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This article discusses the observation of the critically endangered soupfin shark in the Changing Salish Sea. The study confirms the presence of soupfin sharks in Hammersley Inlet through fishing efforts and sampling. The findings suggest that the presence of soupfin sharks may have implications for trophic dynamics and fisheries management in the region. The article also provides a list of references for further research on marine ecosystems in the Salish Sea and surrounding areas. [Extracted from the article]

Worldwide, lobsters are considered key predators that control urchin populations. It has been widely reported that lobster size plays a significant role in the size of urchins they feed on, as does the size of the urchin. Generally, it is thought that small palinurid "spiny" lobsters measuring less than 120 mm carapace length (CL) are morphologically incapable of eating urchins, while large lobsters are voracious predators. Urchin size is expected to affect predation with larger urchins of greater than 90 mm test diameter (TD) presenting the most difficult prey. These generalities, however, have not been quantitatively tested for the eastern spiny lobster Sagmariasus verreauxi and recently the accepted size paradigm for lobsters eating urchins has come into question. The aim of this study was to assess whether lobster predation on urchins would differ with urchin size or species, or the size of lobster. Our results indicate that S. verreauxi does not fit the common lobster patterns regarding urchin predation. There were generally low rates of predation and a significant negative relationship between feeding and both lobster size and urchin size. We found that small lobsters were capable urchin predators with a higher likelihood of eating urchins than larger lobsters, which were more reluctant predators. While we did find the expected effect of smaller urchins being significantly more vulnerable prey, there was none of the expected size limitations for small lobsters eating large urchins and predation did not differ between urchin species, indicating that this was a general pattern. Overall, we observed low rates of predation, suggesting that either S. verreauxi may not be a key urchin predator like other lobster species elsewhere, or that small lobsters are underestimated as urchin predators in temperate marine ecosystems. [ABSTRACT FROM AUTHOR]

The blue shark Prionace glauca plays a critical role as a predator in marine ecosystems but is threatened by by‐catch. To obtain more precise biological data, a Bayesian approach was used, and 536 vertebrae samples collected during 1 year at the landing stage called "Playita Mía" Manta, Ecuador, were analysed. The objective was to estimate the age and growth parameters of the species. The size of the specimens varied between 116 and 310 cm in total length (TL). Using a Bayesian approach based on the Markov Chain Monte Carlo (MCMC) method, growth parameters were evaluated. The von Bertalanffy model was the one that best fitted the data and provided more adequate estimates (females: L∞ = 325.50 cm, L0 = 53.23 cm, and k = 0.12 years; males: L∞ = 331.47 cm, L0 = 51.59 cm, k = 0.12 years −1; combined sexes: L∞ = 329.65 cm, L0 = 53.64 cm, k = 0.11 year−1). The results indicated that females and males have a similar growth, and that the species has a slow growth. Further studies using multi‐model Bayesian approaches and covering a broader range of sizes in the Pacific Ocean are suggested. These studies will provide crucial information for the management and conservation of this species. [ABSTRACT FROM AUTHOR]

Oceanic eddies are recognized as pivotal components in marine ecosystems, believed to concentrate a wide range of marine life spanning from phytoplankton to top predators. Previous studies have posited that marine predators are drawn to these eddies due to an aggregation of their forage fauna. In this study, we examine the response of forage fauna, detected by shipboard acoustics, across a broad sample of a thousand eddies across the world's oceans. While our findings show an impact of eddies on surface temperatures and phytoplankton in most cases, they reveal that only a minority (13%) exhibit significant effects on forage fauna, with only 6% demonstrating an oasis effect. We also show that an oasis effect can occur both in anticyclonic and cyclonic eddies, and that the few high-impact eddies are marked by high eddy amplitude and strong water-mass-trapping. Our study underscores the nuanced and complex nature of the aggregating role of oceanic eddies, highlighting the need for further research to elucidate how these structures attract marine predators. This study explores alternative stable states in microbial communities. Focusing on a respiratory tract community of 6 species, the authors identified four distinct stable states that are predicted to be driven by cooperative growth. The findings contrast with the common association between competitive interactions and multistability in microbial communities. Using a sample of a thousand eddies across the world's oceans, this study examines the response of forage fauna detected by shipboard acoustics. The findings show that a minority of eddies exhibit significant effects on forage fauna, but that an oasis effect can sometimes occur. This highlights the need for further research to elucidate how eddies might attract marine predators. [ABSTRACT FROM AUTHOR]

