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Constantine Alexander
Where Nature runs Wild!
I love not Man the less, but Nature more.
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Acidification of seawater caused by anthropogenic carbon dioxide (CO2) is anticipated to influence the growth of dinitrogen (N2)–fixing phytoplankton, which contribute a large fraction of primary production in the tropical and subtropical ocean. We found that growth and N2-fixation of the ubiquitous cyanobacterium Trichodesmium decreased under acidified conditions, notwithstanding a beneficial effect of high CO2. Acidification resulted in low cytosolic pH and reduced N2-fixation rates despite elevated nitrogenase concentrations. Low cytosolic pH required increased proton pumping across the thylakoid membrane and elevated adenosine triphosphate production. These requirements were not satisfied under field or experimental iron-limiting conditions, which greatly amplified the negative effect of acidification. Continue reading
Posted yesterday at Constantine Alexander's Journal
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The onset of a Sahelian storm. Credit: Françoise GUICHARD/Laurent KERGOAT/CNRS Photo Library. The UK-based Centre for Ecology & Hydrology (CEH) has led an international team of scientists who reveal global warming is responsible for a tripling in the frequency of extreme West African Sahel storms observed in just the last... Continue reading
Posted 2 days ago at Constantine Alexander's Journal
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The validity of the threat status assigned to a species by the International Union for Conservation of Nature's (IUCN) Red List relies heavily on the accuracy of the geographic range size estimate for that species. Range maps used to assess threat status often contain large areas of unsuitable habitat, thereby overestimating range and underestimating threat. In this study, we assessed 18 endemic birds of the Western Ghats biodiversity hotspot to test the accuracy of the geographic range sizes used by the IUCN for their threat assessment. Using independently reviewed data from the world's largest citizen science database (eBird) within a species distribution modeling framework, our results show that: (a) geographic ranges have been vastly overestimated by IUCN for 17 of the 18 endemic bird species; (b) range maps used by IUCN contain large areas of unsuitable habitat, and (c) ranges estimated in this study suggest provisional uplisting of IUCN threat status for at least 10 of the 18 species based on area metrics used by the IUCN for threat assessment. Since global range size is an important parameter for assigning IUCN threat status, citizen science datasets, high resolution and freely available geo-referenced ecological data, and the latest species distribution modeling techniques should be used to estimate and track changes in range extent whenever possible. The methods used here to significantly revise range estimates have important conservation management implications not only for endemic birds in the Western Ghats, but for vertebrate and invertebrate taxa worldwide. Continue reading
Posted 3 days ago at Constantine Alexander's Journal
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Marine circulation and weather conditions greatly affect microplastic aggregation and movement. Microplastics, which are particles measuring less than 5 mm, are of increasing concern. They not only become more relevant as other plastic marine litter breaks down into tiny particles, they also interact with species in a range of marine... Continue reading
Posted 3 days ago at Constantine Alexander's Journal
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Healthy Elkhorn coral (Acropora palmata) near unpopulated Buck Island, US Virgin Islands. Elkhorn coral is one of many important reef-building species that create 3-D structure on the seafloor. Coral reef structure provides habitat for marine life and helps break up waves as they approach the coastline. Credit: Curt Storlazzi, USGS.... Continue reading
Posted 7 days ago at Constantine Alexander's Journal
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Nitrification is a two-step process linking the reduced and oxidized sides of the nitrogen cycle. These steps are typically tightly coupled with the primary intermediate, nitrite, rarely accumulating in coastal environments. Nitrite concentrations can exceed 10 μM during summer in estuarine waters adjacent to Sapelo Island, Georgia, U.S.A. Similar peaks at other locations have been attributed to decoupling of the two steps of nitrification by hypoxia; however, the waters around Sapelo Island are aerobic and well-mixed. Experiments examining the response to temperature shifts of a nitrifying assemblage composed of the same organisms found in the field indicate that ammonia- and nitrite-oxidation become uncoupled between 20 and 30 °C, leading to nitrite accumulation. This suggests that nitrite peaks in coastal waters might be explained by differences in the responses of ammonia- and nitrite-oxidizers to increased summer temperatures. Analysis of field data from 270 stations in 29 temperate and subtropical estuaries and lagoons show transient accumulation of nitrite driven primarily by water temperatures, rather than by hypoxia. Increased climate variability and warming coastal waters may therefore increase the frequency of these nitrite peaks, with potential ecosystem consequences that include increased N2O production, NO2– toxicity, and shifts in phytoplankton community composition. Continue reading
