Hot Spots and Hot Moments in Riparian Zones: Potential for Improved Water Quality Management1

Vidon, Philippe, Craig Allan, Douglas Burns, Tim P. Duval, Noel Gurwick, Shreeram Inamdar, Richard Lowrance, Judy Okay, Durelle Scott, and Steve Sebestyen, 2010. Hot Spots and Hot Moments in Riparian Zones: Potential for Improved Water Quality Management. Journal of the American Water Resources Association (JAWRA) 46(2):278-298. DOI: 10.1111/j.1752-1688.2010.00420.x Abstract: Biogeochemical and hydrological processes in riparian zones regulate contaminant movement to receiving waters and often mitigate the impact of upland sources of contaminants on water quality. These heterogeneous processes have recently been conceptualized as “hot spots and moments” of retention, degradation, or production. Nevertheless, studies investigating the importance of hot phenomena (spots and moments) in riparian zones have thus far largely focused on nitrogen (N) despite compelling evidence that a variety of elements, chemicals, and particulate contaminant cycles are subject to the influence of both biogeochemical and transport hot spots and moments. In addition to N, this review summarizes current knowledge for phosphorus, organic matter, pesticides, and mercury across riparian zones, identifies variables controlling the occurrence and magnitude of hot phenomena in riparian zones for these contaminants, and discusses the implications for riparian zone management of recognizing the importance of hot phenomena in annual solute budgets at the watershed scale. Examples are presented to show that biogeochemical process-driven hot spots and moments occur along the stream/riparian zone/upland interface for a wide variety of constituents. A basic understanding of the possible co-occurrence of hot spots and moments for a variety of contaminants in riparian systems will increase our understanding of the influence of riparian zones on water quality and guide management strategies to enhance nutrient or pollutant removal at the landscape scale.     

Advancing objectives-based,integrated ocean management through marine spatial planning: current and future directions on the Scotian Shelf off Nova Scotia,Canada

The national legislative and policy context for integrated ocean management in Canada is provided by the Oceans Act (1996) and the supporting policy statement, Canada’s Oceans Strategy. Under the Oceans Act, Fisheries and Oceans Canada (DFO) is the lead federal authority for ocean affairs and is charged with leading and facilitating the development and implementation of integrated management plans for all marine waters. Integrated management efforts in Canada are being undertaken through an area-based approach that enables marine planning, management and decision making to occur at appropriate spatial scales, from regional to site-specific. This article focuses on the Eastern Scotian Shelf Integrated Management (ESSIM) process, an offshore-focused effort to develop an integrated ocean management plan for a large portion of the Scotian Shelf, off Nova Scotia. The resulting Eastern Scotian Shelf Integrated Ocean Management Plan (the ESSIM plan) has been developed through a collaborative process involving all interested and affected government departments and ocean stakeholders, and provides an objectives-based approach to ocean management. The ESSIM plan contains a set of long-term, overarching goals for collaborative governance and integrated management, sustainable human use, and healthy ecosystems. These goals are supported by more specific objectives that express desired outcomes and conditions for the marine region. The objectives-based approach seeks to ensure that interrelationships among ecosystem and human use objectives are recognized and reflected in the identification of management strategies and supporting actions. This article considers the role of marine spatial planning within the context of the integrated ocean management process underway for the Scotian Shelf. The policy and management context for integrated ocean management in Canada is briefly described and a summary of the ESSIM plan is provided. The current and potential role for marine spatial planning in implementing the objectives and strategies of the ESSIM plan is highlighted using examples related to multiple ocean use and marine conservation and protected area planning. The article concludes by drawing out key lessons learned to date through the ESSIM process for marine spatial planning and looks to the future in terms of the development of tools and approaches for this integral aspect of integrated ocean management.     

The integration of land and marine spatial planning

Whilst spatial planning has evolved as a tool to manage the development and use of the terrestrial environment over decades, the development of spatial planning systems for the marine environment are in their infancy. This paper focuses on the integration of land and marine based spatial planning systems. This is informed by a brief overview of the regional development of the lands and seas of Europe which underlie spatial planning systems and by a discussion of respective spatial planning systems in terms of economic sectors, land use, and sea use. The integration of spatial planning systems is then considered, followed by evaluation of relationships between spatial planning, and the wider field of environmental management. This includes consideration of organisational and geographical scales, technical management including legal aspects, policy, strategic planning and time scales of decision-making. The paper identifies the significant factors which must be considered in the integration of marine and terrestrial planning systems over the coming decades.     

The distribution of triclosan and methyl-triclosan in marine sediments of Barker Inlet, South Australia

In this work, we investigated the transport and burial of triclosan and its methylated derivative, in surface sediments near the mouth of Barker Inlet in South Australia. The most likely source of this commonly used bactericide to the area is a wastewater outfall discharging at the confluence of the inlet with marine waters. Triclosan was detected in all samples, at concentrations (5-27 μg kg(-1)) comparable to values found in other surface sediments under the influence of marine wastewater outfalls. Its dispersal was closely associated with fine and organic-rich fractions of the sediments. Methyl-triclosan was detected in approximately half of the samples at concentrations <11 μg kg(-1). The occurrence of this compound was linked to both wastewater discharges and biological methylation of the parent compound. Wastewater-borne methyl-triclosan had a smaller spatial footprint than triclosan and was mostly deposited in close proximity to the outfall. In situ methylation of triclosan likely occurs at deeper depositional sites, whereas the absence of methyl-triclosan from shallower sediments was potentially explained by photodegradation of the parent compound. Based on partition equilibrium, a concentration of triclosan in the order of 1 μg L(-1) was estimated in sediment porewaters, a value lower than the threshold reported for harmful effects to occur in the couple of species of marine phytoplankton investigated to date. Methyl-triclosan presents a greater potential for bioaccumulation than triclosan, but the implications of its occurrence to aquatic ecosystem health are difficult to predict given the lack of ecotoxicological data in the current literature.     