An animal's movement is influenced by a plethora of internal and external factors, leading to individual‐ and habitat‐specific movement characteristics. This plasticity is thought to allow individuals to exploit diverse environments efficiently. We tested whether the movement characteristics of white sharks Carcharodon carcharias differ across ontogeny and among habitats along the coast of Central California. In doing so, we elucidate how changes in internal state (physiological changes coinciding with body size) and external environments (differing seascapes and/or diel phases) shape the movement of this globally distributed predator. Twenty‐one white sharks, from small juveniles to large adults, were equipped with motion‐sensitive biologging tags at four contrasting seascapes: two islands, a headland, and an inshore cove. From multisensor biologging data, 20 metrics characterizing movement (i.e., depth use, vertical velocities, activity, turning rates, and bursting events) were derived and subjected to multivariate analyses. Movement characteristics were most different across seascapes, followed by ontogeny and diel phase. Juvenile sharks, which were only encountered at the cove, displayed the most distinct movement characteristics. Sharks at this seascape remained close to the shore traveling over smaller areas, shallower depth ranges, and with lower levels of tail beat frequencies, when corrected for size, than sub‐adult and adult sharks tagged elsewhere. Distinct tortuous daytime versus linear nighttime horizontal movements were recorded from sharks at island seascapes but not from those at the headland or inshore cove. At the offshore islands, the linear nighttime swimming patterns coincided with repeated dives to and from deeper water. The availability of prey and access to deeper water are likely drivers of the differences in movement characteristics described, with varying demographics of pinniped prey found at the subadult and adult aggregation areas and juvenile sharks being piscivorous and their habitat neither adjacent to pinniped haul out areas nor deeper water. This study demonstrates plasticity in the movements of a top predator, which adapts its routine to suit the habitat it forages within. [ABSTRACT FROM AUTHOR]

Predator–prey interactions in marine ecosystems are dynamically influenced by light, as demonstrated by diel vertical migrations of low-trophic level organisms. At high latitudes, the long winter nights can provide foraging opportunities for marine predators targeting vertically migrating prey closer to the surface at night. However, there is limited documentation of such diel patterns in marine predators under extreme light regimes. To address this, we recorded the diving behavior of 17 harbour porpoises just south of the Arctic circle in West Greenland, from summer to winter. Unlike classical diel vertical migration, the porpoises dove 24–37% deeper at night and the frequency of deep dives (> 100 m) increased tenfold as they entered the darkest months. The daily mean depth was negatively correlated with daylength, suggesting an increased diving activity when approaching the polar night. Our findings suggest a light-mediated strategy in which harbour porpoises would either target (i) benthic prey, (ii) pelagic prey migrating seasonally towards the seafloor, or (iii) vertically migrating prey that may be otherwise inaccessible in deeper waters at night, therefore maximizing feeding activity during extended periods of darkness. Extreme light regimes observed at high latitudes are therefore critical in structuring pelagic communities and food webs. [ABSTRACT FROM AUTHOR]

Evidence indicates that members of the marine bird research and management communities should view seabirds from the seabirds' perspective, as marine organisms, rather than the pervading view derived from human's interaction with the sea, i.e., as temporary visitors centered on home ports. By doing so, research results and management plans will be more realistic and effective. Seabirds themselves only temporarily visit land in their reproductive attempts, with most of their time otherwise spent at sea, as much as 90% in the lifetimes of some species. This is especially true among seabirds of the more productive stretches of water, such as eastern boundary currents, which as a rule have relatively few islands on which to nest as well as these waters typically being dominated by seasonal, non-breeding species. A case in point is the Pigeon Guillemot Cepphus columba of the California Current, a species/population that dwells in waters of the Pacific Northwest for most of the year, except for a quick migration south, then back north, for nesting. It ventures south to then have to compete with far more abundant species. The point is that protecting just seabird nesting islands, but ignoring marine issues within the whole of respective annual ranges, is often not a successful strategy, as exemplified to the extreme by the trend toward extinction of African Penguin Spheniscus demersus of the Benguela Current, where seabird species visitors are far more abundant. [ABSTRACT FROM AUTHOR]

