Structural changes in lake functioning induced from nutrient loading and climate variability

Climate variability is increasingly recognized as an important regulatory factor, capable of influencing the structural properties of aquatic ecosystems. Lakes appear to be particularly sensitive to the ecological impacts of climate variability, and several long time series have shown a close coupling between climate, lake thermal properties and individual organism physiology, population abundance, community structure, and food web dynamics. Thus, understanding the complex interplay among meteorological forcing, hydrological variability, and ecosystem functioning is essential for improving the credibility of model-based water resources/fisheries management. Our objective herein is to examine the relative importance of the ecological mechanisms underlying plankton seasonal variability in Lake Washington, Washington State (USA), over a 35-year period (1964–1998). Our analysis is founded upon an intermediate complexity plankton model that is used to reproduce the limiting nutrient (phosphate)–phytoplankton–zooplankton–detritus (particulate phosphorus) dynamics in the lake. Model parameterization is based on a Bayesian calibration scheme that offers insights into the degree of information the data contain about model inputs and allows obtaining predictions along with uncertainty bounds for modeled output variables. The model accurately reproduces the key seasonal planktonic patterns in Lake Washington and provides realistic estimates of predictive uncertainty for water quality variables of environmental management interest. A principal component analysis of the annual estimates of the underlying ecological processes highlighted the significant role of the phosphorus recycling stemming from the zooplankton excretion on the planktonic food web variability. We also identified a moderately significant signature of the local climatic conditions (air temperature) on phytoplankton growth (r = 0.41), herbivorous grazing (r = 0.38), and detritus mineralization (r = 0.39). Our study seeks linkages with the conceptual food web model proposed by Hampton et al. [Hampton, S.E., Scheuerell, M.D., Schindler, D.E., 2006b. Coalescence in the Lake Washington story: interaction strengths in a planktonic food web. Limnol. Oceanogr. 51, 2042–2051.] to emphasize the “bottom-up” control of the Lake Washington plankton phenology. The posterior predictive distributions of the plankton model are also used to assess the exceedance frequency and confidence of compliance with total phosphorus (15 μg L⁻¹) and chlorophyll a (4 μg L⁻¹) threshold levels during the summer-stratified period in Lake Washington. Finally, we conclude by underscoring the importance of explicitly acknowledging the uncertainty in ecological forecasts to the management of freshwater ecosystems under a changing global environment.     

Evaluating and managing wildlife impacts of climate change under uncertainty

Wildlife managers face the daunting task of managing wildlife in light of uncertainty about the nature and extent of future climate change and variability and its potential adverse impacts on wildlife. A conceptual framework is developed for managing wildlife under such uncertainty. The framework uses fuzzy logic to test hypotheses about the extent of the wildlife impacts of past climate change and variability, and fuzzy multiple attribute evaluation to determine best compensatory management actions for adaptively managing the potential adverse impacts of future climate change and variability on wildlife. A compensatory management action is one that can offset some of the potential adverse impacts of climate change and variability on wildlife. Implementation of the proposed framework requires wildlife managers to: (1) select climate impact states, hypotheses about climate impact states, possible management actions for alleviating adverse wildlife impacts of climate change and variability, and future climate change scenarios; (2) choose biological attributes or indicators of species integrity; (3) adjust those attributes for changes in non-climatic variables; (4) define linguistic variables and associated triangular fuzzy numbers for rating both the acceptability of biological conditions under alternative management actions and the relative importance of biological attributes; (5) select minimum or maximum acceptable levels of the attributes and reliability levels for chance constraints on the biological attributes; and (6) define fuzzy sets on the extent of species integrity and biological conditions and select a fuzzy relation between species integrity and biological conditions. A constructed example is used to illustrate a hypothetical application of the framework by a wildlife management team. An overall best compensatory management action across all climate change scenarios is determined using the minimax regret criterion, which is appropriate when the management team cannot assign or is unwilling to assign probabilities to the future climate change scenarios. Application of the framework can be simplified and expedited by incorporating it in a web-based, interactive, decision support tool.     

RIPARIAN ZONE CLASSIFICATION FOR MANAGEMENT OF STREAM WATER QUALITY AND ECOSYSTEM HEALTH1

ABSTRACT: Riparian zones perform a variety of biophysical functions that can be managed to reduce the effects of land use on instream habitat and water quality. However, the functions and human uses of riparian zones vary with biophysical factors such as landform, vegetation, and position along the stream continuum. These variations mean that “one size fits all” approaches to riparian management can be ineffective for reducing land use impacts. Thus riparian management planning at the watershed scale requires a framework that can consider spatial differences in riparian functions and human uses We describe a pilot riparian zone classification developed to provide such a framework for riparian management in two diverse river systems in the Waikato region of New Zealand. Ten classes of riparian zones were identified that differed sufficiently in their biophysical features to require different management. Generic “first steps” and “best practical” riparian management recommendations and associated costs were developed for each riparian class. The classification aims to not only improve our understanding of the effectiveness of riparian zone management as a watershed management tool among water managers and land owners, but to also provide a basis for deciding on management actions.     

