Physical Forcing of Phytoplankton Community Structure and Primary Production in Continental Shelf Waters of the Western Antarctic Peninsula

Analyses of a multidisciplinary data set, collected in continental shelf waters of the Western Antarctic Peninsula (WAP) during austral summer of January 1993, identified a previously unrecognized forcing mechanism that sets up a physical and chemical structure that supports and assures site-specific diatom-dominated communities and enhanced biological production (Prézelin et al., 2000). This forcing is active when the southern boundary of the Antarctic Circumpolar Current (ACC) flows along the shelf edge, thereby facilitating onshelf bottom intrusions of nutrient-rich Upper Circumpolar Deep Water (UCDW), which then is upwelled or mixed into the upper water column. At times or locations where UCDW is not introduced to the upper water column, diatoms no longer dominate phytoplankton assemblages over the mid- to outer WAP continental shelf. This analysis extends the area and seasons studied through similar analyses of multidisciplinary data sets collected on four additional cruises to the WAP that cover all seasons. Results show that onshelf intrusions of UCDW: (1) occur in other regions of the WAP continental shelf; (2) are episodic; (3) are forced by nonseasonal physical processes; and (4) produce areas of diatom-dominated phytoplankton assemblages and enhanced primary production. At times, multiple intrusions are observed on the WAP continental shelf, and each event may be in a different stage. Further, the occurrence of an intrusion event in one area does not necessarily imply that similar events are ongoing in other areas along the WAP shelf. The UCDW bottom intrusions originate along the outer shelf but they can extend into the inner shelf region because the deep troughs that transect the WAP shelf provide connections between the inner and outer shelf. The boundary between the intruded water and the shelf water is variable in location because of the episodic nature of the onshelf intrusions, and is moved farther inshore as an event occurs. These observations show clearly that the phytoplankton community structure on the WAP shelf is determined by physical forcing and that primary production is likely to be considerably greater than previously believed. Moreover, variability in this physical forcing, such as may occur via climate change, can potentially affect the overall biological production of the WAP continental shelf system

The Development of a Novel Questionnaire Approach to the Investigation of Horse Training, Management, and Behaviour.

The Equine Behaviour Assessment and Research Questionnaire (E-BARQ) is a questionnaire instrument developed to obtain quantitative data on the domestic equine triad of training, management, and behaviour of horses. The E-BARQ was developed to identify how changes in training and management impact behaviour over time, to define normal behaviour in horses, and to discover how to improve rider safety and horse welfare, leading to ethical equitation. During the development of the E-BARQ, we also investigated how best to motivate stakeholders to engage with this citizen science project. The pilot version of the E-BARQ collected qualitative data on respondents' experience of the questionnaire. The pilot questionnaire was developed with the assistance of an international panel (with professional expertise in horse training, equitation science, veterinary science, equestrian coaching, welfare, animal behaviour, and elite-level riding), and was used to collect data on 1320 horses from approximately 1194 owner/caregiver respondents, with an option for respondents to provide free-text feedback. A Rotated Principal Component Analysis of the 218 behavioural, management, and training questionnaire items extracted a total of 65 rotated components. Thirty-six of the 65 rotated components demonstrated high internal reliability. Of the 218 questionnaire items, 43 items failed to reach the Rotated Principal Component Analysis criteria and were not included in the final version of the E-BARQ. Survey items that failed the Rotated Principal Component Analysis inclusion criteria were discarded if found to have a less than 85% response rate, or a variance of less than 1.3. Of those that survived the Rotated Principal Component Analysis, items were further assigned to horse temperament (17 rotated components), equitation (11 rotated components), and management and equipment (8 rotated components) groups. The feedback from respondents indicated the need for further items to be added to the questionnaire, resulting in a total of 214 items for the final E-BARQ survey. Many of these items were further grouped into question matrices, and the demographic items for horse and handler included, giving a final total of 97 questions on the E-BARQ questionnaire. These results provided content validity, showing that the questionnaire items were an acceptable representation of the entire horse training, management, and behavioural domain for the development of the final E-BARQ questionnaire

Circulation and Behavior Controls on Dispersal of Eastern Oyster (Crassostrea virginica) Larvae in Delaware Bay