Elasmobranchs play crucial roles as predators in marine ecosystems. Understanding their trophic strategies and interactions is necessary for comprehending food web dynamics and developing ecosystem-based management strategies. Although, feeding strategies can change depending on several factors, including fluctuations in prey availability throughout the year. In this study, we investigated the trophic ecology of the pelagic stingray, Pteroplatytrygon violacea , the only stingray inhabiting the pelagic environment in the western Mediterranean Sea. We found significant temporal differences in diet composition, mostly consuming pelagic zooplankton in spring, whereas benthopelagic teleosts in autumn. After contrasting different studies, P. violacea appears to have a generalist and opportunistic diet consisting of a broad spectrum of pelagic and benthopelagic species, and trophic plasticity in response to environmental fluctuations. Our findings suggest that P. violacea can present different feeding strategies, mainly pelagic, with a relatively low trophic position for a mesopredator compared to other batoids. • Understanding feeding ecology is essential for effective conservation management. • The diet composition of P. violacea changes in time according to prey availability. • Pteroplatytrygon violacea has a generalist and opportunistic feeding behaviour. • Pteroplatytrygon violacea presents different feeding strategies, mainly pelagic. [ABSTRACT FROM AUTHOR]

There is growing interest in the delineation of feeding patterns in animals, but little is known about the interaction of multiple explanatory factors across broad geographical scales. The goal of this study was to identify the factors that together determine population-level patterns in piscivory in a globally distributed aquatic predator, the brown trout (Salmo trutta). A meta-analysis of peer-reviewed studies revealed that the prevalence (frequency of occurrence, %) of piscivory increases from riverine to marine ecosystems, with fish community type and the size-structure (ontogeny) of brown trout populations being the key drivers. Thus, piscivory was related to ecosystem-specific differences in predator body size (increasing in populations with large individuals) and fish community configurations (increasing with fish species richness). Fish species richness imposes important limitations on (i.e. in low diversity scenarios) or facilitate (i.e. in high diversity scenarios) piscivory in brown trout populations, with a low prevalence expected in low-diversity fish communities. In fresh water, piscivory is higher in lentic than lotic ecosystems and, in the former, increases with latitude. Competition in multi-species systems is expected to be higher than in simpler systems because the size-structure and species composition of fish assemblages, explaining cross-ecosystem differences in piscivory. [ABSTRACT FROM AUTHOR]

Both site-selective oviposition and interactions following colonization can play a role in structuring communities, but the relative importance of each has not been well studied for many animals. We manipulated the presence of a small-bodied fish predator (Eastern Mosquitofish, Gambusia holbrooki) and submerged aquatic vegetation (SAV; Utricularia spp.) in 24 mesocosms (n = 6 replicates, 4 treatments) to determine the effects of predators and habitat structure on dragonfly oviposition and naiad success. Adults did not avoid ovipositing in mesocosms with mosquitofish predators, but some species did select for or against SAV. No dragonfly naiads emerged from mesocosms with mosquitofish that lacked SAV. In treatments with SAV, total emergence was almost 3× higher in mesocosms without mosquitofish than mesocosms with mosquitofish. Oviposition patterns generally could not account for emergence patterns in the mesocosms, suggesting that libellulid dragonfly production can be severely limited by postcolonization interactions with mosquitofish. The dominant species emerging from the 3 treatments with naiad success varied consistently, a result suggesting that emerging assemblage composition was altered primarily by tolerances to mosquitofish/interspecific interactions. In mesocosms with SAV, the emerging assemblages were more species rich and more similar in the absence than in the presence of mosquitofish. We suggest that stochastic postcolonization egg or early-naiad survival may account for some assemblage variation in the presence of an efficient stage-specific predator like mosquitofish. This assemblage of libellulids appears to be filtered primarily according to vulnerability to fish predators, with SAV serving to reduce intensity of postcolonization interactions. [ABSTRACT FROM AUTHOR]

