Publications
221 results found
Turney CSM, Fogwill CJ, Palmer JG, et al., 2017, Tropical forcing of increased Southern Ocean climate variability revealed by a 140-year subantarctic temperature reconstruction, CLIMATE OF THE PAST, Vol: 13, Pages: 231-248, ISSN: 1814-9324
Occupying about 14 % of the world's surface, the Southern Ocean plays a fundamental role in ocean and atmosphere circulation, carbon cycling and Antarctic ice-sheet dynamics. Unfortunately, high interannual variability and a dearth of instrumental observations before the 1950s limits our understanding of how marine–atmosphere–ice domains interact on multi-decadal timescales and the impact of anthropogenic forcing. Here we integrate climate-sensitive tree growth with ocean and atmospheric observations on southwest Pacific subantarctic islands that lie at the boundary of polar and subtropical climates (52–54° S). Our annually resolved temperature reconstruction captures regional change since the 1870s and demonstrates a significant increase in variability from the 1940s, a phenomenon predating the observational record. Climate reanalysis and modelling show a parallel change in tropical Pacific sea surface temperatures that generate an atmospheric Rossby wave train which propagates across a large part of the Southern Hemisphere during the austral spring and summer. Our results suggest that modern observed high interannual variability was established across the mid-twentieth century, and that the influence of contemporary equatorial Pacific temperatures may now be a permanent feature across the mid- to high latitudes.
Krüger L, Ramos JA, Xavier JC, et al., 2017, Identification of candidate pelagic marine protected areas through a seabird seasonal-, multispecific- and extinction risk-based approach, Animal Conservation, Vol: 20, Pages: 409-424, ISSN: 1367-9430
With increasing pressure on the oceans from environmental change, there has been a global call for improved protection of marine ecosystems through the implementation of marine protected areas (MPAs). Here, we used species distribution modelling (SDM) of tracking data from 14 seabird species to identify key marine areas in the southwest Atlantic Ocean, valuing areas based on seabird species occurrence, seasonality and extinction risk. We also compared overlaps between the outputs generated by the SDM and layers representing important human threats (fishing intensity, ship density, plastic and oil pollution, ocean acidification), and calculated loss in conservation value using fishing and ship density as cost layers. The key marine areas were located on the southern Patagonian Shelf, overlapping extensively with areas of high fishing activity, and did not change seasonally, while seasonal areas were located off south and southeast Brazil and overlapped with areas of high plastic pollution and ocean acidification. Non-seasonal key areas were located off northeast Brazil on an area of high biodiversity, and with relatively low human impacts. We found support for the use of seasonal areas depending on the seabird assemblage used, because there was a loss in conservation value for the seasonal compared to the non-seasonal approach when using ‘cost’ layers. Our approach, accounting for seasonal changes in seabird assemblages and their risk of extinction, identified additional candidate areas for incorporation in the network of pelagic MPAs.
Coleman MA, Cetina-Heredia P, Roughan M, et al., 2017, Anticipating changes to future connectivity within a network of marine protected areas, Global Change Biology, Vol: 23, Pages: 3533-3542, ISSN: 1365-2486
Continental boundary currents are projected to be altered under future scenarios of climate change. As these currents often influence dispersal and connectivity among populations of many marine organisms, changes to boundary currents may have dramatic implications for population persistence. Networks of marine protected areas (MPAs) often aim to maintain connectivity, but anticipation of the scale and extent of climatic impacts on connectivity are required to achieve this critical conservation goal in a future of climate change. For two key marine species (kelp and sea urchins), we use oceanographic modelling to predict how continental boundary currents are likely to change connectivity among a network of MPAs spanning over 1000 km of coastline off the coast of eastern Australia. Overall change in predicted connectivity among pairs of MPAs within the network did not change significantly over and above temporal variation within climatic scenarios, highlighting the need for future studies to incorporate temporal variation in dispersal to robustly anticipate likely change. However, the intricacies of connectivity between different pairs of MPAs were noteworthy. For kelp, poleward connectivity among pairs of MPAs tended to increase in the future, whereas equatorward connectivity tended to decrease. In contrast, for sea urchins, connectivity among pairs of MPAs generally decreased in both directions. Self-seeding within higher-latitude MPAs tended to increase, and the role of low-latitude MPAs as a sink for urchins changed significantly in contrasting ways. These projected changes have the potential to alter important genetic parameters with implications for adaptation and ecosystem vulnerability to climate change. Considering such changes, in the context of managing and designing MPA networks, may ensure that conservation goals are achieved into the future.
