Sponges interact in various ways with a wide variety of organisms in benthic communities and ecological interactions may influence the distribution, abundance and diversity of these organisms in different sites. Although several studies have already been developed for Demospongiae, knowledge of ecological interactions in the class Calcarea is lacking. Some calcareous sponges are considered weak competitors for space and to have developed strategies to survive in highly dynamic environments, such as exploitation of micro refuges and epibiosis. We aimed to investigate the influence of intra- and interspecific interactions in the abundance, growth and lifespan of the calcareous sponge Clathrina aurea in south-eastern Brazil. Two peaks of abundance and area coverage were observed during the studied year, probably associated with reproductive effort. We found no evidence of intra- or interspecific competition between the sponge and the benthic community. Clathrina aurea was found using parts of other organisms as substrate (epibiosis), such as algae, demosponges and corals. It was seen that the interaction of the sponge with coral polyps positively affects the lifespan of sponge individuals and the interstices of corals probably promote a micro refuge for C. aurea against competitors for space and predators.

The present study investigated the population dynamics of Exhippolysmata oplophoroides in an area influenced by upwelling, focusing on reproductive period, sex ratio, growth rate, longevity, mortality, relative growth and size of sex change. We also tested the hypothesis that the appendices internae increased in size with sex change from the male to the simultaneous hermaphrodite phase as possible replacements for the male appendices masculinae, which are reduced or lost at sex change. Population structure was assessed by the distribution of size frequency in three demographic groups: male phase, hermaphrodite phase with, and without embryos. For relative growth analysis, the length of the following structures was measured: carapace, second pleuron, first pereopod, second pereopod, appendices internae of the second to fifth pleopods, and appendix masculina. Smaller size classes were composed only by male-phase individuals. The sex ratio was significantly biased towards the simultaneous hermaphrodite phase. Reproduction was continuous in the population throughout the year. Slower growth rates but higher maximum body sizes than those estimated at other locations in south-eastern Brazil were observed in the population studied. Cooler temperatures and higher nutrient levels associated with upwelling may have produced this pattern of reproduction and growth, similar to that found in more southerly austral latitudes. We also found that sex change influences the relative growth of body structures such as the second pereopods, appendices internae, and appendix masculina, and hypotheses on the adaptive value of such allometric growth are proposed.

Between 2008 and 2010, 27 acoustic tags were applied to various age and reproductive classes of grey whales in Laguna San Ignacio, Mexico, a part of the Biosphere Reserve ‘El Vizcaino’. Besides previously described S1 and S3 calls, two additional calls were identified: the impulsive S8 call and the slightly frequency-modulated S9 call. These two additional S8 and S9 calls are by far the most common grey whale sounds detected on tags, even though contemporary bottom-mounted acoustic recordings also collected from the lagoon in 2008 yielded no S8 or S9 calls. The new S8 and old S3 calls display similar spectral maxima, even though the S3 is a frequency-modulated harmonic call and the S8 is a broadband impulsive call. This spectral analysis provides evidence that these new call types are not artefacts arising from mechanical vibration or flow noise.

Upon infesting the hermit crab Pagurus proximus the parasitic barnacle Peltogaster reticulatus typically forms a single externa on each host. In vivo, histological and histochemical study revealed that most P. reticulatus with a single mature externa also exhibited three or four primordial externae and several buds of earlier developmental stages. It is shown that stolon buds and primordial externae in P. reticulatus internae intensively express alkaline phosphatase activity, the classical histochemical marker for mammalian embryonic stem and primary germ cells. Ovaries of the most developed primordial externae were filled with growing oocytes, so the process of oogenesis begins in the externa rudiments of P. reticulatus before the externae appear on the surface of the host body. Since the interna, which is connected to the mature externa, also integrated three or four additional primordial externae and several earlier buds, P. reticulatus, a non-colonial species based on the common presence of a single externa in each host, appears to have a hidden colonial organization at the parasitic stage of its life cycle.