Tropical arboreal ant mosaics: innate attraction and imprinting determine nest site selection in dominant ants

The modalities of nest site selection have, until now, been a key factor missing in the understanding of the arboreal ant mosaic, the manipulation of which could be used to favour one ant species to the detriment of others in biological control. We compared two dominant African arboreal ants of economic importance, Tetramorium aculeatum (Myrmicinae) and Oecophylla longinoda (Formicinae). The two species differed in terms of innate attraction to nesting site plants, their hierarchies of attractiveness being nearly inverse. Winged females and workers were confronted with choice tests using four plant species. By using winged females and workers originating from one of the plants to be tested, we showed the existence of a familiarisation process which can supersede innate attraction in both species. We recorded the same effect in neonatal workers bred in the laboratory in contact with a tested plant for 25 days after emergence, while mature workers could not be conditioned. There is, therefore, early learning, with a sensitive period after which the influence of the environment ceases, suggesting that this is a true imprinting process. Choice tests using neonates produced from larvae and pupae bred in the laboratory in contact with the leaves of each tested plant permitted us to demonstrate the existence of pre-imaginal learning. Nest site selection therefore depends on innate selective attraction and on environmental factors whose effect begins at the larval stage. There is, therefore, the potential to “control” imprinting, allowing one ant species to be favoured to the detriment of others in monospecific tree crop plantations. Received: 25 May 1998 / Accepted after revision: 9 October 1998     

COVID-19: the impact of a global crisis on sustainable development teaching

Environment, Development and Sustainability - The COVID-19 pandemic has caused a global crisis, one which also influences the ways sustainability is being taught at universities. This paper...     

Privileged Narratives and Fictions of Consent in Environmental Discourse

In selecting six keywords from the environmental discourse the authors argue that language's 'double motivation' reveals a dialectical structure through which it simultaneously expresses both a utopian narrative and an ideologically driven myth of totality and consensus. The ambiguity of these keywords is of critical significance to all those involved in the environmental discourse, for without agreement on the meaning of commonly used concepts effective policy development is potentially disabled. The keywords we explore are 'community', 'sustainability', 'globalisation', 'diversity', 'democracy' and 'environment' itself.     

Estimating PAH sources in harbor sediments using diagnostic ratios

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the global environment and are subsequently transported into aquatic sediments. As PAHs are formed by various processes, source identification using diagnostic ratios can provide insight to PAH emission sources to distinguish between pyrogenic and petrogenic PAH sources. PAH diagnostic ratios were applied as a forensic source apportionment technique to assess aggregate historical sediment data from 31 small craft harbors (SCHs) across Nova Scotia, Canada. Multiple diagnostic ratios suggest that PAHs present in Nova Scotia SCH sediments are pyrogenic (combustion) in origin, while consistently suggesting that coal‐related PAH sources are potential dominant specific sources. National Institute of Standards and Technology Standard Reference Materials (SRMs) were used as reference for coal tar, urban dust, and diesel exhaust particulates in ratio applications. The SRM for coal tar was most similar to Nova Scotia SCH sediments in multiple ratio applications. Diagnostic ratio results were corroborated by comparing the PAH profile of sediments to source profiles from the literature. Results indicate that Nova Scotia SCH sediments follow global trends by exhibiting a dominant pyrogenic PAH signature, and the specific coal‐related PAH signature of Nova Scotia SCH sediments may be influenced by contamination inputs related to historical industrial coal mining and combustion activities in the province.     

The transition to a sustainable society: a new social contract

This paper explores issues that are central to ecological economics. In spite of a substantial body of research and other literature that has appeared in recent decades on transition, and countless other efforts, no progress has been made to halt the increase in global warming, global emissions, rampant population growth, or several hundred other critical planet sustainability indicators including global species extinction. The opposite is true. Consumption has escalated and it is poised to double and, with it, planetary decay has followed closely. The aim of this work is to introduce a pragmatic solution and the economics mechanisms solidly rooted in science, in the laws of conservation of mass and energy, and in environmental and ecological sustainability that are necessary to overcome the tremendous forces of social, political, and economic resistance to major change. To advance towards a sustainable civilization, adopting a holistic approach with those underlying principles in all aspects of human activity, among others economy, finance, industry, commerce, engineering, politics, architecture, and education, is both lacking and fundamentally required. A short review of the state-of-the-art of the science on the critical status of the planet’s resources and its life-supporting systems is presented, as well as a brief catalog of the seminal works of the science that gave rise to its metrics and established early on the groundwork for the understanding of the degree of sustainability of the planet. We present the argument why past and current schemes of human economics, organization, culture, and politics cannot achieve anything else, but complete and utter failure under their own underlying precepts. A rigorous and disciplined process on how to overcome and avoid the precipitous decline and collapse of the environmental and planetary biosystems on which all life depends, including human life, and a new view towards the world and the universe we all have no choice but to live in, are also offered.     

Pilot study investigating ambient air toxics emissions near a Canadian kraft pulp and paper facility in Pictou County,Nova Scotia

Environmental Science and Pollution Research - Air toxics are airborne pollutants known or suspected to cause cancer or other serious health effects, including certain volatile organic compounds...