Global warming is facilitating the poleward range expansion of plant and animal species. In the Mediterranean Sea, the concurrent temperature increase and abundance of (sub)tropical non-indigenous species (NIS) is leading to the so-called ‘tropicalization’ of the Mediterranean Sea, which is dramatically evident in the south-eastern sectors of the basin. At the same time, the colder north-western sectors of the basin have been said to undergo a process of ‘meridionalization’, that is the establishment of warm-water native species (WWN) previously restricted to the southern sectors. The Gulf of Genoa (Ligurian Sea) is the north-western reach for southern species of whatever origin in the Mediterranean. Recent (up to 2015) observations of NIS and WWN by diving have been collated to update previous similar inventories. In addition, the relative occurrences of both groups of southern species have been monitored by snorkelling between 2009 and 2015 in shallow rocky reefs at Genoa, and compared with the trend in air and sea surface temperatures. A total of 20 southern species (11 NIS and 9 WWN) was found. Two WWN (the zebra seabream Diplodus cervinus and the parrotfish Sparisoma cretense) and three NIS (the SW Atlantic sponge Paraleucilla magna, the Red Sea polychaete Branchiomma luctuosum, and the amphi-American and amphi-Atlantic crab Percnon gibbesi) are new records for the Ligurian Sea, whereas juveniles of the Indo-Pacific bluespotted cornetfish Fistularia commersonii have been found for the first time. While temperature has kept on increasing for the whole period, with 2014 and 2015 being the warmest years since at least 1950, the number of WWN increased linearly, that of NIS increased exponentially, contradicting the idea of meridionalization and supporting that of tropicalization even in the northern sectors of the Mediterranean basin.

Understanding the diet of marine predators is essential to defining their trophic role in an ecosystem. Elasmobranchs (sharks and batoids) are considered pivotal components of marine food webs, and are often included in the top predator or mesopredator groups. However, in comparison with other Mediterranean areas, research focusing on marine predators inhabiting the Levantine Sea (eastern Mediterranean Sea) is very limited. Here, we examined the feeding habits (diet, trophic width and trophic position) of three endangered batoids (Gymnura altavela (Linnaeus, 1758), Raja asterias Delaroche, 1809 and Raja clavata, Linnaeus, 1758) coexisting in Iskenderun Bay (north-eastern Levantine Sea, Mediterranean Basin) by combining stomach content and stable isotope analyses. The results revealed clear differences in the trophic habits between them. Stomach contents showed differences in the diet between species, showing a clear feeding preference for teleosts in the case of G. altavela and a diet composed of fish and crustaceans in the case of R. asterias and R. clavata. In line with stomach content results, interspecific differences in the isotopic values and trophic levels were found. In particular, G. altavela was isotopically segregated from R. asterias and R. clavata, showing lower isotopic trophic width and higher trophic level. The results of this study provide new insights into the ecological role of these three endangered batoid species in the Levantine Sea and are of crucial importance for management and conservation of these species.

Short-term measures of behavioural responses of cetaceans to tourism operations have been used in many studies to interpret and understand potential long-term impacts of biological importance. The short-beaked common dolphin (Delphinus delphis) is the species most frequently observed in the Azores and constitutes an important component of the marine mammal tourism industry in this region. This study investigated the potential effects of tour boats on the behaviour of common dolphins off São Miguel, Azores, with particular focus on the changes in activity budget and the time required to resume activities after a tour boat interaction. Behavioural data were collected from land using a group focal-follow methodology. Markov chains were applied to analyse control and interaction sequences and to assess behavioural transition probabilities in both scenarios. In the presence of tour boats, dolphins significantly reduced the time spent foraging and increased the time engaged in other high energy activities. Dolphins also took significantly longer to resume feeding after an interaction occurred. The average bout length varied significantly between control and interaction scenarios, with foraging bouts being shorter during tour boats interactions. The results presented have management implications since feeding is a biologically critical activity. Disruption of foraging behaviour could lead to a decrease in energy intake for this population. With cetacean tourism likely to increase in the future, a precautionary approach to issuing new licences is advisable and any expansion would warrant an appropriate monitoring programme.

