A Regionally Based Energy End‐Use Strategy: Case Studies from Centre County,Pennsylvania*

The production and use of fossil fuels and nonrenewable electricity creates many forms of environmental degradation. To reduce degradation, this research suggests an energy strategy based on energy end‐use analysis and regional geography. Energy end‐use analysis and regional geography are used to match renewable energy resources with site‐specific, end‐use needs. Fieldwork conducted within Centre County, Pennsylvania, demonstrates that small‐scale solar, wind, and micro‐hydropower resources could displace a proportion of household electricity use. Such an approach meets energy end‐use needs, while conserving fossil fuels and reducing environmental degradation.     

Long-term investigation of benthic fauna and the influence of treated ballast water disposal in Port Valdez,Alaska

Benthic faunal structure and hydrocarbon concentrations in sediments were examined annually for 10 years (1989-1998) in Port Valdez, Alaska, where a near-bottom permitted discharge of treated tanker ballast waters containing residual petroleum has occurred since 1977. Measured concentrations of hydrocarbons in sediments near the discharge showed detectable increases in concentration, but on only one occasion were these increases either to levels exceeding ecotoxicological thresholds (Effects-Range Low, ER-L) or associated with alterations in the benthic community. Changes in faunal structure indicating disturbance were observed at one station near the discharge from 1995 to 1997 and were apparent as increased numbers of opportunistic taxa and anomalous trends in abundance and diversity. Minimum-effect (ME) hypotheses provided evidence of negligible to small effects on benthic infauna from disposal of treated ballast water. ME hypotheses have the potential to assist both researchers and managers by providing a tool to relate scientific results to ecological importance and decision criteria.     

Decoupled stochastic mapping [for mobile robot & AUVnavigation]

This paper describes decoupled stochastic mapping (DSM), a new computationally efficient approach to large-scale concurrent mapping and localization (CML). DSM reduces the computational burden of conventional stochastic mapping by dividing the environment into multiple overlapping submap regions, each with its own stochastic map. Two new approximation techniques are utilized for transferring vehicle state information from one submap to another, yielding a constant-time algorithm whose memory requirements scale linearly with the number of submaps. The approach is demonstrated via simulations and experiments. Simulation results are presented for the case of an autonomous underwater vehicle navigating in an unknown environment with 110 and 1200 features using simulated observations of point features by a forward look sonar. Empirical tests are used to examine the consistency of the error bounds calculated by the different methods. Experimental results are also presented for an environment with 93 features using sonar data obtained in a 3 by 9 by 1 m testing tank     

Abiotic/Biological Interactions in Coastal Marine Communities: Insights from an Alaskan Fjord

Interactions among multi-scale coastal marine ecosystem processes can be expected to play large roles in and interact with biological processes as stresses increase, potentially allowing interfering processes (including biological interactions) to become more prevalent. Retrospective analyses of intertidal (1988–1992) and subtidal (1971–2012) species compositions from a long-term ecological research program in Port Valdez, Alaska evaluated associations between benthic community structure and physical conditions to better understand interactions between regional to local processes on flora and fauna. Low salinity, habitat structure (varying from mudflats to rocky shores over a distance of <18 km), and suspended sediments contributed to intertidal community structure via elimination of predators from low-salinity prey refugia. Subtidal communities demonstrate adjustments by macrofauna to sedimentation with smaller, disturbance-tolerant fauna towards the head of the fjord as well as effects from depth-related covariates. Shared ecological processes result in comparable community trends in subtidal and intertidal habitats among subarctic and arctic fjords and similarly among coastal environments of the North Pacific. Control exerted by interactions among climatic, oceanographic, and local processes interacting with biota contributes to the direction and length of recovery from disturbance events and environmental changes. Feedbacks, mediation of recovery by additional processes, and strengths of interactions also play important roles in determining interaction outcomes. Interactions among local, regional, and global-scale processes may become critical sources of change as global ecosystem transitions through new climate states.     

Ecosystem dynamics of the Pacific-influenced Northern Bering and Chukchi Seas in the Amerasian Arctic

The shallow continental shelves and slope of the Amerasian Arctic are strongly influenced by nutrient-rich Pacific waters advected over the shelves from the northern Bering Sea into the Arctic Ocean. These high-latitude shelf systems are highly productive both as the ice melts and during the open-water period. The duration and extent of seasonal sea ice, seawater temperature and water mass structure are critical controls on water column production, organic carbon cycling and pelagic–benthic coupling. Short food chains and shallow depths are characteristic of high productivity areas in this region, so changes in lower trophic levels can impact higher trophic organisms rapidly, including pelagic- and benthic-feeding marine mammals and seabirds. Subsistence harvesting of many of these animals is locally important for human consumption. The vulnerability of the ecosystem to environmental change is thought to be high, particularly as sea ice extent declines and seawater warms. In this review, we focus on ecosystem dynamics in the northern Bering and Chukchi Seas, with a more limited discussion of the adjoining Pacific-influenced eastern section of the East Siberian Sea and the western section of the Beaufort Sea. Both primary and secondary production are enhanced in specific regions that we discuss here, with the northern Bering and Chukchi Seas sustaining some of the highest water column production and benthic faunal soft-bottom biomass in the world ocean. In addition, these organic carbon-rich Pacific waters are periodically advected into low productivity regions of the nearshore northern Bering, Chukchi and Beaufort Seas off Alaska and sometimes into the East Siberian Sea, all of which have lower productivity on an annual basis. Thus, these near shore areas are intimately tied to nutrients and advected particulate organic carbon from the Pacific influenced Bering Shelf-Anadyr water. Given the short food chains and dependence of many apex predators on sea ice, recent reductions in sea ice in the Pacific-influenced sector of the Arctic have the potential to cause an ecosystem reorganization that may alter this benthic-oriented system to one more dominated by pelagic processes.     

Macoma balthica: An indicator of oil pollution

The intertidal bivalve mollusc Macoma balthica shows potential as an indicator of oil pollution. In experiments designed to simulate stranding of an oil slick on a mudflat, a significant increase in mortality of this species was found to accompany increasing concentration of petroleum in sediment and increasing duration of exposure.