The four charts produced in this number, showing as nearly as possible the positions of the various fishing boats in the neighbourhood of Plymouth, are a continuation of the series of charts already introduced in Nos. 3 and 4 of vol. ii. They represent the conditions found during last September, October, November, and December, and complete the year's observations.

To investigate the response of the fish community structure to a natural disturbance in their habitat, fish abundance, biomass and species composition were analysed in relation to temporal variability of environmental conditions in a seagrass Zostera marina bed. A total of 3024 fishes belonging to 46 taxa (22 families) were collected by quantitative sampling for 10 years from 2007 to 2016 in the Seto Inland Sea, south-western Japan. Seagrass shoot density decreased to less than 1/20 of its original density after disappearance of vegetation caused by heavy rain in the autumn of 2011 and the area did not recover for the next five years. In order to analyse temporal changes of fish community, the fishes were divided into three groups depending on their habitats or lifestyles: pelagic or migratory species (PM), sand or mud bottom-associated species (SM) and seagrass (Z. marina) – or substrate (rocky bottom including macrophytes) – associated species (ZS). Multiple regression analysis showed seagrass shoot density had the most significant effect on biomass of ZS among the three groups, with higher fish biomass under higher seagrass shoot density. Fish community composition changed after the disappearance of the seagrass vegetation coverage with an increase in abundance of SM during the five years of the post-disturbance period. Seagrass vegetation was concluded to affect temporal change of fish community structure through a stronger influence on fish species that are more dependent on seagrass beds as habitat.

A previous study detected mixing of two deeply split mtDNA clades (Clade I and Clade II) for Atlantic and Mediterranean populations of the medusozoan Pelagia noctiluca. The north hemisphere glaciations and the Messinian salinity crisis have been proposed as the two main biogeographic events related to the isolation between the Atlantic Ocean and the Mediterranean Sea. We tested if the splitting time between Clade I and Clade II of P. noctiluca was associated with one of these geological events. Our study was based on DNA sequence data of mitochondrial (COI and 16S ribosomal RNA) and nuclear (18S ribosomal RNA, internal transcribed spacer 1 and 5.8S ribosomal RNA) genes from populations of the Atlantic and Pacific Ocean and the Mediterranean Sea. The rise of the Isthmus of Panama was used to calibrate substitution rates for COI. This calibration was based on the detection of a shallow but significant genetic structure between P. noctiluca populations from the Pacific and the Atlantic Oceans. Considering our calibration for COI, we refute a possible origin of Clades I and II during the Messinian salinity crisis. Our estimates suggest the origin for a putative common ancestor of Clades I and II around 2.57 Ma (with 95% 2.91–2.22 HPD), roughly corresponding to the Gelasian stage of the early Pleistocene. These alterations include changes in the sea level and oceanic currents at the Strait of Gibraltar and other regions of the Mediterranean basin, and could explain the origin of the two P. noctiluca clades.

Cosmopolitan habitat-forming taxa of algae such as the genus Corallina provide an opportunity to compare patterns of biodiversity over wide geographic scales. Nematode assemblages inhabiting Corallina turves were compared between the south coasts of the British Isles and South Korea. A fully nested design was used with three regions in each country, two shores in each region and replicate samples taken from three patches on each shore to compare differences in the taxonomic and biological trait composition of nematode assemblages across scales. A biological traits approach, based on functional diversity of nematodes, was used to make comparisons between countries, among regions, between shores and among patches. The taxonomic and biological trait compositions of nematode assemblages were significantly different across all spatial scales (patches, shores, regions and countries). There is greater variation amongst nematode assemblages at the scale of shore than at other spatial scales. Nematode assemblage structure and functional traits are influenced by the local environmental factors on each shore including sea-surface temperature, the amount of sediment trapped in Corallina spp. and tidal range. The sea-surface temperature and the amount of sediment trapped in Corallina spp. were the predominant factors determining nematode abundance and composition of assemblages and their functional diversity.

