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We investigated how foraging ecotypes of female long-nosed fur seals Arctocephalus forsteri could be identified from vibrissa stable isotopes. We collected regrowths of vibrissae from adult females (n = 18) from Cape Gantheaume, Kangaroo Island, South Australia, from 2 breeding seasons (2016, 2017). The period represented by the regrowth was known, and 8 individuals were administered with 15N-enriched glycine as a biomarker to mark the start date of the regrowth. Non-glycine-marked and glycine-marked vibrissae were used to estimate the rate of the individual vibrissa regrowth. Using individual growth rates (0.18 ± 0.04 mm d-1), we reconstructed a stable isotope (δ13C and δ15N) time series for each regrowth and allocated them to corresponding at-sea locations either based on geolocation tracks (n = 14) or foraging habitat type (shelf or oceanic) based on diving data (n = 2) of the sampled seals. Mean (±SD) δ15N from vibrissa segments was higher when females foraged on the continental shelf region (16.1 ± 0.7‰, n = 29) compared to oceanic waters (15.1 ± 0.7‰, n = 106) in 2017, whereas it was similar in both regions in 2016 (shelf: 15.3 ± 0.4‰, n = 13; oceanic: 15.4 ± 0.4‰, n = 15). Based on the stable isotope signatures of vibrissa segments, model-based clustering analysis correctly classified 79.8% as originating from shelf or oceanic foraging habitats. This demonstrates the potential of using vibrissa stable isotopes for studying the foraging ecology of an important top marine predator.

Urgent necessity to understand the effect of climatic change on scleractinian cold-water coral (CWC) ecosystems arises from increasing ocean warming and acidification over the last decades. Here, presence-absence records of 12 scleractinian CWC species from research expeditions and literature were compiled and merged with model-generated pseudo-absence data and 14 environmental variables. The best results of nine species distribution models (SDM) were combined to an ensemble habitat suitability model for CWCs in the northern Southern Ocean (Weddell Sea and Antarctic Peninsula) by means of the open source R package ‘biomod2’. Furthermore, two future scenarios of increasing bottom sea temperature were used to investigate the spatial response of scleractinians to temperature change. The resulting (current scenario) potential ecological niches were evaluated with good to excellent statistical measures. The results predict that present areas of highest probability of CWC occurrence are around the Antarctic Peninsula, South Orkney Islands and Queen Maud Land with preference to geomorphic features such as seamounts. The distribution of CWC habitats is mainly driven by distance to coast and ice shelves, bathymetry, benthic calcium carbonate, as well as temperature. Under warming conditions, CWCs are predicted to expand their distribution range by 6 and 10% in 2037 and 2150, respectively, compared to present distribution. The future models using increased bottom temperature revealed a stable CWC distribution for most parts of the study area. However, habitat shifts are expected to the Filchner Trough region, the adjacent continental shelves, as well as to the eastern side of the Antarctic Peninsula.

Central place foragers often change their foraging behaviour in response to changes in prey availability in the environment. Lactating long-nosed fur seals Arctocephalus forsteri (LNFS) at Cape Gantheaume in South Australia have been observed to display alternate foraging strategies, whereby they forage on the shelf in summer and switch to oceanic foraging in winter. We investigated the relationship between changes in shelf summertime upwelling and the timing and variability when females switch from predominantly shelf to oceanic foraging. Geolocation tags were deployed on females from summer to winter in 2016 and 2017, giving us longitudinal tracks over the transition period. The timing of switching from shelf to oceanic foraging was primarily driven by seasonal oceanographic changes on the shelf—specifically when the strength of the seasonal localised upwelling began to decline. The individual variability in the timing of the switch was driven by the strength of the coastal upwelling, with variability being greater in years when upwelling strength was weaker. By comparing our results to those of previous studies on the same colony, we found qualitative evidence that inter-annual environmental variability likely influences whether individuals display a single or multiple foraging strategies. This further highlights the flexibility in foraging strategies used by LNFS in response to environmental changes. The effect of inter-annual differences in foraging strategies on overall reproductive success warrants further investigation.