Do salmon farms increase the concentrations of mercury and other elements in wild fish?

Earlier assessments have suggested that salmon farms may act as a source of mercury (Hg) and other elements in local marine environments. In this study, we measured 30 elements in the livers of demersal Atlantic cod (Gadus morhua) and pelagic saithe (Pollachius virens) caught in association with salmon farms (farm associated [FA]; n = 75) or at reference locations (control; n = 80) in three regions throughout the latitudinal extent of Norway (59-70° N). Concentrations of most elements (24 of 30) were higher (20-70%) in cod compared to saithe. In particular, Hg was 6.8 times higher in cod than saithe. Nine elements were significantly different between FA saithe and control saithe, but only four (Hg, U, Cr and Mn) were highest in FA saithe, and this pattern was only detected consistently across all locations for Hg. Thirteen elements differed in concentration between FA cod and control cod, but only three elements (U, Al and Ba) were higher in FA cod than controls, and this pattern was only detected consistently across all locations for Al. After controlling for a set of potentially confounding variables, the estimated concentrations of Hg in saithe livers were ～80% higher in FA fish compared to controls. In contrast, Hg concentrations were ～40% higher in control cod compared to FA cod. Our results do not support the notion that salmon farms in general increase the concentrations of potentially harmful elements in wild fish, and the distribution of Hg and other elements in cod and saithe in Norwegian coastal waters may be more influenced by habitat use, diet, geochemical conditions and water chemistry.     

Biochar incorporation into pasture soil suppresses in situ nitrous oxide emissions from ruminant urine patches

Nitrous oxide (N2O) emissions from grazing animal excreta are estimated to be responsible for 1.5 Tg of the total 6.7 Tg of anthropogenic N2O emissions. This study was conducted to determine the in situ effect of incorporating biochar, into soil, on N2O emissions from bovine urine patches and associated pasture uptake of N. The effects of biochar rate (0-30 t ha(-1)), following soil incorporation, were investigated on ruminant urine-derived N2O fluxes, N uptake by pasture, and pasture yield. During an 86-d spring-summer period, where irrigation and rainfall occurred, the N2O fluxes from 15N labeled ruminant urine patches were reduced by >50%, after incorporating 30 t ha(-1) of biochar. Taking into account the N2O emissions from the control plots, 30 t ha(-1) ofbiochar reduced the N2O emission factor from urine by 70%. The atom% 15N enrichment of the N2O emitted was lower in the 30 t ha(-1) biochar treatment, indicating less urine-N contributed to the N2O flux. Soil NO3- -N concentrations were lower with increasing biochar rate during the first 30 d following urine deposition. No differences occurred, due to biochar addition, with respect to dry matter yields, herbage N content, or recovery of 15N applied in herbage. Incorporating biochar into the soil can significantly diminish ruminant urine-derived N2O emissions. Further work is required to determine the persistence of the observed effect and to fully understand the mechanism(s) of the observed reduction in N2O fluxes.     

Evaluating the efficacy of adaptive management approaches: Is there a formula for success?

Within the field of natural-resources management, the application of adaptive management is appropriate for complex problems high in uncertainty. Adaptive management is becoming an increasingly popular management-decision tool within the scientific community and has developed into two primary schools of thought: the Resilience-Experimentalist School (with high emphasis on stakeholder involvement, resilience, and highly complex models) and the Decision-Theoretic School (which results in relatively simple models through emphasizing stakeholder involvement for identifying management objectives). Because of these differences, adaptive management plans implemented under each of these schools may yield varying levels of success. We evaluated peer-reviewed literature focused on incorporation of adaptive management to identify components of successful adaptive management plans. Our evaluation included adaptive management elements such as stakeholder involvement, definitions of management objectives and actions, use and complexity of predictive models, and the sequence in which these elements were applied. We also defined a scale of degrees of success to make comparisons between the two adaptive management schools of thought. Our results include the relationship between the adaptive management process documented in the reviewed literature and our defined continuum of successful outcomes. Our data suggest an increase in the number of published articles with substantive discussion of adaptive management from 2000 to 2009 at a mean rate of annual change of 0.92 (r2 = 0.56). Additionally, our examination of data for temporal patterns related to each school resulted in an increase in acknowledgement of the Decision-Theoretic School of thought at a mean annual rate of change of 0.02 (r2 = 0.6679) and a stable acknowledgement for the Resilience-Experimentalist School of thought (r2 = 0.0042; slope = 0.0013). Identifying the elements of successful adaptive management will be advantageous to natural-resources managers considering adaptive management as a decision tool.