Search

Sea pen communities are United Nations General Assembly-designated Vulnerable Marine Ecosystems which occur worldwide in soft-bottom sediments where trawling often occurs. However, the ability of marine managers to assess, monitor and mitigate impacts to sea pens at national scales has been constrained by a limited understanding of their environmental requirements, geographical distribution and responses to trawling. In this study, we used random forest species distribution modelling (SDM) to predict the distribution of suitable habitat for 3 sea pen species (tall sea pen Funiculina quadrangularis, slender sea pen Virgularia mirabilis and phosphorescent sea pen Pennatula phosphorea) on the UK continental shelf, exploring the results relative to the distribution of fishing activity. Occurrence of all 3 species corresponded to areas of low current and wave velocity, where suspended matter in the water column was also low. However, for F. quadrangularis, the largest species, the models indicated substantially different drivers of distribution between the Greater North Sea and Celtic Seas ICES Ecoregions. This disparity appears to reflect modification to the range and realised niche of this species in the Greater North Sea, due to trawling impacts. P. phosphorea and V. mirabilis appear to be more resilient to trawling, with no clear negative relationships observed. Our findings illustrate the value of broadscale qualitative comparisons between SDMs and human activity data for insights on pressure-state relationships. When combined with robust distribution maps, this improved understanding of vulnerability will enable marine managers to make ecologically sound, defensible decisions and deliver tangible conservation outcomes for sea pen communities.

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.

In this study, we analysed the structure and functioning of the Portuguese continental shelf ecosystem and investigated the role of sardine Sardina pilchardus using the Ecopath massbalance approach. An Ecopath model was configured to represent the continental shelf waters in the period 2006-2009. The model showed that biomass was concentrated in low and intermediate trophic levels as in other upwelling areas. Several low- and medium-trophic-level groups were identified as dominant groups in the ecosystem (e.g. zooplankton, macrozoobenthos, sardine, chub mackerel Scomber colias, and demersal and benthopelagic invertivorous fish). Furthermore, lowtrophic-level groups were responsible for the main energy flows, and overall higher impact on the ecosystem, emphasizing the importance of bottom-up control of the ecosystem structure. Our results are relevant to understand structure and functioning of this ecosystem and constitute an important step towards an ecosystem approach to fisheries management in the study area. PROMAR project (CERTIFICA) [3103-01-FEP-0032] EU/DG Fisheries Data Collection Regulation, LIFE+ [MarPro. NAT/PT/000038] EEA Grants (SafeSea) [0039] 'Fundacao para a Ciencia e Tecnologia (FCT)Portuguese Foundation for Science and Technology [PD/BD/114540/2016] ARDITI (Regional Agency for Development of Research, Technology and Innovation of Madeira) [M1420-09-5369-FSE-000001]

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.

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.

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.

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.

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.

Bathymodiolus childressi is a foundation species at methane seeps on the upper- continental slope of the Gulf of Mexico. Other species of the genus are known to gain the advan- tage of variable food availability through trophic plasticity, by hosting dual microbial symbionts while retaining their own particle feeding ability. B. childressi, however, hosts only a single methanotrophic symbiont, and the possibility of trophic plasticity has not been fully examined in this species. Feeding strategies of archival specimens from 2 geochemically contrasting seeps from the Gulf of Mexico (Bush Hill and Brine Pool NR-1) were characterized using 4-source mix- ing analysis of δ 13 C, δ 15 N and δ 34 S values. Bush Hill mussels used a single thermogenic methane pool and derived N and S from different sources. Brine Pool mussels used 2 separate methane pools; the primary one being biogenic and the secondary possibly a mix of biogenic and thermo- genic. Utilization of particulate material was less common at Brine Pool than at Bush Hill. Bush Hill appears to offer lower levels of methane-based resources with particulate material having a greater, and sometimes dominant role in nutrition. Spatial patterns within the seeps were found but were not reflective of simple gradients. Some temporal changes occurred at both yearly scales and between samples, which were collected 17 yr apart. The 4-source mixing model used extrap- olations of mussel isotope values and limited environment characterization to infer likely trophic sources. The actual sources, however, remain unidentified. Future research across a wider range of seeps as well as experimental studies should be used to test the validity of the model.

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.

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.

