Large-scale blooms of dinoflagellates, such as Prorocentrum donghaiense and Karenia mikimotoi, have occurred frequently in the East China Sea (ECS) in recent decades. However, little is known about their effects on the entire life history of copepods. Under laboratory conditions, we investigated the effects of these two common dinoflagellates on the survival of Calanus sinicus individuals at different stages and on reproduction of this copepod. Compared with the control treatment (Skeletonema costatum), the presence of P. donghaiense and K. mikimotoi decreased the survival rates of adults and nauplii during the 16 days of the experiment. Survival of nauplii decreased to 49% and 48%, respectively, relative to the nearly 80% survival of adults. Among the six stages of nauplii, individuals at NII and NIII were more susceptible to P. donghaiense and K. mikimotoi. Lower egg production rates were also observed when copepods were exposed to P. donghaiense and K. mikimotoi, and hatching success decreased only with exposure to P. donghaiense. These results suggest that blooms of the two common dinoflagellates may have detrimental effects on the survival of nauplii and the reproduction of C. sinicus, which may pose a major threat to the recruitment of C. sinicus.

The model diatom Thalassiosira pseudonana is believed to be a single species with a global distribution, but it has not been confirmed previously whether isolates from different environmental and geographic origins are genotypically and phenotypically identical. In the present study, a polyphasic approach was employed to characterize nine clonal isolates, plus an additional replicate of one of the isolates, of the diatom T. pseudonana from culture collections to investigate whether there was any cryptic speciation in the publicly available strains of this species. Morphological analysis using scanning electron microscopy concluded that the strains were indistinguishable. Furthermore, conventional DNA barcoding genes (SSU rDNA, ITS1 and ITS2 rDNA and rbcL), revealed no nucleotide variation among the strains tested. On employing a whole genome fingerprinting technique, Amplified Fragment Length Polymorphism (AFLP), three clusters were revealed, although the level of variation between the clusters was surprisingly low. These findings indicate a low level of diversity among these cultured T. pseudonana strains, despite their wide spatial and temporal distribution and the salinity range of their original habitats. Based on the limited number of available strains, this suggests that T. pseudonana is a highly conserved diatom that nevertheless has an ability to tolerate wide ranges of salinity and populate varied geographic locations.

The heteronemertean species Micrura dellechiajei is thus far only known from its type locality in the Gulf of Naples (Italy) and has not been recorded in 120 years. During two oceanographic surveys conducted in Spanish Mediterranean waters, several nemertean specimens were collected, and thorough morphological examination indicated that some of these pertained to the species M. dellechiajei, suggesting that populations may be more widespread than previously thought. Because of the rarity of this species coupled with the fact that its last morphological narrative was given 120 years ago, we here provide a redescription of the species based on the new specimens, complete with illustrations and new data concerning its morphology, and we also place some of the collected specimens in a molecular phylogenetic framework.

This paper deals with a new species of Myrianida collected from Rhodes Island at 1 m depth among algae in April 2014. This new species is mainly characterized by having flattened dorsal cirri; high number of falcigers in parapodia; a trepan with 16 unequal teeth; and a brownish patch (in fixed specimen) on dorsum of each segment. Individuals are at the stage of reproduction, with developing stolons.

In the fourth paper about Ampharetidae from Japan, we describe 12 species in seven genera. The genus Orochi gen. nov. and the eight species Amage ehlersi sp. nov., A. longitorus sp. nov., Glyphanostomum hesslei sp. nov., Lysippe nipponica sp. nov., Melinnopsis augeneri sp. nov., M. mcintoshi sp. nov., Orochi palacephalus gen. et sp. nov., and Samytha annenkovae sp. nov. are newly described. Orochi gen. nov. is characterized by the shovel-like prostomium, the high membrane, from which all four pairs of branchiae emerge and the presence of neuropodia of the abdominal type in the last thoracic unciniger. In the discussions of the remaining genera, we comment on the taxonomic changes suggested by Jirkov (2011). Furthermore, we provide a list of all Ampharetidae species that have been recorded from Japan.

Genus Onyx Cobb, 1891 has been reviewed and 19 valid species including two new species have been reported in the world. Two new species, Onyx rizhaoensis sp. nov. and Onyx minor sp. nov. from the Yellow Sea coast are described and illustrated. In addition to the genus characters Onyx rizhaoensis sp. nov. has relatively long cephalic setae; a single loop-shaped amphidial fovea; 12 S-shaped tubular precloacal supplements in 10 + 2 arrangement, posterior 10 closely spaced, anterior two set apart; female vulva situated at almost midpoint of the body. Onyx minor sp. nov. is characterized by a relatively small body for the genus (body length usually shorter than 800 μm); gubernaculum slender parallel to spicules and with a hooked dorsal apophysis; 12 S-shaped tubular precloacal supplements fairly evenly spaced; female vulva situated at about midbody. At the same time, a dichotomous key for Onyx males is proposed.

