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ArticleSegmentation and crustal structure of the western Mid-Atlantic Ridge flank, 25°25′–27°10′N and 0–29 m.y.(American Geophysical Union, 1997-05-10) Tucholke, Brian E. ; Lin, Jian ; Kleinrock, Martin C. ; Tivey, Maurice A. ; Reed, Thomas B. ; Goff, John A. ; Jaroslow, Gary E.We conducted a detailed geological-geophysical survey of the west flank of the Mid-Atlantic Ridge between 25°25′N and 27°10′N and from the ridge axis out to 29 Ma crust, acquiring Hydrosweep multibeam bathymetry, HAWAII MR1 sidescan-sonar imagery, gravity, magnetics, and single-channel seismic reflection profiles. The survey covered all or part of nine spreading segments bounded by mostly nontransform, right-stepping discontinuities which are subparallel to flow lines but which migrated independently of one another. Some discontinuities alternated between small right- and left-stepping offsets or exhibited zero offset for up to 3–4 m.y. Despite these changes, the spreading segments have been long-lived and extend 20 m.y. or more across isochrons. A large shift (∼9°) in relative plate motion about 24–22 Ma caused significant changes in segmentation pattern. The nature of this plate-boundary response, together with the persistence of segments through periods of zero offset at their bounding discontinuities, suggest that the position and longevity of segments are controlled primarily by the subaxial position of buoyant mantle diapirs or focused zones of rising melt. Within segments, there are distinct differences in seafloor depth, morphology, residual mantle Bouguer gravity anomaly, and apparent crustal thickness between inside-corner and outside-corner crust. This demands fundamentally asymmetric crustal accretion and extension across the ridge axis, which we attribute to low-angle, detachment faulting near segment ends. Cyclic variations in residual gravity over the crossisochron run of segments also suggest crustal-thickness changes of at least 1–2 km every 2–3 m.y. These are interpreted to be caused by episodes of magmatic versus relatively amagmatic extension, controlled by retention and quasiperiodic release of melt from the upwelling mantle. Detachment faulting appears to be especially effective in exhuming lower crust to upper mantle at inside corners during relatively amagmatic episodes, creating crustal domes analogous to “turtleback” metamorphic core complexes that are formed by low-angle, detachment faulting in subaerial extensional environments.
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ArticleRecord of seamount production and off-axis evolution in the western North Atlantic Ocean, 25°25′–27°10′N(American Geophysical Union, 2000-02-10) Jaroslow, Gary E. ; Smith, Deborah K. ; Tucholke, Brian E.Using multibeam bathymetry, we identified 86 axial and 1290 off-axis seamounts (near-circular volcanoes with heights ≥70 m) in an area of 75,000 km2 on the western flank of the Mid-Atlantic Ridge (MAR), 25°25′N to 27°10′N, extending ∼400 km from the inner rift valley floor to ∼29 Ma crust. Our study shows that seamounts are a common morphological feature of the North Atlantic seafloor. Seamount-producing volcanism occurs primarily on the inner rift valley floor, and few, if any, seamounts are formed on the rift valley walls or the ridge flank. The high abundance of off-axis seamounts is consistent with 1–3 km wide sections of oceanic crust being transferred intact from the axial valley to the ridge flank on crust >4 Ma. Significant changes in seamount abundances, sizes, and shapes are attributed to the effects of faulting between ∼0.6 and 2 m.y. off axis in the lower rift valley walls. Few seamounts are completely destroyed by (inward facing) faults, and population abundances are similar to those on axis. However, faulting reduces the characteristic height of the seamount population significantly. In the upper portions of the rift valley, on 2–4 Ma crust, crustal aging processes (sedimentation and mass wasting), together with additional outward facing faults, destroy and degrade a significant number of seamounts. Beyond the crest of the rift mountains (>4 Ma crust) faulting is no longer active, and changes in the off-axis seamount population reflect crustal aging processes as well as temporal changes in seamount production that occurred at the ridge axis. Estimates of population density for off-axis seamounts show a positive correlation to crustal thickness inferred from analysis of gravity data, suggesting that increased seamount production accompanies increased magma input at the ridge axis. We find no systematic variations in seamount population density along isochron within individual ridge segments. Possible explanations are that along-axis production of seamounts is uniform or that seamount production is enhanced in some regions (e.g., segment centers), but many seamounts do not meet our counting criteria because they are masked by younger volcanic eruptions and low-relief flows.
