Estuaries in Brazil are highly threatened environments and habitat loss is the main influential factor for the increase in the number of strandings of Antillean manatee (Trichechus manatus) calves in the north-eastern region of the country. The aim of the present study was to analyse and quantify the spatiotemporal dynamics of mangroves in the state of Paraíba and the association with manatee calf stranding events. The study area encompassed 10 remaining mangroves along the coast of the state, four of which were located within protected areas. Information on the mangrove forests was obtained from satellite images from the last four decades. Data on stranded Antillean manatee calves were obtained from a databank with records from 1980 to 2019. The data were analysed using geoprocessing techniques and statistical analyses. The results demonstrated changes in the mangrove forest over time, with larger areas existing during the 1980s, reductions in the following periods but a slight increase in the last decade. The number of stranded Antillean manatee calves increased over the years, with stranding events concentrated mainly on the northern coast of the state. The smallest number of stranding events occurred in the 1980s, when the mangrove forests were larger. Our findings confirm that the integrity of mangroves is of extreme importance to the maintenance and sustainability of Antillean manatee populations.

The Caymanostellidae is a family of rarely encountered wood-dwelling deep-sea sea-stars, with only six species, in two genera, described to date. During the COBERPES 5 expedition on board the RV ‘Justo Sierra’, off Tabasco, Gulf of Mexico in 2013, 12 specimens were recovered from a single piece of sunken wood. Herein we describe a new genus and species of caymanostellid, Crinitostella laguardai gen. nov., sp. nov. This species represents the shallowest known caymanostellid (418–427 m depth), and the first known occurrence of the Caymanostellidae from the Gulf of Mexico. The family Caymanostellidae displays affinities with several groups, such as Asterinidae and Korethrasteridae, making it difficult to infer its phylogenetic position evidenced by the myriad of contrasting phylogenetic hypotheses proposed. In an attempt to shed some light on the phylogenetic relationships of the family, sequences of nuclear and mitochondrial DNA of the new species were generated and combined with published data. As previously suggested, caymanostellids seem to be part of valvatacean polytomy rather than velatids.

The franciscana dolphin (Pontoporia blainvillei) is a coastal dolphin endemic to the western South Atlantic Ocean. The dolphin is listed as vulnerable in the IUCN Red List, with incidental catches in gillnet fisheries the greatest conservation concern for this species. Insights into the feeding habits of this dolphin are essential to understand its distribution, movements and use of habitat, which are fundamental for effective management of the species. The feeding habits of franciscana dolphins were investigated from analyses of stomach contents of animals incidentally caught by two fishing operations from southern and northern regions of the southern Brazilian coast. In this study we investigate the existence of intrapopulation (sexual maturity and sex-related) variation in the diet of the franciscana dolphin, evaluating the spatial (northern and southern geographic areas) and seasonal influences. The analyses were based on Linear and Generalized Linear Models (LM and GLM). The majority of identified prey species were bottom-dwelling teleosts and the squid Doryteuthis sanpaulensis. The most important prey differed spatially and seasonally between northern and southern regions of the study area, and our results revealed significant differences between sexes and sexual maturity stages, mainly related to prey species sizes. This variation might indicate differences in prey selection, availability or habitat use patterns among these groups. In any case, these dietary differences are likely to minimize intraspecific competition for food resources, and/or indicate spatio-temporal variation in prey availability.

Currently, there is little comparative data on ‘efficiency’ of different engineering species, i.e. species richness, density and biomass of the associated organisms that have been supported by engineering species. The use of fouling communities makes it possible to compare the efficiency of different engineering species under the same conditions, which is necessary to obtain correct estimates and difficult to do when studying natural bottom communities. In this study, we have analysed the fouling communities in four different mussel culture farms in the White Sea to test the following hypotheses. (1) Different engineering species (mussel Mytilus edulis, solitary ascidian Styela rustica, sponge Halichondria panicea) have different assemblages of the associated vagile fauna. (2) Mytilus edulis is the most efficient engineering species, i.e. species richness, species diversity, density and biomass of the associated vagile fauna is higher in the mussel communities than in those dominated by Styela rustica or Halichondria panicea. The first hypothesis was confirmed, while the second was rejected. In all the culture farms studied, all parameters of the mussel-associated vagile fauna were not higher and in most cases were even lower than those of the fauna associated with ascidians or sponges. The reason for this seems to be the very dense packing of mussels in patches. Therefore, Mytilus edulis is not the most efficient engineering species among fouling organisms, at least in the conditions of the subarctic White Sea. The data obtained are particularly important in view of the ever-increasing volume of anthropogenic substrate and fouling communities in coastal marine ecosystems.