The degree of genetic connectivity among populations in a metapopulation has direct consequences for species evolution, development of disease resistance, and capacity of a metapopulation to adapt to climate change. This study used a metapopulation model that integrates population dynamics, dispersal, and genetics within an individual-based model framework to examine the mechanisms and dynamics of genetic connectivity within a metapopulation. The model was parameterized to simulate four populations of oysters (Crassostrea virginica) from Delaware Bay on the mid-Atlantic coast of the United States. Differences among the four populations include a strong spatial gradient in mortality, a spatial gradient in growth rates, and uneven population abundances. Simulations demonstrated a large difference in the magnitude of neutral allele transfer with changes in population abundance and mortality (on average between 14 and 25% depending on source population), whereas changes in larval dispersal were not effective in altering genetic connectivity (on average between 1 and 8%). Simulations also demonstrated large temporal changes in metapopulation genetic connectivity including shifts in genetic sources and sinks occurring between two regimes, the 1970s and 2000s. Although larval dispersal in a sessile marine population is the mechanism for gene transfer among populations, these simulations demonstrate the importance of local dynamics and characteristics of the adult component of the populations in the flow of neutral alleles within a metapopulation. In particular, differential adult mortality rates among populations exert a controlling influence on dispersal of alleles, an outcome of latent consequence for management of marine populations

Modeling the Dispersal of Eastern Oyster (Crassostrea virginica) larvae in Delaware Bay

The interactions of circulation and growth processes in determining the horizontal distribution of eastern oyster (Crassostrea virginica) larvae in the Delaware Bay estuary were investigated with a coupled circulation-individual-based larvae model that used environmental conditions from the spawning seasons (mid-June to mid-September) of 1984, 1985, 1986, 2000, and 2001. Particles, representing oyster larvae, were released at five-day intervals from areas in Delaware Bay that correspond to natural oyster reefs. The simulated larval development time was used to estimate potential larval success, determined by the percent of larvae that successfully reached settlement size (330 µm) within the planktonic larval duration of 30 days. Success rates for simulated larvae released in the upper estuary were less than half of those released in the lower estuary because of the reduction in growth rate from exposure to low salinity. Simulated larval success rates were further reduced during periods of increased river discharge, which produced low salinity conditions. The simulated transport patterns showed a down-estuary drift of oyster larvae during the spawning season, which is consistent with the observed reduction in settlement and recruitment rates in the upper estuary. The simulated transport pathways patterns showed that larvae originating in the middle and lower regions of the estuary had low rates of dispersion and high rates of self-settlement. Larvae released in the upper reaches of the estuary had limited contributions to the Delaware Bay oyster population, in part because of the lower overall simulated larval success in the low salinity regions. The simulated transport patterns suggested that the upper bay exports rather than receives larvae, which has implications for the establishment of genetic traits

Record Drilling Depth Struck in Greenland

On July 1, 1993, after 5 years of drilling, the Greenland Ice Sheet Project (GISP2) penetrated several meters of silty ice and reached bedrock at a depth of 3053.4 m. It then penetrated 1.5 m into the bedrock, producing the deepest ice core ever recovered (Figure 1). In July 1992, a nearby European ice coring effort, the Greenland Ice Core Project (GRIP), reached an ice depth of 3028.8 m, providing more than 250,000 years of record. Comparisons between these ice core records have already demonstrated the remarkable reproducibility of the upper ∼90% of the records unparalleled view of climatic and environmental change

Near-Real-Time Acoustic Monitoring of Beaked Whales and Other Cetaceans Using a Seaglider (TM)

Correction 10 Aug 2012: Klinck H, Mellinger DK, Klinck K, Bogue NM, Luby JC, et al. (2012) Correction: Near-Real-Time Acoustic Monitoring of Beaked Whales and Other Cetaceans Using a Seaglider™. PLOS ONE 7(8): 10.1371/annotation/57ad0b82-87c4-472d-b90b-b9c6f84947f8.In most areas, estimating the presence and distribution of cryptic marine mammal species, such as beaked whales, is extremely difficult using traditional observational techniques such as ship-based visual line transect surveys. Because acoustic methods permit detection of animals underwater, at night, and in poor weather conditions, passive acoustic observation has been used increasingly often over the last decade to study marine mammal distribution, abundance, and movements, as well as for mitigation of potentially harmful anthropogenic effects. However, there is demand for new, cost-effective tools that allow scientists to monitor areas of interest autonomously with high temporal and spatial resolution in near-real time. Here we describe an autonomous underwater vehicle – a glider – equipped with an acoustic sensor and onboard data processing capabilities to passively scan an area for marine mammals in near-real time. The glider was tested extensively off the west coast of the Island of Hawai'i, USA. The instrument covered approximately 390 km during three weeks at sea and collected a total of 194 h of acoustic data. Detections of beaked whales were successfully reported to shore in near-real time. Manual analysis of the recorded data revealed a high number of vocalizations of delphinids and sperm whales. Furthermore, the glider collected vocalizations of unknown origin very similar to those made by known species of beaked whales. The instrument developed here can be used to cost-effectively screen areas of interest for marine mammals for several months at a time. The near-real-time detection and reporting capabilities of the glider can help to protect marine mammals during potentially harmful anthropogenic activities such as seismic exploration for sub-sea fossil fuels or naval sonar exercises. Furthermore, the glider is capable of under-ice operation, allowing investigation of otherwise inaccessible polar environments that are critical habitats for many endangered marine mammal species