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ArticleScience under sail : ocean science education program combines traditional vessels with state-of-the-art technology(Oceanography Society, 2004-09) Bower, Amy S. ; Zettler, Erik R. ; Gawarkiewicz, Glen G.Sea Education Association (SEA), located in Woods Hole, Massachusetts, offers introductory oceanographic instruction in the classroom and hands-on research training at sea to create a unique educational experience for undergraduate students and other groups. Founded by Corwith Cramer in 1971, SEA has been taking students to sea for over 30 years, first on the 125-foot research vessel R/V Westward, and now on two custom-built Sailing School Vessels, the 134-foot steel brigantines SSV Corwith Cramer and SSV Robert C. Seamans. SEA vessels have sailed over 800,000 miles in the Atlantic and Pacific Oceans, and educated over 7,000 students in oceanography, nautical science, and in maritime history, literature, and policy. This article describes recent developments and opportunities in oceanographic education and research at SEA.
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ArticleThe history of ocean resources : modeling cod biomass using historical records(Ecological Society of America, 2005-03) Rosenberg, Andrew A. ; Bolster, W. Jeffrey ; Alexander, Karen E. ; Leavenworth, William B. ; Cooper, Andrew B. ; McKenzie, Matthew G.Managing the remnants of the ocean's resources is a critical issue worldwide, but evidence for what constitutes a healthy fish population remains controversial. Here, we use historical sources to understand ecosystem trends and establish a biomass estimate for a key marine species prior to the industrialization of fishing. Declining trajectories have been described for predatory fishes and complex coral reef systems globally, but few numerical estimates of past abundance exist. We combined historical research methods and population modeling to estimate the biomass of cod on Canada's Scotian Shelf in 1852. Mid 19th-century New England fishing logs offer geographically specific daily catch records, describing fleet activity on fishing grounds with negligible incentive to falsify records. Combined with ancillary fishery documents, these logs provide a solid, reliable basis for stock assessment. Based on these data we estimate a biomass for cod of 1.26 × 106 mt in 1852 – compared with less than 5 × 104 mt of total biomass today. In the current policy debate about rebuilding depleted fisheries and restoring marine ecosystems, it is important to recognize that fisheries for key commercial species like cod were far more productive in the past. As we attempt to rebuild these fisheries, our decisions should reflect real and realistic goals for management, not just recently observed catch levels.
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ArticleWomen in Oceanography : a web site for students, teachers, scientists, and the general public(Oceanography Society, 2005-03) Smith, Deborah K. ; Schiele, Edwin ; Dolby, LoriIn 1999 as the millennium was drawing to a close, we decided that the time was right to introduce a new type of web site highlighting the contributions that women are making to marine science. We envisioned a web site where women considering careers in oceanography could read about the experiences of successful women and learn from their choices; that would convey the excitement of groundbreaking research in oceanography and serve as a resource for teachers, scientists, and the general public; and that would celebrate a group of remarkable women and bring a human face to those working in marine science.
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PreprintHigh apex predator biomass on remote Pacific islands( 2006-09-06) Stevenson, Charlotte ; Katz, Laure S. ; Micheli, Fiorenza ; Block, Barbara A. ; Heiman, Kimberly W. ; Perle, Chris ; Weng, Kevin ; Dunbar, Robert B. ; Witting, Jan H.On coral reefs in Palmyra—a central Pacific atoll with limited fishing pressure—total fish biomass is 428 and 299% greater than on reefs in nearby Christmas and Fanning Islands. Large apex predators –groupers, sharks, snappers, and jacks larger than 50 cm in length- account for 56% of total fish biomass in Palmyra on average, but only 7% and 3% on Christmas and Fanning. These biomass proportions are remarkably similar to those previously reported for the remote and uninhabited Northwest Hawaiian Islands (NWHI) and densely populated Main Hawaiian Islands (MHI), although Palmyra’s reefs are dominated in biomass by sharks (44% of the total), whereas the NWHI by jacks (39%). Herbivorous fish biomass was also greater on Palmyra than on Christmas and Fanning (343% and 207%, respectively). These results and previous findings indicate that remote, uninhabited islands support high levels of consumers, and highlight the importance of healthy coral reef ecosystems as reference points for assessment of human impacts and establishment of restoration goals.
