Megafauna from the Charlie–Gibbs Fracture Zone (northern Mid-Atlantic Ridge) based on video observations from submersibles was analysed. Species composition was examined, frequency of species occurrence on the fracture wall and its base (depth range from 1740 m to 3100 m) and density of megafauna in the depression at the fracture zone bottom (4200–4500 m depth) were evaluated. At depths between 1700 and 2500 m hexactinellid sponges were most common and diverse. Deeper parts of the wall and its base were dominated by anthozoans (especially gorgonian corals) and echinoderms. A set of dominant species in the lower bathyal in the study area was different from that on the lower continental slope in the north-east Atlantic (Porcupine Seabight). An important contribution to local species richness of ‘rare’ species was demonstrated. The elpidiid holothurian, Kolga nana, occurred at high density in the abyssal depression.

The diets and trophic ecology of the dominant fish species from the marine coastal region of Aveiro (north-western Portugal) caught during a summer survey were studied. Mysids were the most important prey group for the fish assemblage analysed. As a consequence, there was a high dietary overlap between species and a low incidence of piscivory. Nevertheless, a clear segregation of trophic niches was observed, with one group (comprising the species Chelidonichthys cuculus, Callionymus lyra, Dicologlossa cuneata and Pomatoschistus lozanoi) showing a stronger preference for infaunal epibenthic prey, such as polychaetes and amphipods, another group (including Arnoglossus imperialis, Arnoglossus laterna, Chelidonichthys obscurus, Chelidonichthys lucernus, Echiichthys vipera, Pagellus acarne and Trisopterus luscus) preying mostly upon suprabenthic prey, mainly mysids, and a third group (Engraulis encrasicolus and Trachurus trachurus) feeding largely on planktonic prey like copepods. Some species, including A. imperialis, C. lyra, E. vipera, T. trachurus and T. luscus, showed ontogenic diet shifts that may be related to the habitat occupied by different size-classes and/or to their ability to capture prey of different size.

Mesozooplankton was studied during 2008 in coastal waters of the İskenderun Bay in order to determine seasonal changes in abundance, biomass, community structure and their relationship with environmental factors. Samples were collected seasonally at five stations using WP-2 net of 200 µ mesh size by vertical hauls. A total of 23 planktonic groups including 30 copepod species, 4 cladocerans and 4 chaetognaths were identified. Copepods were the most important group during the whole period of survey. Penilia avirostris was found to be dominant in spring, while Paracalanus parvus in summer and winter, and Acrocalanus gibber in autumn. Mesozooplankton abundance varied from 438 ind m−3 (autumn) to 7163 ind m−3 (spring), while biomass varied between 2.2 mg m−3 (summer) and 52.9 mg m−3 (autumn). Differences in abundance and biomass between seasons were statistically significant (P < 0.01). Clear seasonal distribution patterns were observed in the area. Two peaks in abundance were defined: a major peak in spring and a second minor one in autumn. It seems that the trophic element was the main factor affecting the density distribution of zooplankton populations, whereas species distributions were more affected by hydrographical parameters, namely: seawater temperature and salinity.

Understanding the spatial distribution of fish species and fish trophic guilds in reef environments may help improve our knowledge about ecological relationships and therefore favour sound strategies for sampling, coastal management and conservation policy. To verify if small-scale changes are important in forming the fish community structure at a tropical rocky coastal island, we assessed the depth, structural complexity and wave exposure gradients. The community structure changed along all gradients analysed. The trophic guilds found on the sheltered, low and intermediate exposure zones, in the deepest areas and in areas of highest structural complexity showed significant differences when compared with the general assemblage. Rocky reefs, even of narrow (transversal) extension, can show great changes in fish community structure at so small a scale that these changes are generally overlooked. The relationships evidenced between community and environment provide strong support for the importance of considering a wide array of such distinct environmental conditions when determining the structure patterns of the community.

