Adaptive Management, Monitoring, and the Ecological Sustainability of a Thermal-Polluted Water Ecosystem: A Case in Sw Spain

The construction of the Almaraz nuclear power plant in Spain in the 1970s posed interesting environmental problems concerning the construction of a cooling reservoir (Arrocampo reservoir) to cool the steam condensers and the consequent heating of the reservoirs water. The socio-political context forced decision makers to set up a project for the monitoring and management of the environmental impacts derived from the construction and operation of the power plant. Numerous scientific and technical specialists collaborated with the representatives of social groups towards two goals: the improvement of the biodiversity and of the efficiency of the cooling system. These goals involved the monitoring and managing of the system with respect to different biological aspects, mainly limnology, ichthyology, avian fauna and vegetation. The management plan yielded numerous results. The control of the water eutrophy is one of the most important due to its repercussion on the rest of the ecosystem, especially the fish fauna. The development of the shore vegetation slowly increased the patchwork nature of the reservoir, leading to a greater diversity of the avian species. This paper describes the monitoring and management of the Arrocampo ecosystem, the condition before and after the construction of the reservoir and the results obtained concerning some biological communities.     

Gully control: Determining treatment priorities for gullies in a network

This report is about a newly developed procedure for setting priorities in gully control. It explains basic gully systems and developments as influenced by geomorphologic processes on which the proposed procedure is based. These processes consist of two types: one, representing interactions between the individual gullies of a network; the other, mechanisms initiated within a given gully by localized instability conditions. Classifying gullies into continuous and discontinuous types not only allows determination of network types but also points to critical locations that must be considered by the designer.The procedure for analyzing gully networks to establish treatment priorities consists of five steps as follows: 1) determining type of network based on gully types; 2) stream ordering of the network gullies; 3) tallying tributaries of each gully; 4) analyzing stage of development of each gully; 5) ranking of treatment priorities.Situations may exist—remote location and negligent downstream effects—where gully control is not desirable and the land manager decides to let nature take its course and to await the establishment of a new stream equilibrium condition before the watershed resources will be intensively utilized. Also political or funding aspects may not permit gully control efforts. Such aspects as well as types of individual treatment measures are beyond the scope of this report. The proposed technique establishes priorities that depend on opportunities to exert greatest control for least cost and to prevent the greatest amount of future erosion.     

Impacts to Water Quality and Fish Habitat Associated with Maintaining Natural Channels for Flood Control

A field investigation conducted on Boulder Creek in Boulder, Colorado evaluated impacts of flood control maintenance activities on flood conveyance, water quality, and fish habitat. Thirty-nine transects were monitored at one control site and two maintenance sites over a period of eight months. Each site was visited on more than 50 occasions in order to characterize pre- and post-maintenance conditions, and to monitor maintenance activities. Measurements along the transects included substrate composition, flow depth, velocity, and elevation. Reach-average values were assigned to variables such as in-stream vegetation, streambank stability, and woody vegetation before and after maintenance. Water temperature, dissolved oxygen, pH, specific conductance, and turbidity were sampled, and habitat suitability indices were developed pre- and post-maintenance for seven indicator fish species. Water quality impacts during maintenance consisted of high turbidity levels (> 400 NTU), which returned to background levels (0.1–15 NTU) overnight, as well as changes in mean temperature and pH. Alteration of physical channel characteristics as a result of maintenance had limited effects on habitat quality for four of seven fish species, but caused improvements in habitat quality for three fish species. The main implications of this study for floodplain management are that: (1) Flood control maintenance practices can be in direct conflict with water quality and fish habitat objectives, and should be carefully designed and implemented by an interdisciplinary team. (2) Physical habitat for some fish species can be improved as well as reduced by maintenance activities. Habitat suitability curves may be useful tools for evaluating limiting factors of the habitat and for identifying opportunities for habitat improvements as part of maintenance.     

Farmers,Streams, Information,and Money: Does Informing Farmers About Riparian Management Have Any Effect?

We assessed relationships between the extent to which farmers reported exposure to relevant information and their attitudes towards, knowledge about, and degree of adoption of riparian management strategies. We also examined associations between knowledge of, or receipt of, financial assistance for riparian fencing/planting and intentions for and extent of adoption of this strategy. A mail survey of 718 pastoral farmers in Otago and Southland in New Zealand [294 surveys returned (41%)] yielded 279 usable questionnaires. Indices were developed to reflect range and frequency of information use and range of practices adopted. Attitudes were measured using Likert-type responses to 11 statements, and knowledge as a score on a ten-question true/false test. Positive relationships between information and the three main response variables (attitude, knowledge, and adoption) were weak but significant and systematic. These associations remained significant when important demographic and farm characteristics were taken into account. Informed farmers were more likely to report intentions to carry out riparian fencing or planting within the next year. Farmers who were aware that funding was available were also more likely to state this intention, independent of information level. The reported extent to which waterways had been fenced to exclude stock was related to receipt of funding, but not to information level. Financial factors were the most influential barrier preventing adoption of permanent fencing. Our research shows a positive correlation between the receipt of information and funding and the adoption of specific riparian management measures.     