We studied biochemical characteristics and the response to low salinity at short and long-term after feeding of alkaline phosphatase (AP) activity in hepatopancreas of the osmoregulator crab Neohelice granulata from Mar Chiquita coastal lagoon (Buenos Aires Province, Argentina) (37°32′–37°45′S 57°19′–57°26′W). The hepatopancreas exhibited a levamisole-insensitive and a levamisole-sensitive AP activity with distinct characteristics. Levamisole-insensitive activity was similar within the range of pH 7.4–9.0 and exhibited a Michaelis–Menten kinetics. Levamisole-sensitive AP activity appeared to be maximal at pH 8.5 and appeared to exhibit an allosteric kinetics. In crabs acclimated to 10 psu (hyper-regulation conditions) levamisole-insensitive and levamisole-sensitive AP activity increased (about 16-fold) over time from short term (2–4 h) to long term (120 h) after feeding while no changes occurred in crabs acclimated to 35 psu (osmoconforming conditions). The changes of AP activity along with the higher values at 120 h after feeding in 10 psu compared with those in 35 psu, and the concomitant changes in proteolytic activity, suggest a role of AP in digestive and metabolic adjustments at the biochemical level upon hyper-regulatory conditions.

Sex change, or sequential hermaphroditism, occurs in the plant and animal kingdoms and often determines a predominance of the first sex. Our aim was to explore changes in sex ratios within the range of the species studied: Patella vulgata and Patella depressa. The broad-scale survey of sex with size of limpets covered a range of latitudes from Zambujeira do Mar (southern Portugal) to the English Channel. Indirect evidence was found for the occurrence of protandry in P. vulgata populations from the south of England, with females predominating in larger size-classes; cumulative frequency distributions of males and females were different; sex ratios were biased towards males and smallest sizes of males were smaller than the smallest sizes of females. In contrast in Portugal females were found in most size-classes of P. vulgata. In P. depressa populations from the south coast of England and Portugal females were interspersed across most size-classes; size distributions of males and females and size at first maturity of males and females did not differ. P. depressa did, however, show some indications of the possibility of slight protandry occurring in Portugal. The test of sex ratio variation with latitude indicated that P. vulgata sex ratios might be involved in determining the species range limit, particularly at the equatorward limit since the likelihood of being male decreased from the south coast of England to southern Portugal. Thus at the southern range limit, sperm could be in short supply due to scarcity of males contributing to an Allee effect.

The limpet Patella vulgata is a key species of northern Atlantic rocky shore-associated communities, and is commonly considered to be important in regulating populations of canopy-forming Ascophyllum nodosum, through consumption of propagules and young recruits. Although P. vulgata is usually regarded as a non-selective epilithic biofilm grazer, a role in the collapse of established A. nodosum through grazing of adult plants has been repeatedly suggested. Factors controlling the preference of P. vulgata for epilithic biofilm or adult algae are still not clearly established. Here, we test the hypothesis that the diet of P. vulgata is mainly driven by the local availability of food sources. Limpets were sampled along the first 6 metres of an A. nodosum bed–bare rock gradient. Stable isotope ratios of their muscle tissue and digestive glands were measured. The contribution of A. nodosum to the diet of limpets was the highest in the immediate vicinity of macroalgae beds, which confirmed our initial hypothesis. However, the contribution of epilithic biofilm did not match our hypothesis, being the lowest for limpets colonizing bare rock. Instead, these limpets relied on a wide array of sources, including ephemeral green algae, biofilm and drifting A. nodosum fragments. Overall, our results indicate that A. nodosum can be readily grazed by limpets, which challenges the hypothesis that these macroalgae dominate rocky shores due to the absence of strong top-down control exerted by herbivores. Our results also highlight the need to consider the small spatial scale to understand the dynamic of herbivore–algae interactions in natural environments.

The introduction of the Manila clam into British coastal waters in the 1980s was contested by conservation agencies. While recognizing the value of the clam for aquaculture, the government decided that it posed no invasive risk, as British sea temperatures would prevent naturalization. This proved incorrect. Here we establish the pattern of introduction and spread of the species over the first 30 years of its presence in Britain. We report archival research on the sequence of licensed introductions and examine their relationship in time and space to the appearance of wild populations as revealed in the literature and by field surveys. By 2010 the species had naturalized in at least 11 estuaries in southern England. These included estuaries with no history of licensed introduction. In these cases activities such as storage of catch before market or deliberate unlicensed introduction represent the probable mechanisms of dispersal. In any event naturalization is not an inevitable consequence of introduction and the chances of establishment over the period in question were finely balanced. Consequently in Britain the species is not currently aggressively invasive and appears not to present significant risk to indigenous diversity or ecosystem function. However it is likely to gradually continue its spread should sea surface temperatures rise as predicted.

