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Constantine Alexander
Where Nature runs Wild!
I love not Man the less, but Nature more.
Recent Activity
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Human activities drive environmental changes at scales that could potentially cause ecosystem collapses in the marine environment. We combined information on marine biodiversity with spatial assessments of the impacts of climate change to identify the key areas to prioritize for the conservation of global marine biodiversity. This process identified six marine regions of exceptional biodiversity based on global distributions of 1729 species of fish, 124 marine mammals, and 330 seabirds. Overall, these hot spots of marine biodiversity coincide with areas most severely affected by global warming. In particular, these marine biodiversity hot spots have undergone local to regional increasing water temperatures, slowing current circulation, and decreasing primary productivity. Furthermore, when we overlapped these hot spots with available industrial fishery data, albeit coarser than our estimates of climate impacts, they suggest a worrying coincidence whereby the world’s richest areas for marine biodiversity are also those areas mostly affected by both climate change and industrial fishing. In light of these findings, we offer an adaptable framework for determining local to regional areas of special concern for the conservation of marine biodiversity. This has exposed the need for finer-scaled fishery data to assist in the management of global fisheries if the accumulative, but potentially preventable, effect of fishing on climate change impacts is to be minimized within areas prioritized for marine biodiversity conservation. Continue reading
Posted 4 hours ago at Constantine Alexander's Journal
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Healthy ocean ecosystems are needed to sustain people and livelihoods and to achieve the United Nations Sustainable Development Goals. Using the ocean sustainably requires overcoming many formidable challenges: overfishing, climate change, ocean acidification, and pollution. Despite gloomy forecasts, there is reason for hope. New tools, practices, and partnerships are beginning to transform local fisheries, biodiversity conservation, and marine spatial planning. The challenge is to bring them to a global scale. We dissect recent successes using a complex adaptive-systems (CAS) framework, which acknowledges the interconnectedness of social and ecological systems. Understanding how policies and practices change the feedbacks in CASs by altering the behavior of different system components is critical for building robust, sustainable states with favorable emergent properties. Our review reveals that altering incentives—either economic or social norms, or both—can achieve positive outcomes. For example, introduction of well-designed rights-based or secure-access fisheries and ecosystem service accounting shifts economic incentives to align conservation and economic benefits. Modifying social norms can create conditions that incentivize a company, country, or individual to fish sustainably, curb illegal fishing, or create large marine reserves as steps to enhance reputation or self-image. In each example, the feedbacks between individual actors and emergent system properties were altered, triggering a transition from a vicious to a virtuous cycle. We suggest that evaluating conservation tools by their ability to align incentives of actors with broader goals of sustainability is an underused approach that can provide a pathway toward scaling sustainability successes. In short, getting incentives right matters. Continue reading
Posted yesterday at Constantine Alexander's Journal
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Climate change is predicted to have widespread impacts on marine ecosystems and the resources within them. As levels of carbon dioxide and other greenhouse gases in the atmosphere increase, models suggest increased sea surface temperatures, changes in the patterns of ocean currents, rising sea levels, and altered habitats for marine fish populations. At the same time, new bio-economic approaches are providing insight into the historical, current, and possible future status of fisheries around the world. Combining these fishery models with climate change predictions provides an improved understanding of the production potential of fisheries in an altered climate, and allows the science to be communicated in relevant and important ways to stakeholders and policymakers. Continue reading
Posted 2 days ago at Constantine Alexander's Journal
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Ocean models predict a decline in the dissolved oxygen inventory of the global ocean of one to seven per cent by the year 2100, caused by a combination of a warming-induced decline in oxygen solubility and reduced ventilation of the deep ocean1, 2. It is thought that such a decline in the oceanic oxygen content could affect ocean nutrient cycles and the marine habitat, with potentially detrimental consequences for fisheries and coastal economies3, 4, 5, 6. Regional observational data indicate a continuous decrease in oceanic dissolved oxygen concentrations in most regions of the global ocean1, 7, 8, 9, 10, with an increase reported in a few limited areas, varying by study1, 10. Prior work attempting to resolve variations in dissolved oxygen concentrations at the global scale reported a global oxygen loss of 550 ± 130 teramoles (1012 mol) per decade between 100 and 1,000 metres depth based on a comparison of data from the 1970s and 1990s10. Here we provide a quantitative assessment of the entire ocean oxygen inventory by analysing dissolved oxygen and supporting data for the complete oceanic water column over the past 50 years. We find that the global oceanic oxygen content of 227.4 ± 1.1 petamoles (1015 mol) has decreased by more than two per cent (4.8 ± 2.1 petamoles) since 1960, with large variations in oxygen loss in different ocean basins and at different depths. We suggest that changes in the upper water column are mostly due to a warming-induced decrease in solubility and biological consumption. Changes in the deeper ocean may have their origin in basin-scale multi-decadal variability, oceanic overturning slow-down and a potential increase in biological consumption Continue reading
