Miniaturized test system for soil respiration induced by volatile pollutants

A miniaturized method based on 96-well microtitre plates was developed and used to study respiration in pristine and contaminated soils following addition of volatile substrates. Small soil samples were exposed to fuel components, which were volatilized from spatially separate reservoirs of 2,2,4,4,6,8,8-heptamethylnonane (HMN) as an organic carrier. Respiration was determined as CO(2) production by means of a pH-indicator and bicarbonate-containing agar, or as (14)CO(2) evolution from (14)C-labelled substrates. Substrate concentrations inducing maximum microbial activity or inhibition were determined and CO(2) production profiles examined by multivariate analysis. When high concentrations of fuel components were applied, distinction of hydrocarbon exposed soils from unexposed soil was achieved within 6 h of incubation. With low concentrations, adequate distinction was achieved after 24 h, probably as a result of community adaptation. Nutrient limitation was identified with the (14)C method for toluene, and the optimal N and P amendment determined. Further potential applications of this rapid and inexpensive method are outlined.     

Conceptual frameworks and key questions for assessing the contribution of marine protected areas to shark and ray conservation

Marine protected areas (MPAs) are key tools in addressing the global decline of sharks and rays, and marine parks and shark sanctuaries of various configurations have been established to conserve shark populations. However, assessments of their efficacy are compromised by inconsistent terminology, lack of standardized approaches to assess how MPAs contribute to shark and ray conservation, and ambiguity about how to integrate movement data in assessment processes. We devised a conceptual framework to standardize key terms (e.g., protection, contribution, potential impact, risk, threat) and used the concept of portfolio risk to identify key attributes of sharks and rays (assets), the threats they face (portfolio risk), and the specific role of MPAs in risk mitigation (insurance). Movement data can be integrated into the process by informing risk exposure and mitigation through MPAs. The framework is operationalized by posing 8 key questions that prompt practitioners to consider the assessment scope, MPA type and purpose, range of existing and potential threats, species biology and ecology, and management and operational contexts. Ultimately, MPA contributions to shark and ray conservation differ according to a complex set of human and natural factors and interactions that should be carefully considered in MPA design, implementation, and evaluation.