Onshore to offshore gradients in marine assemblages have been well documented on coral reefs, with most studies showing a distinct separation between onshore and offshore locations. Here we use enclosed anaesthetic sampling of small, cryptobenthic reef fishes to assess changes in assemblage composition across the Great Barrier Reef continental shelf. The cryptobenthic fishes exhibited fine-scale partitioning across the shelf. Three dominant species of goby accounted for over 55% of all fishes collected, with 1 species characterising each of the 3 key shelf positions: inner-, mid- and outer-shelf. Multivariate analyses of assemblage composition revealed further separation of reefs within the inner- and mid-shelf positions, highlighting the exceptional sensitivity of cryptobenthic reef fish assemblages to shelf position, with a progressive separation of individual reef assemblages with distance from the shore. These among-reef patterns contrast markedly with other reef fish taxa which invariably show 2 broad assemblages across the continental shelf (inner-vs. a composite mid- and outer-shelf community). As a result of this exceptional sensitivity to environmental conditions, cryptobenthic reef fish communities may represent good subjects for high-resolution monitoring of disturbances on coral reefs.

Three killer whale Orcinus orca ecotypes inhabit the northeastern Pacific: residents, transients, and offshores. To investigate intraspecific differences in spatial and temporal occur-rence off the outer coast of Washington State, USA, 2 long-term acoustic recorders were deployed from July 2004 to August 2013: one off the continental shelf in Quinault Canyon (QC) and the other on the shelf, off Cape Elizabeth (CE). Acoustic encounters containing pulsed calls were analyzed for call types attributable to specific ecotypes, as no calls are shared between ecotypes. Both sites showed killer whale presence year-round, although site CE had a higher number of days with en- counters overall. Transients were the most common ecotype at both sites and were encountered mainly during the spring and early summer. Residents were encountered primarily at site CE and showed potential seasonal segregation between the 2 resident communities, with northern resi- dents present mainly during summer and early fall when southern residents were not encountered. Offshore encounters were higher at site QC, with little evidence for seasonality. Spatial and temporal variability of residents and transients matches the distribution of their prey and can potentially be used for further inferences about prey preferences for different transient groups.

We introduce a new, coupled modeling approach for simulating ecosystem-wide patterns in larval fish foraging and growth. An application of the method reveals how interplay between temperature and plankton dynamics during 1970-2009 impacted a cold-water species (Atlantic cod Gadus morhua) and a warm-water species (European anchovy Engraulis encrasicolus) in the North Sea. Larval fish growth rates were estimated by coupling models depicting traitbased foraging and bioenergetics of individuals, spatiotemporal changes in their prey field, and the biogeochemistry and hydrodynamics of the region. The biomass composition of modeled prey fields varied from 89% nano-, 10% micro-, and 1% mesoplankton to 15% nano-, 20% micro-, and 65% mesoplankton. The mean slope of the normalized biomass size spectrum was near -1.2, consistent with theoretical and empirical estimates. Median larval fish growth rates peaked in June for cod (24% d(-1)) and in July for anchovy (17% d(-1)). Insufficient prey resources played a substantial role in limiting the growth rates of cod larvae. Anchovy were consistently limited by cold temperatures. Faster median larval growth during specific months was significantly (p < 0.05) positively associated with detrended (i.e. higher than expected) juvenile recruitment indices in cod (rank correlation Kendall's tau = 22%) and anchovy (tau = 42%). For cod, the most predictive month was February, which was also when food limitation was most prevalent. The continued development of modeling tools based on first principles can help further a mechanistic understanding of how changes in the environment affect the productivity of living marine resources.