This is the first study performed to determine the health status of the geoduck Panopea abbreviata in the San José and San Matías Gulfs (North Patagonia, Argentina). The study was based on 120 geoducks collected (30 specimens in each season) at Fracasso Beach (42°25′S 64°07′W) (San José Gulf) and 30 specimens collected during the austral summer at Puerto Lobos (42°00′S 65°05′W) (San Matías Gulf). The parasites found (prevalence in parentheses) were: prokaryotic inclusions (32.2%) were recorded in the epithelium of the digestive gland and gill filaments; ciliates (79%) mainly found in gills; Porospora-like gregarines (15.2%) in the connective tissue between inner and outer mantle epitheliums; the turbellarian Paravortex panopea (27.1%) in the intestine lumen; the nemertean Malacobdella arrokeana (98.3%) in the pallial cavity; and the green alga Coccomyxa parasitica (51%) parasitizing the haemocytes in the connective tissue of the distal end of the siphon. The highest mean parasitic abundance value was found in the late austral spring (November), coinciding with the lowest values of the condition index of the host. The populations of P. abbreviata from San José Gulf seemed to be devoid of severe pathogens.

Knowledge of the population dynamics and productivity of exploited species is essential to achieve the sustainable development of fisheries, and to ensure sustainable, long-term use of these resources. The venerid clam Anomalocardia brasiliana is harvested as a fishery resource from the French West Indies to Brazil. Yet, the exploitation of this species is not backed by management or regulations based on scientific knowledge. This can result in reduced (or even depleted) A. brasiliana density and biomass. Here, we examined the population dynamics of A. brasiliana over the course of 1 year at Cidade Beach, a sheltered sandy beach located in south-eastern Brazil. Sampling was done monthly from March 2007 to February 2008. The sampled population was predominantly juvenile. Growth and recruitment were continuous, indicating no major fluctuation in limiting factors, such as temperature, salinity and food. Nevertheless, the abundance and the turnover rate (P/B ratio) of A. brasiliana at Cidade were much smaller than the values observed in other areas of occurrence. The mortality was more intense in young individuals, and the peak of individual production occurred in individuals with a 25 mm shell length, suggesting that individuals smaller than this size should not be exploited.

Growth rates and size-age at maturity are life history traits that combine in different ways to achieve maximal fitness. The marine scavenger Buccinanops globulosus was used as a model to explore the variation on female size-age at maturity and reproductive effort among three populations characterized by different growth rates (slow, moderate and rapid). This species constitutes the target of an artisanal fishery in North Patagonia. Here, a suite of different estimators of size-age at maturity derived from gonad histological analysis and the study of females carrying egg capsules were obtained. Data were modelled using a logistic function and the maturity patterns were compared among populations. We found that female size and age at maturity were variable and site-specific. The fastest-growing population showed the lowest reproductive effort. Slow and rapid-growing females mature at different sizes but at the same age whereas moderate-growing females mature both at a different size and age (intermediate size and at earlier age). Thus, results obtained here are difficult to reconcile with a single reaction norm for a single genotype in the studied populations. Growth rate variation is not enough to explain the patterns described here. The information provided could be used for the establishment of fishery management actions, such as minimum landing size.

Doris verrucosa Linnaeus, 1758 is the type species of Doris, the type genus of Dorididae. Its currently accepted distribution includes the Mediterranean, Eastern (Europe and Africa) and Western Atlantic (Massachusetts, USA to Santa Catarina, Brazil). Until now, papers on the anatomy of this species dealt with restricted characters such as rhinophores, radula and reproductive organs, never comparing specimens from different localities. In this study we have examined the anatomy of species similar to D. verrucosa from the Brazilian coast, and compared them with samples of D. verrucosa from Europe, the type locality. After an extensive complementary anatomical study of the circulatory, excretory, digestive, reproductive and nervous systems, the identity of the Brazilian specimens is clarified, proving that they belong to a different species. To solve the consequent nomenclatural gap, we revalidate Staurodoris januarii Bergh, 1878, described from Brazil, transferred to the genus Doris. The nominal species Doris verrucosa is, therefore, restricted to European waters.

Cephalopods are common inhabitants of the deep ocean's mesopelagic zones worldwide, yet very little is known about their behaviour due to the inaccessibility of this environment. Recent studies suggest that, contrary to historical predictions, deep-sea cephalopods exhibit a wide array of visual behaviours. We used in situ footage from remotely operated vehicles, coupled with laboratory observations to assemble the first behavioural ethogram for the juvenile and subadult life stages of the mesopelagic squid, Chiroteuthis calyx. The number of behavioural components we described is comparable to or exceeds those recognized in ethograms of shallow-water teuthids. We used the ethogram to make a detailed behavioural comparison between the juvenile and subadult life stages, and found distinctly different patterns. Behavioural and morphological differences between the two life stages support the hypothesis that juvenile C. calyx mimic the abundant siphonophore Nanomia bijuga, in order to deter predation.

