Population characteristics can be influenced by specific factors of the habitat and the natural variability of populations can confuse the effect related to protected environments. This study compares the demographic characteristics of Octopus tehuelchus in three coastal environments: two Marine Protected Areas (San Antonio Bay (SAB) and Islote Lobos (IL)) and a traditional fishing zone (El Fuerte (EF)). Weight–frequency distributions, sex-ratio and recruitment were monthly compared between the three intertidal zones. Octopus tehuelchus was smaller in IL, where fishing intensity is lower or null, and reached the largest sizes in the main fishing area of EF and within SAB (where there is no regulation and a mid–high fishing intensity). The sex proportion in SAB and EF was 1:1 all along the year. Although the proportion of mature females in IL was higher, the highest recruitment was observed in EF (the traditional fishing ground). These new data suggest that previous studies, which reported that Marine Protected Areas have positive effects for O. tehuelchus populations, can no longer be supported, and highlight the importance of understanding and quantifying the magnitude and range of natural variability in each environment when assessing the effectiveness of Marine Protected Areas.

The reproductive cycle of Cardisoma guanhumi was described from the analysis of seasonal variation of the gonadal maturation stages. The first maturity for both sexes was determined based on three different tests: inflexion point on the curve; relevant character (morphometry); and histological analysis (physiology). In addition, some aspects of sexual dimorphism for the population were studied. A total of 353 individuals caught in north-eastern Brazil between December 2006 and November 2007 were analysed. The sex-ratio was statistically equal (P ≥ 0.05) and the carapace width (CW) of the females ranged from 4.34 to 8.56 cm and of the males from 2.84 to 9.22 cm. Mature females with fully developed gonads begin to appear in the dry season (August) and ovigerous females occurred from November to February, suggesting that spawning occurs mainly during the rainy season. The CW of first sexual maturity for females ranged from 5.87 cm to 6.70 cm and males from 6.22 cm to 7.20 cm. The highest percentage of individuals caught were juveniles, indicating the need for a targeted effort to preserve the species.

Individual growth histories of the shortfin squid Illex argentinus were reconstructed in 1512 individuals obtained during seven years of commercial exploitation in southern-south-eastern Brazil. Growth increments were directly measured on the gladius dorsal surface from the anterior part to posterior end in two-thirds of the entire length. Gladius growth increments were deposited at the same rate as statolith rings and the daily nature of the growth increments was supported. Because gladius length is strongly related to mantle length, growth increments closely approximated mantle length growth rates, allowing the reconstruction of both size- and age-dependent growth. Individual reconstruction was possible between 4 and 347 mm of gladius length, almost the entire life cycle of the species. The variability of the acceleration in gladius growth evidenced four life history transitions where the most noticeable occurred between paralarval/juvenile stages, delimiting male/female size differentiation. The changes in acceleration in growth throughout the size-range may be influenced by the thermal gradients experienced by individuals during life history events transitions in Brazilian waters.

Chromatic polymorphisms in shells may be associated with adaptive characteristics in molluscs. Colouring among Hastula cinerea reveals different patterns in large aggregations of individuals. Although the impacts of temperature are considered critical in the intertidal region, selective effects associated with colouring in H. cinerea shells, in addition to possible physiological consequences, remain an open issue. In this context, H. cinerea is a viable evolutionary model for investigating selective processes related to chromatic polymorphism in shells given its abundance and biological characteristics. Individuals from the same population were classified into three groups according to shell colour: light, reddish and dark. They were then examined with regard to frequency of colour morphs and morphological patterns in each group. Reddish and light-coloured specimens were the most abundant, while those with dark coloration were less common and morphologically distinct from the first two colour morphs. Morphological differences in the anterior region of dark shells, which may be associated with movement ability and lower frequencies in these specimens, suggest possible selective effects on types that are less reflective to light in the intertidal zone.