Predation risk for aquatic prey is affected by habitat characteristics and the predator community. Relative predation risk for aquatic prey from terrestrial and aquatic predators may differ in drought and nondrought conditions because access to aquatic prey may be affected by water depth. We compared predation risk for crayfish in a human-dominated landscape during severe drought conditions to that during a nondrought year with a standardized assay in which tethered crayfish were exposed to predators. We placed trail cameras at tethering locations to detect whether mortality was from terrestrial or aquatic predators. We evaluated effects of crayfish size, in-stream characteristics, and landscape context on crayfish mortality. Risk factors for crayfish changed between the drought and nondrought conditions. During the drought of 2012, predation risk was associated negatively with cover of submerged vegetation, whereas crayfish size was the main risk factor in 2013 when streams returned to normal or above-normal streamflow. Risk was driven primarily by aquatic predators, although predation by terrestrial predators increased during the drought. Predation risk was related positively to stream size and negatively to urbanization, but only during nondrought conditions. Increased variability in hydrology expected under climate change may alter predation risk for crayfish and other aquatic prey in streams. [ABSTRACT FROM AUTHOR]

A wide range of pelagic predators survive in the open ocean, yet little is known about how they use that environment. Much of the current information on these species comes from studies in shelf waters, and it is not clear how representative the results are of their oceanic lifestyle. We used pop-up satellite tags to explore the horizontal and vertical use of the open ocean by porbeagle sharks ( Lamna nasus) in the south-west Pacific Ocean and to identify possible mitigation measures to reduce their bycatch in tuna longline fisheries. Ten porbeagle sharks were tracked in waters around New Zealand for 72-300 days (median 221 days). Sharks made horizontal movements of hundreds to thousands of kilometres, with a maximum estimated track length of almost 10,000 km. Mature females made seasonal latitudinal migrations from ~46-48°S in summer to ~35-38°S during winter-spring, where they are hypothesised to give birth to pups. Porbeagle sharks exhibited diel vertical migration, diving deeper during the day than at night. Dives generally began at dawn and finished at dusk and lasted 11-15 h depending on day length. Porbeagles feed mainly on mesopelagic fish and squid and appear to forage in the vertically migrating deep scattering layer. All sharks dived to at least 600 m with a maximum recorded depth of 1024 m. During the day, most of their time was spent at depths of 200-600 m in the open ocean. Porbeagle shark bycatch could be substantially reduced by limiting longline fishing to daylight hours when they are too deep to be caught. However, longliners currently set mainly at night to avoid seabird bycatch, which would increase unless other mitigation measures were implemented to protect them. A review of factors affecting the bycatch of various species, and the impact of mitigation measures on catches of target species, is required to identify an appropriate suite of management measures. [ABSTRACT FROM AUTHOR]

Invasive alien aquatic species, including marine and freshwater macroinvertebrates, have become increasingly important in terms of both environmental and socio-economic impacts. In order to assess their environmental and economic costs, we applied the Generic Impact Scoring System (GISS) and performed a comparison with other taxa of invaders in Europe. Impacts were scored into six environmental and six socioeconomic categories, with each category containing five impact levels. Among 49 aquatic macroinvertebrates, the most impacting species were the Chinese mitten crab, Eriocheir sinensis (Milne-Edwards, 1853) and the zebra mussel, Dreissena polymorpha (Pallas, 1771). The highest impacts found per GISS impact category were, separately; on ecosystems, through predation, as competitors, and on animal production. Eleven species have an impact score > 10 (high impact) and seven reach impact level 5 in at least one impact category (EU blacklist candidates), the maximum score that can be given is 60 impact points. Comparisons were drawn between aquatic macroinvertebrates and vertebrate invaders such as fish, mammals and birds, as well as terrestrial arthropods, revealing invasive freshwater macroinvertebrates to be voracious predators of native prey and damaging to native ecosystems compared with other taxa. GISS can be used to compare these taxa and will aid policy making and targeting of invasive species for management by relevant agencies, or to assist in producing species blacklist candidates. [ABSTRACT FROM AUTHOR]