Posted Feb 15, 2017 at Constantine Alexander's Journal
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We use a new, well-calibrated 500-year paleorecord off southern California to determine collapse frequency, cross-correlation, persistence and return times of exploited forage fish populations. The paleorecord shows that “collapse” (defined as <10% of the mean peak biomass) is a normal state repeatedly experienced by northern anchovy, Pacific hake and Pacific sardine which were collapsed 29 − 40% of the time, prior to commercial fishing exploitation. Mean (±SD) persistence of “fishable biomass” (defined as 1/3 mean peak biomass from the paleorecord) was 19 ± 18, 15 ± 17, and 12 ± 7 years for anchovy, hake, and sardine. Mean return times to the same biomass was 8 years for anchovy, but 22 years for sardine and hake. Further, we find that sardine and anchovy are positively correlated over 400 years, consistent with coherent declines of both species off California. Persistence and return times, combined with positive sardine-anchovy correlation indicates that on average 1 − 2 decades of fishable biomass will be followed by 1 − 2 decades of low forage. Forage populations are resilient on the 500-year time scale, but their collapse and recovery cycle (based on the paleorecord) is suited to alternating periods of high fishing mortality and periods of little or no fishing. Continue reading
Posted Feb 15, 2017 at Constantine Alexander's Journal
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Scientists and government officials met at the United Nations yesterday to consider possible solutions to a global problem: how to protect whale species in their most important marine habitats that overlap with shipping lanes vital to the economies of many of the world's nations. The event titled "At The Crossroads:... Continue reading
Posted Feb 15, 2017 at Constantine Alexander's Journal
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Scientists from the University of East Anglia and Ocean University China have discovered that tiny marine bacteria can synthesise one of the Earth's most abundant sulfur molecules, which affects atmospheric chemistry and potentially climate. This molecule, dimethylsulfoniopropionate (DMSP) is an important nutrient for marine microorganisms and is the major precursor... Continue reading
Posted Feb 14, 2017 at Constantine Alexander's Journal
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UM Rosenstiel School researchers develop model to simulate track of floating debris. A new study on how ocean currents transport floating marine debris is helping to explain how garbage patches form in the world's oceans. Researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science and... Continue reading
Posted Feb 14, 2017 at Constantine Alexander's Journal
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The ocean is the largest sink for anthropogenic carbon dioxide (CO2), having absorbed roughly 40 per cent of CO2 emissions since the beginning of the industrial era1, 2. Recent data show that oceanic CO2 uptake rates have been growing over the past decade3, 4, 5, 6, 7, reversing a trend of stagnant or declining carbon uptake during the 1990s8, 9, 10, 11, 12, 13, 14. Here we show that ocean circulation variability is the primary driver of these changes in oceanic CO2 uptake over the past several decades. We use a global inverse model to quantify the mean ocean circulation during the 1980s, 1990s and 2000s, and then estimate the impact of decadal circulation changes on the oceanic CO2 sink using a carbon cycling model. We find that during the 1990s an enhanced upper-ocean overturning circulation drove increased outgassing of natural CO2, thus weakening the global CO2 sink. This trend reversed during the 2000s as the overturning circulation weakened. Continued weakening of the upper-ocean overturning is likely to strengthen the CO2 sink in the near future by trapping natural CO2 in the deep ocean, but ultimately may limit oceanic uptake of anthropogenic CO2. Continue reading
Posted Feb 13, 2017 at Constantine Alexander's Journal
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Human activities are creating conservation challenges for cetaceans. Spatially explicit risk assessments can be used to address these challenges, but require species distribution data, which are limited for many cetacean species. This study explores methods to overcome this limitation. Blue whales (Balaenoptera musculus) are used as a case study because they are an example of a species that have well-defined habitat and are subject to anthropogenic threats. Continue reading
Posted Feb 9, 2017 at Constantine Alexander's Journal