The Bering Sea is a highly productive ecosystem with abundant prey populations in the summer that support some of the largest seabird colonies in the Northern Hemisphere. In the fall, the Bering Sea is used by large numbers of migrants and post-breeding seabirds. We used over 22 000 km of vessel-based surveys carried out during summer (June to July) and fall (late August to October) from 2008 to 2010 over the southeast Bering Sea to examine annual and seasonal changes in seabird communities and spatial relationships with concurrently sampled prey. Deep-diving murres Uria spp., shallow-diving shearwaters Ardenna spp., and surface-foraging northern fulmars Fulmarus glacialis and kittiwakes Rissa spp. dominated summer and fall seabird communities. Sea- bird densities in summer were generally less than half of fall densities and species richness was lower in summer than in fall. Summer seabird densities had high interannual variation (highest in 2009), whereas fall densities varied little among years. Seabirds were more spatially clustered around breeding colonies and the outer continental shelf in the summer and then dispersed throughout the middle and inner shelf in fall. In summer, the abundance of age-1 walleye pollock Gadus chal co - grammus along with spatial (latitude and longitude) and temporal (year) variables best explained broad-scale seabird distribution. In contrast, seabirds in fall had weaker associations with spatial and temporal variables and stronger associations with different prey species or groups. Our results demonstrate seasonal shifts in the distribution and foraging patterns of seabirds in the southeastern Bering Sea with a greater dependence on prey occurring over the middle and inner shelf in fall.

Manta rays (Manta spp.) are plankton-feeding elasmobranchs classified as vulnerable to extinction on the IUCN Red List for Threatened Species. Despite increasing public and scientific interest in manta rays, major knowledge gaps concerning their movement ecology and dispersal capabilities remain. Here, we used pop-off satellite-linked archival transmitting tags to examine the horizontal movements and habitat use patterns of reef manta rays (M. alfredi) departing Lady Elliot Island in the southern Great Barrier Reef, Australia. Tagged individuals moved across a latitudinal range of 1035 km, travelling up to 2441 km in 118 d, diving down to 294.5 m and venturing up to 155 km off the continental shelf. Using random walk simulations, we showed that manta rays spent significantly more time in an offshore region characterised by the mesoscale cyclonic Capricorn Eddy than would be expected by chance. A behaviour-switching state-space model suggested this area to be an important foraging ground for M. alfredi off eastern Australia. We document the movements of 1 individual using offshore waters between 2 known aggregation regions off eastern Australia. Reef manta rays thus not only occupy inshore continental shelf and shelf-edge waters but also use offshore environments to exploit productive hotspots and travel long distances. Our findings highlight the need to better understand their movement ecology for effective management.

Accepted manuscript version. Published version available in Marine Ecology Progress Series, 2017;574:127-140 The diving behaviour of adult Atlantic salmon Salmo salar L. post-spawners in the Norwegian and Barents Seas was monitored with pop-up satellite archival tags (PSATs) and data storage tags (DSTs). Salmon from the 3 studied populations showed similar depth use patterns: tagged specimens spent most of their time near the surface (mean of 82% of the time at depths 200 m depth, median time = 2.31 h; range = 0.18 to 22.5 h), the deepest recorded being 707 m. Increased use of greater depths occurred during daytime than night-time in the months between polar day and polar night (August to October). Diel change in depth use around the time of polar night (November to January) was weakest for the population (from the River Alta) that migrated furthest north. Diving was more frequent and shallower when the mixed layer was near the surface during the months of June to October. There was an increase in diving depth (>200 m) when the mixed layer extended to ~200 or 300 m in winter and spring (December to April). Deep diving consisted of ‘U’ shaped dives, possibly indicative of foraging. We hypothesise that seasonal light conditions, dependent on geographical location, affect Atlantic salmon diving, and that changes in diving depth may be due to seasonal differences in prey aggregation.