Hardesty BD, Harari J, Isobe A, et al., 2017, Using Numerical Model Simulations to Improve the Understanding of Micro-plastic Distribution and Pathways in the Marine Environment, FRONTIERS IN MARINE SCIENCE, Vol: 4
- Author Web Link
- Cite
- Citations: 149
Hellweger FL, van Sebille E, Calfee BC, et al., 2016, The role of ocean currents in the temperature selection of plankton: insights from an individual-based model., PLOS One, Vol: 11, ISSN: 1932-6203
Biogeography studies that correlate the observed distribution of organisms to environmental variables are typically based on local conditions. However, in cases with substantial translocation, like planktonic organisms carried by ocean currents, selection may happen upstream and local environmental factors may not be representative of those that shaped the local population. Here we use an individual-based model of microbes in the global surface ocean to explore this effect for temperature. We simulate up to 25 million individual cells belonging to up to 50 species with different temperature optima. Microbes are moved around the globe based on a hydrodynamic model, and grow and die based on local temperature. We quantify the role of currents using the "advective temperature differential" metric, which is the optimum temperature of the most abundant species from the model with advection minus that from the model without advection. This differential depends on the location and can be up to 4°C. Poleward-flowing currents, like the Gulf Stream, generally experience cooling and the differential is positive. We apply our results to three global datasets. For observations of optimum growth temperature of phytoplankton, accounting for the effect of currents leads to a slightly better agreement with observations, but there is large variability and the improvement is not statistically significant. For observed Prochlorococcus ecotype ratios and metagenome nucleotide divergence, accounting for advection improves the correlation significantly, especially in areas with relatively strong poleward or equatorward currents.
Turney CSM, Fogwill CJ, Palmer JG, et al., 2016, Supplementary material to "Tropical forcing of increased Southern Ocean climate variability revealed by a 140-year subantarctic temperate reconstruction"
Turney CSM, Fogwill CJ, Palmer JG, et al., 2016, Tropical forcing of increased Southern Ocean climate variability revealed by a 140-year subantarctic temperate reconstruction
<jats:p>Abstract. Occupying 14% of the world’s surface, the Southern Ocean plays a fundamental role in global climate, ocean circulation, carbon cycling and Antarctic ice-sheet stability. Unfortunately, high interannual variability and a dearth of instrumental observations before the 1950s limits our understanding of how marine-atmosphere-ice domains interact on multi-decadal timescales and the impact of anthropogenic forcing. Here we integrate climate-sensitive tree growth with ocean and atmospheric observations on southwest Pacific subantarctic islands that lie at the boundary of polar and subtropical climates (52–54˚S). Our annually-resolved temperature reconstruction captures regional change since the 1870s and demonstrates a significant increase in variability from the mid-twentieth century, a phenomenon predating the observational record. Climate reanalysis and modelling shows a parallel change in tropical Pacific sea surface temperatures that generate an atmospheric Rossby wave train which propagates across a large part of the Southern Hemisphere during the austral spring and summer. </jats:p>
Fogwill CJ, van Sebille E, Cougnon EA, et al., 2016, Brief communication: impacts of a developing polynya off Commonwealth Bay, East Antarctica, triggered by grounding of iceberg B09B, Cryosphere, Vol: 10, Pages: 2603-2609, ISSN: 1994-0424
The dramatic calving of the Mertz Glacier tongue in 2010, precipitated by the movement of iceberg B09B, reshaped the oceanographic regime across the Mertz Polynya and Commonwealth Bay, regions where high-salinity shelf water (HSSW) – the precursor to Antarctic bottom water (AABW) – is formed. Here we present post-calving observations that suggest that this reconfiguration and subsequent grounding of B09B have driven the development of a new polynya and associated HSSW production off Commonwealth Bay. Supported by satellite observations and modelling, our findings demonstrate how local icescape changes may impact the formation of HSSW, with potential implications for large-scale ocean circulation.
