes and scattered microscleres, supported by diverging spicule tracts formed by oxeas towards the surface. Both species were recorded associated to boring sponges (Spiroxya and Cliona) in excavations of the calcareous scleraxis of precious corals or in organogenic concretions. In the cavities where the tissue of Triptolemma was recorded the wall of the excavation partially lost its typical pattern characterized by ovoid scars and became irregularly eroded. Our hypothesis is that Triptolemma insinuates inside the erosions produced by other sponges and it is able to enlarge them by an etching mechanism based on chemical dissolution only.

The horse mussel Modiolus barbatus is a marine benthic bivalve, distributed mainly in the Mediterranean basin, that constitutes a fishery product of high economic importance and a promising candidate for aquaculture. The current study provides the first insights regarding the genetic profile of M. barbatus populations from the eastern Mediterranean, by analysis of a partial segment of the mitochondrial COI gene in individuals collected from five sampling localities within the Aegean Sea. To the best of our knowledge, the derived haplotypes represent the first DNA barcodes of M. barbatus from the entire Mediterranean region. Maximum likelihood phylogenetic analysis revealed that M. barbatus from the North Sea and M. barbatus from the eastern Mediterranean may not belong to the same species and as a consequence, there might be three species of the genus Modiolus in Europe. On the other hand, eastern Mediterranean M. barbatus haplotypes were found to be more closely related to the Asian-Pacific Modiolus species. All geographic populations analysed displayed high levels of genetic diversity, in terms of haplotype and nucleotide diversity and a considerable number of unique alleles. Divergence among populations was found at generally low levels, corresponding with the majority of pairwise Fst values not being significant. These findings suggest no population structure and high levels of gene flow, a common feature observed in marine bivalves with long pelagic larval phases.

Lissarca notorcadensis, a small pallial-brooding mollusc with a circum-Antarctic distribution, is frequently found attached by stout byssal threads to the spines of sea urchins. Here, complete ontogenetic series can be found. Using standard, structural definitions, the prodissoconch I of L. notorcadensis is small compared to the large prodissoconch II, a feature atypical of brooded young and possibly reflective of a planktotrophic past. Fine commarginal striae are found on prodissoconch II of this subtidal clam, which also possesses more pronounced commarginal striae on the dissoconch prior to brood release. The provinculum is retained and remains functional well into adulthood. A small central ligament pit is present through the postlarval stages. This develops into a large, triangular pit in adulthood that shows obvious growth lines. Calcareous, presumably aragonitic fibres develop in the ligament of specimens still retained in the adult brood. Five to six adult hinge teeth are formed on either side of the ligament. Alignment of shell valves by these well-developed teeth is augmented by retention of larval denticles. The functional and structural demise of the provinculum occurs between 4 and 7 mm shell height and results from denticle erosion and subumbonal shell overgrowth. Many canals permeate larval and adult valves, but external pores in the adult shell differ from those of the larval shell and could indicate mode of formation. Prodissoconch form, provinculum retention, and shell canals are considered primitive traits.

A new species of the genus Caprella (Crustacea: Amphipoda: Caprellidea) is described based on the specimens collected from the Strait of Gibraltar, southern Spain. The new species, Caprella caulerpensis, was found living in mud bottoms with the seaweed Caulerpa prolifera (Forskål) Lamouroux. Caprella caulerpensis can be distinguished from the most related species, Caprella rapax, mainly by the number of articles in the flagellum of antenna 1, the morphology of the dactylus of gnathopod 2 and the pereonites length.

Amiantis umbonella is distributed throughout the coast of the northern Persian Gulf. This study of 893 clams provides data on reproduction, growth and production for the period April 2007 to March 2008 from two transects along the Bandar Abbas coast. Histological preparations showed six stages of gametogenic development: resting stage (Stage 0), early active (Stage I), late active (Stage II), ripe (Stage III), partially spawned (Stage IV) and spent (Stage V). The specimens were gonochoric and showed synchronized spawning. The reproductive cycle commenced in September and finished in March with one major spawning event in January which correlated with lower sea temperature. Von Bertalanffy growth parameters for the sample were asymptotic length (L∞) = 58–62 mm, growth constant (k) = 0.28–0.29 yr−1 and length zero (t0) = –0.48 –0.47. The mean annual clam abundance, mean biomass and production were 10 individuals. m−2, 5.7 g shell free dry weight (SFDW) m−2 and 0.495 g SFDW m−2 yr−1, respectively.

A description of a new species of Magelona, M. parochilis sp. nov. is presented, based on material collected from the Yellow Sea, China. The new species belongs to the ‘Magelona mirabilis group’ of magelonids, possessing a rounded prostomium, lacking prostomial horns and specialized chaetae on chaetiger 9. Paired anteriorly open pouches are present between chaetigers 11–12 and 14–15 (occasionally between chaetigers 17–18). Magelona parochilis sp. nov. inhabits intertidal zones and shallow subtidal waters characterized by sandy mud.

It has been suggested in Part IV of these contributions that the larger diameter of centric diatom cells met with in collections made in the oceans in the lower latitudes might be caused in part by the relatively greater grazing known to take place in these areas (Steemann-Nielsen, 1962; Lohmann, 1912). Eight series of experiments were therefore carried out to determine any effect that might be attributed to animals grazing on populations of centric marine diatoms.

A small orange-coloured Enchytraeid Oligochaete has been known for some years to occur fairly abundantly in certain sheltered parts of the shore on the Cumbraes. It is also generally present, though scarce, on exposed parts of the shore. Hitherto it has been confounded with other species of Lumbricillus, but is now described as a new species.

