In mid-February 1963, a survey of sea temperatures in the western English Channel was made by means of a thermistor towed continuously behind the ship, also by water-bottle samples in a limited area between Plymouth and the Lizard. Evidence is given that surface temperatures, as measured by the thermistor, were representative of the whole water column. Sea temperature records from Torquay indicate that at this time temperatures were near their minimum for this exceptionally cold winter; at Plymouth where sea temperatures are usually more erratic because of estuarine influences the minimum had already been passed. A comparison with data for previous years at Plymouth shows that during January, February and March mean temperatures were lower than in any corresponding month since records were started in 1898.

The sea anemone Anemonia viridis is one of the most common species of the North Aegean Sea. The variety in colour morphs exhibited by this species, causes problems to taxonomy and ecology, and suggests that A. viridis should be subdivided into two distinct species according to the colour of the individuals. The approach used in this study was based on the biometrical cnidae characteristics of the two colour morphs (rustica and smaragdina), as it is known that cnidae biometry has been used as a taxonomic tool for the phylum Cnidaria. More than 20,000 nematocysts were measured to try and find a correlation between these measurements and some body parameters indicative of the maturity grade of the individuals, as potential taxonomic characteristics. Stable cnidae characteristics of the two different colour morphs were compared. However, they differed only in the biometry of the tentacles' a-basitrichs. This slight difference does not support the proposal to subdivide Anemonia viridis into two different species.

The recent establishment of the lessepsian species Leonnates persicus (Annelida: Polychaeta: Nereididae) in Izmir Bay (Aegean Sea) was investigated. A total of four specimens were collected at three stations in December 2001, with two specimens having eggs within their coelomic cavities and parapodia. A re-description of the species together with its ecological and distributional aspects are provided.

Many species of marine sponges on tropical reefs host abundant and diverse symbiont communities capable of varied metabolic pathways. While such communities may confer a nutritional benefit to some hosts (termed High Microbial Abundance (HMA) sponges), other sympatric species host only sparse symbiont communities (termed Low Microbial Abundance (LMA) sponges) and obtain a majority of their C and N from local sources. Sponge communities are widespread across large latitudinal gradients, however, and recent evidence suggests that these symbioses may also extend beyond the tropics. We investigated the role that symbionts play in the ecology of sponges from the temperate, hard-bottom reefs of Gray's Reef National Marine Sanctuary by calculating the niche size (as standard ellipse area (SEAc)) and assessing the relative placement of five HMA and four LMA sponge species within bivariate (δ13C and δ15N) isotopic space. Although photosymbiont abundance was low across most of these species, sponges were widespread across isotopic niche space, implying that microbial metabolism confers an ecological benefit to temperate sponges by expanding host metabolic capability. To examine how these associations vary across a latitudinal gradient, we also compared the relative placement of temperate and tropical conspecifics within isotopic space. Surprisingly, shifts in sponge δ13C and δ15N values between these regions suggest a reduced reliance on symbiont-derived nutrients in temperate sponges compared with their tropical conspecifics. Despite this, symbiotic sponges in temperate systems likely have a competitive advantage, allowing them to grow and compete for space within these habitats.

Observations of citizen scientists have become an indispensable source in the collection of biodiversity data worldwide. In Greece, the findings of these citizen scientists, in collaboration with the Hellenic Network on Aquatic Invasive Species (ELNAIS), have resulted in compiling diverse information on marine alien species. Since 2004, the Liamis Dive Centre has recorded visual data on 12 marine alien species around Pserimos Island (Dodekanisa, Greece), thus enabling us to sequence their progression and displacement amongst other vital information. The real number of biological invasions is likely to be higher than reported here because citizen scientists do not have the scientific skills required for species identification and also due to financial constraints. Nevertheless, the high number of observers to a certain extent compensates the lack of taxonomic expertise.