Some of the largest submarine canyons in the world incise the eastern Bering Sea shelf break. Here, we examine whether 5 large canyons (Bering, Pribilof, Zhemchug, Pervenets and Navarin) are faunally distinct features within the eastern Bering Sea. We compiled data from the eastern Bering Sea that included trawl survey data on fish and invertebrate distributions and observations of ocean conditions and benthic habitat. These data were analyzed using multivariate techniques to determine if the canyons are distinguishable from the adjacent continental slope. We found that the 5 canyons are not faunally distinct features of the eastern Bering Sea slope but that the major characteristics structuring fish and invertebrate communities were depth, latitude and sediment rather than submarine canyons. One notable feature of these canyons is that about one quarter of the coral habitat predicted for the eastern Bering Sea slope occurs in Pribilof Canyon, an area that comprises only ~10% of the total slope area. The predicted coral habitat also extends westward to the adjacent slope, indicating that this coral habitat concentration is not unique to Pribilof Canyon but rather that it is typical for a larger area (Pribilof Canyon and westward).

The western Antarctic Peninsula is experiencing dramatic climate change as warm, wet conditions expand poleward and interact with local physics and topography, causing differen- tial regional effects on the marine ecosystem. At local scales, deep troughs (or canyons) bisect the continental shelf and act as conduits for warm Upper Circumpolar Deep Water, with reduced sea- sonal sea ice coverage, and provide a reservoir of macro- and micronutrients. Shoreward of many canyon heads are Adelie penguin breeding colonies; it is hypothesized that these locations reflect improved or more predictable access to higher biological productivity overlying the canyons. To synoptically assess the potential impacts of regional bathymetry on the marine ecosystem, 4 major canyons were identified along a latitudinal gradient west of the Antarctic Peninsula using a high- resolution bathymetric database. Biologicalphysical dynamics above and adjacent to canyons were compared using in situ pigments and satellite-derived sea surface temperature, sea ice and ocean color variables, including chlorophyll a (chl a) and fucoxanthin derived semi-empirically from remote sensing reflectance. Canyons exhibited higher sea surface temperature and reduced sea ice coverage relative to adjacent shelf areas. In situ and satellite-derived pigment patterns indicated increased total phytoplankton and diatom biomass over the canyons (by up to 22 and 35%, respectively), as well as increases in diatom relative abundance (fucoxanthin:chl a). While regional heterogeneity is apparent, canyons appear to support a phytoplankton community that is conducive to both grazing by krill and enhanced vertical export, although it cannot compensate for decreased biomass and diatom relative abundance during low sea ice conditions.

To better understand seasonal variation in phytoplankton community structure in the East China Sea (ECS), 4 research cruises were carried out between August 2009 and June 2011 over the continental shelf. Phytoplankton community structure and ambient seawater physicochemical parameters were examined. The phytoplankton community in the ECS was mainly composed of diatoms and dinoflagellates, with 242 taxa in 70 genera of diatoms and 104 taxa in 26 genera of dinoflagellates. Several species of Chlorophyta, Chrysophyta, and Cyanophyta were also observed. Chain-forming diatoms were the most dominant phytoplankton group throughout the year, except in spring when dinoflagellates dominated in coastal waters. Monsoon-induced turbulence played a significant role in regulating the dominance of dinoflagellates among seasons, with calm water favoring the growth of dinoflagellates and turbulent water inhibiting them. Phytoplankton abundance was always higher in coastal than offshore waters, mainly determined by nutrient availability. A Prorocentrum dentatum bloom and a Chaetoceros debilis bloom were observed in the Yangtze River estuary in spring 2011 and fall 2010, respectively. The blooms differed greatly in community diversity and cell abundance distribution, potentially affecting organic carbon export. In general, 3 different hydrographic water systems (coastal water, shelf mixed water, and Kuroshio water) were identified from a temperature-salinity plot of the ECS, and phytoplankton abundance showed spatially and temporally different distribution patterns in these 3 water systems. The nutrient N:P ratio, but not the Si:N ratio, played a significant role in regulating the phytoplankton community structure and the formation of the spring coastal dinoflagellate bloom in the ECS.

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.

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.

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.

