All over the world marine waters are under increasing pressure from human activities affecting marine ecosystems. Several EU Directives require assessment of the condition of marine environments; in particular the Marine Strategy Framework Directive (MSFD) applies an ecosystem approach to the management of human activities. In this context, the mapping of pressures in a standardized and comparable way is a critical step to assess the spatial pattern, the temporal change and the ecological impacts of human pressures. Within the MSFD, one of the stressors directly affecting the seafloor is the Physical Loss (PL) pressure, representing the permanent or long-term alteration of marine habitats. The main purpose of this study was to propose a method to estimate the spatial extent of PL pressure in the framework of the Initial Assessment phase of the MSFD. Furthermore, considering that human activities PL-related cause the loss of benthic habitats, and that the Mediterranean sea is characterized by sensitive and protected habitats such as the biogenic substrates sensu MSFD, the distribution of PL pressure was overlaid with the distribution of the seabed habitats to estimate the loss of biogenic substrates. This study represents a useful tool for establishing the baseline condition for PL pressure, to compare future conditions and to evaluate different management scenarios. Moreover, it allows identification of the areas where pressure tends to accumulate as ‘hot spots’ on which to focus in future impact analyses and the areas where few stressors are present.

Relatively little is known about the distribution and diversity of marine mammals around offshore anthropogenic structures. We present results obtained from incidental sightings of marine mammals around oil and gas installations located 200 km off the Danish coast. A total of 131 sightings corresponding to about 288 animals were reported between May 2013 and May 2016. A total of seven marine mammal species were identified, five cetaceans: harbour porpoise (Phocoena phocoena), minke whale (Balaenoptera acutorostrata), white-beaked dolphin (Lagenorhynchus albirostris), killer whale (Orcinus orca), pilot whales (Globicephala spp.) and two species of pinnipeds: harbour (Phoca vitulina) and grey seals (Halichoerus grypus). The most sighted species were harbour porpoise (41%) and minke whale (31%). Relative counts and biodiversity of marine mammals observed around installations corresponded well with the expected distribution in the central North Sea. Several taxon-specific correlations were identified between number of sightings and environmental parameters (depth and latitude) or installation characteristics (installation aerial footprint). Furthermore, 85% of sightings were made during spring and summer and it is unclear whether the pattern observed reflected a natural seasonal occurrence of marine mammals in the area or an effect of reduced effort during autumn and winter. Despite the potential caveats, results obtained during this programme provide an insight into the relationship between marine mammals and oil and gas offshore installations in the North Sea.

The Atlantic–Mediterranean transition zone between the Alborán Sea and the Gulf of Cádiz constitutes the most prominent marine geographic barrier in European waters and includes known phylogeographic breaks such as the Strait of Gibraltar and the Almería-Oran Front. A genetic shift in this area has been previously documented for the European littoral shrimp Palaemon elegans. Here we carried out a phylogeographic analysis with the congeneric and sympatric species Palaemon serratus to test for similar intraspecific genetic differentiation and geographic structure. This littoral prawn is distributed in the Northeastern Atlantic Ocean, the Mediterranean Sea and the Black Sea. We compared DNA sequences from the mitochondrial genes Cox1 and to a lesser extent from 16S rRNA of several Atlantic and Mediterranean populations. Furthermore, sequences from the nuclear gene Enolase were included for corroborating differences between Mediterranean and Atlantic individuals. A pronounced genetic differentiation was detected between the Mediterranean and Atlantic populations, amounting to 10.14% in Cox1 and 2.0% in 16S, indicating the occurrence of two independent evolutionary lineages. Interestingly, specimens from the Atlantic Gulf of Cadiz cluster together with the Mediterranean individuals, indicating that a biogeographic barrier appears to be located west of the Strait of Gibraltar.

A new species of Laeonereis from a shrimp farm associated with a subtropical coastal lagoon on the Mexican Pacific coast is described. The new species is characterized by a deep anterior groove on the prostomium, which is shared only with L. culveri. However, longer tentacular cirri extending back to the anterior margin of chaetiger two, the number of papillae of each group on the maxillary ring of the pharynx, and the relative size of the homogomph falcigers in the new species, allow us to separate the two species. Although the species has not been previously detected in the coastal lagoon surrounding the shrimp farm, we postulate that L. watsoni n. sp. is likely to be part of the invertebrate communities of the upper parts of similar coastal lagoons that are common along the tropical coasts of Mexico.

The stomach of Decapod crustaceans is a complex structure with great interspecific variation. Several studies suggest that the anatomy of the gastric mill varies according to the diet of species in different groups. An alternative view suggests the gastric mill's structure is related to phylogenetic aspects rather than to the diet of a species. The morphology of the gastric mill of Ovalipes trimaculatus, a portunid crab target of fisheries in Argentina and Chile, was studied through stereo-microscope and scanning electron microscope images. Ovalipes trimaculatus has a stomach that corresponds to a macrophagous and predatory diet. The gastric mill is similar to that of other portunids, especially those with predominant animal component in their diet. Our results support the idea that this structure has a basic pattern, given by shape and elements forming the gastric mill; and upon that pattern, trophic habits adaptively shape certain traits.