There have been recent attempts to improve our knowledge about dinoflagellates of the order Dinophysales either in Mexican marine waters or worldwide, and although new records and even new species have reliable illustrations and descriptions, this group is so diverse that it needs to be studied in more detail. This paper is the product of the analysis of net phytoplankton material collected from coasts of the tropical Mexican Pacific (Gulf of California, Central Mexican Pacific and Gulf of Tehuantepec), and the southern Gulf of Mexico. Material was studied using light microscopy and scanning electron microscopy (SEM). Eleven taxa (10 species and one variety) of the section Hastata were fully identified, with nine species studied for the first time by electron microscopy (only Dinophysis hastata and D. schuettii had been previously studied by SEM), and including seven new records for the Mexican Pacific (Dinophysis monacantha, D. nias, D. phalacromoides, D. pusilla, D. swezyae, D. uracantha var. mediterranea, and D. uracanthoides), and one new record for the Gulf of Mexico (Dinophysis uracanthoides). Two species remain as unidentified, as only one specimen of each was found. Additionally, we studied in detail the new species, Dinophysis conjuncta sp. nov., for which a full description is provided. Descriptions, measurements, illustrations and local distribution data are provided for each species.

The morphogenesis and morphology of the marine benthic ciliate Certesia quadrinucleata collected from seawater in Nagasaki Mie Port, Japan, were investigated using microscopic observation of live and protargol-stained specimens. In terms of its morphology, the current isolate possesses diagnostic features of the genus and the species: a row of left marginal cirri, a prominent paroral membrane, 11 frontoventral cirri scattered in frontoventral area, five highly developed transverse cirri, four macronuclear nodules, five dorsal kineties and a caudally located contractile vacuole. Its morphogenesis belongs to the ‘Certesia’ subtype, and main events can be summarized as follow: (1) the oral primordium in the opisthe develops de novo in a subcortical pouch; (2) the old paroral membrane is completely replaced by the new one in the proter, but the parental adoral zone of membranelles is wholly inherited; (3) five streaks of cirral anlagen are formed in a primary mode for the proter and the opisthe, which gives rise to cirri in the pattern of 3:3:3:3:3 from left to right; (4) the leftmost frontoventral cirrus develops de novo on the cell surface in both dividers, and has no connection with the undulating membrane anlage; and (5) the anlagen for marginal cirri and dorsal kineties occur intrakinetally. Current observations confirm the separation of Certesiidae from other euplotids at the familial level.

Near-shore benthic sediment samples collected at low tide from the western Atlantic Ocean (Sable Island, Nova Scotia, Canada) and the eastern Pacific Ocean (Haida Gwaii (Queen Charlotte Islands), British Columbia, Canada) were searched for little-known species of the rhizarian (Cercozoa) genera Pinaciophora, Rabdiaster and other related rotosphaerids. Several representatives with complete investitures of silica-scales (the structure of which is taxonomically diagnostic) were studied by transmission and scanning electron microscopy. The validity of the genus Pinaciophora (sensu Penard, 1904) as defined by a single type of plate-scale only, was strengthened by the discovery of Pinaciophora rubicunda and of another previously undescribed entity, both of which lacked spine-scales. Several earlier reports of loose scales from marine habitats, and erroneously identified as the freshwater P. fluviatilis, might be assigned to P. marina sp. nov. The new genus Thomseniophora was erected to include all ‘Pinaciophora' previously known to produce spine-scales and seven new taxa were described. Six other little-known species of Thomseniophora, Pinaciophora and Rabdiaster were described from the Canadian west coast (Pacific Ocean) including one new species of Pinaciophora. The addition of Thomseniophora brings the number of genera assigned to the Rotosphaerida to six: Pinaciophora, Thomseniophora, Rabdiaster, Rabdiophrys and Pompholyxophrys. The presence of several apparently closely related taxa in the same collection (same location and sampling date) strengthens the conclusion that relatively small differences in the morphology of their siliceous scales were more likely caused by genetic differences than by environmental influences.

Six new marine species of the silica-scaled heterotrophic genus Thaumatomastix are formally described: two were found in Canadian Atlantic Ocean coastal waters (T. asymmetrica sp. nov. and T. sablensis sp. nov.) and four from Canadian Pacific Ocean coastal waters (T. inornata sp. nov., T. multipora sp. nov., T. gwaii sp. nov. and T. curvata sp. nov.). These discoveries more than double the number of known marine species of this genus from four to ten. The scale structures of all differ significantly from those of previously known species and therefore warrant erection as new species. Amended descriptions of two previously little-known freshwater species (T. triangulata and T. nigeriensis) are provided based on specimens found in freshwater ponds and lakes in Ontario, Lanada, and provide evidence refuting the recent published proposals to transfer T. triangulata back to the photo-autotrophic genus Chrysosphaerella and to transfer T. nigeriensis to the related thaumatomonad genus Reckertia. Until now, all known species of Reckertia (including several taxa previously classified in Thaumatomastix) were marine. This paper describes the first known freshwater species of Reckertia (R. hindoni sp. nov.) found in two separate Ontario ponds. The similarities and differences among many of the marine and freshwater species of Thaumatomastix suggest a common ancestor but significant evolutionary divergence over time and space.