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On timescales significantly greater than 105 years, atmospheric pCO2 is controlled by the rate of mantle outgassing relative to the set-point of the silicate weathering feedback. The weathering set-point has been shown to depend on the distribution and characteristics of rocks exposed at the Earth’s surface, vegetation types and topography. Here we argue that large-scale climate impacts caused by changes in ocean circulation can also modify the weathering set-point and show evidence suggesting that this played a role in the establishment of the Antarctic ice sheet at the Eocene–Oligocene boundary. In our simulations, tectonic deepening of the Drake Passage causes freshening and stratification of the Southern Ocean, strengthening the Atlantic meridional overturning circulation and consequently raising temperatures and intensifying rainfall over land. These simulated changes are consistent with late Eocene tectonic reconstructions that show Drake Passage deepening, and with sediment records that reveal Southern Ocean stratification, the emergence of North Atlantic Deep Water, and a hemispherically asymmetric temperature change. These factors would have driven intensified silicate weathering and can thereby explain the drawdown of carbon dioxide that has been linked with Antarctic ice sheet growth. We suggest that this mechanism illustrates another way in which ocean–atmosphere climate dynamics can introduce nonlinear threshold behaviour through interaction with the geologic carbon cycle. Continue reading
Posted Feb 6, 2017 at Constantine Alexander's Journal
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Credit: Griffith University. The Griffith University study, conducted in collaboration with national and international experts in reef and chemical ecology, showed that if the world continues with 'business as usual' CO2 emissions important reef building corals will suffer significantly by 2050 and die off by 2100. Associate Professor Guillermo Diaz-Pulido,... Continue reading
Posted Feb 4, 2017 at Constantine Alexander's Journal
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Both natural and human-related foraging strategies by the common bottlenose dolphin (Tursiops truncatus) have resulted in social segregation in several areas of the world. Bottlenose dolphins near Savannah, Georgia beg at an unprecedented rate and also forage behind commercial shrimp trawlers, providing an opportunity to study the social ramifications of two human-related foraging behaviors within the same group of animals. Dolphins were photo-identified via surveys conducted throughout estuarine waterways around Savannah in the summers of 2009–2011. Mean half-weight indices (HWI) were calculated for each foraging class, and community division by modularity was used to cluster animals based on association indices. Pairs of trawler dolphins had a higher mean HWI (0.20 ± 0.07) than pairs of non-trawler dolphins (0.04 ± 0.02) or mixed pairs (0.02 ± 0.02). In contrast, pairs of beggars, non-beggars, and mixed pairs all had similar means, with HWI between 0.05–0.07. Community division by modularity produced a useful division (0.307) with 6 clusters. Clusters were predominately divided according to trawler status; however, beggars and non-beggars were mixed throughout clusters. Both the mean HWI and social clusters revealed that the social structure of common bottlenose dolphins near Savannah, Georgia was differentiated based on trawler status but not beg status. This finding may indicate that foraging in association with trawlers is a socially learned behavior, while the mechanisms for the propagation of begging are less clear. This study highlights the importance of taking into account the social parameters of a foraging behavior, such as how group size or competition for resources may affect how the behavior spreads. The positive or negative ramifications of homophily may influence whether the behaviors are exhibited by individuals within the same social clusters and should be considered in future studies examining social relationships and foraging behaviors. Continue reading
Posted Feb 4, 2017 at Constantine Alexander's Journal
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Southern Ocean abyssal waters, in contact with the atmosphere at their formation sites around Antarctica, not only bring signals of a changing climate with them as they move around the globe but also contribute to that change through heat uptake and sea level rise. A repeat hydrographic line in the Indian sector of the Southern Ocean, occupied three times in the last two decades (1994, 2007, and, most recently, 2016), reveals that Antarctic Bottom Water (AABW) continues to become fresher (0.004 ± 0.001 kg/g decade−1), warmer (0.06° ± 0.01°C decade−1), and less dense (0.011 ± 0.002 kg/m3 decade−1). The most recent observations in the Australian-Antarctic Basin show a particularly striking acceleration in AABW freshening between 2007 and 2016 (0.008 ± 0.001 kg/g decade−1) compared to the 0.002 ± 0.001 kg/g decade−1 seen between 1994 and 2007. Freshening is, in part, responsible for an overall shift of the mean temperature-salinity curve toward lower densities. The marked freshening may be linked to an abrupt iceberg-glacier collision and calving event that occurred in 2010 on the George V/Adélie Land Coast, the main source region of bottom waters for the Australian-Antarctic Basin. Because AABW is a key component of the global overturning circulation, the persistent decrease in bottom water density and the associated increase in steric height that result from continued warming and freshening have important consequences beyond the Southern Indian Ocean. Continue reading
Posted Feb 1, 2017 at Constantine Alexander's Journal
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An international team of researchers has discovered why fresh water, melted from Antarctic ice sheets, is often detected below the surface of the ocean, rather than rising to the top above denser seawater. The research, led by the University of Southampton, is published this week in the journal Nature in... Continue reading