The size structure of zooplankton communities in the Gulf of Lion, NW Mediterranean Sea, was studied in May 2010 and January 2011. The integrated physical and biological measurements provided a 3D view with high spatial resolution of the physical and biological variables and their correlations over the whole gulf. The effects of physical processes such as freshwater input, coastal upwelling, and water column mixing by winds on phytoplankton and zooplankton distributions were analyzed using these data. During the winter, strong northerly winds mixed the water column, and the vertical distributions of biological variables were uniform over most of the gulf while there were local hot spots with high chlorophyll a (chl a) concentrations in front of the Rhône mouths and in coastal areas. During the spring, light winds and water column stratification resulted in less vertical mixing, and the Rhône River freshwater plume spread over a large part of the gulf. The nutrients delivered by the freshwater input encouraged high primary production in the surface layer. In the pycnocline, a thin layer of high particle concentration was associated with these high phytoplankton biomasses. Three habitats were distinguished based on statistical analysis performed on biological and physical variables: (1) the coastal area characterized by shallow waters, high chl a concentrations, and a steep slope of the normalized biomass size spectrum (NBSS); (2) the area affected by the Rhône with high stratification and flat NBSS slope; and (3) the continental shelf with a deep mixed layer, relatively low particle concentrations, and moderate NBSS slope. Defining habitat is a relevant approach to designing new zooplankton sampling strategies, validating distribution models and including the zooplankton compartment in trophodynamic studies.

The analysis of environmental characteristics to explain the distribution of endan- gered seabirds can aid in the identification of important areas at sea and lead to more effective conservation. We used high resolution Global Positioning System (GPS) tracking data to study the at-sea patterns of chick-rearing Chatham albatrosses Thalassarche eremita across 3 years (2007, 2008 and 2009) in relation to bathymetry, slope, sea surface temperature (SST) and chlorophyll a (chl a) concentration. Birds mostly foraged within 400 to 600 km of their colony, located within the southeastern part of New Zealand's continental shelf, the Chatham Rise. Despite little spatial overlap across years, foraging areas were predominantly associated with waters of less than 2500 m depth, slopes of 1 to 4°, SST between 15 and 16°C, and chl a concentrations >1 mg m �3 in all years. According to boosted regression tree models, no single habitat variable particularly explained the spatial occurrence of foraging areas. However, bathymetry was of higher relative importance in 2008 and 2009, while chl a was relatively more important in 2007, a year of increased primary productivity. Our results suggest that chick-rearing Chatham albatrosses rely on resources that are generally predictable in location, but that they also respond to fine-scale changes within their foraging environment. Incorporating such dynamics into conservation planning might be best addressed by mitigating incidental bycatch in fishing operations, as well as implementing a protected area southeast of the breeding site, which we identified as a key foraging zone.

Understanding the drivers of broad-scale patterns of biodiversity is an overarching goal in ecology. We analysed environmental drivers of macroalgal species richness and composition on the continental shelf seabed of Australia's Great Barrier Reef (GBR), and mapped these patterns to show phycologically diverse and depauperate areas. Although shelf seabed habitats constitute similar to 61% of the GBR Marine Park area, previous floristic studies have been largely confined to intertidal and coral reef areas. Recognising the lack of knowledge of this habitat, the GBR Seabed Biodiversity Project (SBP) surveyed environmental variables and associated biodiversity across the shelf. We used SBP data for 1195 epibenthic sled sites, of which 639 sites recorded 370 macroalgal taxa, including 250 taxa not previously described in the GBR. Regression Random Forests were used to identify the environmental variables that most influence algal richness. Patterns of species composition, or assemblages, were investigated using partitioning around medoids (pam) clustering, and classification Random Forests identified the environmental variables most influential, and shapes of responses, for each assemblage. The 5 assemblages were distinguished based on taxonomy, dominant species, functional form or abundance and species richness. Overall, sediment grain size composition and light availability had the greatest influence on species richness and assemblages, with strong thresholds at 20% mud and at relative benthic irradiance of similar to 0.06 (equivalent to PAR approximate to 120 mu mol m(-2) s(-1)). This study is the first systematic analysis of the macroalgal communities of the GBR shelf seabed, providing valuable information to stimulate future research on taxonomy, productivity and ecosystem services of this habitat.