A description of the first known mutualistic interaction between a cnidarian and a pelagic tunicate is presented. Calycopsid anthomedusan polyps, belonging in the genus Bythotiara, were discovered associated with individual zooids of a new doliopsid (Thaliacea: Doliolida: Doliopsidae) collected from the mesopelagic waters of Monterey Bay. One hundred and seventy five polyp-bearing doliopsid colonies have been observed and 43 were collected from 1995 to 2004. Colonies were observed in situ and then brought back to the laboratory and maintained in aquaria. More than 250 individual anthomedusan polyps were removed from positions at the buccal siphon of their doliopsid host zooids and maintained in the laboratory until they released medusae. The morphology and taxonomy of the polyps and medusae are described. A unique tentacle-based asexual reproduction strategy is discussed. The relationship between the doliopsid and the polyp appears to be mutualistic, with the doliolid obtaining both nutrition and protection from the anthomedusan polyps, while the polyps gain access to a mobile, food-rich substrate.

The diet of common wolffish Anarhichas lupus from the North Sea is described, from a total of 143 wolffish stomachs, of which 112 contained food. The main prey were crustaceans and molluscs, together representing almost 70% of diet by relative frequency of occurrence in stomachs. Wolffish >55 cm preferred polychaetes and gastropods while wolffish <55 cm preferred sea urchins and brittle stars. The occurrence of empty stomachs was significantly less in spring than in summer or in autumn/winter. Meal size was lowest in winter and highest in spring. These data reflect a period of low food intake in winter during spawning and tooth replacement, followed by a recovery feeding episode in spring.

Amongst the numerous subjects which have occupied the attention of the fishery authorities of the United States, that of the great decline in the productiveness of the lobster fishing industry has received much consideration, and several competent naturalists have, in consequence, devoted themselves to a scientific study of the habits and life-history of the American species. This species (Homarus Americanus) is so nearly allied to the European lobster (Homarus vulgaris), that the results arrived at for it, with regard to such questions as the time of year at which spawning takes place, the length of time during which the eggs are carried by the female attached to the under side of the abdomen, and the time of year at which the eggs are hatched, might be expected to apply, to some extent at least, to the latter. That this is so, appears to be abundantly proved by Dr. Ehrenbaum's study of the lobsters which frequent the shores of Heligoland, and certain observations which I have been able to make on lobsters taken in the neighbourhood of Plymouth during the last two years, in the course of my work on the nervous system of the embryo, also tend to confirm this view.

This study aimed to describe the ethnoecology of the franciscana (Pontoporia blainvillei) using the traditional knowledge of artisanal fishermen in the villages of Peças Island (VPI) and Superagui Island (VSI) in the World Heritage listed Paranaguá Estuarine Complex, Brazil. Between March and September 2012, 90 fishermen were interviewed (VPI – 40; VSI – 50) using a semi-structured questionnaire. Using Fuzzy logic (MATLAB 7.6) it was verified the species is easily recognized by body size, colour and occurrence area (VPI – 87.5%; VSI – 38.0%). Fishermen most frequently identified adults and young franciscanas in groups of two to five individuals (VPI – 40.0%; VSI – 58.0%). Adults were sighted throughout the year, while the young were restricted to summer and winter. Five common behavioural ethno categories were described: ‘eat’ (VPI – N = 15; VSI – N = 1); ‘float/sink/dive’ (VPI – N = 34; VSI – N = 12); ‘breathe’ (VPI – N = 11; VSI – N = 5); ‘mothers surrounding the shoal, play caught up and the youth captures’ (suggesting care parental related with feeding of infant) (VPI – N = 1; VSI – N = 2); and ‘to play’ (VPI – N = 6; VSI – N = 1). The information from the fishermen highlights the use of the area by franciscana for feeding and reproduction and these data are comparable with the literature. These results extend the knowledge about the species in an area of ecological interest and the traditional knowledge, but also illustrate the benefits of engaging fishermen to promote collaboration in scientific and management processes.