The genus Histodermella grows to four species with the addition of H. kagigunensis sp. nov. from the North Pacific. The new species is described and compared with all congeners. Histodermella kagigunensis shows affinities to H. ingolfi Lundbeck 1910 as it has the same spicule types but differs clearly in size, habitus and the dimensions of two occurring spicule types. The discovery of H. kagigunensis represents the first record of the genus Histodermella in the North Pacific Ocean.

Serpulid polychaetes are often important components of marine communities, yet current knowledge of serpulid reproduction, development and settlement is largely based on the study of only a few species. This study examined whether spawning and sexual development of the mid-intertidal serpulid Spirobranchus cariniferus are typical of patterns observed in other serpulids, and also examined the effect of diet on larval development and identified cues that induce metamorphosis. Populations of S. cariniferus on the east and west coasts of New Zealand's North Island had an extended spawning season with a high proportion (75–100%) of individuals carrying ripe gametes at any given time from the late spring to early autumn, consistent with other serpulid species. However, contrary to proposed patterns of sexual development in serpulids, sex-ratios and average male and female body masses suggest S. cariniferus are not protandric hermaphrodites. A diet experiment revealed that larval growth was fastest when provided with a mixed diet of three algal species. Solutions of 3-isobutyl-1-methylxanthine at a concentration of 10−4 M were potent inducers of metamorphosis in S. cariniferus larvae, revealing that competence is reached by 13–15 days after fertilization. When exposed to surfaces coated with conspecific tube or tissue homogenates, 6% of competent larvae settled and metamorphosed on surfaces coated with tube homogenate whereas none settled on tissue homogenate or in the controls, suggesting specific cues are required for settlement and the likely presence of a settlement cue in the tubes of adult worms, consistent with the highly gregarious distribution of the species.

This paper reviews the alien polychaete species in the world's oceans and their impacts on the marine ecosystems and humans. A total of 292 polychaete species belonging to 164 genera and 39 families have been transported around the world's oceans with human-mediated assistance. Almost 15% of total number of known polychaete genera and 3.4% of total number of species are included in this phenomenon. A total of 180 species have become established in the world's oceans and 31 species (casual species) have a potential to establish viable populations in a new location. The most speciose genera are Hydroides (16 species) and Polydora (16 species), both accounting for 10% of the total number of alien species. The families Spionidae (53 species) and Serpulidae (46 species) have the highest number of alien species. The Mediterranean Sea (134 species), and the coasts of the Hawaii Islands (47 species) and the USA Pacific (34 species) have been intensively invaded by alien polychaetes. The origins of alien species vary among regions. Alien polychaete species in the Mediterranean Sea mostly originated from the Red Sea and Indo-Pacific areas. Benthic habitats of the areas between 40°N and 40°S were colonized by polychaetes mostly originating from other tropical and subtropical regions. The Suez Canal and shipping are the major vectors for species introductions. Some species imported and exported as fishing baits have become established at non-native localities. The invasive polychaete species have greatly altered habitat structures in some areas, restructured the food webs, and created important economic problems.

Nuclear 18S rRNA gene sequences of oyster shell borers, Polydora websteri, P. calcarea and P. haswelli (Polychaeta: Spionidae), were determined for the first time. A wide range of morphological variation, particularly with regard to pigmentation, is observed among these three species. This variation was characterized at the species level. Black pigmentation pattern on the palps is suggested to be a key characteristic for species determination. Polydora websteri and P. haswelli were sister species. This is the first record of P. calcarea from Japan and Australia and P. haswelli from Japan.