Physiological characteristics of inorganic C uptake were examined in Southern Oceanice algae and phytoplankton assemblages. Ice algal and phytoplankton assemblages were largelydominated by diatoms and Phaeocystis antarctica, and showed a high capacity for HCO3−utilization, with direct HCO3− transport accounting for ~60% of total inorganic C uptake. Extracellularcarbonic anhydrase (eCA) was detectable in all samples, but with significantly lower activityin sea ice algae. Neither HCO3− transport nor eCA activity was related to the in situ partial pressureof CO2 (pCO2) or taxonomic composition of samples. The half-saturation constant (KS) for inorganicC ranged from ~100 to 5000 μM, and showed significantly more variability among sea ice algaethan phytoplankton assemblages. For the phytoplankton assemblages, there were significant positivecorrelations between in situ pCO2 and KS (higher C substrate affinity in low pCO2 waters), andalso between KS and maximum C uptake rates (Vmax). In contrast, KS and Vmax in sea-ice algal assemblageswere not correlated to each other, or to any other measured variables. The C isotopecomposition of particulate organic carbon (δ13C-POC) in the phytoplankton assemblages showedmodest variability (range −30 to −24.6‰) and was significantly correlated to the ratio of inferredgrowth rates (derived from Vmax) and in situ CO2 concentrations, but not to any measured C uptakeparameters. δ13C-POC in sea ice algal samples (range −25.7 to −12.9‰) was significantly heavierthan in the phytoplankton assemblages, and not correlated to any other variables. Our results provideevidence for the widespread occurrence of carbon-concentrating mechanisms in SouthernOcean sea ice algae and phytoplankton assemblages.

Characterizing the behaviors of sea turtles and identifying high-use areas as they vary in time and space is important for conservation planning, particularly when turtles overlap with fisheries that may unintentionally harm them. Between July 2006 and March 2010, 27 satel- lite transmitters were deployed at sea on juvenile loggerheads Caretta caretta captured as bycatch in the Uruguayan and Brazilian pelagic longline fisheries operating in the Southwestern Atlantic Ocean. Tracking duration ranged from 3 to 639 d (mean ± SD: 259 ± 159 d; n = 27), during which turtles moved between latitudes of 25 to 45° S and longitudes 35 to 54° W. High-use areas for the tracked turtles were over the continental shelf and slope within the Uruguayan, Argentin- ian, and Brazilian exclusive economic zones and in adjacent international waters. Diving informa- tion was available for 5 turtles. The maximum dive depth recorded varied between 100 and 300 m. Two turtles demonstrated potential bottom-feeding behaviors by diving to depths that corre- sponded closely with the depth of the seafloor (

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.

Changes in benthic habitats occur as a result of natural variation or human-induced processes. It is important to understand natural fine-scale inter-annual patterns of change to separate these signals from patterns of long-term change. Describing change from an acoustic remote sensing standpoint has been facilitated by the recent availability of full coverage swath acoustic datasets, but is limited by cost pressures associated with multiple surveys of the same area. We studied the use of landscape transition analysis as a means to differentiate seemingly random patterns of habitat change from systematic signals of habitat transition at a shallow (10 to 50 m depth) 18 km2 site on the temperate Australian continental shelf in 2006 and 2007. Supervised classifications for each year were accomplished using inde pendently collected highresolution swath acoustic and video reference data. Of the 4 representative biotic clas ses considered, signals of directional systematic changes occurred be tween a kelp-dominated class, a sessile invertebrate-dominated class and a mixed class of kelp and sessile invertebrates. We provide a detailed analysis of the components of the traditional change detection cross tabulation matrix, allowing identification of the strongest signals of systematic habitat transitions. Iden tifying patterns of habitat change is an important first step toward understanding the processes that drive them.

Oceanographic features and physical processes in the ocean can create regions where prey, and therefore predators, may accumulate. Beluga whales Delphinapterus leucas are the most numerous cetacean in the Arctic. In the Alaskan Beaufort Sea, they prefer continental slope habitat in summer and autumn, presumably because such areas provide enhanced foraging opportunities. Passive acoustic detections of beluga whale calls, current velocity measurements, historical wind records, and 29 yr of beluga whale observations from aerial surveys were used to explore the hypothesis that the foraging success of beluga whales in Barrow Canyon and along the western Beaufort Sea slope is enhanced when the Alaska Coastal Current (ACC) is well- developed and flows east-northeastward and is diminished when the flow of the ACC and its shelf break extension are reversed. Aerial sightings of beluga whales, average observed beluga whale group size, and hours with whale vocalizations were more common when the ACC was well- developed and flowed east-northeastward. When the ACC flow is strong, it is separated from Arctic basin waters by a well-defined front that promotes aggregation of prey species. We specu- late that the greater numbers of animals per group sighted and hours with recorded vocalizations may be indicative of enhanced foraging opportunities for beluga whales.

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.