The estimation of age and growth of cephalopod stocks is a key issue for their sustainable management. Recently, several studies have successfully validated the daily deposition of growth rings in the vestigial shell or stylets of several octopus species. Octopus vulgaris eggs were incubated at two different temperatures, 18 and 22°C, until hatching to determine stylet size at hatching and assess the effect of temperature in the stylet dimensions. The 3-day-old hatchlings were sectioned transversally and 6 μm sections were stained to enhance the stylet position and visibility. The sections were observed under transmitted light microscopy at a magnification of 1000×, and the stylets identified as blue/green structures inside the mantle–funnel retractor muscle. The transversal sections of the whole paralarvae allowed the diameter of the embryonic stylet of an octopus species to be measured for the first time. The mean stylet diameter in 3-day-old paralarvae is 3.99 μm independently of the thermal conditions. Moreover, significant differences in stylet size between captive and wild paralarvae were observed; the latter showed significantly larger stylets, an indication that they are over 3 days old. Our results also indicate that the stylet nucleus is much smaller than previously thought based on measurements in stylets of juveniles and adults.

In Pakistan, although the sea cucumber fishery has not yet been developed, Holothuria arenicola is abundant on its coast. Nineteen months of sampling was carried out to study the population structure, allometric relationships and reproductive status of H. arenicola stocks in Manora and Buleji rocky shores. All measured biometric characters showed significant temporal variations and width/length, weight/length, gutted weight/length and gutted weight/weight relationships followed negative allometry, indicating a change in body shape as the animal grows. Length-frequency distribution analysis was bimodal in both summer and autumn consisting of small-sized and medium-sized individuals while in winter and spring three modes were found at Manora. At Buleji, the population was unimodal in all seasons consisting of small-sized individuals. Sex in H. arenicola cannot be determined externally but can be identified on examination of gonad colour which is orange-like in females and creamy yellow in males. The sex was further confirmed on histological examination and maturation was divided into five stages, i.e. undetermined, early developing, late developing, mature and partially spawned. The sex ratio in H. arenicola was approximately 1:1 and increase in gonad index was observed during spring and early summer, followed by a decrease in GI in autumn and winter, which showed the spawning followed by resting phase. The GI showed a significant negative correlation with salinity and non-significant correlation with temperature. There is a need to undertake more biological/ecological studies on H. arenicola in order to take effective measures for its management.

Multiple tagging devices have been developed for long-term studies and estimating demographic parameters in sea urchins. In this study, we evaluated the use of passive integrated transponders (PIT-tag), and two types of nylon tags (T-bar and S-tag) in the sea urchin Diadema antillarum by measuring retention rate and apparent survival. The PIT-tags exhibited the highest retention, followed by T-bars, and lastly the S-tags. Differences in recapture were detected among the three types of tags (H = 6.99, P = 0.030). An a posteriori pairwise comparison test found significant differences between PIT-tags and each of the other two types (P < 0.05), whereas T-bar and S-tag did not exhibit significant differences between them (P > 0.05). The semi-captivity experiment exhibited similar results to the field experiment in terms of retention. This experiment also found higher mortality with T-bars. Differences between previous studies conducted under controlled conditions and experiments carried out in the field reflect high variability and the necessity of testing tagging procedures under both settings. The S-tag induced high spine autotomy and low retention; whereas the T-bar demonstrated low retention and low survival. Although the retention rate of PIT-tags was significantly higher than the other two, retention rates were still too low for practical utility in long-term field experiments. In conclusion, the present study does not support the use of any of these tags for long-term studies in D. antillarum.

A total of 1725 specimens of Dentex maroccanus caught in the eastern coast of Algeria from June 2011 to May 2012 were examined for an age and reproduction study. Total length (TL) ranged from 10.4 cm (16.05 g) to 26.8 cm (300.80 g). The maximum estimated age was 7 years for females and 8 years for males. The growth function of Von Bertalanffy fitted to back-calculated size at age data was: TL = 36.64[1 − e−0.2(t−0.5)] and TL = 37.26[1 − e−0.2(t−0.5)] for females and males respectively. Total length – eviscerated weight (We) relationship was estimated as We = 0.012 TL3.046 for females and We = 0.011 TL3.067 for males, being allometrically positive for both sexes. Sex-ratio was 1:0.9 in favour of females. A five-stage maturity scale based on macroscopic characteristics was identified and used to classify the gonads. The reproductive season, evaluated from a gonadosomatic index, extended from May to September. Fifty per cent maturity of the tested sample was reached at a total length of 14.4 cm TL for females and 15.1 cm TL for males.