Near-Real-Time Acoustic Monitoring of Beaked Whales and Other Cetaceans Using a Seaglider™

In most areas, estimating the presence and distribution of cryptic marine mammal species, such as beaked whales, is extremely difficult using traditional observational techniques such as ship-based visual line transect surveys. Because acoustic methods permit detection of animals underwater, at night, and in poor weather conditions, passive acoustic observation has been used increasingly often over the last decade to study marine mammal distribution, abundance, and movements, as well as for mitigation of potentially harmful anthropogenic effects. However, there is demand for new, cost-effective tools that allow scientists to monitor areas of interest autonomously with high temporal and spatial resolution in near-real time. Here we describe an autonomous underwater vehicle – a glider – equipped with an acoustic sensor and onboard data processing capabilities to passively scan an area for marine mammals in near-real time. The glider was tested extensively off the west coast of the Island of Hawai'i, USA. The instrument covered approximately 390 km during three weeks at sea and collected a total of 194 h of acoustic data. Detections of beaked whales were successfully reported to shore in near-real time. Manual analysis of the recorded data revealed a high number of vocalizations of delphinids and sperm whales. Furthermore, the glider collected vocalizations of unknown origin very similar to those made by known species of beaked whales. The instrument developed here can be used to cost-effectively screen areas of interest for marine mammals for several months at a time. The near-real-time detection and reporting capabilities of the glider can help to protect marine mammals during potentially harmful anthropogenic activities such as seismic exploration for sub-sea fossil fuels or naval sonar exercises. Furthermore, the glider is capable of under-ice operation, allowing investigation of otherwise inaccessible polar environments that are critical habitats for many endangered marine mammal species

Rapid circulation of warm subtropical waters in a major glacial fjord in East Greenland

Author Posting. © The Authors, 2009. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature Geoscience 3 (2010): 182-186, doi:10.1038/ngeo764.The recent rapid increase in mass loss from the Greenland Ice Sheet is primarily attributed to an acceleration of outlet glaciers. One possible cause is increased melting at the ice/ocean interface driven by the synchronous warming of subtropical waters offshore of Greenland. This hypothesis is largely untested, however, because of the lack of observations from Greenland’s glacial fjords and our limited understanding of their dynamics. Here, we present new ship-based and moored oceanographic data, collected in Sermilik Fjord, a large glacial fjord in East Greenland, showing that subtropical waters are present throughout the fjord and are continuously replenished via a wind-driven exchange with the shelf, where they occur year-round. The temperature and rapid renewal of these waters suggest that, at present, they drive enhanced submarine melting at the terminus. Key controls on the melting rate are the volume and properties of subtropical waters on the shelf and the patterns of the along-shore winds, suggesting the glaciers’ acceleration was triggered by a combination of atmospheric and oceanic changes. These measurements provide evidence of rapid advective pathway for the transmission of oceanic variability to the ice-sheet margins and highlight an important process that is missing from prognostic ice-sheet models.F.S. acknowledges support from WHOI’s Ocean and Climate Change Institute’s Arctic Research Initiative and from NSF OCE 0751896, and G.S.H and L.A.S from NASA’s Cryospheric Sciences Program. Funding for the hooded seal deployments was obtained from the International Governance and Atlantic Seal Research Program, Fisheries and Oceans, Canada, to G. B. S. and to the Greenland Institute of Natural Resources to A. R. A

Pulmonary Abnormalities in Mice with Paracoccidioidomycosis: A Sequential Study Comparing High Resolution Computed Tomography and Pathologic Findings

Paracoccidioidomycosis (PCM) is a fungal infection caused by the dimorphic fungus Paracoccidioides brasiliensis. It occurs preferentially in rural workers in whom the disease is severe and may cause incapacitating pulmonary sequelae. Assessment of disease progression and treatment outcome normally includes chest x-rays or CT studies. Existing experimental PCM models have focused on several aspects, but none has done a radiologic or image follow-up evaluation of pulmonary lesions considered as the fungus primary target. In this study, the lungs of mice infected with fungal conidia were studied sequentially during the chronic stage of their experimental mycosis by noninvasive high resolution medical computed tomography, and at time of sacrifice, also by histopathology to characterize pulmonary abnormalities. Three basic lung lesion patterns were revealed by both techniques: nodular-diffuse, confluent and pseudo-tumoral which were located mainly around the hilus thus accurately reflecting the situation in human patients. The experimental design of this study decreases the need to sacrifice a large number of animals, and serves to monitor treatment efficacy by means of a more rational approach to the study of human pulmonary diseases. The findings we are reporting open new avenues for experimental research, increase our understanding of the mycosis pathogenesis and consequently have repercussions in patients' care