A morphological comparison of narrow,low-gradient streams traversing wetland environments to alluvial streams

Twelve morphological features from research on alluvial streams are compared in four narrow, low-gradient wetland streams located in different geographic regions (Connecticut, Indiana, and Wisconsin, USA). All four reaches differed in morphological characteristics in five of the features compared (consistent bend width, bend cross-sectional shape, riffle width compared to pool width, greatest width directly downstream of riffles, and thalweg location), while three reaches differed in two comparisons (mean radius of curvature to width ratio and axial wavelength to width ratio). The remaining five features compared had at least one reach where different characteristics existed. This indicates the possibility of varying morphology for streams traversing wetland areas further supporting the concept that the unique qualities of wetland environments might also influence the controls on fluvial dynamics and the development of streams. If certain morphological features found in streams traversing wetland areas differ from current fluvial principles, then these varying features should be incorporated into future wetland stream design and creation projects. The results warrant further research on other streams traversing wetlands to determine if streams in these environments contain unique morphology and further investigation of the impact of low-energy fluvial processes on morphological development. Possible explanations for the morphology deviations in the study streams and some suggestions for stream design in wetland areas based upon the results and field observations are also presented.     

Landscape-scale spatial population dynamics in human-impacted stream systems

The movement of individuals among populations can be critical in preventing local and landscape-scale species extinctions in systems exposed to human perturbation. Current understanding of spatial population dynamics in streams is largely limited to the reach scale and is therefore inadequate to address species response to spatially extensive perturbation. Using model simulations, I examined species response to perturbation in a drainage composed of multiple, hierarchically arranged stream-patches connected by in-stream and overland pathways of dispersal. Patch extinction probability, the proportion of initially occupied patches extinct after 25 years, was highly sensitive to the extent of species occupancy and perturbation within the drainage, longitudinal species distribution, perturbation decay rate and the covariance pattern of stochastic effects on colonization and extinction probabilities. Results of these simulations underscore the importance of identifying and preserving source populations and dispersal routes for stream species in human-impacted landscapes. They also highlight the vulnerability of headwater specialist taxa to anthropogenic perturbation, and the strong positive effect on species resilience of habitat rehabilitation when recolonization is possible. Efforts to conserve and manage stream species may be greatly improved by accounting for landscape-scale spatial population dynamics.     

A preliminary model of nutrient cycling in sediments of a Mediterranean lagoon

A model of nitrogen and phosphorus cycles in the sediment of a lagoon has been developed. This model was applied to the Thau lagoon (southern France). Sediment was sliced in three layers to reproduce the oxygen profile, which is simulated within the model. Following an equilibrium hypothesis, the model was calibrated against field data. State variables and fluxes were estimated in the sediment and across the sediment-water interface. A Monte Carlo sensitivity analysis was performed to determine the most sensitive parameters and sediment state variables. A dynamic simulation with varying oxygen concentrations then showed the influence of anoxia on the phosphorus and nitrogen fluxes between water and sediment.     

Stream corridor management in the Pacific Northwest: II. Management strategies

King County, Washington is part of the rapidly growing Pacific Northwest region. Analysis of past and current federal, state, and county regulations and administation reveals how stream corridors have been protected to date. This article draws on scientific literature and a case study to suggest future management strategies and guidelines for controlling development in King County watersheds.     

Prognosis of the State of Aquatic Animal Populations under Conditions of Disturbed Ionic Composition of Water

In the crustacean Eudiaptomus gracilisSars, relationships between mortality (D) and the ratio of main cations (R, the ratio of the sum of potassium and sodium equivalent concentrations to the sum of calcium and magnesium equivalent concentrations) were studied. The calculated regression equation D= 315 – 355/Rwas used for predicting the state of E. gracilispopulation in Lake Poppalijarvi (Karelia) polluted with mining waste. At R< 0.47, the population will survive; at R> 1.53, its extinction should be expected. The results of hydrobiological observations on Lake Poppalijarvi confirmed the prognosis based on the equation.     

FOREST‐RIVER INTERACTIONS: INFLUENCE ON HYPORHEIC DISSOLVED ORGANIC CARBON CONCENTRATIONS IN A FLOODPLAIN TERRACE1

ABSTRACT: In large floodplain rivers, hyporheic (subsurface) flow‐paths transfer nutrients from productive riparian terraces to oligotrophic off‐channel habitats. Because dissolved organic carbon (DOC) fuels microbial processes and hyporheic microorganisms represent the first stage of retention and transformation of these nutrients, understanding DOC flux can provide information on the constraints of microbial metabolism in the hyporheic zone of rivers. We monitored hydrology, physicochemical indicators, and dissolved organic carbon (DOC) dynamics during low and high discharge periods in the hyporheic zone of a riparian terrace on the Queets River, Washington, to understand what processes control the supply of carbon to subsurface microbial communities. As discharge increased, terrace hyporheic flowpaths changed from parallel to focused, and the location of surface water inputs to the terrace shifted from the terrace edge to head. Overall, DOC concentrations decreased along hyporheic flowpaths; however, concentrations at points along the flowpaths varied with position along the head gradient and age of the overlying vegetation. We estimated that there is insufficient DOC in adverting surface water to support hyporheic microbial metabolism in this riparian terrace. These trends indicate that there are additional carbon sources to the subsurface water, and we conclude that DOC is leaching from overlying riparian soils within the forest patches. Thus, subsurface DOC concentrations reflect a balance between surface water inputs, metabolic uptake, and allochthonous inputs from forest soils.