Restoration of an Indiana, USA, stream: bridging the gap between basic and applied lotic ecology

BRIDGES BRIDGES is a recurring feature of J-NABS intended to provide a forum for the interchange of ideas and information between basic and applied researchers in benthic science. Articles in this series Abstract. Stream restoration attempts to reverse the global degradation of rivers and streams, but rigorous evaluations are needed to advance the science. We evaluated a 3 rd -order channelized Indiana (USA) stream that was restored in 1997 by constructing two meanders, each ϳ400 m long. Pool and riffle sequences were constructed, coarse substrate and wood were added to the channel, banks were stabilized and revegetated, and sedimentation was reduced by creating a sediment retention basin upstream. Habitat, periphyton, macroinvertebrates, and fishes were measured before restoration and for 5 y after restoration in the restored reaches and in an upstream, unrestored reach. Restoration improved habitat conditions (e.g., more pools, fewer fine sediments) in both restored reaches compared to the unrestored reach. Within 1 y after restoration, major trophic groups (i.e., periphyton, macroinvertebrates, and fishes) recovered to or exceeded levels in the degraded, unrestored reach. However, biotic responses varied with time, trophic level, and community parameter measured. Five years after the restoration, habitat quality, algal abundance, and macroinvertebrate density remained higher in the restored reaches, whereas macroinvertebrate diversity and fish abundance in the restored reaches were similar to or below levels in the unrestored, channelized reach. Although biotic recovery was relatively rapid, long-term persistence is uncertain because of continued sedimentation at a watershed scale. In many instances, reach-scale restorations may be ineffective in the face of basin-wide degradation. This study illustrates the importance of conducting long-term assessments of stream restorations, which can improve both knowledge and management of stream ecosystems

肥満糖尿病ラットにおける胃バイパス後の選択的腸管刺激による糖代謝への影響

研究科: 医学薬学府学位:千大院医薬博甲第医1000号要約博士(医学)千葉大

Environmental context and contaminant biotransport by Pacific salmon interact to mediate the bioaccumulation of contaminants by stream-resident fish

1. The extent to which environmental context mediates the uptake of biotransported contaminants by stream-resident organisms is not understood. For example, there is no clear understanding of the extent to which contaminant type, instream characteristics, or resident fish identity interact to influence the uptake of contaminants deposited by Pacific salmon (Oncorhynchus spp.) during their spawning runs. 2. To address this uncertainty, we sampled four stream-resident fish species from 13 watersheds of the Laurentian Great Lakes in locations with and without salmon across a gradient of instream and watershed characteristics. We determined the polychlorinated biphenyl (PCB) and mercury (Hg) concentration along with the stable isotope ratio of C and N for each stream-resident fish. 3. We found that stream-resident fish PCB concentrations were 24-fold higher in reaches with salmon and were positively related to δ15N. In contrast, stream-resident fish Hg concentrations were similar or lower in reaches with salmon and either exhibited a negative or no relationship with δ15N. 4. Based upon AICc, stream-resident fish exhibited species-specific PCB concentrations that were positively related to salmon PCB flux. Hg burdens exhibited an interaction between fish length and salmon Hg flux – as salmon Hg inputs increased, Hg levels decreased with increasing resident fish length. We found no support for models that included the mediating influence of instream or watershed factors. Salmon eggs are enriched in PCBs but have very low Hg concentrations, so our results may be driven by the consumption of salmon eggs by stream-resident fish. 5. Synthesis and applications. Our results highlight that contaminants bioaccumulate differently depending on contaminant type, species identity, and the trophic pathway to contamination. Consequently, consideration of the recipient food web and route of exposure is critical to understanding the fate of biotransported contaminants in ecosystems. The transfer of contaminants by migratory organisms represents an understudied stressor in ecology. Effective management of biotransported contaminants will require the delineation of “hot-spots” of biotransport and implementation of best management practices in those watersheds that receive contaminants from spawning salmon

