Lack of theoretical basis for predicting rate and pathways of recovery

An inadequate basis for precisely predicting the outcome of lotic ecosystem recovery, whether due to unaided natural processes or management techniques or both, exists because: (1) the field of ecology has not yet matured as a rigorous predictive science; (2) the precise sequence of events, including climatic occurrences, affecting the recovery process may be unique events and thus rarely or never repeated; and (3) even when attempts are made to control the recolonization process through introduction of species, etc., the interaction of these species may not follow deterministic models. Although this symposium focuses on lotic ecosystems, such systems are influenced strongly by exports from the surrounding land mass and, under certain circumstances, this may be the overriding influence on the recovery process; therefore, unless the boundary conditions are determined realistically, the recovery process may not follow desirable pathways. Despite the lack of a robust theoretical support base for lotic ecosystem recovery, some remarkable and rapid recoveries have occurred to either a close approximation of the original condition or to a condition ecologically superior to the damaged condition. In some cases, the recovery was due entirely to natural processes and, in others, often followed relatively straightforward management practices. There is evidence indicating that lotic ecosystem restoration is both cost effective and likely to produce satisfying results relatively rapidly. It is both fortunate that this is the case, since society is likely to support such efforts when the results have been extraordinarily successful, and unfortunate since restoration ecology needs a predictive capability.     

Seasonal evolution of gas-phase PCB concentrations in the Venice Lagoon area

The concentrations of gas-phase PCBs were measured from March 2002 to June 2003 at two sites of the Venice Lagoon and at one site of the Euganei hills. The aims of this study were to evaluate the various gas-phase PCB sources, the spatial and temporal variability of PCB concentrations in the gas-phase that enter the Venice Lagoon atmosphere and the influence of the air temperature on PCB trends. The highest annual average concentration of summation PCBs was observed at the station directly influenced by "urban" sources with values about 3 and 1.5 times higher compared to the concentrations found at the stations where "marine" sources and "not subjected to direct local sources" were respectively sampled from. The temporal trends of summation PCBs concentrations were similar at the three sampling stations corresponding to seasonal temperature changes. Greater concentrations occurred in the summer and first autumn months while the lower ones occurred in late autumn and winter. The temperature dependences were investigated using plots of the natural logarithm of the summation PCBs concentrations vs. reciprocal mean temperatures.     

Is the quest for sustainable use of the planet unworldly?

SUMMARY

Is the quest for sustainable use of the planet utopian and unworldly, or an act of enlightened self-interest? Few would label the attempts to increase human longevity unworldly, yet what significance will it have in an unsustainable world? Achieving sustainability will require entire societies to emulate attributes that humans profess to admire in others. Among the dictionary definitions of unworldly are: not seeking material advantage, and spiritually minded. Since our global life-support system is vulnerable to irresponsible individual and societal practices, the consequences of unethical behaviour and lack of compassion might well be catastrophic for human society. This paper consists of a preliminary exploration of some of these issues.     

A COMPARISON OF METHODS AND INSTRUMENTATION OF BIOLOGICAL EARLY WARNING SYSTEMS1

ABSTRACT: Rapid biological information systems using aquatic organisms to monitor water and waste water quality have only recently begun to develop technologically for practical on-site applications. One approach which has been demonstrating its feasibility recently monitors the ventilatory behavior of fish to assess, for example, the quality of drinking water supplies and industrial waste water discharges. A comparison of the basic strategies of the various biological monitoring systems making use of this concept is presented. In addition, the applications and potential utilization of these systems are discussed.     

Management options for rehabilitation and enhancement of surface-mined ecosystems

There are four basic management options for surface-mined land: (a)restoration to original condition; (b)rehabilitation of some desirable characteristics; (c) development ofalternative ecosystems that may be quite unlike the original but may be desirable for a variety of reasons; (d)neglect ornatural reclamation when evidence suggests that unaided natural processes will produce better results than human intervention. Checklists are provided so that essential information will be available in selecting the most suitable option.     

Ecological considerations in reclaiming surface mined lands

The opportunities for, and ecological problems of, reclaiming surfaced-mined land are reviewed. It is suggested that existing methods permit the achievement of ecologically viable goals, although further research would be beneficial. However, an ecologically improved condition will only rarely reproduce the original condition and acceptance of this philosophy will entail compromise by both ecologists and mine operators.     

A SYSTEM FOR RECORDING AND PROCESSING TAXONOMIC DATA1

ABSTRACT: A system in which taxonomic information is recorded in a form that can be directly utilized by computer is described. How such a system can greatly facilitate the acquisition and analysis of data is also discussed.