This paper studies the age and the growth of male and female of the Tunisian blue mackerel Scomber scombrus during 2004–2006. The age was determined by interpreting and counting daily increments on the otoliths sagitta of 320 individuals sampled from landings caught by different gears specially by purse seine. The parameters of the Von Bertalanffy growth curve were estimated for sexes combined: Lf = 31.46(1 − e−0.228 (t+3.034)) (L∞ = 31.46 cm, k = 0.228 per year, t0 = −3.034 years); for male Lf = 27.43(1 − e−0.422 (t+1.747)) (L∞ = 27.43 cm, k = 0.422 per year, t0 = −1.747 years) and for female Lf = 31.70(1 − e−0.227 (t+2.196)) (L∞ = 31.70 cm, k = 0.227 per year, t0 = −2.916 years) for the whole study period. The difference between the growth of male and female is not significant. The relationship between length and weight shows a length growth faster than of the weight with parameters of the equation Wt = a*Lb; a = 9.89*10−5 and b = 2.37 for the sexes combined.

Diel rhythms in feeding and spawning were investigated in Centropages tenuiremis from Xiamen Bay in March to May, 2006. Circular statistics were used to determine the peak time of spawning. The results showed that the feeding activities of females were stably higher at night-time, and there was a remarkable earlier shift in spawning peak time with warmer seawater. Thus, the lag times between peak times of gut pigment content and spawning were shortened with the increase of temperature. It suggested that there was a direct effect of feeding rhythms on egg production variations in copepods, and the seawater temperature would work on the converting time and then influence the spawning peak time. So the effect of temperature cannot be ignored in the investigation of the effects of feeding on egg production.

The diversity and distribution of polychaete species under the families Nereididae, Syllidae and Eunicidae in sub-tidal fouling assemblage was studied by submerging wood as test substratum. Wooden panels were fitted onto a raft and submerged in Kudankulam coastal waters (south east coast of India) in pre-monsoon, monsoon and post-monsoon seasons from May 2003 to July 2005. Panels (in replicate) were retrieved from the raft at 15-day intervals. A total of 24 polychaete species belonging to the three families were identified from the test panels. Perinereis cultrifera, Platynereis dumerilii, Syllis variegata, Syllis truncata, and Eunice australis were the dominant species observed on the test panels. The abundance of major polychaete group was varied considerably between the panel series submerged in May 2003 (post-monsoon), November 2003 (monsoon) and July 2004 (pre-monsoon). The major difference in the polychaete community structure was the low abundance of both nereidids on pre-monsoon season panels and the eunicids on monsoon and post-monsoon season panels.

Jellyfish display strong population variability. Competitive interactions between fish and jellyfish have been depicted as a major mechanism controlling this variability. Biological associations involving jellyfish are, however, more diverse than predation–prey interactions and remain poorly understood. Parasitic associations in particular may have relevant effects on jellyfish host populations. We studied basic patterns (temporal patterns of parasite intensity–biomass and the distribution pattern of parasites among hosts) of the association between the parasitic anemone Peachia chilensis and its scyphozoan host, Chrysaora plocamia. The mean number of parasites per host (MI) was high (average = 465) and showed significant differences during the pelagic life phase of the medusa. The mean biomass of parasites per host was also significantly different among months but showed a different temporal pattern to that of MI, which may reflect recruitment pulses of parasitic larvae. The mean biomass of P. chilensis per host averaged 56.3 mg ash-free dry mass, which represents a trophic flow of energy probably linking pelagic and benthic food webs. The distribution of parasites among hosts was best fitted to the negative binomial distribution model, as typical for host–parasite systems. We concluded that the parasite-induced host mortality and reduction of fecundity, represented by parasitic castration, is restricted to a few hosts and is therefore under the expected levels that characterize the dynamic equilibrium of host–parasite systems.

