Behavioural plasticity in a large marine herbivore: contrasting patterns of depth utilisation between two green turtle (Chelonia mydas) populations

We used time-depth recorders to measure depth utilisation in gravid green turtles (Chelonia mydas) during the internesting period at northern Cyprus (Mediterranean), a nesting area where individuals feed, and at Ascension Island (mid-Atlantic), a nesting area where individuals fast. There were contrasting patterns of depth utilisation between the two sites, illustrating that the behaviour of this species is shaped by local conditions. For example, the amount of time spent shallower than 4 m was 90% at Cyprus but only 31% at Ascension Island, and there was a clear difference between the mean depth at Cyprus (2.7 m, n=9 internesting intervals) versus Ascension Island (9.5 m, n=6 internesting intervals) (t ₅=5.92, P=0.002). At Cyprus, turtles spent the greatest percentage of their time at very shallow depths, where surveys reveated a high abundance of seagrass on which this population feeds. In contrast, the deeper distribution at Ascension Island may reflect the preferred depth for resting on the seabed. Published online: 23 July 2002     

Diethylaminoethyl-cellulose clean-up of a large volume naphthenic acid extract

The Athabasca oil sands of Alberta, Canada contain an estimated 174 billion barrels of bitumen. During oil sands refining processes, an extraction tailings mixture is produced that has been reported as toxic to aquatic organisms and is therefore collected in settling ponds on site. Investigation into the toxicity of these tailings pond waters has identified naphthenic acids (NAs) and their sodium salts as the major toxic components, and a multi-year study has been initiated to identify the principal toxic components within NA mixtures. Future toxicity studies require a large volume of a NA mixture, however, a well-defined bulk extraction technique is not available. This study investigated the use of a weak anion exchanger, diethylaminoethyl-cellulose (DEAE-cellulose), to remove humic-like material present after collecting the organic acid fraction of oil sands tailings pond water. The NA extraction and clean-up procedure proved to be a fast and efficient method to process large volumes of tailings pond water, providing an extraction efficiency of 41.2%. The resulting concentrated NA solution had a composition that differed somewhat from oil sands fresh tailings, with a reduction in the abundance of lower molecular weight NAs being the most significant difference. This reduction was mainly due to the initial acidification of tailings pond water. The DEAE-cellulose treatment had only a minor effect on the NA concentration, no noticeable effect on the NA fingerprint, and no significant effect on the mixture toxicity towards Vibrio fischeri.     

Role of plant activity and contaminant speciation in aquatic plant assimilation of 2,4,5-trichlorophenol

Aquatic plants uptake, transform and sequester organic contaminants and are used as a bioremediation strategy for the removal of pollutants from wastewaters. A better understanding of factors affecting rate of uptake of contaminants by aquatic plants is needed to improve engineered systems for removal of pollutants from wastewaters. This work focused on delineating sorption to plant surfaces and understanding effects of plant metabolic activity, inhibition, and media pH on the uptake of the ionizable contaminant 2,4,5-trichlorophenol (TCP) by aquatic plant Lemna minor. During L. minor exposure to TCP (0.5-13.9 mg l(-1)), a range of plant metabolic activities was measured using oxygen production rate (0-18.4 micromol h(-1)). A positive correlation was shown between contaminant uptake rate and plant activity. Contaminant uptake was examined at a range of media pH values (6-9) and uptake rates were linearly correlated to fraction of contaminant in protonated form. These results demonstrated a link between plant activity and uptake of contaminant by plants and stress the importance of incorporating plant metabolic activity and contaminant speciation in development of natural and engineered phytoremediation systems. This research also indicates that aquatic plants can actively accumulate trace-organic contaminants and may ultimately serve as a sink for these materials in the natural environment.     