Ethylacetate extract of the gorgonian coral Suberogorgia reticulata was obtained and its effects on the larval settlement by acorn barnacle Balanus (=Amphibalanus) reticulatus and pearl oyster Pinctada martensii and spore germination of green algae Ulva linza and U. lactuca and red alga Gracilaria tenuistipitata was assessed in this study. Results showed that no larval settlement or spore germination occurred at the dose of 100 μg cm−2. Both larval settlement and spore germination were significantly inhibited by the extract at doses of 1 μg cm−2 for B. reticulatus, 0.1 μg cm−2 for U. linza and U. lactuca, and 0.01 μg cm−2 for P. martensii and G. tenuistipitata. It could be concluded that the gorgonian coral S. reticulata may produce bioactive substances with a broad spectrum of activity against a range of marine sessile organisms including macroalgae and invertebrates.

Sampling in subtidal waters of the Persian Gulf revealed a new species of ghost shrimp from the family Gourretiidae. Gourretia qeshmensis sp. nov. resembles G. sinica from the South China Sea and G. manihinae from Tanzania. Gourretia qeshmensis sp. nov. differs from these two species by characters of the ischium of the large cheliped, pereopod 3, exopod of the uropod and maxilliped 3.

A new species of Leptostraca, Nebalia cambodiana sp. nov. (Crustacea: Malacostraca), is described from Cambodia. The specimen was collected by light traps on a diving deck where the bottom consisted of fine sand and gravel. The new species is distinguished from all other known species of Nebalia by the following characteristics: rostrum very long, length nearly 3.5 times width; a compound eye with one distinct dorsal papilla and four small lobes on distal margin; an antennular flagellum with nine articles; the fourth article of the antennular peduncle with only one distal thick seta; the antennular scale is elliptical, with a length that is 2 times the width; exopod of the second maxilla is the same length as first article of its endopod; pleonites 5 to 7 with rounded denticles along their posterior dorsal margins; the protopod of pleopod 4 lacks serration along the posterior margin; and anal plates with distinct lateral ‘shoulder’.

The new species is the first species of Leptostraca found in South-east Asia. In this paper, we provide illustrations and a detailed description of the diagnostic characteristics of N. cambodiana sp. nov.

This study investigated the features of mudballs produced by male and female Uca annulipes. Both sexes formed mudballs from mud excavated from within the burrow during the final hour of the low tide period. Males placed the centre of the mudball aggregation and the furthest mudball significantly further from the burrow than females. These observations suggest that the placement of male mudballs was not simply a by-product of burrow excavation.

Imposex, the development of male sexual organs in female gastropods, is mainly induced by organotin compounds used as biocides in antifouling paints. As part of our continued efforts to report the occurrence of imposex gastropods along the coast of mainland China, this study investigates the imposex prevalence in Mauritia arabica (Mesogastropod: Cypraeidae). A total of 529 adults were collected from 11 sites in south-eastern China between March 2001 and June 2005. Of these, 303 were females and 226 were males. Imposex is classified into six stages representing the sequence from the initial appearance of the seminal groove or small penis (S1) to the point when this duct blocks the pallial oviduct and aborted egg capsules appear (S6). All six stages of imposex were found in M. arabica with three different types (a, b and c) of expression in stages 1 and 3, two types (a and b) in stage 2, and one type in stages 4, 5, and 6. Imposex development was also measured by various indices such as the vas deferens sequence index (VDS), female penis length (FPL), percentage of affected females (%I), the relative penis length (RPL), and relative penis size (RPS—the cubed form of RPL). Imposex individuals were found in all 11 sites with %I ranged from 26% to 100%. Excluding the data from site 3 (with only one female and one male), VDS scores ranged from 1.05 to 4.07, with an average of 2.86, and the RPL ranged from 0.9 to 56.8. High correlations were observed among VDS, FPL, %I, RPL, and the RPS. Our findings suggest that M. arabica is an ideal bioindicator for organotin pollution along the south-eastern coast of China, and can be used in conjunction with the rock shell, Thais clavigera, a well-established bioindicator of tributyltin and triphenyltin contamination. To our knowledge, this is the first detailed report of imposex in M. arabica.