Broadcast-spawning marine organisms with long pelagic larval duration are often expected to be genetically homogeneous throughout their ranges. When genetic structure is found in such taxa, it may be in the form of chaotic genetic patchiness: i.e. patterns that might seem independent of any un- derlying environmental variation. The joint analysis of population genetic data and marine environmental data can elucidate factors driving such spatial genetic diversity patterns. Using meso-scale sampling (at a scale of 10s to 100s of km), microsatellite data and advection connectivity simulations, we studied the effect of temperate southern Australian ocean circu - lation on the genetic structure of the snail Nerita atramentosa. This species has a long pelagic larval duration and is represented as a single metapopula- tion throughout its ~3000 km range, but even so, we found that its dispersal potential is lower than ex- pected. Connectivity simulations indicate that this is a result of the larvae that remain on the continental shelf (where currents are erratic and often shoreward) re- turning to the coast in much larger numbers than lar- vae that become entrained in the region's shelf-edge boundary currents. Our study contributes to the growing evidence that departures from the expecta- tions of panmixia along continuous and environ - mentally homogeneous coastlines are not limited to low-dispersal species, and it identifies on-shelf larval retention as an important factor limiting dispersal.

In the California Current ecosystem, krill availability is a well-known influence on the demography of commercially and ecologically valuable fish, seabirds, and marine mammals. Modeling factors that enhance or inhibit krill aggregations, or 'hotspots', will benefit management of marine predators of conservation concern and contribute to ecosystem approaches to fisheries. Here, we link an oceanographic model (ROMS) and an individual-based model (IBM) parameter- ized for the krill species Euphausia pacifica to test the hypothesis that occurrences of krill hotspots are disassociated from centers of upwelling along the central-northern California coast due to strong advective currents that transport zooplankton away from the productive continental shelf environment. We compare the distribution of modeled to observed hotspots derived from hydroa- coustic surveys from 2000 to 2008. Both acoustic data and modeled hotspots show the greater Gulf of the Farallones and Monterey Canyon as areas of persistent krill hotspots. In this large retention zone, we found no clear relationships between krill hotspots and proxies of upwelling. In contrast, modeled hotspots were associated with reduced upwelling (warmer sea surface temperature (SST) and lower alongshore currents) to the north of Pt. Reyes, and with enhanced upwelling (cooler SST and greater alongshore currents) south of Pt. Sur. Our model highlights the role spatial variability of physical forcing plays in determining the likelihood of krill hotspots forming in par- ticular regions. Notably, our model reproduced the spatial organization of krill hotspots using only simple oceanographic forcing mechanisms and diurnal vertical migration behavior.

The Palmer Long Term Ecological Research study region west of the Antarctic Penin- sula is experiencing warming and changing seasonal sea ice dynamics. Abundance patterns of 3 species of pelagic secondary producers were analyzed for trends, cycles, range extensions or shifts in the location of highest density, and for changes in population dynamics over a 16 yr period (1993�2008). Species analyzed represented different hydrographic regimes and are known to have contrasting responses to seasonal sea ice dynamics: krill Euphausia superba, seasonal sea ice zone; tunicates Salpa thompsoni, warmer waters with minimal sea ice; and larval Antarctic silver- fish Pleuragramma antarcticum, cold continental shelf waters. Cycles were observed in grid-wide abundance and recruitment for E. superba. Maximum grid-wide densities did not decrease, but the location of highest densities shifted southward 200 km, away from Adelie penguin rookeries at the northern end. A distinct change post-1999 was apparent in the frequency of occurrence and abundance of S. thompsoni. Mixtures of krill and salps became common, but neither peak densi- ties nor the frequency of peak years for salps increased. As with Antarctic krill, highest salp den- sities shifted southward alongshore. Larval P. antarcticum were abundant in the northern coastal region in the early 1990s, but virtually disappeared in that region after 1999/2000. Possible mech- anisms underlying these observations include the southerly movement of the sea ice edge during spring, changes in proximity of source populations (salps), and changes in transport pathways (larval P. antarcticum). Patterns are compared to those in the SW Atlantic.