Posted 7 days ago at Constantine Alexander's Journal
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March for Science is a series of rallies and marches set to be held in Washington, D.C. and over 500 cities across the world on April 22, 2017. March for Science is a celebration of science. It's not only about scientists and politicians; it is about the very real role... Continue reading
Posted Apr 21, 2017 at Constantine Alexander's Journal
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The subtropical ocean gyres are recognized as great marine accumulation zones of floating plastic debris; however, the possibility of plastic accumulation at polar latitudes has been overlooked because of the lack of nearby pollution sources. In the present study, the Arctic Ocean was extensively sampled for floating plastic debris from the Tara Oceans circumpolar expedition. Although plastic debris was scarce or absent in most of the Arctic waters, it reached high concentrations (hundreds of thousands of pieces per square kilometer) in the northernmost and easternmost areas of the Greenland and Barents seas. The fragmentation and typology of the plastic suggested an abundant presence of aged debris that originated from distant sources. This hypothesis was corroborated by the relatively high ratios of marine surface plastic to local pollution sources. Surface circulation models and field data showed that the poleward branch of the Thermohaline Circulation transfers floating debris from the North Atlantic to the Greenland and Barents seas, which would be a dead end for this plastic conveyor belt. Given the limited surface transport of the plastic that accumulated here and the mechanisms acting for the downward transport, the seafloor beneath this Arctic sector is hypothesized as an important sink of plastic debris. Continue reading
Posted Apr 20, 2017 at Constantine Alexander's Journal
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Over the past 17 years, the western boundary current system of the Labrador Sea has been closely observed by maintaining the 53°N observatory (moorings and shipboard station data) measuring the top-to-bottom flow field offshore from the Labrador shelf break. Volume transports for the North Atlantic Deep Water (NADW) components were calculated using different methods, including gap filling procedures for deployment periods with suboptimal instrument coverage. On average the Deep Western Boundary Current (DWBC) carries 30.2 ± 6.6 Sv of NADW southward, which are almost equally partitioned between Labrador Sea Water (LSW, 14.9 ± 3.9 Sv) and Lower North Atlantic Deep Water (LNADW, 15.3 ± 3.8 Sv). The transport variability ranges from days to decades, with the most prominent multiyear fluctuations at interannual to near decadal time scales (±5 Sv) in the LNADW overflow water mass. These long-term fluctuations appear to be in phase with the NAO-modulated wind fluctuations. The boundary current system off Labrador occurs as a conglomerate of nearly independent components, namely, the shallow Labrador Current, the weakly sheared LSW range, and the deep baroclinic, bottom-intensified current core of the LNADW, all of which are part of the cyclonic Labrador Sea circulation. This structure is relatively stable over time, and the 120 km wide boundary current is constrained seaward by a weak counterflow which reduces the deep water export by 10–15%. Continue reading
Posted Apr 16, 2017 at Constantine Alexander's Journal
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Migratory animals are threatened by human-induced global change. However, little is known about how stopover habitat, essential for refuelling during migration, affects the population dynamics of migratory species. Using 20 years of continent-wide citizen science data, we assess population trends of ten shorebird taxa that refuel on Yellow Sea tidal mudflats, a threatened ecosystem that has shrunk by >65% in recent decades. Seven of the taxa declined at rates of up to 8% per year. Taxa with the greatest reliance on the Yellow Sea as a stopover site showed the greatest declines, whereas those that stop primarily in other regions had slowly declining or stable populations. Decline rate was unaffected by shared evolutionary history among taxa and was not predicted by migration distance, breeding range size, non-breeding location, generation time or body size. These results suggest that changes in stopover habitat can severely limit migratory populations. Continue reading
Posted Apr 15, 2017 at Constantine Alexander's Journal
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Newport, Southern California. A new study assessing the underwater soundscape off Southern California found that blue, fin and humpback whales experience a range of acoustic environments, including noise from shipping traffic as well as quieter areas within a national marine sanctuary. The study appeared in a special issue of Endangered... Continue reading
Posted Apr 12, 2017 at Constantine Alexander's Journal