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PreprintDistribution and seasonal variability in the benthic eukaryotic community of Río Tinto (SW, Spain), an acidic, high metal extreme environment( 2007-02-14) Aguilera, Angeles ; Zettler, Erik R. ; Gomez, Felipe ; Amaral-Zettler, Linda A. ; Rodríguez, Nuria ; Amils, RicardoThe eukaryotic community of Río Tinto (SW, Spain) was surveyed fall, winter, and spring through the combined use of traditional microscopy and molecular approaches including Denaturing Gradient Gel Electrophoresis (DGGE) and sequence analysis of 18S rRNA gene fragments. We compared eukaryotic assemblages of surface sediment biofilms collected in January, May and September 2002 from 13 sampling stations along the river. Physicochemical data revealed extremely acidic conditions (pH ranged from 0.9 to 2.5) with high concentrations of heavy metals including up to 20 g l-1 Fe, 317 mg l-1 Zn, 47 mg l-1 As, 42 mg l-1 Cd, and 4 mg l-1 Ni. In total, 20 taxa were identified, including members of the Bacillariophyta, Chlorophyta, and Euglenophyta phyla as well as ciliates, cercomonads, amoebae, stramenopiles, fungi, heliozoan and rotifers. In general, total cell abundances were highest in fall and spring decreasing drastically in winter and the sampling stations with the most extreme conditions showed the lowest number of cells as well as the lowest diversity. Species diversity does not vary much during the year. Only the filamentous algae showed a dramatic seasonal change almost disappearing in winter and reaching the highest biomass during the summer. PCA showed a high inverse correlation between pH and most of the heavy metals analyzed as well as Dunaliella sp., while Chlamydomonas sp. is directly related to pH during May and September. Three heavy metals (Zn, Cu and Ni) remained separate from the rest and showed an inverse correlation with most of the species analyzed except for Dunaliella sp.
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ArticleProkaryotic community structure in algal photosynthetic biofilms from extreme acidic streams in Rio Tinto (Huelva, Spain)(Spanish Society for Microbiology (SEM), 2008-12) Souza-Egipsy, Virginia ; Gonzalez-Toril, Elena ; Zettler, Erik R. ; Amaral-Zettler, Linda A. ; Aguilera, Angeles ; Amils, RicardoFour algal photosynthetic biofilms were collected from the Rio Tinto (SW Spain) at four localities: AG, Euglena and Pinnularia biofilms; ANG, Chlorella and Pinnularia biofilms; RI, Cyanidium and Dunaliella biofilms; and CEM, Cyanidium, Euglena and Pinnularia biofilms. Community composition and structure were studied by a polyphasic approach consisting of 16S rRNA analysis, scanning electron microscopy by back-scattered electron detection mode (SEM-BSE), and fluorescence in-situ hybridization (FISH). Acidophilic prokaryotes associated with algal photosynthetic biofilms included sequences related to the Alpha-, Beta-, and Gammaproteobacteria (phylum Proteobacteria) and to the phyla Nitrospira, Actinobacteria, Acidobacteria and Firmicutes. Sequences from the Archaea domain were also identified. No more than seven distinct lineages were detected in any biofilm, except for those from RI, which contained fewer groups of Bacteria. Prokaryotic communities of the thinnest algal photosynthetic biofilms (<100 μm) were more related to those in the water column, including Leptospirillum populations. In general, thick biofilms (>200 μm) generate microniches that could facilitate the development of less-adapted microorganisms (coming from the surrounding environment) to extreme conditions, thus resulting in a more diverse prokaryotic biofilm.
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ArticleGooseneck barnacles (Lepas spp.) ingest microplastic debris in the North Pacific Subtropical Gyre(PeerJ, 2013-10-22) Goldstein, Miriam C. ; Goodwin, Deborah S.Substantial quantities of small plastic particles, termed “microplastic,” have been found in many areas of the world ocean, and have accumulated in particularly high densities on the surface of the subtropical gyres. While plastic debris has been documented on the surface of the North Pacific Subtropical Gyre (NPSG) since the early 1970s, the ecological implications remain poorly understood. Organisms associated with floating objects, termed the “rafting assemblage,” are an important component of the NPSG ecosystem. These objects are often dominated by abundant and fast-growing gooseneck barnacles (Lepas spp.), which predate on plankton and larval fishes at the sea surface. To assess the potential effects of microplastic on the rafting community, we examined the gastrointestinal tracts of 385 barnacles collected from the NPSG for evidence of plastic ingestion. We found that 33.5% of the barnacles had plastic particles present in their gastrointestinal tract, ranging from one plastic particle to a maximum of 30 particles. Particle ingestion was positively correlated to capitulum length, and no blockage of the stomach or intestines was observed. The majority of ingested plastic was polyethylene, with polypropylene and polystyrene also present. Our results suggest that barnacle ingestion of microplastic is relatively common, with unknown trophic impacts on the rafting community and the NPSG ecosystem.