Posted Feb 1, 2017 at Constantine Alexander's Journal
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With radar interferometry, the next-generation Surface Water and Ocean Topography satellite mission will improve the measured sea surface height resolution down to 15 km, allowing us to investigate for the first time the global upper ocean variability at the submesoscale range. Here, by analysing shipboard Acoustic Doppler Current Profiler measurements along 137°E in the northwest Pacific of 2004–2016, we show that the observed upper ocean velocities are comprised of balanced geostrophic flows and unbalanced internal waves. The transition length scale, Lt, separating these two motions, is found to depend strongly on the energy level of local mesoscale eddy variability. In the eddy-abundant western boundary current region of Kuroshio, Lt can be shorter than 15 km, whereas Lt exceeds 200 km along the path of relatively stable North Equatorial Current. Judicious separation between the geostrophic and internal wave signals represents both a challenge and an opportunity for the Surface Water and Ocean Topography mission. Continue reading
Posted Feb 1, 2017 at Constantine Alexander's Journal
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Lake Kivu. New research shows there may have been more nitrogen in the ocean between one and two billion years ago than previously thought, allowing marine organisms to proliferate at a time when multi-cellularity and eukaryotic life first emerged. UBC researchers travelled to Lake Kivu in the Democratic Republic of... Continue reading
Posted Feb 1, 2017 at Constantine Alexander's Journal
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Natural World Heritage Sites (NWHS), via their formal designation through the United Nations, are globally recognized as containing some of the Earth's most valuable natural assets. Understanding changes in their ecological condition is essential for their ongoing preservation. Here we use two newly available globally consistent data sets that assess changes in human pressure (Human Footprint) and forest loss (Global Forest Watch) over time across the global network of terrestrial NWHS. We show that human pressure has increased in 63% of NWHS since 1993 and across all continents except Europe. The largest increases in pressure occurred in Asian NWHS, many of which were substantially damaged such as ManasWildlifeSanctuary. Forest loss occurred in 91% of NWHS that contain forests, with a global mean loss of 1.5% per site since 2000, with the largest areas of forest lost occurring in the Americas. For example WoodBuffaloNationalPark and RíoPlátanoBiosphereReserve lost 2581 km2 (11.7%) and 365 km2 (8.5%) of their forest respectively. We found that on average human pressure increased faster and more forest loss occurred in areas surrounding NWHS, suggesting they are becoming increasingly isolated and are under threat from processes occurring outside their borders. While some NWHS such as the SinharajaForestReserve and ManaPoolsNationalPark showed minimal change in forest loss or human pressure, they are in the minority and our results also suggest many NWHS are rapidly deteriorating and are more threatened than previously thought. Continue reading
Posted Jan 31, 2017 at Constantine Alexander's Journal
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Demographic connectivity is vital to sustaining metapopulations yet often changes dramatically through time due to variation in the production and dispersal of offspring. However, the relative importance of variation in fecundity and dispersal in determining the connectivity and dynamics of metapopulations is poorly understood due to the paucity of comprehensive spatio-temporal data on these processes for most species. We quantified connectivity in metapopulations of a marine foundation species (giant kelp Macrocystis pyrifera) across 11 years and approximately 900 km of coastline by estimating population fecundity with satellite imagery and propagule dispersal using a high-resolution ocean circulation model. By varying the temporal complexity of different connectivity measures and comparing their ability to explain observed extinction–colonization dynamics, we discovered that fluctuations in population fecundity, rather than fluctuations in dispersal, are the dominant driver of variation in connectivity and contribute substantially to metapopulation recovery and persistence. Thus, for species with high variability in reproductive output and modest variability in dispersal (most plants, many animals), connectivity measures ignoring fluctuations in fecundity may overestimate connectivity and likelihoods of persistence, limiting their value for understanding and conserving metapopulations. However, we demonstrate how connectivity measures can be simplified while retaining utility, validating a practical solution for data-limited systems. Continue reading
Posted Jan 31, 2017 at Constantine Alexander's Journal