Variations in the rate of embryonic malformations of the anchoveta Engraulis ringens in a spawning area off central–southern Chile were assessed. Eggs in stages of development subsequent to blastodisc formation were collected and preserved. Several severe malformations were identified and grouped by: (1) proliferation of disorganized tissue in early and late developmental stages; (2) irregular blastopore closure; and (3) notochordal deformation, of which the second had the highest incidence among the embryos. The average rate of malformation was 5.64%, a value close to that reported for other Clupeiformes and below the rate of 10%, indicating the influence of purely endogenous factors. The expected relationship between temperature variations and malformation rates was not observed, probably because the natural temperature range experienced by the embryos was above that at which severe malformation had previously been observed in the laboratory. The relationship between egg size and malformation rates over the spawning season was not determined; however, a relationship between egg size and malformation rates was detected among the samples from each sampling date, which suggests that malformations may be attributable to endogenous factors rather than to environmental factors acting directly on the eggs in the plankton.

The ichthyoplankton of Galway Bay was sampled over the spring and summer of 2007 and 2008 to determine what environmental factors influenced the distribution of larval and early juvenile fish. A total of 549 fish representing 27 taxa were caught. Catches decreased throughout each sampling season, and were generally poor in 2007. Catches were numerically dominated by sprat (Sprattus sprattus), dab (Limanda limanda), sand eel (Hyperoplus immaculatus) and whiting (Merlangius merlangus). Environmental factors driving distribution of fish were modelled using a binomial generalized linear model. The strength and direction of wind in the five days preceding sampling was the only significant environmental factor. Sustained onshore winds increased the probability of encountering larval fish in the areas sampled. The rainfall, tidal state, tow depth and wind conditions during sampling were not significant. Among the parameters measured it appears that onshore winds sufficiently strong to overcome the residual circulation are the main physical driver for the distribution of larval fish in Galway Bay.

Recent studies of the large cheilostome bryozoan genus Scrupocellaria have shown a greater degree of taxonomically informative morphological variation in zooids, opesia, and polymorphic structures than previously recognized. Only one subgenus has been named within the genus, Retiscrupocellaria d'Hondt, 1988, erected for Scrupocellaria jolloisii. In this work we further analyse S. jolloisii and its related species, resurrecting an earlier genus name, Licornia van Beneden, 1850 for Licornia jolloisii, and nine relatives, L. annectens, L. cervicornis, L. cyclostoma, L. diadema, L. ferox, L. gaspari, L. longispinosa, L. macropora, and L. prolata. Licornia jolloisii was originally described from the Red Sea, and most species of the genus occur in the Indo-Pacific region. The species, however, has now been found in the Western Atlantic, in the Florida Keys, US, and in Bahia de Todos Santos, Brazil.

Acceleration data loggers can be used to construct time–energy budgets or identify specific behaviours in free living animals. Within a marine context such devices have been largely deployed on vertebrates with comparatively little attention paid to commercially important invertebrates such as cephalopod molluscs. Here we tested the utility of tri-axial accelerometers to tease apart six discrete behaviours in the common cuttlefish Sepia officinalis. By considering depth profiles in conjunction with body pitch and roll and overall dynamic body acceleration we were able to make distinctions between resting at the seabed, active swimming, mating, post-coital panting and active manoeuvring along the seabed.

Among invertebrates, cephalopods have one of the most well-organized nervous systems. However, with respect to the ontogeny of the nervous system, the post-embryonic development of the cephalopod brain has only been documented for a few species. Here, we investigated the development of the brain of captive oval squid Sepioteuthis lessoniana during the post-hatching phase. The central part of the brain of the oval squid is divided into four main regions, namely, the supraoesophageal, anterior suboesophageal, middle suboesophageal, and posterior suboesophageal masses, each consisting of several lobes. At various ages in juvenile squid, the total volume of the central part of the brain (except the optic lobe) is significantly correlated with its body size, indicated by mantle length and wet body weight. The vertical lobe, superior frontal lobe, and anterior subesophageal mass drastically increase in relative volume as the squid grows. In contrast, the middle suboesophageal mass and posterior suboesophageal mass do not increase in volume with increasing squid age and body size. The effects of these results have been discussed in relation to the onset of squid behaviours during post-hatching.