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ArticleDistribution of surface plastic debris in the eastern Pacific Ocean from an 11-Year data set(American Chemical Society, 2014-04-07) Law, Kara L. ; Moret-Ferguson, Skye E. ; Goodwin, Deborah S. ; Zettler, Erik R. ; DeForce, Emelia A. ; Kukulka, Tobias ; Proskurowski, GioraWe present an extensive survey of floating plastic debris in the eastern North and South Pacific Oceans from more than 2500 plankton net tows conducted between 2001 and 2012. From these data we defined an accumulation zone (25 to 41°N, 130 to 180°W) in the North Pacific subtropical gyre that closely corresponds to centers of accumulation resulting from the convergence of ocean surface currents predicted by several oceanographic numerical models. Maximum plastic concentrations from individual surface net tows exceeded 106 pieces km–2, with concentrations decreasing with increasing distance from the predicted center of accumulation. Outside the North Pacific subtropical gyre the median plastic concentration was 0 pieces km–2. We were unable to detect a robust temporal trend in the data set, perhaps because of confounded spatial and temporal variability. Large spatiotemporal variability in plastic concentration causes order of magnitude differences in summary statistics calculated over short time periods or in limited geographic areas. Utilizing all available plankton net data collected in the eastern Pacific Ocean (17.4°S to 61.0°N; 85.0 to 180.0°W) since 1999, we estimated a minimum of 21 290 t of floating microplastic.
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DatasetShipboard ADCP profiles, central equatorial Pacific Ocean, 2003-2012( 2014-07-17) Karnauskas, Kristopher B. ; Witting, Jan H.This data set contains 23 individual NetCDF files, each containing subsurface zonal and meridional velocity profiles (along with time/space coordinates) measured by shipboard ADCP.
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ArticleThe Equatorial Undercurrent and TAO sampling bias from a decade at SEA(American Meteorological Society, 2014-09) Leslie, William R. ; Karnauskas, Kristopher B.The NOAA Tropical Atmosphere Ocean (TAO) moored array has, for three decades, been a valuable resource for monitoring and forecasting El Niño–Southern Oscillation and understanding physical oceanographic as well as coupled processes in the tropical Pacific influencing global climate. Acoustic Doppler current profiler (ADCP) measurements by TAO moorings provide benchmarks for evaluating numerical simulations of subsurface circulation including the Equatorial Undercurrent (EUC). Meanwhile, the Sea Education Association (SEA) has been collecting data during repeat cruises to the central equatorial Pacific Ocean (160°–126°W) throughout the past decade that provide useful cross validation and quantitative insight into the potential for stationary observing platforms such as TAO to incur sampling biases related to the strength of the EUC. This paper describes some essential sampling characteristics of the SEA dataset, compares SEA and TAO velocity measurements in the vicinity of the EUC, shares new insight into EUC characteristics and behavior only observable in repeat cross-equatorial sections, and estimates the sampling bias incurred by equatorial TAO moorings in their estimates of the velocity and transport of the EUC. The SEA high-resolution ADCP dataset compares well with concurrent TAO measurements (RMSE = 0.05 m s−1; R2 = 0.98), suggests that the EUC core meanders sinusoidally about the equator between ±0.4° latitude, and reveals a mean sampling bias of equatorial measurements (e.g., TAO) of the EUC’s zonal velocity of −0.14 ± 0.03 m s−1 as well as a ~10% underestimation of EUC volume transport. A bias-corrected monthly record and climatology of EUC strength at 140°W for 1990–2010 is presented.