Space is one of the primary limiting resources for organisms on the intertidal rocky shore. This paper examined the effect of reduced density on key traits (mortality and growth) on the intertidal barnacles, Chthamalus montagui and Semibalanus balanoides, on the mid-shore in Plymouth, UK. Intra- and interspecific treatments comprising of C. montagui and S. balanoides were manipulated to reduce densities at two similar sites. Changes in mortality and operculum growth were assessed over an 8-week period using digital photography. Covariates of growth included nearest neighbour distance, competition between closest pairs and initial size. Conflicting patterns were observed when comparing growth rates between treatments and sites. At Site 1, interspecific treatments had a lower growth rate than intraspecific treatments, whereas at Site 2, interspecific growth rates were higher. ANCOVA showed that nearest neighbour distance had no significant effect on growth, but when comparing differences in growth of closest neighbouring pairs, C. montagui treatment showed evidence of competition whereas S. balanoides did not. ANCOVA analysis indicated no difference in growth between each outcome of pair competition, suggesting winners are initially bigger than losers. Comparisons of mortality between treatments indicated mortality over time with no significant differences observed between treatments, but response surface methodology (RSM) revealed no effects of competition on mortality of S. balanoides, but negative effects of both intra- and interspecific competition on C. montagui survivorship. Examination of natural populations of barnacles in the mid-shore indicated there was strong spatial variation in growth rates, perhaps driven by small-scale differences within sites.

Modiolus modiolus L. (horse mussel) reefs are a priority marine habitat of high conservation value that is currently listed as endangered and/or threatened across its European distribution. Population structure, density or shell morphology may influence the biodiversity of a reef, either directly or indirectly. Thus, such metrics are important considerations for successful conservation management of these biodiversity hotspots. Population structure, shell morphology and growth rates were examined in M. modiolus reefs across the UK range of the habitat to examine differences between key populations, including those near the Lleyn Peninsula in Wales (southern range), off Port Appin in Western Scotland (mid-range) and in Scapa Flow in the Orkney Isles, Scotland (northern range). Additionally, the influence of physical conditions (temperature and tidal flow) to growth rate and predicted maximum shell length for each population was examined. Growth rates were determined using acetate peels of sectioned shells. Lower juvenile abundance was observed in Scapa Flow. Small, narrow-shaped shells were found to be characteristic of North Lleyn mussels, and larger, globular-shaped shells were characteristic of mussels in Scapa Flow and off Port Appin. Mussels in Scapa Flow were slower growing, yet reached a longer asymptotic length (L∞) than mussels of Port Appin and North Lleyn. Growth curves from sites within this study were analysed with other published data. A trend of higher L∞ at higher latitudes and at lower flow rates was observed. Variations in growth and age are discussed in relation to flow regimes, connectivity to other reefs, density and latitude.

Increasingly, baseline knowledge of habitat preferences and movement patterns of marine species is required to inform anthropogenic developments. The aim of this study was to determine baseline spatio-temporal distribution and habitat preference of cetaceans in the coastal waters of Algoa Bay. Areas of potential conflict with anthropogenic activities were also assessed. Monthly sea-based surveys were conducted between June 2008 and May 2011. A total of 500 cetacean sightings comprising six species were recorded in 106 surveys. Tursiops aduncus (Indo-Pacific bottlenose dolphin), Sousa plumbea (Indian Ocean humpback dolphin), Delphinus capensis (long-beaked common dolphin) and Balaenoptera brydei (Bryde's whale) were observed year-round, while Eubalaena australis (southern right whale) and Megaptera novaeangliae (humpback whale) were recorded from May to December. A large portion of sightings were associated with a Marine Protected Area and shipping zones. Eubalaena australis, T. aduncus and S. plumbea were found inshore (water depths < 12 m), while the other species were associated with deeper waters. Tursiops aduncus were most commonly seen (233 sightings). Megaptera novaeangliae were sighted often in austral winter, with 113 sightings. Only nine D. capensis sightings were recorded. Spatial distributions of species were corrected for search effort to identify habitat preferences. A number of key observations were made, including opportunistic foraging in M. novaeangliae, and the expansion of nursery grounds for E. australis, to include Algoa Bay. Four preferred habitat areas are proposed, providing important information for conservation and management of cetaceans in Algoa Bay. The spatial approach can be used to inform future relevant management decisions elsewhere.