Teske PR, Sandoval-Castillo J, van Sebille E, et al., 2016, Oceanography promotes self-recruitment in a planktonic larval disperser, Scientific Reports, Vol: 6, ISSN: 2045-2322
The application of high-resolution genetic data has revealed that oceanographic connectivity in marine species with planktonic larvae can be surprisingly limited, even in the absence of major barriers to dispersal. Australia's southern coast represents a particularly interesting system for studying planktonic larval dispersal, as the hydrodynamic regime of the wide continental shelf has potential to facilitate onshore retention of larvae. We used a seascape genetics approach (the joint analysis of genetic data and oceanographic connectivity simulations) to assess population genetic structure and self-recruitment in a broadcast-spawning marine gastropod that exists as a single meta-population throughout its temperate Australian range. Levels of self-recruitment were surprisingly high, and oceanographic connectivity simulations indicated that this was a result of low-velocity nearshore currents promoting the retention of planktonic larvae in the vicinity of natal sites. Even though the model applied here is comparatively simple and assumes that the dispersal of planktonic larvae is passive, we find that oceanography alone is sufficient to explain the high levels of genetic structure and self-recruitment. Our study contributes to growing evidence that sophisticated larval behaviour is not a prerequisite for larval retention in the nearshore region in planktonic-developing species.
Qin X, Menviel L, Sen Gupta A, et al., 2016, Iron sources and pathways into the Pacific Equatorial Undercurrent, Geophysical Research Letters, Vol: 43, Pages: 9843-9851, ISSN: 0094-8276
Using a novel observationally constrained Lagrangian iron model forced by outputs from an eddy-resolving biogeochemical ocean model, we examine the sensitivity of the Equatorial Undercurrent (EUC) iron distribution to EUC source region iron concentrations. We find that elevated iron concentrations derived from New Guinea Coastal Undercurrent (NGCU) alone is insufficient to explain the high concentrations observed in the EUC. In addition, due to the spread in transit times, interannual NGCU iron pulses are scavenged, diluted, or eroded, before reaching the eastern equatorial Pacific. With an additional iron source from the nearby New Ireland Coastal Undercurrent, EUC iron concentrations become consistent with observations. Furthermore, as both the New Guinea and New Ireland Coastal Undercurrents strengthen during El Niño, increased iron input into the EUC can enhance the iron supply into the eastern equatorial Pacific. Notably, during the 1997/1998 El Niño, this causes a simulated 30% iron increase at a 13 month lag.
van Sebille E, Spathi C, Gilbert A, 2016, The ocean plastic pollution challenge: towards solutions in the UK, Publisher: Grantham Institute, Imperial College London, 19
Doblin MA, van Sebille E, 2016, Drift in ocean currents impacts intergenerational microbial exposure to temperature, Proceedings of the National Academy of Sciences of the United States of America, Vol: 113, Pages: 5700-5705, ISSN: 1091-6490
Microbes are the foundation of marine ecosystems [Falkowski PG, Fenchel T, Delong EF (2008) Science 320(5879):1034-1039]. Until now, the analytical framework for understanding the implications of ocean warming on microbes has not considered thermal exposure during transport in dynamic seascapes, implying that our current view of change for these critical organisms may be inaccurate. Here we show that upper-ocean microbes experience along-trajectory temperature variability up to 10 °C greater than seasonal fluctuations estimated in a static frame, and that this variability depends strongly on location. These findings demonstrate that drift in ocean currents can increase the thermal exposure of microbes and suggests that microbial populations with broad thermal tolerance will survive transport to distant regions of the ocean and invade new habitats. Our findings also suggest that advection has the capacity to influence microbial community assemblies, such that regions with strong currents and large thermal fluctuations select for communities with greatest plasticity and evolvability, and communities with narrow thermal performance are found where ocean currents are weak or along-trajectory temperature variation is low. Given that fluctuating environments select for individual plasticity in microbial lineages, and that physiological plasticity of ancestors can predict the magnitude of evolutionary responses of subsequent generations to environmental change [Schaum CE, Collins S (2014) Proc Biol Soc 281(1793):20141486], our findings suggest that microbial populations in the sub-Antarctic (∼40°S), North Pacific, and North Atlantic will have the most capacity to adapt to contemporary ocean warming.