Asari clam (or Manila clam) Ruditapes philippinarum is an important bivalve for local fisheries. This species exhibits a large variation in shell morphology, and the shell roundness tends to be greater in more unsuitable habitats. To test whether the increments in shell size parameters (length, height and width) were affected solely by environmental conditions or by internal factors such as initial shell shapes or growth rate, a field caging experiment was conducted at two different sites of unsuitable and suitable habitats in Matsukawaura Lagoon, Japan, where shell shapes of wild clams were significantly different between the habitats. In the experiment, clams were released from the two sites to the same site or to the other site and were re-collected after 3, 6 and 12 months of caging. Caged clams originating from unsuitable habitats and released to suitable habitats showed a reduction in shell height relative to shell length, while clams from suitable habitats introduced to unsuitable habitats showed marked increases in both shell height and width. Generalized linear mixed models suggested that the increase in shell height was affected largely by the release habitat (environment) whereas the increase in shell width was affected largely by the individual growth rate. These results suggest that marginal growths in shell height and width respond differently to external and internal factors of clams, resulting in plasticity in their shell shapes according to the environments to which they are translocated.

The amathillopsid subfamily Cleonardopsinae Lowry, 2006 is reviewed. The only species of the subfamily, Cleonardopsis carinata K.H. Barnard, 1916, should be regarded as a species-complex. A new genus and species of the subfamily, Carinocleonardopsis seisuiae gen. et sp. nov., is described from the Sea of Kumano, Japan as the second species of the subfamily Cleonardopsinae as well as the first record of the subfamily from the North Pacific. This new genus can be easily distinguished from Cleonardopsis by the presence of distinct large eyes and the dorsal carination on head, pereonites and pleonites.

Petroleum hydrocarbons (PH) toxicity and bioaccumulation in aquatic organisms have been investigated for almost 50 years. Continuous oil spillages necessitate a further understanding of the toxicological effects of PH on brachyuran crabs. Crabs can be exposed to PH through various routes such as the water column, sediment and diet. Numerous investigations have been dedicated to evaluating PH toxicity on different life stages of crab species, but the majority of them have focused on the blue crab Callinectes sapidus as it represents an edible and favourable seafood commodity for human consumption. The objective of the review is to critically assess studies related to PH toxicity on different life stages of 41 crab species representing 13 families across the world. Several physiological, biochemical and genetic endpoints of marine crabs were evaluated in addition to the sublethal effects of PH on crab metabolism, behaviour, moulting, growth and survival. A concise summary of PH deleterious effects on different taxonomic species of marine crabs is discussed and provides evidence that crabs can be used as indicator organisms of biomarker significance for marine pollution. Overall, larval stages appeared to be the most sensitive to the deleterious effects of PH compared with juveniles and adults. However, adult stages have received more research attention than other life stages, followed by larval stages, and juvenile stages are the least investigated stages with respect to PH toxicity. Finally, hepatopancreas and gills were the organs where greatest accumulation of PH was recorded.

Age and growth of the yellowmouth barracuda Sphyraena viridensis (Cuvier, 1829) was examined in 698 individuals (184 < TL (mm) < 1210; 25 < TW (g) < 7125), sampled monthly from commercial catches in eastern coasts of Algeria between January 2007 and January 2008. Marginal increment analysis of 159 sectioned sagittal otoliths combined with information derived from length–frequency distribution showed that annulus formation occurs between June and August. Maximum observed age of males and females is 14 and 13 years respectively. Back calculations of total length-at-age were used to fit the data to the Bertalanffy growth model: TL = 1113(1 – e−0.165(t+2.251)) in males and TL = 958.3 (1 – e−0.247(t+1.422)) in females. The coefficient of allometry of the length weight relationship is 3.02 and 2.99 in males and females, respectively. Growth performance index Ø = 3.33. Natural mortality (M) was estimated as 0.45 year−1, fishing mortality (F) was 0.06 year−1and the exploitation rate (E) was 0.11.