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SECORE International, the California Academy of Sciences and The Nature Conservancy join forces to implement larger-scale coral restoration. Healthy Caribbean reef site, Eastpoint, Curacao. Photo by Paul Selvaggio. With the Global Coral Restoration Project, SECORE International, the California Academy of Sciences and The Nature Conservancy seal their commitment to help... Continue reading
Posted Apr 12, 2017 at Constantine Alexander's Journal
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The European Commission and the European Investment Bank (EIB) have announced the first loan agreement backed by the Natural Capital Financing Facility. The EUR 6 million loan agreement with Rewilding Europe Capital is expected to provide support for over 30 nature-focused businesses across Europe. Rewilding Europe Capital is Europe's first... Continue reading
Posted Apr 11, 2017 at Constantine Alexander's Journal
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Logging in tropical forests causes, among other impacts, the accumulation of organic debris on many beaches after it is carried to the coast by rivers and concentrated by oceanographic processes. Such accumulated beach organic material (ABOM) has the potential to exert important negative effects on the reproductive success of marine turtles. Females must be able to exit the ocean and cross sandy beaches to nest and, as no parental care is provided, hatchlings must cross the beach to reach the sea following emergence from the nest. We investigated how ABOM affects nest site selection and hatchling dispersal at a globally important rookery for leatherback turtles Dermochelys coriacea in Colombia. Detailed surveys were combined with field experiments in which the amount of ABOM was manipulated. Areas with higher ABOM had a similar rate of nesting, but females spent significantly more time in nest camouflage, suffered external lesions and nested closer to the shoreline, increasing the risk of egg mortality caused by flooding and erosion. When ABOM was manually removed from several beach sectors, nest site selection moved towards areas with less risk of flooding or tidal erosion. In nesting seasons with higher ABOM, a lower rate of female recapture was experienced, suggesting a greater dispersion of nests, possibly emigration. ABOM represents a barrier for many hatchlings, causing them to spend significantly more time reaching the sea, thereby increasing their energy output and their risk of predation or desiccation. Continue reading
Posted Apr 11, 2017 at Constantine Alexander's Journal
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Ocean acidification (OA) describes a change in the ocean's carbonate chemistry. Whereas its chemical processes are largely understood, the biological and socioeconomic consequences particularly in relation to fisheries are less known. Norway is a major fishing nation worldwide and is potentially affected by OA. To improve the understanding of the socioeconomic consequences of OA, we conducted a risk assessment among the Norwegian counties using a modified version of a risk assessment framework introduced in the Intergovernmental Panel on Climate Change's “Special Report: Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation,” which considers risk to be the sum of hazard, exposure, and vulnerability. Our results show that about 13 of 19 counties are likely to experience moderate to high risk from OA. We highlight that the success of integrated risk assessments highly depends on the availability of detailed environmental, economic, and societal data. In the case of Norway, modeling data regarding the progress of OA, improved information on potential biological impacts on a larger number of species, and statistical data on social variables are required. We conclude that although still in its infancy, integrated risk assessments are important prerequisites for any form of interdisciplinary research on OA and the development of successful response strategies. Integr Environ Assess Manag 2016;00:000–000. Continue reading
Posted Apr 10, 2017 at Constantine Alexander's Journal
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In long-lived monogamous animals, pair bond strength and durability are usually associated with higher fitness. However, whether pairs maximise fitness during the non-breeding season by maintaining contact during the winter or, instead, prioritise individual condition is unclear. Using geolocators recording spatial (light) and behavioural (immersion) data, we tracked pairs of the long-term monogamous Atlantic puffin Fratercula arctica during the non-breeding season to determine whether and how migratory strategies were related to future pair breeding performance and whether within-pair similarity in migratory movements or individual behaviour best predicted future fitness. While pair members migrated separately, their routes were similar in the first part of the non-breeding season but diverged later on; nonetheless, pairs showed synchrony in their return to the breeding colony in spring. Pairs following more similar routes bred earlier and had a higher breeding success the following spring. However, female (but not male) winter foraging effort was also a strong predictor of subsequent fitness, being associated with future timing of breeding and reproductive success. Overall, females had higher daily energy expenditure than males, especially in the late winter when their route diverged from their partner’s and they foraged more than males. Our study reveals that female winter foraging, probably linked to pre-breeding condition, may be more critical for fitness than maintaining the pair bond outside of the breeding season. However, even without contact between mates, pairs can benefit from following similar migration routes and synchronise their returns, but the mechanisms linking these processes remain unclear. Continue reading
