Trophic structure of coastal Antarctic food webs associated with changes in sea ice and food supply

Predicting the dynamics of ecosystems requires an understanding of how trophic interactions respond to environmental change. In Antarctic marine ecosystems, food web dynamics are inextricably linked to sea ice conditions that affect the nature and magnitude of primary food sources available to higher trophic levels. Recent attention on the changing sea ice conditions in polar seas highlights the need to better understand how marine food webs respond to changes in such broad-scale environmental drivers. This study investigated the importance of sea ice and advected primary food sources to the structure of benthic food webs in coastal Antarctica. We compared the isotopic composition of several seafloor taxa (including primary producers and invertebrates with a variety of feeding modes) that are widely distributed in the Antarctic. We assessed shifts in the trophic role of numerically dominant benthic omnivores at five coastal Ross Sea locations. These locations vary in primary productivity and food availability, due to their different levels of sea ice cover, and proximity to polynyas and advected primary production. The delta15N signatures and isotope mixing model results for the bivalves Laternula elliptica and Adamussium colbecki and the urchin Sterechinus neumeyeri indicate a shift from consumption of a higher proportion of detritus at locations with more permanent sea ice in the south to more freshly produced algal material associated with proximity to ice-free water in the north and east. The detrital pathways utilized by many benthic species may act to dampen the impacts of large seasonal fluctuations in the availability of primary production. The limiting relationship between sea ice distribution and in situ primary productivity emphasizes the role of connectivity and spatial subsidies of organic matter in fueling the food web. Our results begin to provide a basis for predicting how benthic ecosystems will respond to changes in sea ice persistence and extent along environmental gradients in the high Antarctic.     

Adapting to climate change: the role of organisational personalities in natural resource management

Regional Environmental Change - Preparing for climate change represents a significant challenge to environmental managers and is influenced by their ability to access and use the latest...     

Na+-K+-adenosine triphosphatase activities in gills of marine teleost fishes: Changes with depth,size and locomotory activity level

Activities of the primary enzyme responsible for monovalent ion regulation, Na⁺-K⁺-adenosine triphosphatase (Na⁺-K⁺-ATPase), were measured in gills of marine teleost fishes with different depths of occurrence (0 to 4800 m), body weights (a range of five orders of magnitude), and locomotory capacities. Specimens were collected off the coasts of California and Oregon in 1983–1989, and at the Galápagos Spreading Center and 13°N East Pacific Rise hydrothermal vent sites in 1987 and 1988, respectively. Except for two hydrothermal vent fishes, deep-sea species had much lower Na⁺-K⁺-ATPase activities g^–1 gill filament than shallow-living species, indicating that osmoregulatory costs, like total metabolic rate, are greatly reduced in most deep-living fishes. Within a species, the total branchial Na⁺-K⁺-ATPase activity per individual was dependent on size; the average allometric scaling exponent was 0.83. Using published values for oxygen consumption rates, and the total branchial Na⁺-K⁺-ATPase activities as an index of osmoregulatory costs, we estimated the maximal cost (as percent of ATP turnover) for osmoregulation in ten teleosts. Osmoregulatory costs averaged about 10% of total ATP turnover among these species, and maximal costs were no greater than about 20%. The percent costs of osmoregulation did not differ between shallow- and deep-living fishes. The reduced total ATP expenditure for osmoregulation in deep-living fishes is proposed to result from the sluggish locomotory habits of these fishes, not from selection for reduced osmotic coastper se. Thus, the reduced swimming abilities of these fishes lead to lower rates of water flow over the gills and less blood flow through the gills due to reduced demands for oxygen. Consequently, passive flux of water and ions through the gills is much lower than in more active fishes, and osmotic costs are thereby minimized. The relatively high activities of Na⁺-K⁺-ATPase in gills of the two hydrothermal vent fishes suggest that these fishes may be more active and have higher metabolic rates than other deep-sea fishes.     

Irrigation of treated wastewater in Braunschweig, Germany: an option to remove pharmaceuticals and musk fragrances

In this study the fate of pharmaceuticals and personal care products which are irrigated on arable land with treated municipal wastewater was investigated. In Braunschweig, Germany, wastewater has been irrigated continuously for more than 45 years. In the winter time only the effluent of the sewage treatment plant (STP) of Braunschweig is used for irrigation, while during summer digested sludge is mixed with the effluent. In the present case study six wells and four lysimeters located in one of the irrigated agricultural fields were monitored with regard to the occurrence of 52 pharmaceuticals and two personal care products (PPCPs; e.g. betablockers, antibiotics, antiphlogistics, carbamazepine, musk fragrances, iodinated contrast media (ICM) and estrogens). No differences in PPCP pollution of the groundwater were found due to irrigation of STP effluents with and without addition of digested sludge, because many polar compounds do not sorb to sludge and lipophilic compounds are not mobile in the soil-aquifer. Most of the selected PPCPs were never detected in any of the lysimeter or groundwater samples, although they were present in the treated wastewater irrigated onto the fields. In the groundwater and lysimeter samples primarily the ICM diatrizoate and iopamidol, the antiepileptic carbamazepine and the antibiotic sulfamethoxazole were detected up to several mugl(-1), while the acidic pharmaceuticals, musk fragrances, estrogens and betablockers were likely sorbed or transformed while passing the top soil layer. Potential estrogenic effects are likely to disappear after irrigation, since the most potent steroid estrogens were not measurable.     