The distribution and feeding ecology of two puffer fish, Sphoeroides testudineus (Linnaeus, 1758) and Colomesus psittacus (Bloch & Schneider, 1801), were investigated in a tropical estuary (north-eastern Brazil). The hypothesis tested was that these two species partition available resources spatially, and that the effects of interspecific competition can be reduced by changes in the feeding strategy and using alternative resources. This study was carried out between February 2011 and January 2012, on a beach and three tidal creeks of the Mamanguape River estuary. Data on the distribution and relative abundance of the two species were collected using beach seine, with data on temperature, salinity and turbidity also recorded. The diets of the species (S. testudineus N = 399; C. psittacus N = 108) were analysed by the Index of Relative Importance (IRI). Sphoeroides testudineus was found in the entire area, but was particularly abundant in the upper estuary, while C. psittacus was captured exclusively in the upper estuary, with all individuals assumed to be juveniles. In regard to feeding, juvenile S. testudineus predated on Bivalves, Ceratopogonidae larvae, calanoids and gastropods; whilst C. psittacus showed a diet more specialized in Brachyura and Cirripedia. These results suggest that there are differences in both habitat utilization and feeding habits of these two puffer fish species in this estuary.

Kelp forests are regarded as important nursery and foraging habitats for commercially important species of finfish and shellfish despite an absence of fishery-independent data in many regions. Here, we conducted targeted surveys at 12 subtidal reefs, distributed across 9° of latitude in the UK, using three complementary techniques (Underwater Visual Census (UVC), Baited Remote Underwater Video (BRUV) and deployment of prawn pots) to quantify the abundance of crustaceans within kelp forests. Commercially important species were recorded at all sites; Cancer pagurus (brown/edible crab) and Necora puber (velvet swimming crab) were the most abundant and commonly observed, although Maja brachydactyla (spider crab), Homarus gammarus (European lobster) and Palaemon serratus (common prawn) were also recorded. The abundance of some species exhibited pronounced regional variability, with higher abundances of C. pagurus within northern regions and, conversely, higher abundances of M. brachydactyla and P. serratus within southern regions. Each sampling technique yielded similar spatial patterns for the most abundant species but had varying sensitivity to some species. Most individuals observed were juvenile or sub-adults, suggesting kelp forests serve as important nursery grounds for commercially and ecologically important crustaceans. Further monitoring efforts, conducted across greater spatiotemporal scales and in different habitat types, are needed to provide a robust baseline against which to detect changes and to inform management and conservation actions.

After the recent detection, by both morphology and DNA barcodes, of the larval stages of an unknown species of pea crab (Pinnotheres sp.) in European waters, adults of this crab are herein reported and described as a new species. The current known geographic distribution of the species comprises the Gulf of Cádiz in the eastern Atlantic and the adjacent Mediterranean waters of the south of the Iberian Peninsula (Alboran Sea), where this crab is well-established inside the anomiid bivalve Anomia ephippium. In the Gulf of Cádiz, the species displayed a relatively high prevalence: on average, 55.6–77.7%, in A. ephippium samples. The dominant demographic categories of the new species were soft females (61.8–77.0%) with fewer males (17.7–21.10%). Most of the host bivalves carried only one crab; in bivalves harbouring two crabs, heterosexual pairs were collected more frequently than expected by chance, which suggests that they could be mated pairs. A strong correlation between host size and soft female size was found (r = 0.73, P < 0.01) indicating that space availability within hosts seems to be relevant in determining the size of the sedentary phase of the new crab species.

The worldwide population of the leatherback turtle (Dermochelys coriacea) encompasses seven subpopulations among the Pacific, Atlantic and Indian Oceans. It has experienced declines across parts of its distribution, with the subpopulation of the South-west Atlantic listed as critically endangered by the IUCN Red List. The main threats to this subpopulation include its interaction with fisheries, coastal development, pollution and climate change. In this study, we sequenced mitochondrial DNA from 52 leatherback turtles in Brazil and combined these with published data from other Atlantic Ocean rookeries. The haplotype diversities of the Atlantic population rookeries ranged from 0.112 to 0.533 and are not directly proportional to current rookery sizes. The Brazilian rookery, despite recording low nest numbers per year, had the second-highest haplotype diversity among all Atlantic rookeries (h = 0.532). A mixed-stock analysis revealed that the South American pelagic aggregate is primarily composed of individuals from West Africa (84%), with contributions from the North Atlantic rookeries (14%). Leatherback turtles appear to have a complex phylogeographic pattern, showing evidence of multiple colonization events and a lack of isolation by distance. Our novel dataset, based on DNA sequences of 695 base pairs, will provide baseline data needed to understand population dynamics in the region, building comprehensive population assessments to support and develop management strategies. Having both the only known regular rookery in the South-west Atlantic, and a mixed-origin foraging area for the species along its coast, Brazil has a key role in the conservation of the leatherback turtle.

