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Stream Biota (stream + biota)
Selected AbstractsResponse of secondary production by macroinvertebrates to large wood addition in three Michigan streamsFRESHWATER BIOLOGY, Issue 8 2009SALLY A. ENTREKIN Summary 1.,We measured responses in macroinvertebrate secondary production after large wood additions to three forested headwater streams in the Upper Peninsula of Michigan. These streams had fine-grained sediments and low retention capacity due to low amounts of in-channel wood from a legacy of past logging. We predicted that wood addition would increase macroinvertebrate secondary production by increasing exposed coarse substrate and retention of organic matter. 2.,Large wood (25 logs) was added haphazardly to a 100-m reach in each stream, and a 100-m upstream reach served as control; each reach was sampled monthly, 1 year before and 2 years after wood addition (i.e. BACI design). Macroinvertebrate secondary production was measured 1 year after wood addition in two habitat types: inorganic sediments of the main channel and debris accumulations of leaf litter and small wood. 3.,Overall macroinvertebrate production did not change significantly because each stream responded differently to wood addition. Production increased by 22% in the main-channel of one stream, and showed insignificant changes in the other two streams compared to values before wood addition. Changes in main-channel macroinvertebrate production were related to small changes in substrate composition, which probably affected habitat and periphyton abundance. Macroinvertebrate production was much greater in debris accumulations than in the main-channel, indicating the potential for increased retention of leaf litter to increase overall macroinvertebrate production, especially in autumn. 4.,Surrounding land use, substrate composition, temperature and method of log placement are variables that interact to influence the response of stream biota to wood additions. In most studies, wood additions occur in altered catchments, are rarely monitored, and secondary production is not a common metric. Our results suggest that the time required for measurable changes in geomorphology, organic matter retention, or invertebrate production is likely to take years to achieve, so monitoring should span more than 5 years, and ecosystem metrics, such as macroinvertebrate secondary production, should be incorporated into restoration monitoring programs. [source] Differences in temperature, organic carbon and oxygen consumption among lowland streamsFRESHWATER BIOLOGY, Issue 12 2005KAJ SAND-JENSEN Summary 1. Temperature, organic carbon and oxygen consumption were measured over a year at 13 sites in four lowlands streams within the same region in North Zealand, Denmark with the objectives of determining: (i) spatial and seasonal differences between open streams, forest streams and streams with or without lakes, (ii) factors influencing the temperature dependence of oxygen consumption rate, (iii) consequences of higher temperature and organic content in lake outlets on oxygen consumption rate, and (iv) possible consequences of forecasted global warming on degradation of organic matter. 2. High concentrations of easily degradable dissolved (DOC) and particulate organic carbon (POC) were found in open streams downstream of plankton-rich lakes, while high concentrations of recalcitrant DOC were found in a forest brook draining a forest swamp. Concentrations of predominantly recalcitrant POC and DOC were low in a groundwater-fed forest spring. Overall, DOC concentration was two to 18 times higher than POC concentrations. 3. Oxygen consumption rate at 20 °C was higher during summer than winter, higher in open than shaded streams and higher in lake outlets than inlets. Rate was closely related to concentrations of chlorophyll and POC but not to DOC. The ratio of oxygen consumption rate to total organic concentrations (DOC + POC), serving as a measure of organic degradability, was highest downstream of lakes, intermediate in open streams and lowest in forest streams. 4. Temperature coefficients describing the exponential increase of oxygen consumption rate between 4 and 20 °C averaged 0.121 °C,1 (Q10 of 3.35) in 70 measurements and showed no significant variations between seasons and stream sites or correlations with ambient temperature and organic content. 5. Oxygen consumption rate was enhanced downstream of lakes during summer because of higher temperature and, more significantly, greater concentrations of degradable organic carbon. Oxygen consumption rates were up to seven times higher in the stream with three impoundments than in a neighbouring unshaded stream and 21 times higher than in the groundwater-fed forest spring. 6. A regional climate model has calculated a dramatic 4,5 °C rise in air temperature over Denmark by 2070,2100. If this is realised, unshaded streams are estimated to become 2,3 °C warmer in summer and winter and 5,7 °C warmer in spring and, thereby, increase oxygen consumption rates at ambient temperature by 30,40% and 80,130%, respectively. Faster consumption of organic matter and dissolved oxygen downstream of point sources should increase the likelihood of oxygen stress of the stream biota and lead to the export of less organic matter but more mineralised nutrients to the coastal waters. [source] Relative influence of variables at multiple spatial scales on stream macroinvertebrates in the Northern Lakes and Forest ecoregion, U.S.A.FRESHWATER BIOLOGY, Issue 8 2003Brian M. Weigel Summary 1We used 94 sites within the Northern Lakes and Forests ecoregion spanning Minnesota, Wisconsin and Michigan to identify environmental variables at the catchment, reach and riparian scales that influence stream macroinvertebrates. Redundancy analyses (RDA) found significantly influential variables within each scale and compared their relative importance in structuring macroinvertebrate assemblages. 