Posted Apr 8, 2017 at Constantine Alexander's Journal
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Regional, multi-actor environmental collaborations bring together diverse parties to achieve environmental protection and stewardship outcomes. Involving a range of participants helps involve alternative forms of knowledge, expertise, and perspectives; it may also present greater challenges in reaching agreements, particularly when both Indigenous and non-Indigenous parties are involved. The authors conduct a cross-case study of 39 regional partnerships involving Indigenous nations from the Great Lakes basin of North America with the aim of determining the factors that enable Indigenous partners to remain engaged in multi-actor collaborations. Six characteristics influenced Indigenous nations’ willingness to remain engaged: respect for Indigenous knowledges, control of knowledge mobilization, intergenerational involvement, self-determination, continuous cross-cultural education, and early involvement. Being attentive of these factors can help partnerships achieve their environmental goals by keeping important partners at the table. Continue reading
Posted Apr 6, 2017 at Constantine Alexander's Journal
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Marine turtles exhibit temperature-dependent sex determination (TSD). During critical periods of embryonic development, the nest's thermal environment directs whether an embryo will develop as a male or female. At warmer sand temperatures, nests tend to produce female-biased sex ratios. The rapid increase of global temperature highlights the need for a clear assessment of its effects on sea turtle sex ratios. However, estimating hatchling sex ratios at rookeries remains imprecise due to the lack of sexual dimorphism in young marine turtles. We rely mainly upon laparoscopic procedures to verify hatchling sex; however, in some species, morphological sex can be ambiguous even at the histological level. Recent studies using immunohistochemical (IHC) techniques identified that embryonic snapping turtle (Chelydra serpentina) ovaries overexpressed a particular cold-induced RNA-binding protein in comparison to testes. This feature allows the identification of females vs. males. We modified this technique to successfully identify the sexes of loggerhead sea turtle (Caretta caretta) hatchlings, and independently confirmed the results by standard histological and laparoscopic methods that reliably identify sex in this species. We next tested the CIRBP IHC method on gonad samples from leatherback turtles (Dermochelys coriacea). Leatherbacks display delayed gonad differentiation, when compared to other sea turtles, making hatchling gonads difficult to sex using standard H&E stain histology. The IHC approach was successful in both C. caretta and D. coriacea samples, offering a much-needed tool to establish baseline hatchling sex ratios, particularly for assessing impacts of climate change effects on leatherback turtle hatchlings and sea turtle demographics. Anat Rec, 2017. Continue reading
Posted Apr 2, 2017 at Constantine Alexander's Journal
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Museum collections offer scientists ocean health baselines long before human records. The Hawaiian petrel flies great distances over the north Pacific Ocean to feed, and all the while nitrogen from its diet is slowly integrated into its bone collagen. The birds come to land only to raise their young in... Continue reading
Posted Mar 29, 2017 at Constantine Alexander's Journal
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A 2 °C increase in global temperature above pre-industrial levels is considered a reasonable target for avoiding the most devastating impacts of anthropogenic climate change. In June 2015, sea surface temperature (SST) of the South China Sea (SCS) increased by 2 °C in response to the developing Pacific El Niño. On its own, this moderate, short-lived warming was unlikely to cause widespread damage to coral reefs in the region, and the coral reef “Bleaching Alert” alarm was not raised. However, on Dongsha Atoll, in the northern SCS, unusually weak winds created low-flow conditions that amplified the 2 °C basin-scale anomaly. Water temperatures on the reef flat, normally indistinguishable from open-ocean SST, exceeded 6 °C above normal summertime levels. Mass coral bleaching quickly ensued, killing 40% of the resident coral community in an event unprecedented in at least the past 40 years. Our findings highlight the risks of 2 °C ocean warming to coral reef ecosystems when global and local processes align to drive intense heating, with devastating consequences. Continue reading
Posted Mar 24, 2017 at Constantine Alexander's Journal