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.

Thermoregulation has been suggested to influence mitochondrial DNA (mtDNA) evolution. Previous studies revealed that the mitochondrial protein-coding genes of fish living in temperate climates have smaller dN/dS (Non-synonymous substitution rate/Synonymous substitution rate) than tropical species. However, it is unknown whether different geographic populations of one fish species experience stronger selective pressures between cold and warm climates. The biological characteristics of the Japanese sand lance, Ammodytes personatus in the North-western Pacific is well-suited for assessing the performance of mtDNA evolution among separate geographic populations. In this study, we focused on the mitochondrial ATP6 gene of A. personatus using 174 individuals from eight different sea temperature populations. Two distinct haplotype lineages and a significant population structure (P = 0.016) were found in this species. The frequencies of the two lineages varied with the changes of annual sea temperature. The southern lineage (lineage A, dN/dS = 0.0384) showed a larger dN/dS value than the northern lineage (lineage B, dN/dS = 0.0167), suggesting that sea temperature greatly influences the evolution of the two lineages. The result provides robust evidence of local adaptation between populations in A. personatus.

Twenty-three observations of 26 fin whales Balaenoptera physalus are documented for the northern Adriatic. Records were more common along the eastern coast and have increased over the last decades. The latter coincides with the increased presence of other planktivorous vertebrates (humpback whale, basking shark) and possibly follow changes in the zooplankton abundance.

Two specimens of the Chinese mitten crab Eriocheir sinensis (Crustacea: Decapoda: Brachyura) were caught in the River Tyne, north-east England during 2001. The specimens were brought back to the laboratory, sexed, measured and stored in 95% ethanol. Unconfirmed reports of this species' occurrence in the River Tyne were first circulated in 1997.

This study aims to determine the relationship between physico-chemical variables on a seasonal basis and wild fish assemblages beneath sea-cage fish farms. Assemblages of wild fish were counted monthly on two separate days at each of six fish farms between August 2015 and July 2017, by six rapid visual counts (RVC) in 5 minutes with scuba by two divers. Seawater samples were simultaneously taken by a Nansen bottle during the RVC from the fish farm barge. SST (°C), salinity (ppm), dissolved oxygen (mg l−1) and pH were measured by YSI multiparameter, while Secchi disk was also used for light transmittance. Wild fish species richness went up with increasing temperature and salinity in the Izmir region, however, this stopped at about 26°C and about 39 ppm. Wild fish richness increased when the DO was at a level of 7 mg l−1 and the pH at about 7.9 in Izmir. Between 10 and 20 m, light transmittance showed greater wild fish species richness in Izmir region. In contrast, the wild fish species richness of the Muğla region fluctuated more. In terms of wild fish species richness, these fluctuations increased with salinity and DO, while they decreased with SST, pH and light transmittance. However, the range of variation of the recorded physico-chemical variables is rather narrow. The results of the correlation matrix indicate that the relationship between wild fish species richness and pH and SST was statistically significant in Izmir region (P < 0.05).

Small vagile epiphytic crustaceans formed the greatest proportion of the diet of worm pipefish. There were significant differences in the number (Mann–Whitney U=22006·5, P<0·001) and diversity (Mann–Whitney U=11546·0, P<0·05) of prey consumed by male and female pipefish. Harpacticoid copepods are the most numerically dominant form of prey consumed. Further gender analysis of mature pipefish revealed that reproductively mature females and egg-bearing male worm pipefish show significantly greater predatory effort (Kruskal–Wallis H=24·15, df=2, P<0·001). Increased feeding activity, within these groups, is suggested to alleviate the substantial reproductive costs for both female and egg-bearing male pipefish.