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ArticleOligotyping reveals community level habitat selection within the genus Vibrio(Frontiers Media, 2014-11-13) Schmidt, Victor T. ; Reveillaud, Julie ; Zettler, Erik R. ; Mincer, Tracy J. ; Murphy, Leslie G. ; Amaral-Zettler, Linda A.The genus Vibrio is a metabolically diverse group of facultative anaerobic bacteria, common in aquatic environments and marine hosts. The genus contains several species of importance to human health and aquaculture, including the causative agents of human cholera and fish vibriosis. Vibrios display a wide variety of known life histories, from opportunistic pathogens to long-standing symbionts with individual host species. Studying Vibrio ecology has been challenging as individual species often display a wide range of habitat preferences, and groups of vibrios can act as socially cohesive groups. Although strong associations with salinity, temperature and other environmental variables have been established, the degree of habitat or host specificity at both the individual and community levels is unknown. Here we use oligotyping analyses in combination with a large collection of existing Vibrio 16S ribosomal RNA (rRNA) gene sequence data to reveal patterns of Vibrio ecology across a wide range of environmental, host, and abiotic substrate associated habitats. Our data show that individual taxa often display a wide range of habitat preferences yet tend to be highly abundant in either substrate-associated or free-living environments. Our analyses show that Vibrio communities share considerable overlap between two distinct hosts (i.e., sponge and fish), yet are distinct from the abiotic plastic substrates. Lastly, evidence for habitat specificity at the community level exists in some habitats, despite considerable stochasticity in others. In addition to providing insights into Vibrio ecology across a broad range of habitats, our study shows the utility of oligotyping as a facile, high-throughput and unbiased method for large-scale analyses of publically available sequence data repositories and suggests its wide application could greatly extend the range of possibilities to explore microbial ecology.
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ArticleCorrigendum(American Meteorological Society, 2014-12) Leslie, William R. ; Karnauskas, Kristopher B. ; Witting, Jan H.
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ArticleSeabirds, gyres and global trends in plastic pollution(Elsevier, 2015-04-11) van Franeker, Jan A. ; Law, Kara L.Fulmars are effective biological indicators of the abundance of floating plastic marine debris. Long-term data reveal high plastic abundance in the southern North Sea, gradually decreasing to the north at increasing distance from population centres, with lowest levels in high-arctic waters. Since the 1980s, pre-production plastic pellets in North Sea fulmars have decreased by ∼75%, while user plastics varied without a strong overall change. Similar trends were found in net-collected floating plastic debris in the North Atlantic subtropical gyre, with a ∼75% decrease in plastic pellets and no obvious trend in user plastic. The decreases in pellets suggest that changes in litter input are rapidly visible in the environment not only close to presumed sources, but also far from land. Floating plastic debris is rapidly “lost” from the ocean surface to other as-yet undetermined sinks in the marine environment.
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ArticleInfluence of Central Pacific oceanographic conditions on the potential vertical habitat of four tropical tuna species(University of Hawai'i Press, 2015-10) Deary, Alison L. ; Moret-Ferguson, Skye E. ; Engels, Mary ; Zettler, Erik R. ; Jaroslow, Gary E. ; Sancho, GorkaClimate change has resulted in the geographic and vertical expansion of oxygen minimum zones but their impact on the vertical distribution of commercially important species, such as tunas, is not well understood. Although La Niña events are characterized by increased upwelling along the equator, the increased primary productivity and bacterial proliferation drive the expansion of oxygen minimum zones. Vertical habitat of four tropical tuna species were characterized using direct observations of the oceanographic conditions of the Central Pacific Ocean during the 2008 La Niña event and existing primary literature on temperature and dissolved oxygen physiological tolerances for these tunas. Concentrations of potential prey were estimated using Acoustic Doppler Current Profiler raw backscatter and surface zooplankton tows. Based on the oceanographic conditions observed from February to June, low dissolved oxygen levels, more so than low temperatures, were inferred to restrict the predicted vertical habitat of four commercially important tuna species (bigeye, yellowfin, skipjack, and albacore). During peak La Niña conditions, temperature and dissolved oxygen tolerance limits of all four tuna species were reached at approximately 200m. Zooplankton and myctophid fish densities peaked in the upper 200m between 0° N and 5° N, which corresponded to a region with a shallow thermocline (150 m). Our findings suggest the possibility that competition and susceptibility to surface fishing gears may be increased for tropical tunas during a strong La Niña event due to vertical habitat restrictions.
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ArticleThe biogeography of the Plastisphere : implications for policy(Ecological Society of America, 2015-12) Amaral-Zettler, Linda A. ; Zettler, Erik R. ; Slikas, Beth ; Boyd, Gregory D. ; Melvin, Donald W. ; Morrall, Clare E. ; Proskurowski, Giora ; Mincer, Tracy J.Microplastics (particles less than 5 mm) numerically dominate marine debris and occur from coastal waters to mid-ocean gyres, where surface circulation concentrates them. Given the prevalence of plastic marine debris (PMD) and the rise in plastic production, the impacts of plastic on marine ecosystems will likely increase. Microscopic life (the “Plastisphere”) thrives on these tiny floating “islands” of debris and can be transported long distances. Using next-generation DNA sequencing, we characterized bacterial communities from water and plastic samples from the North Pacific and North Atlantic subtropical gyres to determine whether the composition of different Plastisphere communities reflects their biogeographic origins. We found that these communities differed between ocean basins – and to a lesser extent between polymer types – and displayed latitudinal gradients in species richness. Our research reveals some of the impacts of microplastics on marine biodiversity, demonstrates that the effects and fate of PMD may vary considerably in different parts of the global ocean, and suggests that PMD mitigation will require regional management efforts.