Ocean acidification (OA) is caused by increasing atmospheric concentrations of carbon dioxide, which dissolves in seawater to produce carbonic acid. This carbonic acid reduces the availability of dissolved aragonite needed for production of some invertebrate exoskeletons with potentially severe consequences for marine calcifier populations. There is a lack of public information on OA with less than 1% of press coverage on OA compared with climate change; OA is not included in UK GCSE and A Level specifications and textbooks; environmental campaigners are much less active in campaigning about OA compared with climate change. As a result of the lack of public awareness OA is rarely discussed in the UK Parliament. Much more public education about OA is needed so that people can respond to the urgent need for technological and lifestyle changes needed to massively reduce carbon dioxide emissions.

The stomach contents of 1261 striped marlins caught from 2007 to 2010 by the sport-fishing fleet of Cabo San Lucas, Baja California Sur, Mexico, were analysed, taking into account sea surface temperatures estimated using satellite images of the study area and the Oceanic Niño Index (ONI). The analysis allowed the identification of three anomalously cold periods during 2007, 2008 and 2010 and a warm period in 2009. The stomach content results showed 89 different prey items eaten during the study period. Of the specimens captured, 868 (69%) stomachs contained food items. The most important prey items were cephalopods (Dosidicus gigas and Argonauta spp.) and fish (Scomber japonicus, Selar crumenophthalmus and Sardinops caeruleus). Despite having a broad trophic spectrum, the striped marlin was classified as a specialist consumer, with Bi = 0.03. Based on the diet breadth value and the prey-specific index of relative importance (PSIRI), the jumbo squid, D. gigas, was the main prey species, coinciding with cold periods. On the other hand, the fishes S. caeruleus and S. japonicus showed the highest PSIRI values during the 2009 warm anomalies. Analysis of similarity showed the formation of four groups in relation to PSIRI values. According to a non-metric multidimensional scaling ordination, these groups were formed with a similarity of 30% and a stress of 0.17. These results demonstrate inter-annual variation in the diet as well as in the availability and abundance of prey items.

Fish catch composition in 21 gill net samplings performed between 2014 and 2015 at Rhodes Island (Aegean Sea, Greece) was analysed, with the aim to contribute in filling scattered information on coastal fish assemblages in a Mediterranean region heavily impacted by biological invasions. A total biomass of 183 kg was collected comprising 1070 fish individuals, distributed along 43 native and six Lessepsian migrant species. The alien Siganus luridus prevailed in terms of frequency of occurrence, followed by the native Sparisoma cretense, which exhibited the higher abundance and biomass, followed by S. luridus, Scorpaena scrofa and Siganus rivulatus. Ratios between alien and native species as well as between their abundance and biomass are discussed.

Edible marine gastropods are consumed in northern Patagonia without regulations or knowledge of nutritional composition and food quality. We determined total lipids (TL), fatty acid (FA), paralytic shellfish poison (PSP) and metal contamination in six edible marine gastropods: Buccinanops globulosus, B. cochlidium, Trophon geversianus, Odontocymbiola magellanica, Tegula patagonica and Nacella magellanica. TL was lowest in the foot (0.29–0.56%) and maximum in organs (1.43–3.2%), presenting less TL than other edible species around the world. Saturated FA were similar to other consumed marine gastropods worldwide and dominant in all species studied (33.26–48.19%), while monounsaturated FA reached about 30% only in 2 species, but did not exceed 18% in the other species. Polyunsaturated FA reached up to 23.77%, but generally did not exceed 14%. Highly unsaturated FA (AA, EPA and DHA), reached about 27%. The dominant FA was palmitic acid (0.217 to 2.43 µg mg−1).Differences in FA could be related to the different alimentation of the species. Limit of PSP consumption was exceeded in a few months only for two species. Lead was not detectable (<4 µg g−1) while cadmium ranged from 0.07 to 15.32 µg g−1. Our results can be useful to ensure the safety food of these resources, which are being consumed and exported in low quantities in Argentina, but may be commercialized massively in the near future. Monitoring these and other food resources is essential and should be performed in any established fishery of the species reported here to guarantee the safety human consumption.