The reproductive biology of Mediterranean horse mackerel Trachurus mediterraneus was investigated in the Sea of Marmara over a one-year period. Duration and timing of the spawning season, gonad histology, oocyte development and size at sexual maturity were determined. The presence of all stages of oocytes without any distinct size hiatus indicated that oocyte development of Mediterranean horse mackerel is asynchronous with indeterminate fecundity. Spawning starts in May, peaks in July–August and ends in September. Sizes at 50% maturity were found to be 12.2 and 12.5 cm (total length) for females and males, respectively. Mean batch fecundity was calculated as 10136 ± 703 eggs. Our results on the size at sexual maturity and batch fecundity for the Sea of Marmara differed significantly from published results from the Mediterranean Sea. We ascribe these differences to different stock structures in these seas. Our results form the basis for future reproductive biology studies on the under-studied Marmara–Black Sea stock.

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.

Two new free-living marine nematodes belonging to the family Thoracostomopsidae, subfamily Enoplolaiminae and the genera Epacanthion are described from Patagonian coastal areas, Río Negro and Chubut provinces of Argentina. In Epacanthion bicuspidatum sp. nov. the main features are: two cusps on distal mandible end; presence of two rings of eight setae in the cervical region; and eight crown-shaped setae along the body, presence of one supplement distant two cloacal body diameter (cbd) from cloacae, gubernaculum and short spicule. Epacanthion ampullatum sp. nov. is characterized by having a tubular and long pre-cloacal supplement, short spicule, presence of gubernaculum, presence of three long setae on the tip of the tail, the presence of one supplement distant three cbd from cloacae and the presence of two small cusps on the distal end of the mandible.

A one-year study of the reproductive biology of a population of Diopatra marocensis at the Villaviciosa estuary, northern Spain, was undertaken with emphasis on brooding behaviour, larval development and gametogenesis. Field observations together with a histological study of monthly collected individuals revealed that the population was iteroparous, reproducing annually during a short breeding season extending from March to June. The study demonstrated that all individuals of the population at Villaviciosa estuary were producing at the same time eggs and sperm providing for the first time evidence for the occurrence of simultaneous hermaphroditism in D. marocensis. Mature sperm was of the ent-aquasperm type and was stored in modified nephridial chambers in brooding individuals. In the latter, eggs in advanced cleavage phases were also observed inside the coelom suggesting that fertilization was internal. Eggs in late vitellogenesis presented micronucleoli in the periphery of the nucleus, a phenomenon reported previously for few polychaete species. Pure males and females were never found. It is here suggested that in D. marocensis population size may influence sex allocation and that under conditions of low population densities simultaneous hermaphrodites may be favoured. The study of the larval development confirmed the direct development reported previously for populations of Morocco and Portugal. Further results suggest consumption of nurse eggs and adelphophagy by developing larvae.

Mesophotic coral ecosystems (MCEs) are found on the insular and continental slopes of Caribbean islands and comprise mainly scleractinian corals, sponges and macroalgae. These species provide habitat for a highly diverse and specialized crustacean fauna. A new genus and species of the family Louriniidae is described from samples taken from an MCE in south-west Puerto Rico. The new taxa can be diagnosed by: body elongate, almost cylindrical and with inconspicuous podoplean boundary between prosome and urosome; double genital somite with a discontinuous chitinized cuticular ridge; telson short with rectangular anal operculum; furca short; rostrum sinusoidal, well defined at the base; antennules 7-segmented with aesthetasc on the fourth segment; antenna with a brush-like basal seta and an abexopodal seta, exopod 1-segmented with 2 setae; endopod with 7 elements (1 geniculate seta and 1 modified inner spine); maxilliped well developed, prehensile, composed of syncoxa, basis, one segmented endopod and one claw-like apical seta; leg 1 endopod 3-segmented, first segment with a modified inner seta; legs 2, 3 and 4 with 2-segmented endopod with inner seta on the first segment; leg 5 basendopod fused, well developed with 4 setae, exopod well developed, with 5 setae; leg 6 represented by a single seta; and genital slits wide apart. The new genus and species can be confidently assigned to the family Louriniidae on the basis of the following synapomorphies: rostrum well-developed with rounded tip; antennule of female 7-segmented; mandible palp reduced; maxillule endopod and exopod absent; maxillae endopodite 2 represented by 3 setae; leg 5 basoendopod of female confluent, intercoxal sclerite absent, exopod 1-segmented; eggs retained in a single ventral egg sac; telson shorter than last urosomite; and furca short and with 6 setae.