Recent theoretical considerations have highlighted the importance of the pelagic–benthic coupling in marine food webs. In continental shelf seas, it was hypothesized that the trophic network structure may change along an inshore–offshore gradient due to weakening of the pelagic–benthic coupling from coastal to offshore areas. We tested this assumption empirically using the eastern English Channel (EEC) as a case study. We sampled organisms from particulate organic matter to predatory fishes and used baseline-corrected carbon and nitrogen stable isotope ratios (δ 13 C and δ 15 N) to determine their trophic position. First, hierarchical clustering on δ 13 C and δ 15 N coupled to bootstrapping and estimates of the relative contribution of pelagic and benthic carbon sources to consumers’ diet showed that, at mesoscale, the EEC food web forms a continuum of four trophic levels with trophic groups spread across a pelagic and a benthic trophic pathway. Second, based on the same methods, a discrete approach examined changes in the local food web structure across three depth strata in order to investigate the inshore–offshore gradient. It showed stronger pelagic–benthic coupling in shallow coastal areas mostly due to a reorganization of the upper consumers relative to the two trophic pathways, benthic carbon sources being available to pelagic consumers and, reciprocally, pelagic sources becoming accessible to benthic species. Third a continuous approach examined changes in the mean and variance of upper consumers’ δ 13 C and δ 15 N with depth. It detected a significant decrease in δ 13 C variance and a significant increase in δ 15 N variance as depth increases. A theoretical two-source mixing model showed that an inshore–offshore decrease in the pelagic–benthic coupling was a sufficient condition to produce the δ 13 C variance pattern, thus supporting the conclusions of the discrete approach. These results suggest that environmental gradients such as the inshore–offshore one should be accounted for to better understand marine food webs dynamics. [ABSTRACT FROM AUTHOR]

For many marine organisms, especially large whales that cannot be studied in laboratory settings, our ability to obtain basic behavioral and physiological data is limited, because these organisms occupy offshore habitats and spend a majority of their time underwater. A class of multisensor, suction-cup-attached archival tags has revolutionized the study of large baleen whales, particularly with respect to the predatory strategies used by these gigantic bulk filter feeders to exploit abundant oceanic resources. By integrating these data with those from other disciplines, researchers have uncovered a diverse and extraordinary set of underwater behaviors, ranging from acrobatic diving maneuvers to extreme feeding events during which whales engulf volumes of prey-laden water that are much larger than their own body. This research framework not only improves our knowledge of the individual performance and behavior of these keystone predators but also informs our ability to understand the dynamics of complex marine ecosystems. [ABSTRACT FROM AUTHOR]

While much research has been carried out on mercury in large marine mammals and associated food webs in northern regions, comparatively less has been conducted on lower trophic levels including zooplankton and the subsequent transfer to predators, which marks the entry of mercury into northern marine food webs. We present here the first database for mercury uptake and transfer exclusively within zooplankton food webs in northern marine waters. We have investigated both total (THg) and monomethylmercury (MMHg) concentrations, and isotopic signatures (δ15N and δ13C) in individual zooplankton taxa collected over a period of eight years (2003–2010) from across Hudson Bay (including Hudson Strait and Foxe Basin) as part of research icebreaker cruises. δ15N values ranged from 3.4 to 14.0‰, implying trophic levels ranging from 1 to 4, and THg concentrations ranged from 5 to 242 ng g–1 dw. Food web linkages were identified within the data set, and mercury biomagnification was evident both with THg and MMHg concentrations increasing from prey to predator, and with trophic magnification factors (TMFs). Total mercury and MMHg transfer in a unique prey–predator linkage (Limacina helicina–Clione limacina) are investigated and discussed with regard to known physiological and biochemical characteristics. The results suggest that exposure to mercury at higher trophic levels including humans can be affected by processes at the bottom of Arctic marine food webs. [ABSTRACT FROM AUTHOR]