In Brazil, coastal upwelling is observed in 7 areas along the southeastern/southern region and is most pronounced near Cabo Frio, Rio de Janeiro. This region is exposed to moderate seasonal Ekman-driven upwelling that brings cold water with increased nutrient levels nearshore and is more frequent and intense during the austral spring and summer, primarily due to the prevalence of northeasterly winds. Our aim was to verify the influence of this upwelling on the benthic trophic structure of the inner and outer shelf off Cabo Frio through measurements of sta- ble nitrogen (δ 15 N) and carbon (δ 13 C) isotopes. We identified 1 main pathway of organic matter (OM) transfer from the base to the top of the food web, as observed from the tendencies of the δ 13 C and δ 15 N values. The isotopic signatures of benthic consumers exhibited temporal and spatial vari- ability, with no interaction between them. As the result of a time lag, only consumers (mostly deca- pod carnivores) appeared to reflect the assimilation of 15 N-depleted and 13 C-enriched OM pro- duced and deposited during strong upwelling that occurred 4 mo earlier. Therefore, the intensity and period of the upwelling phenomenon were important for detecting upwelling in benthic food webs. Lighter nitrogen and heavier carbon isotopes were found on the inner shelf. Consumers may have exploited OM of different quality on the inner and outer shelf due to differences in sed- iment, hydrodynamics, mineralisation and assimilation of 13 C-enriched microphytobenthos. Nev- ertheless, 4 trophic levels were estimated in the benthic communities of the continental shelf off the Cabo Frio upwelling system, independent of period or area.

We provide the first reported estimates of anammox activity in tropical continental shelf sediments (southern section of the Great Barrier Reef lagoon; GBRL). The measured contri- bution of anammox to total N2 production was up to 70% but restricted to only 1 of the 4 (2 inshore and 2 offshore) sites assayed. Sediment characteristics (contents of total organic carbon (TOC) and manganese (Mn), C:N ratio) at this site appeared to favour anammox activity and the estimated maximum rate was 4.9 µmol m �2 h �1 . Anammox bacteria may be a significant contributor to N2 pro- duction along the coastal zone of the GBRL. The availability of labile (low C:N) TOC seemed to drive denitrification to completion in the offshore sediments. However, rates of NO3 � reduction to NH4 + at the offshore sites were comparable to or higher than denitrification rates. It was unclear whether dissimilatory or assimilatory processes were responsible for the observed reduction of NO3 � to NH4 + at the offshore sites. At the 2 inshore sites, NO3 � reduction to NH4 + was a larger sink for NO3 � than denitrification. Anammox does exist in the tropical continental shelf sediments of the GBRL and should be studied further to determine its role in larger scale N cycling. The roles of assimilatory and dissimilatory nitrate reduction to ammonium also need to be assessed within the GBRL.

As central-place foragers, seabirds from colonies located close to multiple and/or productive marine habitats might experience increased foraging opportunities and enhanced resilience to food shortages. We tested whether this hypothesis might explain divergent trends in 3 populations of black-legged kittiwakes Rissa tridactyla, a surface-feeding piscivore, in the east- ern Bering Sea. We simultaneously studied the foraging behavior, diet, nutritional stress, and breeding performance of chick-rearing kittiwakes from 2 continental shelf colonies (St. Paul and St. George) and an oceanic colony (Bogoslof). Although shelf-based forage fishes were rare or absent in bird diets during the cold study year, not all kittiwakes from the 3 colonies concentrated foraging along the productive shelf break habitats. Compared to the oceanic colony, birds from both shelf-located colonies had lower chick provisioning rates, higher levels of nutritional stress, and lower breeding performance. Although birds from both shelf-based colonies foraged in nearby neritic habitats during daytime, birds from St. George, a stable population located closest to the continental shelf break, also conducted long overnight trips to the ocean basin to feed on lipid-rich myctophids. In contrast, birds from St. Paul, a declining population located farthest from shelf break/oceanic habitats, fed exclusively over the shelf and obtained less high-energy food. Birds from Bogoslof, an increasing population, foraged mainly on myctophids close to the colony in the oceanic basin and Aleutian coast habitats. Our study suggests that proximity to multiple foraging habitats may explain divergent population trends among colonies of kittiwakes in the southeastern Bering Sea.