Recently the influence of an electric light on the capture of the main groups of deep sea animals by a midwater trawl was described and discussed (Clarke & Pascoe, 1985). With regard to fish it was shown that at depths close to 800 m the total number, the total volume, the volume of the ten largest and the volume of the single largest fish all increased significantly when an electric light was used on the headline of the trawl when compared with controls with the light off. These experiments were carried out both in the Bay of Biscay and off Madeira.

The diet and feeding habits of the sharpsnout seabream, Diplodus puntazzo, from the Gulf of Gabès were investigated using stomach contents of 490 specimens ranging from 12.6 cm to 26.1 cm total length in size and from 29.95 g to 230.83 g in weight collected from commercial catches between April 2008 and March 2009. Of the total number of examined stomachs, 279 were empty (%VI = 56.94). This percentage varied significantly with months, attaining a maximum in spring (74.88%) and a minimum in autumn (37.38%). Eight major taxa were identified (Plantae, Spongia, Tunicata, Echinodermata, Crustacea, Annelida, Mollusca and Teleostei) in stomach contents of D. puntazzo. Plants were the most important food source, constituting 89.88% of the total Index of relative importance. The other groups, such as teleosts, molluscs, crustaceans and annelids represented accessory food. Significant differences in diet were observed in relation to season. Plants were the most important food source item in all seasons, especially during the autumn. The estimation of trophic level gave an average of 2.57 ± 0.2 for the whole population of D. puntazzo in the Gulf of Gabès. Based on the composition of its diet, this species may be considered as an omnivorous fish with a preference for vegetable material, and showing specialist feeding strategy.

Elemental composition and ontogenic change patterns of Sr and Ca were examined in conger eel, Conger myriaster, otoliths. Accumulations of the major elements of seawater, K, Mg, and Na, into otoliths were smaller than the accumulations of 19 other minor elements whose concentrations were determined. Strontium content and Sr:Ca ratios in the otolith fluctuated during the life history transect at 100 to 200 μm from the core of the otolith, indicating a period of metamorphosis. Changes in Sr content and Sr:Ca ratios may be associated with internal physiological factors such as metamorphosis in the early developmental stage in the conger eel.

A saline pond known as the ‘Salts Hole’ at Holkham on the north coast of Norfolk is situated between the pine-covered sand-hills and the fields that have been reclaimed for agriculture from pre-existing salt-marshes. It has a salinity of about 75% of that of sea water and supports a peculiar relict marine fauna. Except for the rare occurrence of flooding for a short period, as in the great storm of 1953, the pond has probably been cut off from the sea for about 250 years. It presents three problems: how it got its fauna and flora; how its marine character is maintained; and how the pond originated geographically. The fauna and flora, as described, show the pond as a refuge where various marine and brackish species have managed to maintain themselves and co-exist in water outside their normal and differing ranges of salinity. The main character of the pond is kept remarkably constant with respect to salinity, alkalinity, temperature and oxygenation. The pond is a study in ‘natural engineering’, constituting a natural marine aquarium with natural controls. It is fed near the level of high-water neap tide by continuous flow from a salt spring of very constant salinity supplied from water contained in the extensive coastal sands. Its only apparent artificial feature is the outlet controlled by a dam through a culvert into a ditch that conveys its water through the fields to the sea at Wells nearly two miles away. Search in the muniment room at Holkham Hall brought to light maps dating back to Elizabethan days which show the history of the Salts Hole.

The seasonal variation of the inshore fish assemblage of Anegada Bay, North Patagonia, Argentina is described here. Three areas were seasonally sampled from 2007 to 2009 by means of a gang of bottom gill-nets. We found 21 coastal fish species, but species richness and fish number and weight changed throughout the year. The six species classified as dominant have national and regional value for artisanal and recreational fishing and were responsible for the seasonal variation in the fish assemblage. Both cluster and non-metric multidimensional scaling analyses based on fish number and fish weight indicated two major sample groups encompassing spring and summer (the warmer seasons) and autumn and winter (the colder seasons). The fish assemblage had higher species richness, dominance and abundance during the warmer seasons than during the colder seasons in the same years and at the same sites. Water temperature was the main environmental factor structuring the fish assemblage in Anegada Bay. We suggest that partial breeding migration toward the bay during warmer months could explain the seasonal pattern observed. Nevertheless, variation in temperature conditions agreed well with the pattern of seasonal changes, leading to an interaction between abiotic and biotic influences in determining the variability in this seasonal fish assemblage. We conclude that an understanding of species temporal and spatial patterns in areas of high ecological and economic value, as exemplified by Anegada Bay, are essential for the implementation of a management approach oriented toward ecosystem sustainability.

1. A brief survey is given of the methods for the estimation of mercury by means of dithizone.

2. The precautions necessary in mercury estimations are outlined and the stability of dithizone in chloroform solutions shown to be satisfactory.

3. Data are presented on the rate of extraction of copper, from sea-water solutions, at low pH values with chloroform and carbon tetrachloride solutions of the reagent. Using the former solvent the rate of extraction of copper is shown to be slow, while mercury is rapidly extracted under the same conditions.

4. The use of potassium cobalticyanide in combination with a chloroform solution of dithizone has enabled a method to be developed which eliminates interference of copper in mercury estimations; with the procedure given, mercury in concentrations of 1 to 55µg/l. may be determined in the presence of copper concentrations up to 69 mg./l.

5. Copper may be determined in the same solution subsequent to the mercury estimation by the use of sodium diethyldithiocarbamate, after the solution has been made alkaline with ammonium hydroxide.