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A view from the study site, UNESCO World Heritage-listed Lord Howe Island, Australia. Credit: Tane Sinclair-Taylor The discovery of a new species of hard coral, found on Lord Howe Island, suggests that the fauna of this isolated location in the Tasman Sea off south eastern Australia is even more distinct... Continue reading
Posted Mar 23, 2017 at Constantine Alexander's Journal
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Marine protected areas (MPAs) are increasingly being used globally to conserve marine resources. However, whether many MPAs are being effectively and equitably managed, and how MPA management influences substantive outcomes remain unknown. We developed a global database of management and fish population data (433 and 218 MPAs, respectively) to assess: MPA management processes; the effects of MPAs on fish populations; and relationships between management processes and ecological effects. Here we report that many MPAs failed to meet thresholds for effective and equitable management processes, with widespread shortfalls in staff and financial resources. Although 71% of MPAs positively influenced fish populations, these conservation impacts were highly variable. Staff and budget capacity were the strongest predictors of conservation impact: MPAs with adequate staff capacity had ecological effects 2.9 times greater than MPAs with inadequate capacity. Thus, continued global expansion of MPAs without adequate investment in human and financial capacity is likely to lead to sub-optimal conservation outcomes. Continue reading
Posted Mar 23, 2017 at Constantine Alexander's Journal
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Factors that affect the removal of organic carbon by heterotrophic bacterioplankton can impact the rate and magnitude of organic carbon loss in the ocean through the conversion of a portion of consumed organic carbon to CO2. Through enhanced rates of consumption, surface bacterioplankton communities can also reduce the amount of dissolved organic carbon (DOC) available for export from the surface ocean. The present study investigated the direct effects of elevated pCO2 on bacterioplankton removal of several forms of DOC ranging from glucose to complex phytoplankton exudate and lysate, and naturally occurring DOC. Elevated pCO2 (1000–1500 ppm) enhanced both the rate and magnitude of organic carbon removal by bacterioplankton communities compared to low (pre-industrial and ambient) pCO2 (250 –~400 ppm). The increased removal was largely due to enhanced respiration, rather than enhanced production of bacterioplankton biomass. The results suggest that elevated pCO2 can increase DOC consumption and decrease bacterioplankton growth efficiency, ultimately decreasing the amount of DOC available for vertical export and increasing the production of CO2 in the surface ocean. Continue reading
Posted Mar 20, 2017 at Constantine Alexander's Journal
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The San Joaquin kit fox (Vulpes macrotis mutica) is a federally endangered small carnivore whose distribution is limited to the San Joaquin Valley in central California. Population decline is due to profound habitat loss, and conservation of all remaining populations is critical. A robust urban population occurs in the city of Bakersfield. In spring of 2013, putative cases of mange were reported in this population. Mites from affected animals were confirmed to be Sarcoptes scabiei morphologically and by DNA sequencing. By the end of 2014, 15 cases of kit foxes with mange had been confirmed. As with other species, sarcoptic mange in kit foxes is characterized by intense pruritus and dermatitis, caused by mites burrowing into the epidermal layers, as well as alopecia, hyperkeratosis, and encrustations, secondary bacterial infections, and finally extreme morbidity and death. Of the 15 cases, six foxes were found dead, six were captured but died during attempted rehabilitation, and three were successfully treated. We have no evidence that untreated kit foxes can recover from mange. Sarcoptic mange constitutes a significant threat to the Bakersfield kit fox population and could pose an even greater threat to this imperiled species if it spreads to populations in nearby natural lands. Continue reading
Posted Mar 17, 2017 at Constantine Alexander's Journal
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Marine phytoplankton inhabit a dynamic environment where turbulence, together with nutrient and light availability, shapes species fitness, succession and selection1, 2. Many species of phytoplankton are motile and undertake diel vertical migrations to gain access to nutrient-rich deeper layers at night and well-lit surface waters during the day3, 4. Disruption of this migratory strategy by turbulence is considered to be an important cause of the succession between motile and non-motile species when conditions turn turbulent1, 5, 6. However, this classical view neglects the possibility that motile species may actively respond to turbulent cues to avoid layers of strong turbulence7. Here we report that phytoplankton, including raphidophytes and dinoflagellates, can actively diversify their migratory strategy in response to hydrodynamic cues characteristic of overturning by Kolmogorov-scale eddies. Continue reading
Posted Mar 16, 2017 at Constantine Alexander's Journal