Euphausiids are an important component of the northern North Atlantic ecosystem and several species are found in the Irminger Sea. However, data on euphausiids in this region are few, particularly for Thysanopoda acutifrons, Thysanoessa inermis and Nematobranchion boöpis. In this paper, we present the first data since the 1930s on the seasonal distribution and population dynamics of these species from net haul data collected in the Irminger Sea during winter, spring and summer 2001–2002. Thysanoessa inermis was the most numerically abundant (0.63–26.62 ind. 1000 m−3) of the three species in the region and comprised a biomass of 3.92–41.74 mg 1000 m−3. The species was largely found in the upper regions of the water column (0–400 m) and was distributed in the more on-shelf/shelf-break regions around East Greenland and Iceland. Growth rates were around 0.03 mm d−1for T. inermis and there was some evidence that either the timing of spawning was delayed, or larval development was prolonged in the region. Thysanopoda acutifrons was predominantly distributed below 400 m in more oceanic regions and had a low abundance (1.23–1.64 ind. 1000 m−3) throughout the Irminger Sea. However, the species comprised a relatively high proportion of biomass (19.39–31.33 mg 1000 m−3) due to its large body size. Our data showed that the species had low rates of growth (0.04 mm d−1) and development throughout the year, and that the reproductive season occurred during the overwintering period (November/December) once individuals had reached two years of age. Nematobranchion boöpis mainly occurred below 400 m at low abundance (0.06–0.18 ind.1000 m−3) levels throughout the region. The species was largely found where Atlantic waters prevailed in the Irminger Current and its growth rates were variable (0.02–0.06 mm d−1). Nematobranchion boöpis was a year-round spawner and the species had fairly rapid rates of post-larval development, with the newly spawned 0-group reaching sexual maturity within the first 6 months. Data presented in this paper provide useful baselines for understanding the possible impacts of long-term, broad-scale environmental change on the ecology of euphausiid communities in the Irminger Sea.

Examination of sampled material and review of the relevant literature revealed the presence of 299 benthic and 46 pelagic amphipod species from the Aegean Sea. Two of the species identified, Caprella hirsuta Mayer, 1890 and Apohyale crassipes (Heller, 1866), are recorded for the first time in the Aegean Sea and the Levantine Basin respectively. A checklist of the Mediterranean amphipods is given, as well as their distribution in the Mediterranean territorial areas and the Black Sea. The faunal comparison of the Mediterranean areas showed that the number of species decreases from west to east. In terms of zoogeographical categories the Atlanto-Mediterranean species dominate in all Mediterranean areas followed by the endemic species concerning the benthic amphipods while in pelagic amphipods cosmopolitan species dominate and are then followed by Atlanto-Mediterranean. Three species, Bemlos leptocheirus (Walker, 1909) and Linguimarea caesaris Krapp-Schickel, 2003, Photis lamellifera Schellenberg, 1928, are lessepsian migrants and are reported in the Levantine and Central Mediterranean Seas.

A new species of eurysquilloid stomatopod, Eurysquilla petronioi sp. nov., is described from the tropical western Atlantic. Eurysquilla petronioi sp. nov. is the fourteenth species of the genus to be recognized worldwide, the fifth species from the western Atlantic and the second from Brazilian waters. It is most closely related to E. maiaguesensis from Puerto Rico, but differs chiefly in having an unarmed versus apically spinous rostral plate and 6 or 7 rather than 8–10 teeth on dactylus of raptorial claw. A key to the species of the genus is provided.

Studies on the settlement and the subsequent recruitment of intertidal organisms are crucial steps in understanding their population structure in a particular bioregion. However, studying the recruitment of intertidal organisms such as barnacles, with two-phase life cycle, and understanding the determinants of recruitment is a complex problem. Many processes which operate during the pelagic pre-settlement phase and benthic post-settlement phase at different spatial and temporal scales can determine the fate of barnacle populations. In this study, observations were carried out on settlement and recruitment of the intertidal barnacle Balanus amphitrite from a tropical environment influenced by monsoons at spatial and temporal scales. Settlement and recruitment both showed significant temporal variations. In general, settlement and recruitment was lower during the monsoon season except during monsoon breaks. Consistency in settlement and recruitment was mostly observed during the pre-monsoon season, and it coincided with peaks in larval abundance observed during the same season. In general, settlement remained more or less similar on different types of substrata, whereas recruitment differed significantly. Temporal variations observed in settlement and recruitment of barnacles could be due to the influence of monsoons in this region, which leads to seasonal fluctuations in physical factors such as local hydrodynamics, that influence the retention and dispersal of larvae in the adult habitats, and could also be due to variations in the availability of food for the larvae and the settled populations.