Ecological interactions involving introduced seaweeds constitute an important research gap, since they could alter the trophic dynamics of native populations, but indirect effects on trophic levels are poorly known. The seaweed Caulerpa racemosa is one of the most notable invaders in the Mediterranean Sea. It is well known that C. racemosa modifies the amphipod community with respect to native habitats, but nothing is known regarding the common use of the same trophic resources. Therefore, the aim of this study was to assess if the feeding habits of amphipods associated with algal habitats are affected by the spread of the invasive C. racemosa, through stomach content analysis of amphipods living in both native and invaded seaweed assemblages. A total of 240 specimens of 14 species of amphipods were examined. Ten species were present in both studied habitats (native and invaded), while two were exclusive to native and invaded habitats, respectively. Ten individuals of each species at each habitat were selected and their gut contents were examined. A total of 11 different items was found in the gut contents: detritus; vegetal detritus; algae; animal tissue; Oligochaeta; Polychaeta; Foraminifera; Crustacea; Sipuncula; diatoms; and non-identified items. The expansion of C. racemosa into the native algal community changes the feeding habits of herbivorous amphipods, since their preferred food (epiphytic algae) is not available in the new habitat produced by C. racemosa. This community change occurs because of the presence of caulerpenyne in C. racemosa, which retards the growth of epiphytic algae. Nevertheless, other species are not affected or benefited by the invasion, such as detritivorous species whose main food source and habitat remains available. Altogether, slight changes in the trophodynamism of amphipod assemblages have been detected, which are not seen as relevant in an initial stage. However, they might be promoting some indirect effects in the energetic budget of populations, which may affect the life history. Further studies on food-web interactions in the ecosystems affected by invasive species are necessary.

In the present study, decapsulated cysts from eleven Tunisian Artemia salina populations were analysed for their fatty acid profile. Results showed that palmitic (16:0), palmitoleic (16:1n-7), stearic (18:0), cis-vaccenic (18:1n-7), oleic (18:1n-9), linoleic (18:2n-6), linolenic (18:3n-3) and eicosapentaenoic (20:5n-3) were the major fatty acids. The ratio of C16:0/C16:1 fatty acids fluctuated between 0.8 and 3.8. Docosahexaenoic acid (22:6n-3) was absent or found in trace (<0.2%) and arachidonic acids (20:4n-6) was found in higher quantity in all marine-type cysts than in freshwater-type cysts samples. Furthermore, based on the fatty acid profile of the studied Artemia salina populations, we can concluded that Sijoumi, Sahline, Bekalta, Mcheguig and El Adhibet strains could be ascribed to marine-type Artemia, whereas the population from Moknine, Sidi El Hani, Sfax, El Melah, Zarzis and Mhabeul could be categorized as freshwater-type. Principal components analysis showed that palmitoleic acid, linolenic acid, eicosapentaenoic acid, arachidonic acid and C16:0/C16:1 ratio are the most important fatty acids variable between cysts samples, with a total contribution of 68.73% relatively to the first component, whereas, for the second component, palmitic acid, cis-vaccenic acid and oleic acid, are the most important variables, with a total contribution of 56.25%. Moreover, palmitoleic acid, linolenic acid, eicosapentaenoic acid, arachidonic acid and C16:0/C16:1 ratio are the most important fatty acids which contribute to the discrimination between freshwater and marine-type Artemia; while palmitic acid, cis-vaccenic acid and oleic acids represent the major fatty acids permitting differentiation between strains from the same Artemia type, especially for freshwater-type Artemia.