Sea urchins can have important ecological effects on benthic communities through their aggregation and feeding behaviour. Urchin movement has been demonstrated to be negatively affected by wave action, but the impact of unidirectional tidal currents on urchin movement has not been investigated. This study examines the effect of unidirectional water velocity on the direction of displacement and movement rate of the green sea urchin, Strongylocentrotus droebachiensis. In laboratory flume experiments there was a clear effect of water currents on the displacement of sea urchins. At speeds ≤30 cm s−1 urchins moved across the current in a downstream direction, but at speeds of ≥36 cm s−1 the urchins switched directions by more than 90° and moved across the current in an upstream direction. There was a significant effect of flow speed on urchin movement speed, with urchin movement speed decreasing as water current speed increased.

A method was developed to attach underwater acoustic transmitters on the knobby sea star Protoreaster nodosus. Cylindrical transmitters, each measuring 36 mm length × 13 mm diameter in size and 11 g in weight, were used in this study. Each transmitter was placed in a neoprene holder that was attached externally to the middle of one arm of P. nodosus with a nylon monofilament fishing line. Attachment was achieved by threading the monofilament line through two small perforations aborally along its mid-ridge and adorally through the ambulacral groove. Some 36 individuals were successfully tagged over a three-year period between 2007 and 2010 on an intertidal reef in Singapore using this technique. Tagging did not appear to affect survival, feeding or movement of sea stars during the period of attachment, which averaged 60 days. This method may work equally well with other types of tags, such as depth recorders and accelerometers.

The epiphytic bryozoan Membranipora membranacea encrusts the surface of kelp blades, causing recurrent large-scale defoliation events in kelp beds off the Atlantic coast of Nova Scotia, Canada. The gastropod Lacuna vincta grazes kelp, creating perforations that weaken blade tissues and increase the fragmentation rate. We assess the interaction between M. membranacea and L. vincta by measuring the grazing rate of snails on bryozoan-encrusted and non-encrusted kelp (Saccharina latissima) in no-choice and choice experiments in the laboratory conducted in November and December 2010. There was no effect of diet on grazing rate in no-choice experiments. In choice experiments, however, L. vincta grazed significantly more non-encrusted than encrusted kelp (7.1 versus 1.1 mg snail−1 d−1), and grazing rate of non-encrusted kelp was almost twice that in the no-choice experiment (3.8 mg snail−1 d−1), indicating that snails may avoid colonies of M. membranacea on partially encrusted kelp blades. We found no effect of diet on growth, reproduction and survival of snails maintained for four weeks on encrusted or non-encrusted kelp. By concentrating grazing damage on non-encrusted areas of blades, L. vincta may act synergistically with M. membranacea to increase the likelihood of blade breakage and canopy loss. This indirect effect of the invasive bryozoan could augment its direct effect on the standing biomass of native kelp beds and detrital export to adjacent communities.

In order to assess the effect of feeding deprivation on growth and condition of field-caught newly settled juvenile plaice Pleuronectes platessa, a 3 week starvation experiment was conducted and changes in RNA/DNA ratio, Fulton's K condition index and recent otolith growth were measured. Fed ad libitum and starved fish were analysed after 0, 1, 2, 3, 4, 5, 7, 9, 14, 16 and 22 days of starvation. In parallel, field newly settled juvenile plaice were collected weekly over the settlement period (between April and May 2005) in the adjacent intertidal zone of the Canche estuary (eastern English Channel, France) and fish performances were estimated. After starvation day 4, Fulton's K condition index and RNA/DNA ratio of juvenile plaice significantly differed between treatments while recent otolith growth differed between treatments after day 9 of the experiment procedure. Results indicate that the three biological parameters are sensitive indices and can be used to accurately assess nutritional condition of wild juvenile fish. Values of 0.32 for RNA/DNA, 0.83 mg. mm−3 for Fulton's K index, and 3.99 µm for recent otolith daily growth were defined as critical threshold values below which juvenile plaice can be classified as ‘starving'. When comparing these experimental values with those from field-caught newly settled juvenile plaice, less than 1% of wild individuals can be classified as ‘starving' whatever the index. Our results suggest that feeding conditions throughout the settlement period on the Canche intertidal nursery ground are favourable to juvenile plaice development and survival, and hence to the recruitment success.