ABSTRACT [ABSTRACT FROM AUTHOR]

Pelagic marine predators face unprecedented challenges and uncertain futures. Overexploitation and climate variability impact the abundance and distribution of top predators in ocean ecosystems. Improved understanding of ecological patterns, evolutionary constraints and ecosystem function is critical for preventing extinctions, loss of biodiversity and disruption of ecosystem services. Recent advances in electronic tagging techniques have provided the capacity to observe the movements and long-distance migrations of animals in relation to ocean processes across a range of ecological scales. Tagging of Pacific Predators, a field programme of the Census of Marine Life, deployed 4,306 tags on 23 species in the North Pacific Ocean, resulting in a tracking data set of unprecedented scale and species diversity that covers 265,386 tracking days from 2000 to 2009. Here we report migration pathways, link ocean features to multispecies hotspots and illustrate niche partitioning within and among congener guilds. Our results indicate that the California Current large marine ecosystem and the North Pacific transition zone attract and retain a diverse assemblage of marine vertebrates. Within the California Current large marine ecosystem, several predator guilds seasonally undertake north-south migrations that may be driven by oceanic processes, species-specific thermal tolerances and shifts in prey distributions. We identify critical habitats across multinational boundaries and show that top predators exploit their environment in predictable ways, providing the foundation for spatial management of large marine ecosystems. [ABSTRACT FROM AUTHOR]

The article explores the use of seagrass microhabitats by olive-headed sea snakes Disteria major to avoid tiger sharks Galeocerdo cuvier predation in Shark Bay, Australia. It notes that prey frequently avert their predators and favor predator-abundant areas to assist escape or discourage attack. It mentions that snakes utilized microhabitats which is equal to food supply when sharks were in short supply and avoided edges. Moreover, it states that it seems that D. major quantify danger across seagrass banks using variability in predator density and seek low-encounter microhabitats.

Aquatic prey encounter an array of threat cues from multiple predators and killed conspecifics, yet the vast majority of induced defenses are investigated using cues from single predator species. In most cases, it is unclear if odors from multiple predators will disrupt defenses observed in single-predator induction experiments. We experimentally compared the inducible defenses of the common marine mussel Mytilus edulis to waterborne odor from pairwise combinations of three predators representing two attack strategies. Predators included the sea star, Asterias vulgaris (= Asterias rubens), and the crabs Carcinus maenas and Cancer irroratus. The mussels increased adductor muscle mass in response to cues from unfed Asterias (a predatory seastar that pulls mussel shells open) and increased shell thickness in response to unfed Carcinus, a predatory crab that crushes or peels shells. However, the mussels did not express either predator specific response when exposed to the combined cues of Asterias and Carcinus, and mussels did not increase shell thickness when exposed to cues from Cancer alone or any pairwise combination of the three predators. Shell closure or ‘clamming up’ did not occur in response to any predator combination. These results suggest that predator-specific responses to the Asterias and Carcinus are poorly integrated and cannot be expressed simultaneously. Simultaneous cues from multiple predators affect the integration of predator specific defenses and predator odors from functionally similar predators do not necessarily initiate similar defenses. Ultimately, the degree that prey can integrate potentially disparate defenses in a multiple predator environment may have ecological ramifications and represent a seldom explored facet of the evolution of inducible defenses. [ABSTRACT FROM AUTHOR]

