Home About us Contact
|
Home About us Contact | ||
|
|
||
Control Streams (control + stream)
Selected AbstractsUSING STREAM BIOASSESSMENT PROTOCOLS TO MONITOR IMPACTS OF A CONFINED SWINE OPERATION,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 3 2006Jeffrey Jack ABSTRACT: The processing of waste from confined animal feeding operations (CAFOs) presents a major environmental challenge. Treatment of waste and subsequent land application is a common best management practice (BMP) for these operations in Kentucky, USA, but there are few data assessing the effect of runoff from such operations on aquatic communities. The authors sampled a stream bordering a CAFO with a land application program to determine if runoff from the fertilized fields was adversely affecting stream communities. Water chemistry, periphyton, and macroinvertebrate samples from riffle habitats downstream of the CAFO were compared to samples collected from an upstream site and a control stream in 1999 and 2000. Riffle communities downstream of the fertilized fields had higher chlorophyll a levels than other sites, but there were no significant differences in macroinvertebrate numbers or in biometrics such as taxa richness among the sites. The BMP in place at this site may be effective in reducing this CAFO's impact on the stream; however, similar assessments at other CAFO sites should be done to assess their impacts. Functional measures such as nutrient retention and litter decomposition of streams impacted by CAFOs should also be investigated to ensure that these operations are not adversely affecting stream communities. [source] Effects of sand sedimentation on the macroinvertebrate fauna of lowland streams: are the effects consistent?FRESHWATER BIOLOGY, Issue 1 2006BARBARA J. DOWNES Summary 1. In lowland streams sand sedimentation can produce sand slugs: very slow moving, discrete volumes of sand that are created episodically. Hypothetically, such sedimentation causes losses of habitat and fauna but little is known about the effects of sand slugs. In south-eastern Australia sand slugs are widespread, especially in streams with granitic catchments. 2. This study in north-central Victoria was centred on three streams that rise in the Strathbogie Ranges and flow out onto lowland plains, where they contain sand slugs. Below the sand slugs, the streams are slow-flowing ,chains of ponds' with a clay streambed. To correct for potential upstream-downstream confounding of comparisons, two unsanded, nearby streams were included as potential controls. Habitat measurements and faunal samples were taken in Spring 1998, from three sites in the sand slug and three sites in the clay-bed, downstream sections of each impacted stream, as well as from three sites in commensurate upstream and downstream sections of the control streams. 3. The sand-slugged sections had significantly higher velocities, shallower depths and less coarse woody debris than the unsanded downstream sections. Macroinvertebrate taxon richness and abundance showed some significant differences between the sand and clay sections compared with commensurate up- and downstream locations in the control streams. Effects were not uniform, however. In Castle Creek there were no significant differences between the sand and clay sections, in Pranjip-Ninemile Creek taxon richness and abundances were higher in sand than in the clay sections, whereas in Creightons Creek the ,expected' results of lower taxon richness and abundance in the sand were found. 4. Of the 40 most common taxa, only eight provided a clear signal related to sand and, of these, one (Slavina sp.) occurred only in the sand slugs, whereas the other seven had significantly higher numbers in the clay sections. Of these taxa, three were ostracods, three were chironomids and one was a tubificid oligochaete, all taxa that live in detritus-rich environments. Overall faunal composition did not show a clear distinction though, between sandy and clay sites. The sand slug community of Creightons Creek was very different from the other communities in all of the streams. There were clear differences in community composition between the sand-affected and the control streams, even for downstream, clay sections, suggesting they cannot act as controls for the impacted sections of the sand-slugged streams. 5. Differences between streams within categories (particularly between sand-slugged streams) and between sites in the same section of stream accounted for most of the variability in species richness and the abundances of each of the 40 most common taxa. That finding was repeated when data were examined at the family level, for both numbers of families per sample and collated lists of families occurring across sites. These results strongly suggest that the effects of sedimentation by sand slugs do not overwhelm background variation in macroinvertebrate density and diversity. Overall the results suggest that many taxa may respond individually, and that there is much variation between sand-affected streams even over relatively small (approximately <10 km) spatial scales. [source] Net spinning caddisflies as stream ecosystem engineers: the influence of Hydropsyche on benthic substrate stabilityFUNCTIONAL ECOLOGY, Issue 3 2004B. J. CARDINALE Summary 1Organisms that physically modify or create habitat (ecosystem engineers) can have a profound influence on community and ecosystem dynamics. 2Here evidence is presented that one of the most abundant and widely distributed lotic insects could act as an ecosystem engineer in streams by increasing the stability of benthic substrates during flooding. 3Natural densities of larval net spinning caddisflies (Hydropsychidae) were established in stream channels that had standardized physical properties. The mobility of three particle sizes were measured during simulated flooding and the fraction of particles eroded compared with that of control streams. 4Larvae increased the initial velocity required to erode sediments by 10,30%. At velocities sufficient to scour 87% of particles from control channels, 57,100% remained stable in channels colonized by larvae. 5Assuming larvae have similar effects in natural streams, caddisflies could be expected to increase the recurrence interval of a substrate scouring flood from 1·67 year to 2·41 year, corresponding to a 17% decrease in the probability of bed scour per year. 6Our study suggests these insects could play an important role in generating the spatial ,refuges' that moderate the resistance of lotic communities to flooding. It is argued that, as has occurred in marine systems, a better understanding of how freshwater organisms engineer their physical environment has much potential to complement our historical focus on the abiotic forces that constrain populations and communities. [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] | ||||||||||