A new suprabenthic mysid, Mysidopsis cachuchoensis sp. nov., is described from specimens sampled with a suprabenthic sled at the ‘Le Danois' Bank (the ‘El Cachucho' Marine Protected Area; southern Bay of Biscay). The main distinguishing features of this new species are the structure of its eyestalk and antennal scale as well as the armature of its telson and uropodal endopods. Inferred from the present unique record (828 m depth, inner basin between the bank and the Cantabrian shelf), it seems to be a rare endemic species of the bank, living on muddy bottoms of the upper bathyal.

The rock goby, Gobius paganellus one of the most common gobiid fish in Bizerta lagoon (north-east of Tunisia), is a gonochoric species that belongs to the Gobiidae family. This study provides the first detailed information of its reproductive biology in lagoon environments. Gobius paganellus was sampled monthly from January 2005 to December 2006 involving 1486 specimens. Total length distribution ranged between 38 and 125 mm. The maximum recorded total lengths were, respectively, 122 mm and 125 mm for female and male. Over the entire population, the sex-ratio was unbalanced in favour of females. According to months, a predominance of females sex-ratio was recorded during the spawning period while according to body size, males were dominating among larger size-classes. In both sexes, the variation of the gonadosomatic index (GSI) was independent of size. Macroscopic and microscopic examination of the gonads added to the monthly monitoring of gonadosomatic index and hepatosomatic index showed that gonads development begins in October and spawning period extends from December to March. The cyclic pattern of gonads development was determined by histology. Results indicated that G. paganellus exhibits a group-synchronous oocyte development. The sizes of first sexual maturity related to 50% of mature individuals were 78.3 mm (CI95: 77–84 mm) for males and 79 mm (CI95: 75–85 mms) for females. The discussion part underlined the impacts of some environmental factors and antropization of this lagoon on sexual cycle of G. paganellus.

Hypermastus tokunagai is a eulimid gastropod infecting the sand dollar Scaphechinus mirabilis. The eulimid is easily detached from the host and thus regarded as a temporary parasite. In this study, the growth and reproductive cycle of H. tokunagai were investigated using specimens collected from S. mirabilis in the western Seto Inland Sea, Japan. Newly recruited individuals of H. tokunagai appeared in early autumn and grew rapidly, while growth was retarded from mid-autumn to winter months. A second rapid growth occurred the following summer. Based on the growth pattern, the life span of H. tokunagai was estimated to be more than 20 months. This longer life span compared to other eulimids could be due to the accessibility and population stability of its host S. mirabilis. Maturation of H. tokunagai occurred within a short period in the summer, and was synchronized with the second growth phase. Hypermastus tokunagai showed size dimorphism between sexes and an investigation on change in shell shape with growth revealed that this characteristic can be attributed to the female's acquisition of a larger shell within a short time during its maturation period.

This paper presents results of a study conducted on the trawling industrial fishery fleet of Merluccius gayi in south-central Chile, and the resulting interactions with the South American sea lion (Otaria flavescens). This study is based on observations made during September 2004, when incidental sea lion catch in the trawls was 6.3 sea lions/working day (1.2 sea lions/trawl−1). A total of 82 animals were incidentally caught, of which 12 were found dead, and the 70 remaining suffered from internal bleeding and/or fractures as a result of their capture. 83.3% of the fatalities occurred during nocturnal trawls, which comprise 30% of all observed trawls. Possible mechanisms of sea lion take are discussed. This note presents the first records of sea lions incidental by-catch by the trawler fleet along the south-east Pacific coast of Chile.