We redescribe and illustrate Halcurias pilatus McMurrich, 1893 and H. mcmurrichi Uchida, 2004 (Endocoelantheae, Halcuriidae) from newly collected specimens from Southern Chile and deep-water reefs off Florida, respectively. Halcurias pilatus was previously considered to have a disjunct distribution until Uchida (2004) described a new species for the material from the Bahamas. However, the description of H. mcmurrichi does not meet modern taxonomic standards. We provide new anatomical and cnidae data for H. pilatus and H. mcmurrichi. Both species differ in the distribution and cnidom of nematocyst batteries in the column, development of microcnemes mesenteries, cnidae and geographical distribution. We find that H. pilatus can have a weak mesogleal marginal sphincter and amend accordingly the diagnoses of the genus Halcurias, family Halcuriidae, and suborder Endocoelantheae. These new records represent the first time both species have been collected since their original descriptions.

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.

The genus Acantholaimus (Chromadoridae: Nematoda) is one of the most species-rich deep-sea nematode genera. The descriptions of two new species and supplemental descriptions of five known species from the Angola Basin (south-east Atlantic Ocean) and a depth of about 5500 m are given. Acantholaimus formosus sp. nov. is characterized by a spindle-shaped body with narrow elongated anterior end, the position of amphideal fovea on the apical tip of the body and by robust rugae and onchia. Acantholaimus skukinae sp. nov. is characterized by its cylindrical body shape; short outer labial, cephalic, cervical, and somatic setae; large amphideal fovea; the position of its amphideal fovea (situated relatively far from the head end); and relatively small onchia. Acantholaimus angustus was previously found in the Peru Basin (central-eastern Pacific) and the Clarion–Clipperton Nodule Province (Equatorial Pacific), about 13,000 km apart from the nearest previous location of finding. The type location of A. verscheldi is the Kenyan coast of the Indian Ocean. New specimens of this species were found about 8000 km apart from the type location. Acantholaimus akvavitus, A. iubilus and A. quintus were previously found in different parts of the Atlantic and the Pacific.

The corallivorous gastropod Coralliophila meyendorffi (family Coralliophilidae) is a well-known predator of the coral Cladocora caespitosa, particularly in the eastern Adriatic Sea, where population outbreaks can drastically reduce coral cover. Coralliophila meyendorffi ranges in size from 5 to 40 mm in shell total length, and smaller specimens are often found living with the coral C. caespitosa. Specimens of C. meyendorffi feed exclusively on live coral tissue, stripping it from the calcium carbonate skeleton. Recent outbreaks of the gastropod C. meyendorffi have caused considerable damage on a C. caespitosa bank in Veliko Jezero (the Mljet National Park, eastern Adriatic Sea). The bank occurs at depths between 6 and 18 m, covering a 65  m2 area. During summer of 2010, a substantial outbreak affected about 5%t of the coral colonies. The gastropods were highly aggregated in sheltered areas of the coral bank (up to 41 specimens/dm2) with smaller clusters (from 8 to 12 specimens/dm2) on coral colonies that were influenced by strong bottom currents (up to 1.23 ms−1).

The assemblage structure of harpacticoid copepods inhabiting the soft sediments of littoral and sublittoral areas of Cat Ba archipelago (South China Sea) is analysed. Three basic types of harpacticoid taxocenes were observed in the upper sublittoral. Main dominant species of taxocenes were Amphiascoides sp., Stenhelia latioperculata, Paramphiascella sp., Phyllopodopsyllus sp., Tisbe sp.1 and Amphiascoides sp. In addition, the main characteristics of harpacticoid species composition in littoral rock pools are described. A comparative analysis of shallow-water harpacticoid communities from different biotopes of the tropical region is presented, and shows that harpacticoid diversity and abundance are lowest in muddy sediments. Highest diversity and abundance are found in washed sands and silty sands with detritus. In general, the structure of muddy bottom communities is the most homogeneous throughout the tropics. Mangrove forests have no significant influence on harpacticoid taxocene structure. Harpacticoid associations of washed sands and silty sands with detritus demonstrate greater diversity and are region-specific.