The ecological value of the stranding record is often challenged due to the complexity in quantifying the biases associated with multiple components of the stranding process. There are biological, physical and social aspects that complicate the interpretation of stranding data particularly at a population level. We show how examination of baseline variability in the historical stranding record can provide useful insights into temporal trends and facilitate the detection of unusual variability in stranding rates. Seasonal variability was examined using harbour porpoise strandings between 1992 and 2014 on the east coast of Scotland. Generalized Additive Mixed modelling revealed a strong seasonal pattern, with numbers increasing from February towards a peak in April. Profiling seasonality this way facilitates detection of unusual variations in stranding frequencies and permits for any change in the incidence of strandings to be quantified by evaluation of the normalized model residuals. Consequently, this model can be used to identify unusual mortality events, and quantify the degree to which they deviate from baseline. With this study we demonstrate that a described baseline in strandings allows the detection of abnormalities at an early stage and can be used as a regional framework of reference for monitoring. This methodology provides means to quantify and partition the variability associated with strandings data and is a useful first step towards improving the stranding record as a management resource.

The compilation of data on alien Sipuncula species reported from the Mediterranean Sea to date yields a total of eight species belonging to four families. Four species have become established in the area, while two species are classified as casual and two as cryptogenic. The pathways of the introduction of alien Sipuncula species were shipping and the Suez Canal. The eastern basin had the higher number of alien Sipuncula species (seven species) mainly due to its proximity to the Suez Canal and dense shipping traffic. Among these species, Aspidosiphon (A.) mexicanus has a wide distributional range in the region, but was considered as a cryptogenic species. The majority of alien Sipuncula species were found on soft subtrata in the region. Brief descriptions of the alien Sipuncula species and their distributional and ecological characteristics are given.

The prevalence of scars and wounds of anthropogenic origin was assessed in seven different coastal bottlenose dolphin communities (Tursiops truncatus) on the south-western coast of Ecuador. Between 2011 and 2017 a total of 117 trips were conducted representing a total sampled distance of 6281 km. Twenty-five of the 189 (13.2%) free-ranging photo-identified dolphins were recorded with dorsal fin damage, V-shaped wounds, sawed edges and deformities in the caudal region. The scarring prevalence ranged from 0 to 44.4% and was associated with either fishing interactions or vessel strikes. Dolphin scarring increased five times in the last 25 years from 2.2 to 11.1% and was correlated with a decrease in population in the inner estuary of the Gulf of Guayaquil. Damaged dorsal fins are associated mainly with fishing gear. V-shaped wounds were recorded in three different communities, Posorja, Estero Salado and Salinas, and given their severity associated with either fishing gear or vessel strikes. During the study period three dolphins were found entangled in fishing gears, two in gillnets and one in a long-line, emphasizing the threats posed by current fishing practice to the species. More effective management measures are urgently needed to reverse the observed population decline. This may include reduction of fishing effort, implementation of area-based approaches to coastal planning (including Marine Protected Area designations) and support for further research to understand the problem. Given the difficulty in taking direct observations, scarring prevalence is proposed as a proxy for estimating boat traffic and fishing gear impacts upon cetaceans.

