The occurrence of 19 cetacean species along the German North Sea coastline as well as the lower reaches of the major rivers discharging into the German Bight is reviewed for the period 1604–2017 based on records of dead animals, either stranded dead or put to death. The harbour porpoise (Phocoena phocoena) is considered the most abundant and only native species in German coastal and riverine waters. Based on written sources its presence can be traced back to at least 1651, although with statistical data only available from 1990. Finds of further 18 species have been documented: white-beaked dolphin (Lagenorhynchus albirostris), bottlenose dolphin (Tursiops truncatus), Atlantic white-sided dolphin (Lagenorhynchus acutus), common dolphin (Delphinus delphis), striped dolphin (Stenella coeruleoalba), Risso's dolphin (Grampus griseus), long-finned pilot whale (Globicephala melas), killer whale (Orcinus orca), beluga whale (Delphinapterus leucas), narwhal (Monodon monoceros), Sowerby's beaked whale (Mesoplodon bidens), northern bottlenose whale (Hyperoodon ampullatus), sperm whale (Physeter macrocephalus), minke whale (Balaenoptera acutorostrata), sei whale (Balaenoptera borealis), fin whale (Balaenoptera physalus), blue whale (Balaenoptera musculus) and humpback whale (Megaptera novaeangliae). This review corrects several false species assignments earlier introduced in literature based on incorrect scientific or ambiguous German vernacular names and recovers lost records of beluga whale, northern bottlenose whale, sperm whale and fin whale.

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.

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.

The aim of this work was to describe and compare the main fatty acids and biodiesel indices of some green and brown macroalgae (seaweeds) collected from the Persian Gulf, as an alternative raw material for renewable biodiesel production. The macroalgae showed low lipid content (< 10% DW) but marine macroalgae with total lipid content > 5% DW are a good source for biodiesel production. The total lipid content and saturated fatty acids (SFAs) of green algae were higher than that of brown algae, while higher accumulation of unsaturated fatty acids (USFAs) was observed in brown seaweeds. Further, the main fatty acid in all studied seaweeds was palmitic acid (C16:0), which was followed by oleic acid (C18:1). The results of this work showed that three of the green algae, especially C. sertularioides, could be a potential source of fatty acids for biodiesel production owing to their high total lipid content, high cold flow indices (long chain saturated factor, cold filter plugging point and cloud point) and a fatty acid profile rich in SFAs with a high amount of C18:1, which is suitable for oil-based bio products. In contrast, the brown seaweeds Sargassum boveanum and Sirophysalis trinodis lipid content had a high proportion of polyunsaturated fatty acids (PUFAs), which makes them suitable for replacing fish oil.

Studies concerning octocoral species from the Persian Gulf coral reefs are few. This study documents the diversity and abundance of octocoral communities from three islands in the north Persian Gulf, namely, Larak Island, Hengam Island and Qeshm Island. Belt transects were used to survey the octocoral communities at these islands. We used a rapid ecological assessment technique (REA) to assess the status and abundance of octocorals. Also, K Independent sample analysis was conducted on abundance and Shannon Diversity index data to determine if octocoral abundance and species diversity varied between islands. A total of 22 morphospecies, belonging to seven alcyonacean families, including Plexauridae, Ellisellidae, Alcyoniidae, Nephtheidae, Briareidae, Acanthogorgiidae and Subergorgiidae, were identified in this study. Statistical analysis indicated octocoral abundance and diversity at Larak Island reefs were higher than those around Hengam and Qeshm islands. The primary data presented in this study could serve as the baseline data for long-term biomonitoring programmes to estimate the status of octocorals in the Persian Gulf.

There is an important small-scale fishery using mechanized dredges and targeting clams (mainly wedge clam Donax trunculus and striped venus clam Chamelea gallina) along the Catalan coast (NW Mediterranean Sea). This study evaluated for the first time the discards and impact of mechanized clam dredging on the Catalan coast. To this end, three surveys were performed on board standard clam vessels (September and November 2016 and January 2017). Surveys were conducted in the three main clam fishing areas (Rosas Bay, South Barcelona and Ebro Delta). The composition of discards and the impact caused to discarded species was assessed using a three-level scale (undamaged; minor or partial damage; and lethal damage). Our study revealed that a large proportion of the catch (between 67–82% weight) is discarded. Even though about 63% of the discarded species were undamaged, 11% showed minor or partial damage and 26% lethal damage. Infaunal and epifaunal species with soft-body or fragile shells were the most impacted by the fishing activity (e.g. the sea urchin Echinocardium mediterraneum (~89%) and the bivalve Ensis minor (~74%)). Our results showed different levels of impact by target species and fishing area.

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.

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.

The complete larval development of the spider crab Maguimithrax spinosissimus (Lamarck, 1818) is re-described and illustrated in detail from laboratory-reared material. The development consisted of the typical pattern reported for the Majoidea, two zoeal stages and one megalopa. The complete larval development from hatching to first crab lasted 5–6 days at temperatures that ranged between 24–28 °C. Both zoeal stages of M. spinosissimus exhibited moderate reduction in the number of setae in the maxilla and maxillipeds, from the first to the second zoeal stage, when compared with other closely related species. Maguimithrax spinosissimus can be easily distinguished from other species belonging to the closely related genus Mithrax by the (i) setation of the endopod of the maxillule, maxilla and second maxilliped in both zoeal stages; (ii) setation of the scaphognathite of the maxilla in the first zoeal stage; (iii) setation of the basis of maxilliped I in the second zoeal stage and megalopa; (iv) morphology of the antennule and antenna in the second zoeal stage; and (v) setation of the antennule, coxal endite of maxilla, and exopod of second maxilliped in the megalopa. All these characters support the recent generic status of Maguimithrax within the Mithracidae. Additional morphological details, not available previously, are provided. This study will provide support for conservation strategies in this species.

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.

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.

Accurate assessment of age and growth of fish is essential to understand population dynamics, namely for age-structured stock assessment and for determining vital rates of fish (e.g. age at sexual maturity) and their relationship with environmental variability. To validate the daily deposition in the otoliths of European sardine (Sardina pilchardus) larvae, these were reared with a range of food densities translating into feeding rates extending from less than required for maintenance to saturated feeding levels. When exogenous feeding began, a high variability in the relationship between number of growth increments (GI) and elapsed days after hatching (dph) was observed, irrespective of the feeding treatment. GI counts using a light microscope were less than one per day for larvae <15 dph (ranging from 0.17–0.43 GI day−1) and similar for larvae reared with different food concentrations. The rate of GI count vs age was significantly higher for larvae older than 15 dph. GI count from 3–30 dph was lower than one per day (0.45–0.75 GI day−1 95% CI) for fed larvae 3–30 dph. Scanning electron microscopy confirmed the daily deposition of GI and revealed some increment widths around 0.2 μm, particularly during the first week post-hatch. Otoliths of wild sardine larvae exhibited narrow GI (<0.5 μm) comparable with reared larvae. This study demonstrates that during the first weeks after hatch the daily increment deposition is underestimated using traditional light microscopy, which must be taken into account in future works determining wild sardine larval growth.

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.