Seagrasses, which form critical subtidal habitats for marine organisms worldwide, are fragmented via natural processes but are increasingly being fragmented and degraded by boating, fishing, and coastal development. We constructed an individual- based model to test how habitat fragmentation and loss influenced predator-prey interactions and cohort size for a group of settling juvenile blue crabs (Callinectes sapidus Rathbun) in seagrass landscapes. Using results from field studies suggesting that strong top-down processes influence the relationship between cannibalistic blue crab populations and seagrass landscape structure, we constructed a model in which prey (juvenile blue crabs) are eaten by mesopredators (larger blue crabs) which in turn are eaten by top-level predators (e.g., large fishes). In our model, we varied the following parameters within four increasingly fragmented seagrass landscapes to test for their relative effects on cohort size: juvenile blue crab (prey) predator avoidance response, hunting ability of mesopredators and predators, the presence of a top-level predator, and prey settlement routines. Generally, prey cohort size was maximized in the presence of top-level predators and when mesopredators and predators exhibited random searching behavior vs. directed hunting. Cohort size for stationary (tethered) prey was maximized in fragmented landscapes, which corresponds to results from field experiments, whereas mobile prey able to detect and avoid predators had higher survival in continuous landscapes. Prey settlement patterns had relatively small influences on cohort size. We conclude that the effects of seagrass fragmentation and loss on organisms such as blue crabs will depend heavily on behaviors of prey and predatory organisms and how these behaviors change with landscape structure. [ABSTRACT FROM AUTHOR]

Fishing and other human activities can alter the abundances, size structure, and behavior of species playing key roles in shaping marine communities (e.g., keystone predators), which may in turn cause ecosystem shifts. Despite extensive evidence that cascading trophic interactions can underlie community-wide recovery inside no-take marine reserves by protecting high-level predators, the spatial extent of these effects into adjacent fished areas is unknown. I examined the potential for community-wide changes (i.e., the transition from overgrazed coralline barrens to macroalgal beds) in temperate rocky reefs within and around a no-take marine reserve. For this purpose I assessed distribution patterns of predatory fishes, sea urchins, and barrens across the reserve boundaries. Predatory fishes were significantly more abundant within the reserve than in adjacent locations, with moderate spillover across the reserve edges. In contrast, community-wide changes of benthic assemblages were apparent well beyond the reserve boundaries, which is consistent with temporary movements of predatory fishes (e.g., foraging migration) from the reserve to surrounding areas. My results suggest that no-take marine reserves can promote community-wide changes beyond their boundaries. [ABSTRACT FROM AUTHOR]

Discusses how the breeding performance of higher predators has often been used to monitor fluctuations in the abundance of important prey stocks in marine ecosystems.

Environmental conditions can shape genetic and morphological divergence. Release of new habitats during historical environmental changes was a major driver of evolutionary diversification. Here, forces shaping population structure and ecotype differentiation ('pelagic' and 'coastal') of bottlenose dolphins in the North-east Atlantic were investigated using complementary evolutionary and ecological approaches. Inference of population demographic history using approximate Bayesian computation indicated that coastal populations were likely founded by the Atlantic pelagic population after the Last Glacial Maxima probably as a result of newly available coastal ecological niches. Pelagic dolphins from the Atlantic and the Mediterranean Sea likely diverged during a period of high productivity in the Mediterranean Sea. Genetic differentiation between coastal and pelagic ecotypes may be maintained by niche specializations, as indicated by stable isotope and stomach content analyses, and social behaviour. The two ecotypes were only weakly morphologically segregated in contrast to other parts of the World Ocean. This may be linked to weak contrasts between coastal and pelagic habitats and/or a relatively recent divergence. We suggest that ecological opportunity to specialize is a major driver of genetic and morphological divergence. Combining genetic, ecological and morphological approaches is essential to understanding the population structure of mobile and cryptic species. [ABSTRACT FROM AUTHOR]

The article describes rapid changes in the Black Sea ecosystem caused by overfishing. Predatory fishes were heavily insufficient in the 1960s causing a cascade of effects down the food chain in the 1970s which became dominated by planktivorous fishes. A second shift happened in the early 1990s when there was a population collapse of planktivorous fishes and an outburst of an alien jellyfish. Using time series data from fishery catches, it is suggested that overfishing is the driver of both these shifts rather than pollution or alien jellyfish invasion. The top level of predatory fishes has not recovered despite the appearance of the jellyfish which preys on alien jellyfish, which may promote the recovery of the next highest trophic layer of planktivorous fish.