2Environmental variables included landcover, geology and groundwater delivery estimates at the catchment scale, water chemistry, channel morphology and stream habitat at the reach scale, and landcover influences at three distances perpendicular to the stream at the riparian scale. Macroinvertebrate responses were characterised with 22 assemblage attributes, and the relative abundance and presence/absence of 66 taxa. 3Each scale defined macroinvertebrates along an erosional to depositional gradient. Wisconsin's macroinvertebrate index of biotic integrity, Ephemeroptera,Plecoptera,Trichoptera taxa and erosional taxa corresponded with forest streams, whereas organic pollution tolerant, Chironomidae and depositional taxa corresponded with wetland streams. Reach scale analyses defined the gradient similarly as dissolved oxygen and wide, shallow channels (erosional) opposed instream macrophytes and pool habitats (depositional). Riparian forests within 30 m of the stream coincided with an erosional assemblage and biotic integrity. 4Next, we combined all significant environmental variables across scales to compare the relative influence of each spatial scale on macroinvertebrates. Partial RDA procedures described how much of the explained variance was attributable to each spatial scale and each interrelated scale combination. 5Our results appeared consistent with the concept of hierarchical functioning of scale in which large-scale variables restrict the potential for macroinvertebrate traits or taxa at smaller spatial scales. Catchment and reach variables were equally influential in defining assemblage attributes, whereas the reach scale was more influential in determining relative abundance and presence/absence. 6Ultimately, comprehending the relative influence of catchment and reach scale properties in structuring stream biota will assist prioritising the scale at which to rehabilitate, manage and derive policies for stream ecosystem integrity. [source] Stream Temperature Surges Under Urbanization and Climate Change: Data, Models, and Responses,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 2 2007Kären C. Nelson ABSTRACT: Multiple anthropogenic stressors, including increased watershed imperviousness, destruction of the riparian vegetation, increased siltation, and changes in climate, will impact streams over the coming century. These stressors will alter water temperature, thus influencing ecological processes and stream biota. Quantitative tools are needed to predict the magnitude and direction of altered thermal regimes. Here, empirical relationships were derived to complement a simple model of in-stream temperature [developed by Caissie et al. Canadian Journal of Civil Engineering25 (1998) 250; Journal of Hydrology251 (2001) 14], including seasonal temperature shifts linked to land use, and temperature surges linked to localized rainstorms; surges in temperature averaged about 3.5°C and dissipated over about 3 h. These temperature surges occurred frequently at the most urbanized sites (up to 10% of summer days) and could briefly increase maximum temperature by >7°C. The combination of empirical relationships and model show that headwater streams may be more pervasively impacted by urbanization than by climate change, although the two stressors reinforce each other. A profound community shift, from common cold and coolwater species to some of the many warmwater species currently present in smaller numbers, may be expected, as shown by a count of days on which temperature exceeds the "good growth" range for coldwater species. [source] Buffering an Acidic Stream in New Hampshire with a Silicate MineralRESTORATION ECOLOGY, Issue 3 2004Gene E. Likens Abstract Ground and pelletized Wollastonite (Wo; CaSiO3) was added to a 50-m reach of an anthropogenically acidified stream within the Hubbard Brook Experimental Forest, New Hampshire, to evaluate its buffering and restoration potential. The Wo was highly effective in raising the pH, acid-neutralizing capacity (ANC), dissolved inorganic carbon (DIC), and Ca2+ concentrations of the stream water, but during the short duration of the experiment had no discernable effect on the stream biota. After initial, spike-like fluctuations in pH and concentrations of ANC, DIC, and Ca2+, the relatively slow dissolution rates of the Wo dampened extreme concentrations and contributed to relatively long-lasting (4 months) amelioration of streamwater acidity. Changes in concentrations of Ca2+, dissolved Si, ANC, and DIC were inversely related to streamflow. After several high, stream-discharge events, concentrations quickly and consistently returned to pre-event conditions. [source] Appraising riparian management effects on benthic macroinvertebrates in the Wye River systemAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue S1 2010Esther Clews Abstract 1.Agriculture, urbanization or forestry in river catchments can influence river organisms through diffuse effects on hydrology and hydrochemistry, or local effects on habitat character, bank erosion and sediment delivery. Riparian buffer zones are sometimes established to mitigate undesirable effects on salmonids, but consequences for organisms such as macroinvertebrates are less well known. 2.Riparian fencing and tree coppicing were carried out on upland tributaries of the Welsh River Wye (UK) from 1997 onwards with the aim of enhancing conditions for salmonid fish. The present study used routine, agency monitoring data to compare assemblages in three recently managed streams and five adjacent control streams. Data between 1995 and 2004 were used to assess treatment effects through time. 3.Post-treatment (2000,2004) assemblages were richer in recently managed streams than in controls, mostly due to apparent gains of taxa typical of channel margins and lowland, warmer conditions. However, results were equivocal because invertebrate families typical of lowland, more eutrophic conditions increased in occurrence in all reaches irrespective of treatment, while overall richness declined. 4.This study illustrates how routine monitoring data can reveal some effects of riparian land-use and management on stream biota. However, improved experimental design, ideally using a before,after control,intervention approach, would have allowed more effective assessment in this case study where confounding trends were so marked. We advocate using such approaches in future restoration studies to allow stronger inference and greater statistical power. The recent general decline in the richness of typical headwater organisms in the Wye system requires investigation. Copyright © 2010 John Wiley & Sons, Ltd. [source] | ||||||||||