Cetina-Heredia P, van Sebille E, Matear R, et al., 2016, Lagrangian characterization of nitrate supply and episodes of extreme phytoplankton blooms in the Great Australian Bight
<jats:p>Abstract. Phytoplankton growth is the foundation for energy transfer into higher trophic levels, influences climate by the uptake of atmospheric CO2, and plays an important role in nutrient cycling. Here we use a novel lagrangian approach to characterize the nitrate supply to the Great Australian Bight, identify episodes of extreme phytoplankton blooms and ascertain the origin of the nitrate sources that fuel them. We find that 55 % of nitrate used by phytoplankton enters the GAB in the upper 100 m and that 88 % originates locally from a region between the GAB and the Sub Antarctic Front, rather than from more remote oceans; thus, most of the nitrate is recycled locally. Our results show extreme phytoplankton blooms have an annual periodicity, peaking in the Austral autumn when the mixed layer deepens. This suggests that stratification erosion is key supplying nutrients into the euphotic zone and triggering these episodes. </jats:p>
Cetina-Heredia P, van Sebille E, Matear R, et al., 2016, Supplementary material to &quot;Lagrangian characterization of nitrate supply and episodes of extreme phytoplankton blooms in the Great Australian Bight&quot;
Fogwill CJ, van Sebille E, Cougnon EA, et al., 2016, Supplementary material to &quot;Brief Communication: Evidence of a developing Polynya off Commonwealth Bay, East Antarctica, triggered by grounding of iceberg&quot;
Sen Gupta A, McGregor S, van Sebille E, et al., 2016, Future changes to the Indonesian Throughflow and Pacific circulation: The differing role of wind and deep circulation changes, Geophysical Research Letters, Vol: 43, Pages: 1669-1678, ISSN: 0094-8276
Climate models consistently project a substantial decrease in the Indonesian Throughflow (ITF) in response to enhanced greenhouse warming. On interannual timescales ITF changes are largely related to tropical Pacific wind variability. However, on the multidecadal timescales investigated here we demonstrate that regional winds and associated changes in the upper ocean circulation cannot explain the projected ITF decrease. Instead, the decrease is related to a weakening in the northward flow of deep waters entering the Pacific basin at ~40°S and an associated reduction in the net basin-wide upwelling to the north of the southern tip of Australia. This can be traced back to consistent changes in the Antarctic Circumpolar Current and Southern Ocean overturning, although questions still remain as to the ultimate drivers. In contrast to the ITF decrease, substantial projected changes to the upper ocean circulation of the Pacific basin are well explained by robust changes in the surface winds.
Yit Sen Bull C, van Sebille E, 2016, Sources, fate, and pathways of Leeuwin Current water in the Indian Ocean and Great Australian Bight: A Lagrangian study in an eddy-resolving ocean model, Journal of Geophysical Research: Oceans, Vol: 121, Pages: 1626-1639, ISSN: 2169-9291
The Leeuwin Current is the dominant circulation feature in the eastern Indian Ocean, transporting tropical and subtropical water southward. Whilst it is known that the Leeuwin Current draws its water from a multitude of sources, existing Indian Ocean circulation schematics have never quantified the fluxes of tropical and subtropical source water flowing into the Leeuwin Current. This paper uses virtual Lagrangian particles to quantify the transport of these sources along the Leeuwin Current's mean pathway. Here, the pathways and exchange of Leeuwin Current source waters across six coastally bound sectors on the south-west Australian coast are analysed. This constitutes the first quantitative assessment of Leeuwin Current pathways within an offline, 50-year integration time, eddy-resolving global ocean model simulation. Along the Leeuwin Current's pathway we find a mean poleward transport of 3.7 Sv in which the tropical sources account for 60-78% of the transport. Whilst the net transport is small, we see large transports flowing in and out of all the offshore boundaries of the Leeuwin Current sectors. Along the Leeuwin Current's pathway, we find that water from the Indonesian Throughflow contributes 50-66% of the seasonal signal. By applying conditions on the routes particles take entering the Leeuwin Current, we find particles are more likely to travel offshore north of 30°S, while south of 30°S particles are more likely to continue downstream. We find a 0.2 Sv pathway of water from the Leeuwin Current's source regions, flowing through the entire Leeuwin Current pathway into the Great Australian Bight.