The chromosome number and karyotype of amphioxus Branchiostoma belcheri tsingtauense were studied using embryonic cells. The diploid chromosome number (2n) of B. belcheri tsingtauense is 36, and its karyotype 2n=36, 2st+34t, FN=36. This is the first report on the karyotype of the cephalochordate. Evidence suggesting the possible presence of a pair of sex-chromosomes in the amphioxus has been provided.

Copula trials in Neptunea arthritica were conducted to provide possible hypotheses explaining the outcomes of reproductive interaction with regards to size differences and female resistance in the context of conflict over copula duration between the sexes. Size asymmetry predicted the outcome of copula duration to favour the largest individuals. Female resistance was expressed consistently and increased with consecutive copulas, generating variation in copula duration. When resistance was removed, copula duration increased in contrast with natural trials suggesting intense conflict. Overall, males showed a tendency to mate with large females, which represents higher rejection risk, indicating that benefits from mating with large females might offset the risk of failure against resistance. Conflict possibly stems from a ‘power asymmetry’ in which individuals of one sex could sequester control over some aspects of mating to the detriment of the opposite sex.

Germination of cysts serves as inoculum for the proliferation of some dinoflagellates, and cyst abundance in sediments represents crucial information to understand and possibly predict Harmful Algae Blooms (HABs). Cyst distribution is related to the physical characteristics of the sediments and the hydrodynamics (circulation) of a particular region. In the northern Gulf of California (nGC) several Gymnodinium catenatum HABs have been recorded. However, the presence of resting cysts and the effect of hydrodynamics on their distribution in the nGC have not been investigated. This study evaluated cyst abundance, distribution and their relation to local circulation in surface sediments during two periods that coincided with a non-bloom year condition (July 2016) and after a major HAB registered in the nGC that occurred in January 2017. Also, a numerical ocean model was implemented to characterize the transport and relocation of cysts and sediments in the region. Gymnodinium catenatum cysts were heterogeneously distributed with some areas of high accumulation (as high as 158 cyst g−1, and 27% of total cyst registered). Cysts seemed to be transported in an eastward direction after deposition and accumulated in an extensive area that probably is the seedbed responsible for the initiation of HABs in the region. The nGC is a retention area of cysts (and sediments) that permit the formation of seedbeds that could be important for G. catenatum HAB development. Our results provide key information to understand G. catenatum ecology and specifically, to understand the geographic and temporal appearance of HABs in the nGC.

Antarctic krill, Euphausia superba, normally live in social aggregations (schools) but rarely aggregate in laboratory tanks. In order to study the effect of stress on solitary living we tethered krill to wooden skewers and measured heart rate both when they were held isolated from conspecifics and when they were held at normal schooling distances (∼1 body length). Heart rate did not differ significantly with sex or body size. However, intermoult krill had a significantly lower heart rate than postmoult animals. When two individuals were held at schooling distance, with one slightly higher in the water column than the other, the heart rate of the higher individual slowed significantly (106–98 beats min−1), while that of the lower individual remained the same. We interpret these results to mean that krill living solitarily are stressed but will respond to neighbouring individuals by decreasing their metabolic rate and saving energy.

A new spionid polychaete, Malacoceros jennicus, is described from the crater of a hydrothermally active submarine volcano near Grenada in the Caribbean, Lesser Antilles Arc region. The new species is characterized by having prominent lateral frontal horns on the prostomium, paired eye spots, neurosetae that include simple capillaries, inferior sabre setae, numerous bidentate hooded hooks, and a pygidium bearing four digitiform anal cirri surrounding the anus. Worms were collected in regions of diffuse venting with a suction sampler deployed on an ROV. Specimens representing a range of sizes including sexually mature and reproductive individuals containing eggs and sperm were found. Stable isotope analysis of 13C and 15N indicate mixed feeding on photosynthetic and hydrothermal vent source material.