The city of São Sebastião (SS), in south-eastern Brazil, is one of the hotspots for marine research since the establishment of the Centre of Marine Biology of the University of São Paulo in the 1960s. The SS region experienced intense transformation during the past 50 years, including increasing urbanization and construction of maritime facilities. Ascidian surveys during the past 50 years have found 62 species, eight of which were described as new and 12 are introduced. Didemnidae and Styelidae are the most speciose families in São Sebastião Channel, with 20 and 15 species respectively. Phallusia nigra, Didemnum psammatodes, Trididemnum orbiculatum, Botrylloides nigrum and Symplegma rubra are the most common ascidians. Most of the species are of tropical origin and São Paulo is their southern geographical limit. Comparisons of reports of the ascidians from different time periods allowed detection of species introductions and shifts in assemblage structure in terms of both species composition and abundance. Additionally, we discuss the main taxonomic issues regarding ascidians from south-eastern Brazil and identify profitable areas for future research. We believe that the temporal data compiled here will serve as a baseline for monitoring and management of ascidians in SS. Additionally, this study provides one of the most detailed datasets of ascidian diversity from the south-western Atlantic Ocean.

In this research age composition, sex-ratio, growth, survival, mortality and exploitation rates were determined in the south-eastern Black Sea region of Turkey during the 2010–2011 fishing season. Anchovy in the age group 2 was the most abundant (64.06%), followed by age groups 1 (33.12%), 3 (1.80%) and 0 (1.02%). Mean length and weight of the total sample, males and females, were 11.63 ± 0.02 cm, 9.98 ± 0.04 g; 11.39 ± 0.03 cm, 9.40 ± 0.07 g; and 11.98 ± 0.02 cm, 10.73 ± 0.05 g, respectively. The mean condition factor was CF = 0.63 and the sex composition was 61.27% female, 34.40% male and 4.33% unidentified. Equations describing the relationship between length and weight, age and length, and age and weight were derived as W = 0.011 × L2.742, L(t) = 16.368*(1–e−0.425*(t +1.35)) and W(t) = 23.516*(1 –e–0.425*(t+1.35))2,747, respectively. The survival (S), instantaneous total mortality (Z), annual mortality (A), natural mortality (M) and fishing mortality (F) rates were found to be S = 5.8%, Z = 2.84 yr–1,, A = 94.2%, M = 0.66 yr−1, and F = 2.18 yr–1, respectively. The exploitation rate was calculated as 0.77, which is higher than the optimum exploitation level.

Some crustaceans show variations of their reproductive biology within their geographical distribution, and knowledge about such variations is important for the comprehension of their reproductive adaptations. This study compared two populations of the fiddler crab Uca uruguayensis from two locations on the south-western Atlantic coast: Ubatuba Bay, São Paulo, Brazil and Samborombón Bay, Buenos Aires, Argentina. The population features analysed were the body size variation (carapace width = CW) and the size at the onset of sexual maturity (SOM) in order to test the hypothesis that the size at SOM, should be the same in relative terms (RSOM), independently of the latitudinal position. In the Brazilian population the CW ranged from 4.18 to 11.60 mm for males and 3.90 to 9.80 mm for females, and in the Argentinean population from 3.60 to 14.10 mm for males and 2.85 to 12.00 mm for females. In the Brazilian population the SOM was 7.1 (RSOM = 0.58) and 5.9 mm CW (RSOM = 0.57) for males and females, respectively, and in the Argentinean population it was 7.0 (RSOM = 0.42) and 6.75 mm CW (RSOM = 0.53) for males and females, respectively. This fact is probably related to a great plasticity in the life history features of Uca uruguayensis under different environmental conditions.