The 1949 production of young fish and plankton in Plymouth off-shore waters continued to remain at the low level characteristic of the last few years. Collections were made by half-hour oblique hauls of the 2 m. stramin ring-trawl; the dates are given in Table I. The fortnightly averages of all young fish, excluding clupeids, are shown in Table II with comparative figures for 1948 and for the period 1930–34. The highest value, in the second half of June, may have been unduly weighted, since only one collection was made in the fortnight. The monthly total catches of young fish are given in Table III. The sum of the monthly averages for all young fish (459) was slightly higher than the 1948 value (3111), due to larger catches of clupeids; young fish other than clupeids continued to decrease. A few post-larval herring were present in January, and for the third successive year young Mugil spp. occurred; two in October and one in December. No young plaice were caught, although a very small number of plaice eggs were present in January and February. Plankton, other than young fish, was very sparse throughout the year, Calanus being even scarcer than in 1948. Sagitta setosa was the dominant Sagitta species, although never abundant, and as in recent years the numbers were particularly low from February to June. A few S. elegans occurred in November and December (maximum, 66 specimens). The abundance and percentages of the Sagitta species are shown in Fig. 1.

The digestive system of the thalassinidean mud-shrimp Upogebia stellata was investigated using scanning electron microscopy (SEM). Within the lumen of the midgut both filamentous and rod-shaped bacteria were observed. The hindgut microbial populations were dominated by dense mats of epimural rod-shaped bacteria. The gut contents were often dominated by diatoms but also contained bacteria, dinoflagellates, plant and algal fragments. Direct bacterial counts by epifluorescence microscopy along the length of the gut revealed a slight decrease in numbers within the midgut moving from the anterior to the posterior regions, and then a dramatic rise in numbers within the hindgut. Numbers decreased again in the posterior regions of the hindgut. Common in the transient / resident samples (bacterial population when gut contents were present) were enterobacteria and an unidentified fermenter conforming to an isolate named X-ferm. However, nearly 30% of the bacterial isolates remained unidentified. The resident-only bacterial isolates from the gut (determined when the gut was empty) were dominated by the X-ferm bacteria and to a lesser extent by the genera Vibrio and Aeromonas. With respect to the enzyme capabilities of the gut bacteria, the resident-only collection of bacterial isolates showed much higher levels of amylase, cellulase, chitinase, protease and lipase activity than the transient/resident bacterial isolate collections, suggesting that the indigenous bacteria are likely to play a significant role in the digestion of the gut contents. Thalassinidean shrimps are likely to play an important role in the breakdown of plant and detrital material, and the recycling of nutrients in marine benthic systems.

On Tarifa Island (Strait of Gibraltar) several amphipod species were studied from intertidal algae: Ampithoe ferox, Apherusa mediterranea, Hyale spinidactyla, Hyale cf. youngi and Jassa cadetta. The allometric growth of gnathopod 2 in male is demonstrated for A. ferox. Jassa cadetta had been recorded previously only from the northern Adriatic Sea, while Hyale spinidactyla and Hyale cf. youngi had been only known from the Atlantic Ocean. Along the intertidal area, A. mediterranea and J. cadetta were dominant in the low levels located near the infralittoral area, while A. ferox, Hyale spinidactyla and Hyale cf. youngi were distributed in intermediate and upper levels, closer to the supralittoral zone. All the species showed the maximum peaks of abundance from April to October, coinciding with the maximum seawater temperatures.

Otolith microstructure analysis was used to determine daily growth rate and hatching periods of young of the year (YOY) annular seabream, Diplodus annularis, collected by using beach seine from Çanakkale shallow waters between January and December 2007. Total length of the YOY D. annularis was between 20 and 85 mm and the daily ages ranged between 27 and 205 d. Somatic growth rate, estimated by fitting a linear regression to the age–length data set, was calculated as 0.369 mm d−1. Seasonal changes in the growth rate of the YOY D. annularis have been found to be 0.381, 0.369, 0.357 and 0.308 mm d−1 for individuals that hatched in spring, summer, autumn and winter, respectively. Analysis of covariance indicated that there were no significant differences (P > 0.05) in the growth rates between the seasons. Hatching period of the YOY D. annularis was estimated to occur between March and September, with relatively higher hatching frequency in June.