Patterns in soil fertility and root herbivory interact to influence fine-root dynamics

Fine-scale soil nutrient enrichment typically stimulates root growth, but it may also increase root herbivory, resulting in trade-offs for plant species and potentially influencing carbon cycling patterns. We used root ingrowth cores to investigate the effects of microsite fertility and root herbivory on root biomass in an aggrading upland forest in the coastal plain of South Carolina, USA. Treatments were randomly assigned to cores from a factorial combination of fertilizer and insecticide. Soil, soil fauna, and roots were removed from the cores at the end of the experiment (8-9 mo), and roots were separated at harvest into three diameter classes. Each diameter class responded differently to fertilizer and insecticide treatments. The finest roots (< 1.0 mm diameter), which comprised well over half of all root biomass, were the only ones to respond significantly to both treatments, increasing when fertilizer and when insecticide were added (each P < 0.0001), with maximum biomass found where the treatments were combined (interaction term significant, P < 0.001). These results suggest that root-feeding insects have a strong influence on root standing crop with stronger herbivore impacts on finer roots and within more fertile microsites. Thus, increased vulnerability to root herbivory is a potentially significant cost of root foraging in nutrient-rich patches.     

Modeling military trampling effects on glacial soils in the humid continental climate of southern New York

The purpose of this research is to create a baseline model of soil compaction response to trampling and a methodology to model the effects of trampling on soil. Although trampling studies have been conducted in the past, the analysis of military training in part provides a different perspective and approach. The data showed bulk densities remained relatively constant for a time and then began to increase at an increasing rate for several hundred passes and finally leveled and remained at or below 1.30 g/cm3 through the remainder of the experiment. Mathematical models were created based on empirical data from a trampling experiment using a more standard logistical growth curve as well as curves based on Weibull and gamma cumulative distribution functions (CDFs). The experiment and the resulting models give quantifiable continuous inference on the effects of trampling, as opposed to the existing qualitative assessments. These baseline models will be the foundation for future studies of land management when trampling occurs.     

Dilemmas and challenges for the shelter sector: lessons learned from the Sphere revision process

Key dilemmas and challenges for those involved in the shelter sector are described, based on issues that emerged from the extensive global consultative process undertaken to inform the revision of the Sphere handbook. The range of perspectives on the major themes is presented, with suggestions as to how these issues could be progressed. Themes include the poor definition of the sector and the lack of a consistent approach among the leading shelter actors; the absence of a common terminology; the conflict between "temporary" versus "durable" solutions; the disconnect between technical advisers and the field; the need for greater recognition of local coping strategies and the local context; the involvement of recipients and host governments in policy development; the need for better "how-to" guidance; and the limited incorporation of the emerging themes of livelihoods etc. to date.     

Assessment of AWT systems in the metro Atlanta area

A study was conducted to evaluate the performance of six advanced wastewater treatment facilities using biological nutrient removal processes as the primary mechanism for removing carbon, nitrogen, and phosphorus from domestic wastewater. One year of operating data was obtained from monthly operating reports provided by the Georgia Environmental Protection Division (EPD) in Atlanta. Additional information about facility operations and the types of chemicals used was gathered through review of EPD files and interviews with plant personnel. Data evaluated were: influent and effluent five-day Biochemical Oxygen Demand (BOD(5)); influent and effluent total suspended solids (TSS); influent Total Kjeldahl Nitrogen and effluent Total Nitrogen; and influent and effluent Total Phosphorus (TP). Although varying from plant to plant, effluent requirements for BOD(5), TSS, ammonia, and TP were met. Chemicals utilized, design capacity, and monthly effluent concentrations are presented in this study.     

Rapid Assessment of Soil Erosion in the Rio Lempa Basin, Central America, Using the Universal Soil Loss Equation and Geographic Information Systems

Soil erosion is a severe problem for many developing regions that lack adequate infrastructure to combat the problem. The authors established a first-order method for prioritizing areas to be examined and remediated using preexisting data and expert knowledge where data are lacking. The Universal Soil Loss Equation was applied to the Rio Lempa Basin in Central America using geographic information systems and remote sensing technologies, and the estimated erosion rates were compared with sediment delivery ratios. Spatial analysis indicates that agriculture on very steep slopes contributes only a small fraction to the total estimated soil erosion, whereas agriculture on gentle and moderately steep slopes contributes a large fraction of the erosion. Although much of the basin is in El Salvador, the greatest estimated amount of erosion is from Honduras. Data quality and availability were impaired by a lack of coordination among agencies and across countries. Several avenues for improving the authors’ methods are described.