Schuyler QA, Wilcox C, Townsend KA, et al., 2016, Risk analysis reveals global hotspots for marine debris ingestion by sea turtles, GLOBAL CHANGE BIOLOGY, Vol: 22, Pages: 567-576, ISSN: 1354-1013
- Author Web Link
- Open Access Link
- Cite
- Citations: 112
Wilcox C, Van Sebille E, Hardesty BD, 2016, Threat of plastic pollution to seabirds is global, pervasive, and increasing (vol 112, pg 11899, 2015), PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Vol: 113, Pages: E491-E491, ISSN: 0027-8424
- Author Web Link
- Cite
- Citations: 1
Ypma SL, van Sebille E, Kiss AE, et al., 2016, The separation of the East Australian Current: A Lagrangian approach to potential vorticity and upstream control, Journal of Geophysical Research: Oceans, Vol: 121, Pages: 758-774, ISSN: 2169-9291
The East Australian Current (EAC) is the western boundary current flowing along the east coast of Australia separating from the coast at approximately 34°S. After the separation two main pathways can be distinguished, the eastward flowing Tasman Front and the extension of the EAC flowing southward. The area south of the separation latitude is eddy-rich and the separation latitude of the EAC is variable. Little is known of the properties of the water masses that separate at the bifurcation of the EAC. This paper presents new insights from the Lagrangian perspective, where the water masses that veer east and those that continue south are tracked in an eddy-permitting numerical model. The transport along the two pathways is computed, and a 1:3 ratio between transport in the EAC extension and transport in the Tasman Front is found. The results show that the “fate” of the particles is to first order already determined by the particle distribution within the EAC current upstream of the separation latitude, where 85% of the particles following the EAC extension originate from below 460 m and 90% of the particles following the Tasman Front originate from the top 460 m depth at 28°S. The separation and pathways are controlled by the structure of the isopycnals in this region. Analysis of anomalies in potential vorticity show that in the region where the two water masses overlap, the fate of the water depends on the presence of anticyclonic eddies that push isopycnals down and therefore enable particles to travel further south.
Sherman P, van Sebille E, 2016, Modeling marine surface microplastic transport to assess optimal removal locations, Environmental Research Letters, Vol: 11, ISSN: 1748-9326
Marine plastic pollution is an ever-increasing problem that demands immediate mitigation and reduction plans. Here, a model based on satellite-tracked buoy observations and scaled to a large data set of observations on microplastic from surface trawls was used to simulate the transport of plastics floating on the ocean surface from 2015 to 2025, with the goal to assess the optimal marine microplastic removal locations for two scenarios: removing the most surface microplastic and reducing the impact on ecosystems, using plankton growth as a proxy. The simulations show that the optimal removal locations are primarily located off the coast of China and in the Indonesian Archipelago for both scenarios. Our estimates show that 31% of the modeled microplastic mass can be removed by 2025 using 29 plastic collectors operating at a 45% capture efficiency from these locations, compared to only 17% when the 29 plastic collectors are moored in the North Pacific garbage patch, between Hawaii and California. The overlap of ocean surface microplastics and phytoplankton growth can be reduced by 46% at our proposed locations, while sinks in the North Pacific can only reduce the overlap by 14%. These results are an indication that oceanic plastic removal might be more effective in removing a greater microplastic mass and in reducing potential harm to marine life when closer to shore than inside the plastic accumulation zones in the centers of the gyres.