A specimen of Arnoux's beaked whale was recorded from the coast of Brazil on 4 August 1993. The specimen was identified from the skeleton in 1994. Arnoux's beaked whales (Berardius arnuxii) are known to have a circumpolar distribution in the Southern Hemisphere, from the Antarctic continent and ice edge (78°S) north to about 35°S in the southern Pacific, southern Atlantic, and Indian Ocean. Few sighting and stranding records are known. Its distribution in deep and cold waters, mainly far from the coast and in higher latitudes, is probably the main reason preventing the collection of more information on the biology of this species. It is still considered as ‘insufficiently known’ by the International Union for the Conservation of Nature and Natural Resources. Sighting records are more common in Antarctic waters, where some individuals sometimes become trapped in ice holes, and in the South Pacific. Strandings are relatively rare. About 30 strandings were reported around New Zealand, and single ones occurred in southern Australia, in South Africa, Argentina and the Falkland Islands. The majority of records occurred south of the latitude 40°S (Ross, 1984).

Three new species of Strongylacidon from north-east Brazil are described: Strongylacidon oxychaetum sp. nov. and Strongylacidon solangeae sp. nov. from Bahia State, and Strongylacidon chelospinata sp. nov. from Fernando de Noronha Archipelago, Pernambuco State. Strongylacidon oxychaetum sp. nov. has thinly encrusting shape with lobate projections, strongyles, oxychaetes and arcuate chelae; S. solangeae sp. nov. is characterized by having massive shape with hispid surface, strongyles and unguiferate chelae; and S. chelospinata sp. nov. present thinly encrusting shape, strongyles, and arcuate isochelae with large spines on the outer edge of the axis. An identification key for the nine valid species of Strongylacidon from the Tropical Western Atlantic is provided. New morphological characters, viz., oxychaetes and spined arcuate isochelae (here termed acanthochelae), are added to the definition of the genus Strongylacidon and of the family Chondropsidae.

The specimen which forms the subject of this note was sent to Dr. Allen by Miss Olivia L. Fox, of Falmouth, at the beginning of December, 1906, preserved in formalin. Dr. Allen sent it to me in London, and requested me to study and describe it. The specimen is 4·4 cm. in length, and presents a condition which has never previously been described in any species of flat-fish. I have examined it with great interest, and would express here my thanks to Dr. Allen for sending it to me.

The seastar Ophidiaster ophidianus is a vulnerable and protected species in the Mediterranean Sea but is common on North Atlantic islands such as the Azores and Madeira archipelagos. This work presents new insights into the phylogeography and genetic diversity of O. ophidianus from the Azores, based on 67 sequences of the 16S mitochondrial gene and 46 sequences of the nuclear ATP intron 5 gene. Twenty-six samples from the Mediterranean and seven samples from Madeira were used as out-groups. The results revealed that there is a lack of genetic differentiation between O. ophidianus from the Azores and the out-groups. All, therefore, belong to the same lineage and argue for a fast and recent range expansion of this species into the Azores. Our results also suggest the existence of distinctive periods of strong gene flow followed by periods of either low or non-existent gene flow between the Mediterranean Sea and this archipelago, which could explain the presence of private haplotypes in all studied areas.

Sixteen sponge species were recorded from Little Letite Passage, an area of highvelocity tidal currents located in the Bay of Fundy near Deer Island, New Brunswick, Canada. Of these 16 species, four species (Myxilla fimbriata, Hymeniacidon heliophila, Hemigellius sp. aff. flagellifer, and Crella rosea) have not previously been recorded from the Bay of Fundy. One new species, Hymedesmia canadensis, is described, based on the presence of a second peculiar chelate microsclere added to the spicule armament.

Presumptive viral erythrocytic necrosis (VEN) was recorded from 1/4 of the benthopelagic fish Coryphaenoides (Nematonurus) armatus (Teleostei: Macrouridae) trawled from the abyss west of Portugal. In a blood smear made from the caudal vein of this fish, 8·6% of erythrocytes contained 1–2 intracytoplasmic inclusions which were invariably round and 1·13 ±0·43 μm in diameter. An eosinophilic granular area accompanied many inclusions. In comparison with erythrocytes from uninfected specimens of C. (N.) armatus, most of those from the infected fish were larger. Erythrocytes with suspected VEN exhibited either normal staining, or were pale, with swollen or crenated nuclei which were often displaced to the cell periphery. Erythrocyte ghosts, with and without inclusions and granules, were present in the same infected fish, suggesting osmotic damage to red cells resulting from the infection. None of 13 other C. (N.) armatus and 27 fish examined from collections made south of Maderia, representing another 20 species of benthic, benthopelagic and mid-water fish, had detectable infections.