A male of the new species Stygiopontius senckenbergi belonging to the family Dirivultidae Humes & Dojiri, 1980 (Copepoda: Siphonostomatoida) and endemic to deep-sea hydrothermal vents, is described from a raised fault block structure south of Edison seamount of the New Ireland Fore-Arc system (Papua New Guinea). The copepods were collected in by box-corer during cruise SO-133 of the RV ‘Sonne’ at a depth of 1610–1625 m, 3°19′S 152°35′E. The new species belongs to a group of eight species that are separate from 21 congeners on the basis of setation of legs 1 and 4: the coxa of leg 1 has an inner seta (absent on the others) and the third exopodal segment of leg 4 has three outer spines (instead of two spines). The new species shares with S. pectinatus Humes, 1987 a pectinate maxilliped but differs from it in lacking two pectinate, terminal claw-like setae on the endopod of the antenna.

A new bathyal leucothoid amphipod, Leucothoe cathalaa sp. nov., is described and illustrated based on specimens collected at the Le Danois Bank (‘El Cachucho’ Marine Protected Area), southern Bay of Biscay. This species can be distinguished from the other species of the genus Leucothoe by the hardly visible eyes (translucent ocelli, in preserved specimens); antenna 1 with minute accessory flagellum; coxae 1–3 with 2 serrations on posterodistal margin; epimeron 3 posterodistal corner produced, bifid, with one seta between blunt lobes and telson apex pointed without accessory teeth. In live specimens, the eyes are easily visible, each represented as a rounded whitish-pigmented spot. The new species has been found living on fine sandy soft-bottoms between 486 and 574 m depth at the top of the bank. An identification key to the deep Atlantic European species of Leucothoe is provided, as well as ecological and biological comments.

A sample of 3393 garfish, Belone belone (Linnaeus, 1761) was captured using a seine net between January 2003 and December 2008, along the eastern Adriatic Sea. The range in total length was 20.8–75.4 cm and in weight was 12.21–639.25 g. Length–length equations for converting size measurements (standard length and fork length to total length (TL)) were linear. In the length–weight relationship, positive allometry was established (b = 3.4818). Age, determined from sagittal otoliths, ranged from 1+ to 8+ years. The estimated von Bertalanffy model growth parameters for garfish were L∞ = 90.3 cm, K = 0.158 year−1, t0 = −0.109. Otolith weight was endorsed as a possible age predictor, as it showed highly exponential correlation with total garfish length and age (Wo = 0.0012 TL2.189; Wo = 0.568t1.486). These findings were used to examine mortality rates and exploitation in order to improve conservation and management of this pelagic species.

Relationships between sediment characteristics and the spatial organization of biogenic structures remain poorly understood, albeit important for characterizing bioturbation impacts and small-scale ecological patterns. Using axial tomodensitometry (CT-scan) and core sectioning, we studied the spatial distribution of Alitta virens burrows in sediment cores from two mudflats with different degrees of exposure along the St Lawrence Estuary, Canada. A variety of burrow morphologies was observed at both sites, with most being I-shaped. Most values measured (organic matter content, mean tomographic intensity, the number and diameter of burrow shafts and the percentage of space they occupy per transverse section) covaried with depth. The more sheltered site had higher organic matter and mud contents, and lower average tomographic intensity values. The spatial distribution of burrow shafts also differed between sites, with the more sheltered site having a higher number of burrow shafts and percentage of biogenic space in the upper sediment column, as well as a greater volume of biogenic structures that were connected to the surface (although intra-site variability was great). Along the horizontal plane and at various depths within sediments, burrow shafts were more randomly distributed at the exposed site, compared to a more even, maximal spacing at the sheltered site. In addition to finding differences in burrow organization at two spatial scales, we found significant correlations between tomographic intensity and (1) the number of burrow shafts, (2) biogenic space and (3) organic matter content. CT-scan data, including tomographic intensity, are useful for examining and comparing biogenic structures in sediment cores.