In order to investigate social structure, 11 years of individual photo-identification data of bottlenose dolphin were analysed. We examined the type of association indices between pairs of identified individuals; the patterns of affiliation between individual dolphins and the probabilities of association between individuals over time. Between 2001 and 2012, there were 272 encounters which resulted in the identification of 501 individuals. The discovery curve resulting from the photo-identification analysis indicated an open population with regular recruitment of new individuals. All individuals were found to be associated at an association index of <0.05. A total of 291 individuals recorded from 2004 to 2012 were used to assess the temporal pattern of the social structure. The model fit to the Standardized Lagged Association Rate (SLAR) that best described the studied bottlenose dolphin population was ‘casual acquaintances’, and the analysis of associations over time showed a decreasing SLAR curve that falls until reaching the null rate, confirming random associations. The decline of the SLAR curve after ~500 days (1.4 years) suggests disassociation over that time period which can be explained by demographic events such as mortality or emigration. In an open ocean habitat like Madeira this is not unexpected, as there are neither geographic boundaries nor enclosed environments. This population presented a dynamic and fluctuating social structure, where groups change in size and composition. In future conservation efforts this population should be considered as one large community, where individuals associate, disassociate and reassociate with each other over time.

Very little information is available on bottlenose dolphin (Tursiops truncatus) habitat use in the South-western Atlantic. It is, however, essential in understanding their ecology and to improve conservation management. In this study, habitat use of bottlenose dolphins was examined in Bahía San Antonio, an area frequented by the species. Given the large tidal amplitude and extended intertidal zone in this bay, special focus was given to the intertidal vs subtidal habitat use patterns. Bottlenose dolphins were observed in only half of the surveyed area, with on average 1 dolphin group encountered per 100 km surveyed. All dolphin groups were seen in shallow waters <10 m deep. GLM analyses showed that especially during high tide, depth had an important effect on the dolphin encounter rate, with most dolphin groups encountered in the intertidal zone. While in the intertidal zone, most dolphin groups were observed to be engaged in surface feeding activities. The presented data indicate dolphins remained in shallow waters, and moved to the intertidal zone during high tide where they appear to find feeding opportunities. This information is believed to be of high value in understanding this population's ecological needs, and essential when aiming to improve marine conservation efforts at times of increased anthropogenic pressures in the area.

Knowledge of growth patterns of an animal species is fundamental to understand their life history. This information is also used to help define population boundaries of threatened cetaceans, such as the Franciscana dolphin, Pontoporia blainvillei. A total of 108 Franciscana dolphins incidentally captured in artisanal fishing nets in estuarine and marine coastal waters of the northern part of the Franciscana Management Area IV (North FMA IV), Argentina, were studied. The objective of the present paper was to study age and growth parameters of Franciscanas from North FMA IV and to compare these parameters between estuarine and marine potential populations within this area. We used von Bertalanffy and Gompertz growth curves to model growth trajectories. The estimated asymptotic lengths demonstrated that Franciscana dolphins from this area were smaller (females: 136.3 cm and males, 122.1 cm) than southern FMA IV values previously published. They also showed the reverse sexual size dimorphism that is known across their range. However, the estimated asymptotic length was not statistically different between the estuarine and marine females within the study area. In spite of this, the fact that the northern forms of the FMA IV were smaller than the southern specimens supports the hypothesis of more than one population of the species within this management area. The North FMA IV has the highest reported mortality levels of Franciscana dolphins within the FMA IV; these results are relevant to the knowledge base of Franciscana dolphins in the region.

Early life traits (ELT) of the sand-burrowing cryptic marine fish Sindoscopus australis (family Dactyloscopidae) were compared between cohorts hatched during winter and spring 2013, in nearshore rocky reefs off central Chile. Pelagic larvae were similarly abundant during both periods, but larger larvae were collected during austral spring. The sagittal otolith microstructure and size analyses also indicated that size-at-hatch was larger (4.7 mm) for the winter cohort, but winter larvae experienced slower growth rates (0.145 mm day−1 ± 0.008). Conversely, larvae from the spring cohort hatched at smaller sizes (2.9 mm), but they grew faster (0.182 mm day−1 ± 0.008). Hatching periods were coupled with the lunar cycle; in winter, hatching events were related to neap tides (first and third quarter moon), increasing chances of self-recruitment. Meanwhile, during spring, hatching occurred during spring tides, particularly over the new moon, decreasing chances of larval mortality by predation. Otolith traits used to test asymmetry among cohorts showed inconsistent results. Only sagittal perimeter presented fluctuating asymmetry, showing higher variance for the winter cohort. We conclude that this burrowing species displays different reproductive tactics at a seasonal scale.

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.