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ArticleComparative mitochondrial and chloroplast genomics of a genetically distinct form of Sargassum contributing to recent “Golden Tides” in the Western Atlantic(John Wiley & Sons, 2016-12-20) Amaral-Zettler, Linda A. ; Dragone, Nicholas B. ; Schell, Jeffrey M. ; Slikas, Beth ; Murphy, Leslie G. ; Morrall, Clare E. ; Zettler, Erik R.Over the past 5 years, massive accumulations of holopelagic species of the brown macroalga Sargassum in coastal areas of the Caribbean have created “golden tides” that threaten local biodiversity and trigger economic losses associated with beach deterioration and impact on fisheries and tourism. In 2015, the first report identifying the cause of these extreme events implicated a rare form of the holopelagic species Sargassum natans (form VIII). However, since the first mention of S. natans VIII in the 1930s, based solely on morphological characters, no molecular data have confirmed this identification. We generated full-length mitogenomes and partial chloroplast genomes of all representative holopelagic Sargassum species, S. fluitans III and S. natans I alongside the putatively rare S. natans VIII, to demonstrate small but consistent differences between S. natans I and VIII (7 bp differences out of the 34,727). Our comparative analyses also revealed that both S. natans I and S. natans VIII share a very close phylogenetic relationship with S. fluitans III (94- and 96-bp differences of 34,727). We designed novel primers that amplified regions of the cox2 and cox3 marker genes with consistent polymorphic sites that enabled differentiation between the two S. natans forms (I and VIII) from each other and both from S. fluitans III in over 150 Sargassum samples including those from the 2014 golden tide event. Despite remarkable gene synteny and sequence conservation, the three Sargassum forms differ in morphology, ecology, and distribution patterns, warranting more extensive interrogation of holopelagic Sargassum genomes as a whole.
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ArticleProduction, use, and fate of all plastics ever made(American Association for the Advancement of Science, 2017-07-19) Geyer, Roland ; Jambeck, Jenna ; Law, Kara L.Plastics have outgrown most man-made materials and have long been under environmental scrutiny. However, robust global information, particularly about their end-of-life fate, is lacking. By identifying and synthesizing dispersed data on production, use, and end-of-life management of polymer resins, synthetic fibers, and additives, we present the first global analysis of all mass-produced plastics ever manufactured. We estimate that 8300 million metric tons (Mt) as of virgin plastics have been produced to date. As of 2015, approximately 6300 Mt of plastic waste had been generated, around 9% of which had been recycled, 12% was incinerated, and 79% was accumulated in landfills or the natural environment. If current production and waste management trends continue, roughly 12,000 Mt of plastic waste will be in landfills or in the natural environment by 2050.
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ArticleTrends in physical properties at the southern New England shelf break(American Geophysical Union, 2020-01-21) Harden, Benjamin E. ; Gawarkiewicz, Glen G. ; Infante, MiaWe analyze 11 years (2003–2013) of repeat temperature and salinity sections from across the New England shelf break south of Cape Cod during early summer (June–July). The mean sections resolved the shelf break front which supports the Shelf Break Jet, a vital component of the regional circulation. Individual sections showed a great deal of variability associated with meanders in the shelf break front consistent with previous studies in the region. Over the 11 year record, the shelf region (inshore of the 100 m isobath) warmed by 0.26 °C yr -1, with the majority of this warming occurring shallower than 20 m (0.58 °C yr -1). The full‐depth trend agrees well with previous studies of shelf warming to the north and the south of our study region. The temperature and salinity of the offshore edge of the Cold Pool Water on the shelf did not change significantly during this period. The surface warming on the shelf resulted in a decrease in near‐surface density of 0.12 kg m -3 yr -1 and an increase in stratification between 10 and 15 m of 6.7 X 10(-5) S -2 yr -1 . Offshore of the shelf break, the Slope Water also warmed and became more saline by 0.21 °C yr -1 and 0.04 yr -1 respectively, resulting in a maximal reduction in density of 0.01 kg m -3 yr -1. In the Shelf Break Front, there is some evidence of freshening and a reduction in density, which may have resulted from an offshore shift in the Cold Pool but the statistical significance is small.