The state of Sergipe in northeastern Brazil is the largest nesting area for olive ridley turtles along this nation's coast, and constitutes a major rookery in the western Atlantic as well. Conservation efforts with a focus on nesting activities have been implemented there since 1982, but little is known about other aspects of the life cycle, specifically post-nesting movements of females and the locations of foraging grounds. To address this issue, satellite transmitters were deployed on 10 females that nested between February and April 2006. The turtles were monitored for an average of 113 d (range: 14 to 297 d), and an average movement of 1669 km (range: 407 to 4265 km) was recorded. Of the 10 turtles monitored, 6 moved along the Brazilian continental shelf to neritic foraging areas. Five of these turtles utilized foraging areas along the northern and north- eastern coasts of Brazil, while one foraged along the southeastern coastline. Two females were tracked to equatorial oceanic waters, with one first moving to an inshore foraging site where she remained for 34 d before migrating to oceanic waters off the Brazilian coast. Signal transmission of 3 of the 10 turtles tracked ceased during their post-nesting migrations, preventing identification of their feeding areas. Olive ridley turtles nesting on the coast of Sergipe displayed a range of post-nesting movements including to coastal sites along the continental shelf as well as offshore oceanic areas. Inter-nesting habitats, migration routes and foraging grounds showed great over- lap with a variety of coastal fisheries, as well as with longline fishing in oceanic waters, a key con- sideration for developing conservation strategies for this species in the western Atlantic.

We investigated the potential use of open coastal habitat over the continental shelf as a nursery area for the common thresher shark Alopias vulpinus. Seven juvenile threshers were tracked using acoustic telemetry to determine their movement patterns and nursery habitat in the Southern California Bight (SCB). Tracked sharks occupied waters over the continental shelf 87% of the time. These waters had an average (± SD) sea surface temperature of 18.8 ± 1.6°C and chlorophyll concen- trations that were an order of magnitude higher than in adjacent waters offshore of the continental shelf. Tracked sharks had a mean rate of movement of 1.63 ± 0.56 km h -1 , and some sharks exhibited high site fidelity. The vertical distribution of juvenile threshers was generally limited to the upper 20 m of the water, and most sharks showed diel depth distribution patterns, with daytime depths significantly greater than nighttime depths. An analysis of SCB commercial fishery observer data confirms that juvenile common threshers are most frequently captured over the continental shelf. This region appears to provide juvenile threshers with ample food resources and reduced predation risk relative to adult habitat, and partially satisfies more quantitative nursery area criteria recently established in the literature.

We quantified native fish densities along a depth-temperature gradient within a tem- perate-tropical marine transition zone (North Carolina continental shelf) to examine the role of depth and temperature in structuring these communities. We also examined the distribution of in- vasive lionfish (Pterois volitans, P. miles) to evaluate a laboratory-derived thermal minimum for lion- fish. We collected year-round continuous bottom water temperature data from 2000 to 2010 and sur- veyed lionfish (2004 to 2010), conspicuous fishes (2006 to 2010) and cryptic smaller-bodied fishes (2007 to 2010) at depths from 5 to 46 m using SCUBA. Bottom water temperatures were constant across the depth gradient during summer and increased from inshore to offshore during winter. The conspicuous fish community was structured by 3 depth zones, 5-14, 15-37 and 38-46 m, that corre- sponded with winter mean temperatures of 13.9, 17.9 and 20.9°C, respectively. The cryptic fish community was structured by 4 depth zones, 5-15, 18-24, 27-38.5 and 39.5-46 m, with correspon- ding winter mean bottom temperatures of 13.8, 15.6, 18.7 and 20.9°C. In contrast, summer tempera- tures were not important in structuring either the conspicuous or the cryptic fish community. Thus, fish communities in the spring/summer appear to be structured by the pattern of bottom water tem- perature experienced the previous winter, supporting previous studies that indicate winter mini- mum temperature is important for determining fish distribution and abundance in temperate marine ecosystems. In addition, the deeper fish communities were dominated by tropical species. Lionfish, a tropical species, was found in the highest densities from 38 to 46 m and present in loca- tions with a winter mean of 15.3°C and higher. Increasing temperatures could favor a potential ex- pansion of invasive lionfish and native tropical species into the nearshore waters on the North Car- olina shelf, resulting in unforeseen community structure and trophic disruptions.