Biastoch A, Durgadoo JV, Morrison AK, et al., 2015, Atlantic multi-decadal oscillation covaries with Agulhas leakage., Nature Communications, Vol: 6, ISSN: 2041-1723
The interoceanic transfer of seawater between the Indian Ocean and the Atlantic, 'Agulhas leakage', forms a choke point for the overturning circulation in the global ocean. Here, by combining output from a series of high-resolution ocean and climate models with in situ and satellite observations, we construct a time series of Agulhas leakage for the period 1870-2014. The time series demonstrates the impact of Southern Hemisphere westerlies on decadal timescales. Agulhas leakage shows a correlation with the Atlantic Multi-decadal Oscillation on multi-decadal timescales; the former leading by 15 years. This is relevant for climate in the North Atlantic.
van Sebille E, Wilcox C, Lebreton L, et al., 2015, A Global Inventory of Small Floating Plastic Debris, Environmental Research Letters, Vol: 10, Pages: 124006-124006, ISSN: 1748-9326
Microplastic debris floating at the ocean surface can harm marine life. Understanding the severity of this harm requires knowledge of plastic abundance and distributions. Dozens of expeditions measuring microplastics have been carried out since the 1970s, but they have primarily focused on the North Atlantic and North Pacific accumulation zones, with much sparser coverage elsewhere. Here, we use the largest dataset of microplastic measurements assembled to date to assess the confidence we can have in global estimates of microplastic abundance and mass. We use a rigorous statistical framework to standardize a global dataset of plastic marine debris measured using surface-trawling plankton nets and coupled this with three different ocean circulation models to spatially interpolate the observations. Our estimates show that the accumulated number of microplastic particles in 2014 ranges from 15 to 51 trillion particles, weighing between 93 and 236 thousand metric tons, which is only approximately 1% of global plastic waste estimated to enter the ocean in the year 2010. These estimates are larger than previous global estimates, but vary widely because the scarcity of data in most of the world ocean, differences in model formulations, and fundamental knowledge gaps in the sources, transformations and fates of microplastics in the ocean.
Cetina-Heredia P, Roughan M, van Sebille E, et al., 2015, Strengthened currents override the effect of warming on lobster larval dispersal and survival, GLOBAL CHANGE BIOLOGY, Vol: 21, Pages: 4377-4386, ISSN: 1354-1013
- Author Web Link
- Open Access Link
- Cite
- Citations: 56
van Sebille E, Waterman S, Barthel A, et al., 2015, Pairwise surface drifter separation in the Western Pacific Sector of the Southern Ocean, Journal of Geophysical Research: Oceans, Vol: 120, Pages: 6769-6781, ISSN: 2169-9275
The Southern Ocean plays a critical role in global climate, yet the mixing properties of the circulation in this part of the ocean remain poorly understood. Here, dispersion in the vicinity of the Southern Antarctic Circumpolar Current Front, one of the branches of the Antarctic Circumpolar Current, is studied using ten pairs of surface drifters deployed systematically across the frontal jet and its flanks. Drifter pairs were deployed with an initial separation of 13m and report their position every hour. The separation of the pairs over seven months, in terms of their Finite Scale Lyaponuv Exponents (FSLE), dispersion, and diffusivity, is characterized and related to expected behavior from Quasi-geostrophic (QG) and Surface Quasi-geostrophic (SQG) theories. The FSLE analysis reveals two submesoscale regimes, with SQG-like behavior at scales below 3.2km and mixed QG/SQG behavior at scales between 3.2km and 73km. The dispersion analysis, however, suggests QG-like behavior for the smallest scales. Both dispersion and diffusivity appear isotropic for scales up to 500km. Finally, there is no clear indication of a cross-jet variation of drifter dispersion.