In a recent paper (Bagenal, 1955) on the growth rate of the Long Rough Dab Hippoglossoides platessoides (Fabr.) in the Clyde Sea area, a serious mistake was made.

The ages of 1561 Long Rough Dabs, which were collected from October 1953 to September 1954, were determined from an examination of the otoliths, and from the age analysis each fish was allocated to a population f to a, de-pending on when it was supposed to have spawned. This procedure was designed to obviate the difficulty during the winter and spring when fish of the same year-class would be grouped differently according to the condition of the otolith edge.

Nymphonella tapetis (Pycnogonida, Ascorhynchidae) is an endoparasitic sea spider affecting bivalves. Recently, sea spiders have been found on a massive scale in the commercially important Manila clams (Veneridae, Ruditapes philippinarum) in Japan (Tokyo Bay). Simultaneously, mass mortality has occurred in this area. Local fishers assumed that this mass mortality was caused by the parasitic sea spider, despite the effect of the parasite and parasite intensity on the host being unknown. To evaluate the susceptibility of the Manila clam to sea spider infestation and the impact on mortality levels, we established six treatments at different infection intensities (density of newly hatched larvae of sea spiders) over a 6-month long laboratory experiment. We monitored mortality and three susceptibility indices (clearance rate, sand-burrowing speed and adductor muscle strength) under sufficient food conditions. Parasitization by sea spider affected clearance rate and sand-burrowing speed. The pattern of parasitic intensity effects on survival of Manila clam hosts was shown to be dependent on the levels of parasite numbers, i.e. clams with lower parasitic levels (total of <200 hatching larvae of sea spider given to a host) have a higher survival rate, and high mortality of host clams was shown in excessively higher parasitic densities (400–4000 individuals). Such pattern of parasitic effects on host survival might be one of the causes of mass mortality of Manila clams occurring in the field.

Biological data are presented on two specimens of Taningia danae, an adult female caught by a trawler in Galician waters (north-west Spain) and a juvenile caught in a deep-water research trawl in Scottish waters (UK). The species has not previously been recorded in either area, although its presence has been inferred from beaks found in sperm whale stomach contents.

A temporal analysis of the benthic polychaete community and its relationship with environmental variables was conducted by comparing coastal sediment samples collected in three separate sampling events between 1998 and 2013 from the southern end of the Southern California Bight (SCB). Environmental variables indicated a spatio-temporal increase of the sand fraction in sediment composition. Station stratification by depth from shallow to deep, and a reduction of trace metal enrichment (Co, Cr, Cu, Mn, Ni, Pb and Zn) was also found. There was a notable change in polychaete family composition due to high abundances and frequency of Spionidae, Chaetopteridae and Phyllodocidae in 2013, especially close to the Binational wastewater treatment plant discharge. An increase in polychaete abundance, richness and diversity was indicative of a probable relationship with regional weather conditions (El Niño-Southern Oscillation and recent drought events during sampling) along with local anthropogenic discharges of wastewater treatment plants in the area.

The antifouling activity of a series of hexane, ethyl acetate, ethanol and aqueous extracts from 11 species of marine sessile organisms collected from the south-east coast of China was investigated. Settlement inhibition of cyprid larvae of the barnacle Balanus albicostatus was used to evaluate their antifouling efficacy. Screening of the 44 extracts showed antifouling activity in 90.9% of the hexane extracts followed by 90.9% of the ethyl acetate, 72.7% of the ethanol and 36.4% of the aqueous extracts. The hexane extracts of Tubularia mesembryanthemum, Notarcus leachii cirrosus and Styela canopus, the ethyl acetate extracts of Bugula neritina and N. leachii cirrosus, and the ethanol extracts of B. neritina and Anthopleura sp. were the most active in inhibiting the settlement of B. albicostatus, with EC50 values all below 50 μg/ml. At least one of the four extracts of each tested species exhibited antifouling activity, suggesting that all 11 marine sessile organisms contained antifouling substances and they may have evolved chemical defences against biofouling on their surfaces.