Saline lagoons are priority habitats in the United Kingdom supporting several protected specialist species. One specialist, the amphipod Gammarus insensibilis, is infected with behaviour-altering microphallid trematodes such as Microphallus papillorobustus. In saline lagoons around the coast of England (Gilkicker and Lymington–Keyhaven on the Hampshire coast and Moulton Marsh in Lincolnshire) there is variation in the prevalence of this parasite in the gammarid populations (0 at Salterns in the Lymington–Keyhaven lagoon system to 98% at Gilkicker). Infection intensity ranged from 0 to 20 metacercariae in individual amphipods. Higher infection intensity can alter the shape of the amphipod's head. Under experimental conditions respiration rate is significantly reduced in infected animals and reproductive output (expressed as early stage embryos mg g dry weight−1) is significantly lower in infected females. It is important to consider the role of host–parasite interactions in order to understand the ecology of specialist lagoon species such as G. insensibilis and their lagoon habitats.

Octopus mimus is the main octopus targeted by the small-scale fishery in the Eastern Pacific. Commercial catches of octopus from the Reserva de Producción Faunística Marino-Costera Puntilla de Santa Elena (REMACOPSE) Marine Protected Area in Ecuador were sampled from July to December 2013 in order to describe the reproduction and population structure of this octopus. The 4171 sampled octopuses ranged from 56 to 250 mm in mantle length (ML) and 45 to 3178 g in body weight (BW). Mean octopus weight did not change monthly. Males were mostly mature while the majority of females were immature. Presence of some mature and a few spent females in all months sampled suggests that the population shows an extended spawning period. No spawning peak could be properly defined. Sex ratios did not significantly shift from the expected 1:1 in most samples. Females mature at a larger size (1234 g, BW; 165 mm, ML) than males (487 g BW; 114 mm ML). We recommend considering a minimum legal size of 1200 g BW. A year-long sampling programme for O. mimus should also be completed in order to detect any spawning peak.

Gelatinous zooplankton are an abundant and diverse group of animals in the pelagic environment. However, knowledge of species diversity and spatial distributions, as well as their ecological role, is scarce. We present information of epi- and mesopelagic gelatinous zooplankton recorded by the ‘DeepSee’ submersible between 2006 and 2012 at Isla del Coco (Cocos Island), Costa Rica, an oceanic island in the Eastern Tropical Pacific. Two species of scyphomedusae, three species of hydromedusae, two genera of siphonophores, and two species of ctenophores were observed in the videos, at depths between 50 and 400 m. None of these species had been previously recorded in the waters around the island. Furthermore, except for the jellyfish Pelagia noctiluca and a siphonophore in the genus Praya, all are new records for Costa Rican waters. This study also includes the first record of the cnidarians Modeeria rotunda, Solmissus sp., Halitrephes maasi and Apolemia spp., and the ctenophore Thalassocalyce inconstans in the Eastern Tropical Pacific. We show that surveys in regions with little information about gelatinous zooplankton may broaden our knowledge of their natural history and may result in new records of gelatinous species.

The complete larval development of the lobster shrimp Leonardsaxius amurensis (Kobjakova, 1937) (Decapoda: Axiidea: Axiidae) is described and illustrated for the first time. The first zoeae of this species were collected from the plankton samples and reared in the laboratory before moulting to the megalopa. A molecular genetic analysis based on comparison of partial mitochondrial COI, 12S rDNA and 16S rDNA sequence data confirmed the identity of axiid larvae found in the plankton and L. amurensis adults collected in the same area. The larval development of L. amurensis includes five zoeal stages and a single megalopa. Zoeae I of L. amurensis are characterized by the presence of one short posterodorsal spine on the fifth pleonite in contrast to the larvae of related sympatric species Boasaxius princeps having four posterodorsal spines on the pleonites 2–5. Leonardsaxius amurensis occupies an intermediate position between lobster shrimps with abbreviated pelagic development (2–3 zoeal stages) and species with long development (up to eight zoeal stages). Thus, the number of zoeal stages in the family Axiidae varies widely, similarly to that in the families Callianassidae and Upogebiidae.