The presence of a diverse range of epibionts was found on Pagurus bernhardus from the west coast of Scotland. The invertebrate species found on the shell inhabited by the crab were the hydrozoans Hydractinia echinata and Dycorine conferta, the cirripeds Balanus balanus and Balanus crenatus, the polychaetes Hydroides norvegica, Pomatoceros triqueter and Circeis armoricana, and the molluscs Hiatella arctica and Anomia ephippium. On the crab were observed the polychaete Circeis armoricana and the amphipod Podoceropsis nitida. In addition, on the gastropod shells occupied by P. bernhardus, ciliate protozoan species were found attached to the hydrozoan Dycorine conferta, this being hyperepibiosis. These ciliates were 6 suctorian (Conchacineta constricta, Corynophrya anisostyla, Actinocyathula homari, Actinocyathula crenata, Acineta sulcata and Acineta corophii), and one peritrich species (Zoothamnium sp.). This is the first time that this hyperepibiosis was observed. In contrast to the epibiont communities observed in previous surveys in the same sampling area, basibiont specimens without D. conferta did not show ciliate epibionts. The ciliate epibionts also were not present on the surface of the shell and crab in specimens with D. conferta; they only appeared in hyperepibiosis on the surface of the hydrozoan. The spatial distribution and abundance of the invertebrate epibiont species were analysed, as well as the morphology, taxonomy and distribution of the ciliate hyperepibionts.

The ultrastructure of the spermatophores and spermatozoa of the Mediterranean hermit crab Pagurus excavatus are described, using transmission electron microscopy. The size of the different parts of the spermatophore and spermatozoa are given and their ultrastructure described and compared to similar data already present in the literature for other hermit crabs. The morphology and ultrastructure of the spermatophore and spermatozoa of P. excavatus are species-specific, clearly distinguishing the species from the others already described. The spermatophore and spermatozoa show some similarities with those produced by other representatives of the genus. In particular, the tripartite spermatophore is divided into two halves by the lateral ridge and, as with the spermatophores produced by other species belonging to the genus Pagurus, it is morphologically very different from any other Paguroidea. The spermatozoa are composed of an ovoidal acrosomal vesicle capped by the operculum; the acrosome has a length:width ratio of approximately 1.75, therefore larger than 1 as reported for all anomurans studied to date. At the base of the acrosomal vesicle, there is the thin cytoplasm, the large nucleus and three arms positioned to form a 120° angle between each other. The present description is an important additional step allowing for better understanding of the relationships among the different hermit crab taxa.

Larvae of the Holarctic marine chironomid, Halocladius variabilis (Staeger), have strong fidelity to the tuft-forming brown alga, Elachista fucicola (Velley) Areschoug, an abundant epiphyte on intertidal fucoids of the North Atlantic. We show that larvae are sufficiently motile to select an algal host in a Petri dish within 3–4 cm, and that larvae show differential behaviour with respect to host selection in the presence or absence of a predator. In the absence of predators 53% of larvae found an algal host within 1 hour; however, after 24 hours, there was no significant difference in host selection. When an isopod predator (Idotea sp.) was present, more larvae found a host within 1 hour (81%) and Elachista was chosen over three of the four other hosts. Furthermore, when larvae were present in Elachista, predator (Carcinus maenus) success was significantly reduced relative to two other algal hosts. The adaptive significance of Elachista as a refuge from predation was confirmed by experiments demonstrating that larval growth with other algal hosts was greater than with Elachista. These experiments suggest that microhabitat selection by larvae of H. variabilis reveals important tradeoffs for growth and predator avoidance.

The aim of this study was to apply indicators for monitoring the impacts of harvest in a recreational surf clam fishery. We investigated trends in abundance, biomass and size structure and proportion of sexual maturity for the pipi (Donax deltoides) in Venus Bay, Australia. The surf clam stock was sampled during the peak harvesting season in the Australian summer (November to February) at four sites exposed to varying degrees of recreational harvest. Sampling was based on three transects at each site; with 0.027 m3 (0.3 m × 0.3 m × 0.3 m) quadrats stratified within transects by tidal position. Restricted maximum likelihood mixed model analyses were used to examine fixed effect combinations after including a priori random effect for transect within site. Results demonstrated that relative abundance varied significantly (P = 0.0090) among sampling months but not among sites. Relative abundance declined across the peak summer harvest season. The proportion of maturity varied significantly (P = 0.00026) among sites whereas relative biomass varied significantly (P = 0.0043) among months by sites. Relative biomass and the proportion of maturity were considerably higher at the site exposed to minimal harvest compared to other sites. This study demonstrates that a suite of indictors including biomass, size–frequency and proportion of maturity are likely to provide a more accurate assessment of stock status in recreationally fished surf clam populations, than relative abundance. This highlights the need to develop methods to estimate relative biomass in surf clam populations that are not exploited commercially.