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Macroinvertebrate Samples (macroinvertebrate + sample)
Selected AbstractsStream food web response to a salmon carcass analogue addition in two central Idaho, U.S.A. streamsFRESHWATER BIOLOGY, Issue 3 2008ANDRE E. KOHLER Summary 1. Pacific salmon and steelhead once contributed large amounts of marine-derived carbon, nitrogen and phosphorus to freshwater ecosystems in the Pacific Northwest of the United States of America (California, Oregon, Washington and Idaho). Declines in historically abundant anadromous salmonid populations represent a significant loss of returning nutrients across a large spatial scale. Recently, a manufactured salmon carcass analogue was developed and tested as a safe and effective method of delivering nutrients to freshwater and linked riparian ecosystems where marine-derived nutrients have been reduced or eliminated. 2. We compared four streams: two reference and two treatment streams using salmon carcass analogue(s) (SCA) as a treatment. Response variables measured included: surface streamwater chemistry; nutrient limitation status; carbon and nitrogen stable isotopes; periphyton chlorophyll a and ash-free dry mass (AFDM); macroinvertebrate density and biomass; and leaf litter decomposition rates. Within each stream, upstream reference and downstream treatment reaches were sampled 1 year before, during, and 1 year after the addition of SCA. 3. Periphyton chlorophyll a and AFDM and macroinvertebrate biomass were significantly higher in stream reaches treated with SCA. Enriched stable isotope (,15N) signatures were observed in periphyton and macroinvertebrate samples collected from treatment reaches in both treatment streams, indicating trophic transfer from SCA to consumers. Densities of Ephemerellidae, Elmidae and Brachycentridae were significantly higher in treatment reaches. Macroinvertebrate community composition and structure, as measured by taxonomic richness and diversity, did not appear to respond significantly to SCA treatment. Leaf breakdown rates were variable among treatment streams: significantly higher in one stream treatment reach but not the other. Salmon carcass analogue treatments had no detectable effect on measured water chemistry variables. 4. Our results suggest that SCA addition successfully increased periphyton and macroinvertebrate biomass with no detectable response in streamwater nutrient concentrations. Correspondingly, no change in nutrient limitation status was detected based on dissolved inorganic nitrogen to soluble reactive phosphorus ratios (DIN/SRP) and nutrient-diffusing substrata experiments. Salmon carcass analogues appear to increase freshwater productivity. 5. Salmon carcass analogues represent a pathogen-free nutrient enhancement tool that mimics natural trophic transfer pathways, can be manufactured using recycled fish products, and is easily transported; however, salmon carcass analogues should not be viewed as a replacement for naturally spawning salmon and the important ecological processes they provide. [source] The use of indicator taxa as representatives of communities in bioassessmentFRESHWATER BIOLOGY, Issue 8 2005R. C. NIJBOER Summary 1. Sampling and processing of benthic macroinvertebrate samples is time consuming and expensive. Although a number of cost-cutting options exist, a frequently asked question is how representative a subset of data is of the whole community, in particular in areas where habitat diversity is high (like Dutch surface water habitats). 2. Weighted averaging was used to reassign 650 samples to a typology of 40 community types, testing the representativeness of different subsets of data: (i) four different types of data (presence/absence, raw, 2log- and ln-transformed abundance), (ii) three subsets of ,indicator' taxa (taxa with indicator weights 4,12, 7,12, and 10,12) and (iii) single taxonomic groups (n = 14) by determining the classification error. 3. 2log- and ln-transformed abundances resulted in the lowest classification error, whilst the use of qualitative data resulted in a reduction of 10% of the samples assigned to their original community type compared to the use of ln-transformed abundance data. 4. Samples from community types with a high number of unique indicator taxa had the lowest classification error, and classification error increased as similarity among community types increased. Using a subset of indicator taxa resulted in a maximum increase of the classification error of 15% when only taxa with an indicator weight 10,12 were included (error = 49.1%). 5. Use of single taxonomic groups resulted in high classification error, the lowest classification error was found using Trichoptera (68%), and was related to the frequency of the taxonomic group among samples and the indicator weights of the taxa. 6. Our findings that the use of qualitative data, subsets of indicator taxa or single taxonomic groups resulted in high classification error implies low taxonomic redundancy, and supports the use of all taxa in characterising a macroinvertebrate community, in particular in areas where habitat diversity is high. [source] USING 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] Littoral macroinvertebrates as indicators of lake acidification within the UKAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue S1 2010Ben McFarland Abstract 1.The Water Framework Directive (WFD) requires the assessment of acidification in sensitive water bodies. Chemical and littoral macroinvertebrate samples were collected to assess acidification of clear and humic lakes in the UK. 2.Of three acid-sensitive metrics that were regressed against acid neutralizing capacity (ANC) and pH, highly significant responses were detected using the Lake Acidification Macroinvertebrate Metric (LAMM). This metric was used to assign high, good, moderate, poor and bad status classes, as required by the WFD. 3.In clear-water lakes, macroinvertebrate changes with increasing acidification did not indicate any discontinuities, so a chemical model was used to define boundaries. In humic lakes, biological data were able to indicate a distinct, good,moderate boundary between classes. 4.Humic lakes had significantly lower pH than clear lakes in the same class, not only at the good,moderate boundary where different methods were used to set boundaries, but also at the high,good boundary, where the same chemical modelling was used for both lake types. These findings support the hypothesis that toxic effects are reduced on waters rich in dissolved organic carbon (DOC). 5.A typology is needed that splits humic and clear lakes to avoid naturally acidic lakes from being inappropriately labelled as acidified. 6.Validation using data from independent lakes demonstrated that the LAMM is transportable, with predicted environmental quality ratios (EQRs) derived from mean observed ANC, accurately reflecting the observed EQR and final status class. 7.Detecting and quantifying acidification is important for conservation, in the context of appropriate restoration, for example, by ensuring that naturally acid lakes are not treated as anthropogenically acidified. Copyright © 2009 John Wiley & Sons, Ltd and Crown Copyright 2009 [source] | ||||||||||