Three deep-water species of the north-eastern Atlantic have been studied: Caryophyllia abyssorum Duncan, 1873, C. calveri Duncan, 1873, C. sarsiae n.sp. Of these only C. abyssorum has not been found in the Mediterranean. In the north-eastern Atlantic these species appear characteristic of somewhat different depths, but occasionally can be found together. Obtained by early deep-sea expeditions (“Porcupine” cruise of 1870, cruises of Prince Albert I of Monaco), all three species have been previously confused and assigned, chiefly, to the little-known fossil species C. arcuata and C. cylindracea. In order to show the world-wide confusion about C. arcuata, some other records, from Cape Verde Islands to Japan through Antarctica, are quoted.

The spiny butterfly ray Gymnura altavela (Linnaeus 1758) is classified as Endangered by the International Union for Nature Conservation (IUCN) and considered Critically Endangered in the Mediterranean Sea and South-west Atlantic. Despite its status, few studies on the population biology and genetics for the species are available, undermining conservation efforts. In the present study, we evaluated the taxonomic status of Gymnura altavela along both sides of the Atlantic using COI sequences. Our genetic data support the existence of two genetically differentiated G. altavela lineages (West and East Atlantic) and further studies are required to evaluate the hypothesis that these lineages could, in fact, be cryptic species within this endangered batoid's genus.

The influence of estuarine zonation in a coastal lagoon on the population variability of exploited penaeid shrimps Farfantepenaeus aztecus, F. brasiliensis, F. duorarum and F. notialis (Crustacea: Decapoda) at the ‘Ría Celestún’ Biosphere Reserve, Mexico, was evaluated. Monthly samples of shrimp and environmental factors were taken throughout 1997 and 1998 in three zones (seaward, middle, inner) of Celestún lagoon. Salinity and aquatic vegetation biomass exhibited a clear spatial heterogeneity of habitat. A total of 20,757 shrimps were collected mainly at the seaward zone, which registered the highest salinity and aquatic vegetation biomass. This revealed the critical contribution of the seaward zone as the most suitable habitat for shrimp populations, mainly for recruits. Results support the implementation of spatially-explicit management strategies, such as the closure of the seaward zone for fishing activities. The significant relationship between the recruits and the subsequent abundance of shrimp in the lagoon also support this operational measure.

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.

Morphometric characteristics and spatial distribution of Tontonia grandis sp. nov. were investigated in the northern East China Sea and the adjacent sea areas. Tontonia grandis has a large conical body shape, 113 μm (70–155 μm) in length by 55 μm (40–113 μm) in width, a caudal appendix, multiple macronuclei and 14 (13–16) anterior and 28 (24–33) ventral polykinetids. Some cells have numerous cortical platelets on the surface and others do not. These two forms showed different horizontal distribution, and hence the presence of cortical platelets might be influenced by the environment inhabited. However, various forms of caudal appendix were observed, which constitute a continuous series of their developmental stages. This result might suggest that the caudal appendix is replaced by new growth and repeats its developing and sloughing spontaneously.

In early 1956 and again in 1957 small samples of mature female Plaice Pleuronectes platessa L. were collected for fecundity estimates to be compared with Simpson's (1951) results for the North Sea populations, and the data from elsewhere that Simpson summarizes.

Seasonal changes in spatial structure of biomass of submerged aquatic vegetation (SAV) and environmental variables were evaluated in Celestun Lagoon, an estuarine habitat in Mexico. Geostatistical techniques were used to evaluate spatial autocorrelation and to predict the spatial distribution by kriging. The relative contribution of 11 environmental variables in explaining the spatial structure of biomass of SAV was evaluated by canonical correspondence analysis. Spatial partitioning between species of SAV was evident: the seagrasses Halodule wrightii and Ruppia maritima dominated the seaward and central zones of the lagoon, respectively, whereas the green alga Chara fibrosa was constrained to the inner zone. The spatial structure and seasonal variability of SAV biomass were best explained by organic carbon in the sediments, salinity and total suspended solids in the water column. Analysis at different spatial scales allowed identifying the importance of spatial structure in biotic and abiotic variables of this estuarine habitat.