Atmospheric heavy metal deposition in Northern Vietnam: Hanoi and Thainguyen case study using the moss biomonitoring technique,INAA and AAS

Background, aim, and scope  

The moss technique is widely used to monitor atmospheric deposition of heavy metals in many countries in Europe, whereas this technique is scarcely used in Asia. To implement this international reliable and cheap methodology in the Asian countries, it is necessary to find proper moss types typical for the Asian environment and suitable for the biomonitoring purposes. Such a case study was undertaken in Vietnam for assessing the environmental situation in strongly contaminated areas using local species of moss Barbula indica.     

The Links Between Resource Dependency and Attitude of Commercial Fishers to Coral Reef Conservation in the Red Sea

The imperative to further constrain extractive uses of natural resources will strengthen as resources degrade through over-use or exposure to climate changes. Here, we explore an approach to increase the support for marine conservation among coral reef fishers. We explore the proposition that resource dependency in the Egyptian Red Sea can act as a barrier to conservation. We administered face-to-face surveys to 49% of the fishing industry to: (i) identify the level of compliance to the local marine protected area (MPA), (ii) assess the level of dependency on marine resources in the region and (iii) examine the relationship between resource dependency and conservation attitudes. Only 11.4% of fishers were aware of the MPA. Fishers were mostly limited in their social flexibility and livelihood options. Results suggest that resource dependency is highly and negatively correlated with conservation attitudes suggesting that management efforts need to seriously focus on reducing dependency if conservation goals are to be met.     

Determination of 14 amines in air samples using midget impingers sampling followed by analysis with ion chromatography in tandem with mass spectrometry

An Ion Chromatography-Mass Spectrometry (IC-MS) method was developed for the simultaneous quantification of 14 volatile amines in air. The method includes collection of compounds into two midget impingers in a row filled with 15 ml of ultrapure water. The analytical performances with mass spectrometry detection were compared to those obtained with classical conductivity detection. The use of mass spectrometry detection (in SIM mode) overcomes most of the coelutions encountered with conductivity detection. Although the linearity domain of calibrations is reduced for the MS detection as compared with the CD detection, the detection limits in MS detection are highly lowered allowing the quantification of amines at the levels of μg m(-3) in air with a good accuracy for most compounds (RSD of less than 10%). This method was successfully applied to the analysis of amines released from polyurethane foams. Seven amines were identified and some in high concentrations, like dimethylaminoethanol, NIAX and TEDA.     

Data fusion modeling for groundwater systems

Engineering projects involving hydrogeology are faced with uncertainties because the earth is heterogeneous, and typical data sets are fragmented and disparate. In theory, predictions provided by computer simulations using calibrated models constrained by geological boundaries provide answers to support management decisions, and geostatistical methods quantify safety margins. In practice, current methods are limited by the data types and models that can be included, computational demands, or simplifying assumptions. Data Fusion Modeling (DFM) removes many of the limitations and is capable of providing data integration and model calibration with quantified uncertainty for a variety of hydrological, geological, and geophysical data types and models. The benefits of DFM for waste management, water supply, and geotechnical applications are savings in time and cost through the ability to produce visual models that fill in missing data and predictive numerical models to aid management optimization. DFM has the ability to update field-scale models in real time using PC or workstation systems and is ideally suited for parallel processing implementation. DFM is a spatial state estimation and system identification methodology that uses three sources of information: measured data, physical laws, and statistical models for uncertainty in spatial heterogeneities. What is new in DFM is the solution of the causality problem in the data assimilation Kalman filter methods to achieve computational practicality. The Kalman filter is generalized by introducing information filter methods due to Bierman coupled with a Markov random field representation for spatial variation. A Bayesian penalty function is implemented with Gauss–Newton methods. This leads to a computational problem similar to numerical simulation of the partial differential equations (PDEs) of groundwater. In fact, extensions of PDE solver ideas to break down computations over space form the computational heart of DFM. State estimates and uncertainties can be computed for heterogeneous hydraulic conductivity fields in multiple geological layers from the usually sparse hydraulic conductivity data and the often more plentiful head data. Further, a system identification theory has been derived based on statistical likelihood principles. A maximum likelihood theory is provided to estimate statistical parameters such as Markov model parameters that determine the geostatistical variogram. Field-scale application of DFM at the DOE Savannah River Site is presented and compared with manual calibration. DFM calibration runs converge in less than 1 h on a Pentium Pro PC for a 3D model with more than 15,000 nodes. Run time is approximately linear with the number of nodes. Furthermore, conditional simulation is used to quantify the statistical variability in model predictions such as contaminant breakthrough curves.     

A Protocol for Plant Conservation by Translocation in Threatened Lowland Fynbos

Abstract: A form of lowland, sandplain Fynbos restricted to the Cape Flats near the city of Cape Town is the South African vegetation type most threatened by urban and agricultural development. Cape Flats Fynbos remnants, totaling 4.8 km², contain 14 plant species endemic to the Cape Flats scattered through four protected areas and 11 unprotected vegetation fragments on public land. Despite their small size and management problems, the remaining protected areas are under pressure from the public and developers to function as "lifeboats," or places of safety, for attractive indigenous plant species from the unprotected areas destined for development because the popular perception is that any indigenous plant population threatened by habitat destruction should be saved by being transplanted into a protected area. The urgency for dealing with the issue of plant rescue in the Cape Town metropolitan area was the catalyst for a workshop held at the University of Cape Town in 1998 to develop protocols for Fynbos plant species translocations. We report on points raised by managers and academics at the workshop, including the selection of target taxa, individuals, and establishment sites, and methods for introduction, and present case histories illustrating possible solutions to the problems encountered.