Graham RM, De Boer AM, van Sebille E, et al., 2015, Inferring source regions and supply mechanisms of iron in the Southern Ocean from satellite chlorophyll data, Deep Sea Research Part I: Oceanographic Research Papers, Vol: 104, Pages: 9-25, ISSN: 0967-0637
Grist JP, Josey SA, Jacobs ZL, et al., 2015, Extreme air–sea interaction over the North Atlantic subpolar gyre during the winter of 2013–2014 and its sub-surface legacy, Climate Dynamics, Vol: 46, Pages: 4027-4045, ISSN: 1432-0894
Exceptionally low North American temperaturesand record-breaking precipitation over the BritishIsles during winter 2013–2014 were interconnectedby anomalous ocean evaporation over the North Atlanticsubpolar gyre region (SPG). This evaporation (or oceaniclatent heat release) was accompanied by strong sensibleheat loss to the atmosphere. The enhanced heat loss overthe SPG was caused by a combination of surface westerlywinds from the North American continent and northerlywinds from the Nordic Seas region that were colder,drier and stronger than normal. A distinctive feature of the air–sea exchange was that the enhanced heat loss spannedthe entire width of the SPG, with evaporation anomaliesintensifying in the east while sensible heat flux anomalieswere slightly stronger upstream in the west. The immediateimpact of the strong air–sea fluxes on the ocean–atmospheresystem included a reduction in ocean heat content ofthe SPG and a shift in basin-scale pathways of ocean heatand atmospheric freshwater transport. Atmospheric reanalysisdata and the EN4 ocean data set indicate that a longertermlegacy of the winter has been the enhanced formationof a particularly dense mode of Subpolar Mode Water(SPMW)—one of the precursors of North Atlantic DeepWater and thus an important component of the AtlanticMeridional Overturning Circulation. Using particle trajectoryanalysis, the likely dispersal of newly-formed SPMWis evaluated, providing evidence for the re-emergence ofanomalously cold SPMW in early winter 2014/2015.
Wilcox C, Van Sebille E, Hardesty BD, 2015, Threat of plastic pollution to seabirds is global, pervasive, and increasing, Proceedings of the National Academy of Sciences of the United States of America, Vol: 112, Pages: 11899-11904, ISSN: 1091-6490
Plastic pollution in the ocean is a global concern; concentrations reach 580,000 pieces per km(2) and production is increasing exponentially. Although a large number of empirical studies provide emerging evidence of impacts to wildlife, there has been little systematic assessment of risk. We performed a spatial risk analysis using predicted debris distributions and ranges for 186 seabird species to model debris exposure. We adjusted the model using published data on plastic ingestion by seabirds. Eighty of 135 (59%) species with studies reported in the literature between 1962 and 2012 had ingested plastic, and, within those studies, on average 29% of individuals had plastic in their gut. Standardizing the data for time and species, we estimate the ingestion rate would reach 90% of individuals if these studies were conducted today. Using these results from the literature, we tuned our risk model and were able to capture 71% of the variation in plastic ingestion based on a model including exposure, time, study method, and body size. We used this tuned model to predict risk across seabird species at the global scale. The highest area of expected impact occurs at the Southern Ocean boundary in the Tasman Sea between Australia and New Zealand, which contrasts with previous work identifying this area as having low anthropogenic pressures and concentrations of marine debris. We predict that plastics ingestion is increasing in seabirds, that it will reach 99% of all species by 2050, and that effective waste management can reduce this threat.
Froyland G, Horenkamp C, Rossi V, et al., 2015, Studying an Agulhas ring's long-term pathway and decay with finite-time coherent sets, Chaos, Vol: 25, ISSN: 1089-7682
Coherent sets in dynamical systems are regions in phase space that optimally “carry mass” withthem under the system’s evolution, so that these regions experience minimal leakage. The dominanttool for determining coherent sets is the transfer operator, which provides a complete description ofLagrangian mass transport. In this work, we combine existing transfer operator methods with awindowing scheme to study the spatial and temporal evolution of a so-called Agulhas ring: a largeanticyclonic mesoscale eddy playing a key role in inter-ocean exchange of climate-relevant properties.Our focus is on ring decay over time and the windowing scheme enables us to study how themost coherent region (our estimate of the ring) varies in position and size over a period of more thantwo years. We compare the eddy-like structure and its spatio-temporal changes as revealed by ourmethod and by a classical Eulerian approach.
Teske PR, Sandoval-Castillo J, van Sebille E, et al., 2015, On-shelf larval retention limits population connectivity in a coastal broadcast spawner, MARINE ECOLOGY PROGRESS SERIES, Vol: 532, Pages: 1-12, ISSN: 0171-8630
- Author Web Link
- Cite
- Citations: 35
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.