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Seabird aggregations at sea have been shown to be associated with concentrations of prey. Previous research identified Central California as a highly used foraging area for seabirds, with locally breeding seabirds foraging close to their colonies on Southeast Farallon Island. Herein, we focus on nonresident (i.e. non-locally breeding) seabird species off of Central California. We hypothesized that high-use foraging areas for nonresident seabirds would be influenced by oceanographic and bathymetric factors and that spatial and temporal distributions would be similar within planktivorous and generalist foraging guilds but would differ between them. With data collected by the Applied California Current Ecosystem Studies (ACCESS) partnership during cruises between April and October from 2004–2013, we developed generalized linear models to identify high-use foraging areas for each of six nonresident seabird species. The four generalist species are Phoebastria nigripes (black-footed albatross), Ardenna griseus (sooty shearwater), Ardenna creatopus (pink-footed shearwater), and Fulmarus glacialis (northern fulmar). The two planktivorous species are Phalaropus lobatus (red-necked phalarope) and Phalaropus fulicarius (red phalarope). Sea surface temperature was significant for generalist species and sea surface salinity was important for planktivorous species. The distance to the 200-m isobath was significant in five of six models, Pacific Decadal Oscillation with a 3-month lag in four models, and sea surface fluorescence, the distance to Cordell Bank, and depth in three models. We did not find statistically significant differences between distributions of individual seabird species within a foraging guild or between guilds, with the exception of the sooty shearwater. Model results for a multi-use seabird foraging area highlighted the continental shelf break, particularly within the vicinity of Cordell Bank, as the highest use areas as did Marxan prioritization. Our research methods can be implemented elsewhere to identify critical habitat that needs protection as human development pressures continue to expand to the ocean. Continue reading
Posted Jan 30, 2017 at Constantine Alexander's Journal
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In two sea voyages throughout the Mediterranean (2011 and 2013) that repeated the historical travels of Archduke Ludwig Salvator of Austria (1847–1915), 71 samples of floating plastic debris were obtained with a Manta trawl. Floating plastic was observed in all the sampled sites, with an average weight concentration of 579.3 g dw km−2 (maximum value of 9298.2 g dw km−2) and an average particle concentration of 147,500 items km−2 (the maximum concentration was 1,164,403 items km−2). The plastic size distribution showed microplastics (<5 mm) in all the samples. The most abundant particles had a surface area of approximately 1 mm2 (the mesh size was 333 μm). The general estimate obtained was a total value of 1455 tons dw of floating plastic in the entire Mediterranean region, with various potential spatial accumulation areas. Continue reading
Posted Jan 21, 2017 at Constantine Alexander's Journal
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Nature is increasingly threatened by rapid infrastructure expansion. For the first time, to our knowledge, we quantify the high pervasiveness of transportation infrastructure in all European countries. Unfortunately, spatial definition of the areas ecologically affected by infrastructure at large scales is complicated. Thus, we present a method for assessing the spatial extent of the impacts on birds and mammals at regional and national scales. As an illustration, its application to Spain shows that most of the country is affected, predicting moderate and severe declines for birds and mammals, respectively. The lack of areas that could be used as controls implies that scientists may no longer be able to measure the magnitude of road effects on wide-ranging mammals in most of Europe. Continue reading
Posted Jan 21, 2017 at Constantine Alexander's Journal
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New research shows limpets are construction workers of the seashore. Common or European Limpet in litoral of the Finistére, near Porspoder, in the region that was affected by the Amoco Cadiz tanker disaster in 1978. Photo by Stefan Thiesen (CC 3.0). New research from a beach-roaming biomechanics engineer paints a... Continue reading
Posted Jan 21, 2017 at Constantine Alexander's Journal
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Localized data helps economies and infrastructure adapt. Florida Sea Lever Rise. New U.S. regional sea level scenarios developed by NOAA and its partners will give coastal communities better, more localized data to help them plan for and adapt to the risk of rising sea levels to their economies and infrastructure.... Continue reading
Posted Jan 20, 2017 at Constantine Alexander's Journal
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To evaluate policies to reduce greenhouse-gas emissions, economic models require estimates of how future climate change will affect well-being. So far, nearly all estimates of the economic impacts of future warming have been developed by combining estimates of impacts in individual sectors of the economy1, 2. Recent work has used variation in warming over time and space to produce top-down estimates of how past climate and weather shocks have affected economic output3, 4, 5. Here we propose a statistical framework for converting these top-down estimates of past economic costs of regional warming into projections of the economic cost of future global warming. Combining the latest physical climate models, socioeconomic projections, and economic estimates of past impacts, we find that future warming could raise the expected rate of economic growth in richer countries, reduce the expected rate of economic growth in poorer countries, and increase the variability of growth by increasing the climate’s variability. This study suggests we should rethink the focus on global impacts and the use of deterministic frameworks for modelling impacts and policy. Continue reading
Posted Jan 18, 2017 at Constantine Alexander's Journal