Long-term fish community response to a reach-scale stream restoration

At a global scale, aquatic ecosystems are being altered by human activities at a greater rate than at any other time in history. In recent years, grassroots efforts have generated interest in the restoration of degraded or destroyed aquatic habitats, especially small wetlands and streams where such projects are feasible with local resources. We present ecological management lessons learned from 17 years of monitoring the fish community response to the channel relocation and reach-level restoration of Juday Creek, a 3rd-order tributary of the St. Joseph River in Indiana, USA. The project was designed to increase habitat complexity, reverse the effects of accumulated fine sediment (< 2 mm diameter), and mitigate for the impacts of a new golf course development. The 1997 restoration consisted of new channel construction within two reaches of a 1.2-km section of Juday Creek that also contained two control reaches. A primary social goal of the golf course development and stream restoration was to avoid harm to the non-native brown trout fishery, as symbolic of community concerns for the watershed. Our long-term monitoring effort revealed that, although fine sediment increased over time in the restored reaches, habitat conditions have promoted the resurgence of native fish species. Since restoration, the fish assemblage has shifted from non-native Salmonidae (brown trout, rainbow trout) to native Centrarchidae (rock bass, largemouth bass, smallmouth bass). In addition, native, nongame species have remained stable or have increased in population abundance (e.g., Johnny darter, mottled sculpin). The results of this study demonstrate the value of learning from a restoration project to adjust management decisions that enhance environmental quality

An Evaluation of the Effects of Geothermal Energy Development on Aquatic Biota in the Gysers Area of California

The Geysers of Sonoma County, California, currently the larges geothermal energy field in the world, is expected to expand its electrical generating capacity considerably in the coming years. However, these future developments may result in watershed modification and potentially deleterious effects on aquatic biota due to the topography of the area. Analysis of the response of benthic populations and communities to past and ongoing geothermal energy development and operational practices was undertaken by means of an extensive six site sampling program on Big Sulfur Creek and a concentrated colonization study above, in, and below a heavily impacted tributary (Little Geysers Creek).Differences in species diversity were noted among the six Big Sulfur Creek sites that were selected relative to the presence or absence of natural fumaroles or hot springs and the absence or stage of geothermal energy development. Distribution and colonization patterns of a population of sericostomatid caddisfly, Gumaga nigricula, and especially its dominance in high silt areas, suggest that both siltation and fumarole activity may select for certain populations

The Separation of Thermal and Chemical Effects in Evaluating Geothermal Influences on Aquatic Biota

In this study a field based, stream microcosm system to experimentally separate the effects of the thermal and chemical components of geothermal fluids on the benthic community was developed. Using this system in the separate and combined influences of these components on the numerical abundance of bacteria, the standing crop and productivity of algae, and the density, standing stock, and community structure of macroinvertebrates were evaluated. This microcosm study was designed on the basis of the results from an in-stream study which was a natural comparison of benthic communities in geothermally influenced and uninfluenced stream segments.Additionally, a new type of field experiment to determine the upper lethal temperature thresholds for three insect species found in a geothermally influenced stream was developed. This heat shock experiment simulated acute thermal effects on organisms that drift into the lethal temperature zones that seasonally occur in geothermal streams. It also mimicked the effects of heated effluents on aquatic organisms that are drawn into the cooling water intake of a power plant, or entrained in the discharge plume.Although the in-stream study demonstrated that a moderate addition of geothermal fluids into a non-geothermal stream could substantially alter the structure of the benthic community, the analysis did not establish the cause of the alteration. The stream microcosm study demonstrated that the thermal component of those geothermal fluids had greater influence than the chemical component in determining the structure of the benthic community

Evaluating the Influence of Geochemical Origin and Drought Conditions on Aquatic Biota of The Geysers Known Geothermal Resources Area of California

From 1976-1983, a series of studies were undertaken at The Geysers K.G.R.A. in Sonoma and Lake Counties, California to evaluate the effects of geothermal energy development on aquatic biota at The Geysers. A major objective throughout the eight years of the research project has been to develop quantitative methods to analyze and monitor benthic communities. This report summarizes the methods used and presents examples of the data such approaches have produced.Each report on a sampling approach contains: (1) a summary of the advantages and disadvantages of the device; (2) an illustration of the device; (3) a description of its use either at The Geysers or in pilot studies to test the appropriateness of its use at The Geysers; and (4) a sample data set