Bioassessment VI: River Studies
Presiding: B Johnson, U.S. Environmental Protection Agency; M Wooten, ORSANCO
NB44A-01 15:30h
Macroinvertebrates Associated With Dikes in the Mississippi River: Spatial and Temporal Patterns
Fine sediments and rocky substrates are dominant benthic macroinvertebrate habitats in the Mississippi River. We sampled macroinvertebrates in fine sediments downstream of wing dikes on four occasions and on rocks upstream of wing dikes on two occasions. We identified 65 taxa in the fine sediments and 50 taxa on the rocks, with only 26 taxa found in both habitats. Presumably, assemblage differences reflect flow and substrate differences. Assemblages in both habitats exhibited considerable temporal variability. Macroinvertebrate densities in the fine sediments ranged from 3737 to 8706 individuals m-2 y-1, with oligochaetes representing 77-92% of total density. Macroinvertebrate density on the rocks ranged from 57,770 to 162,966 individuals m-2 y-1, with hydropsychid caddisflies (Hydropsyche bidens/orris and Potamyia flava) representing 82-97% of total density. A literature survey found that macroinvertebrate assemblages in large rivers of the Mississippi River Basin (e.g., Upper and Lower Mississippi, Illinois, Ohio, and Missouri Rivers) tend to be dominated by a few taxa. Because of this, we believe that traditional approaches to describing community structure (e.g., species richness, relative abundance) in biological assessments may be insensitive to subtle differences among large river faunas.
NB44A-02 15:45h
Integration of Invertebrate Monitoring Data Into a Chemical-Based Water Quality Index for Selected Rivers in British Columbia, Canada.
The Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI) is a recently developed tool used to summarize complex water quality data for communication to senior managers and the public. Within the index, water quality is assessed relative to its desirable state, as defined by water quality objectives, and indicates the degree to which it is affected by human activities. The index combines water quality measures of concern at a particular site (e.g. coliforms, metals, dissolved oxygen) and compares them to objectives to provide a ranking (e.g. good, fair, poor) for rivers and lakes. In British Columbia, the federal and provincial governments collaboratively maintain a network of water quality stations which are sampled routinely for a range of chemical variables. Environment Canada incorporated an annual biomonitoring component at 10 of these stations using the reference condition approach. Benthic invertebrates are used in this approach to assess the health of a stream by comparing expected invertebrate communities with observed communities. At one station the biological community indicated an impaired environment where the CCME WQI indicated "good" water quality. We will discuss options for incorporating the information provided by the benthic invertebrate community into the calculation of the index.
NB44A-03 16:00h
Biological Assessment of Newfoundland Rivers Based on the Depauperate Macroinvertebrate Fauna With Emphasis on the Mayfly, Stonefly and Caddisfly Fauna: a Cautionary Tale.
The fauna of insular Newfoundland compared to the mainland is depauperate, e.g., 35 spp of mayflies versus about 160 spp in Maine. The question is can this depauperate fauna provide good biomonitoring information? A comparative study using present /absent data from 85 sites in eastern Newfoundland was analyzed with particular reference to the Ephemeroptera, Plecoptera and Trichoptera fauna. The results indicated these data did differentiate regions sampling type and land use when run through a simple Principle Component Analysis (PCA). The PCA 1 and 2 components varied from no to a strong correlation with both Ephemeroptera and Trichoptera richness and taxa richness of the major feeding groups. However, applying previously published biotic indices of species that occur in Newfoundland did not provide satisfactory results. It appears these indices may reflect oxygen gradients rather than pollutant concentrations and in our cold well oxygenated streams yield unsatisfactory discrimination among natural and perturb streams.
NB44A-04 16:15h
A Methods Comparison for Collecting Macroinvertebrates in the Ohio River
Collection of representative benthic macroinvertebrate samples from large rivers has been challenging researchers for many years. The objective of our study was to develop an appropriate method(s) for sampling macroinvertebrates from the Ohio River. Four existing sampling methods were compared in the Markland Pool of the Ohio River (ORM 436.2 - 531.5). Ten sites were sampled in triplicate using Hester-Dendy samplers (H-D), deep Hester-Dendy samplers, multihabitat sweeps (MH), and kick nets. All sites and methods combined produced 167 separate taxa, with H-Ds collecting the highest number of taxa for an individual method with 107 and the MH collecting the lowest with 65. Each method produced taxa unique to a particular sampling method, with only 33 taxa common across all four methods. Although the MH method collected the fewest taxa, it produced the largest amount of unique taxa with 15. Preliminary results indicate that multiple collection methods are necessary for more representative macroinvertebrate surveys in the Ohio River. These resulting field methods will ultimately be used to develop a macroinvertebrate bioassessment protocol for the Ohio River.
NB44A-05 16:30h
Trace Metal Concentrations and Macroinvertebrate Assemblages in Black Shale-Draining Streams
Natural and anthropogenic release of metals into surface waters and sediments may alter benthic community structure. To better understand the effect of trace metals on aquatic communities of black shale-draining streams in Arkansas, we collected water, sediment and macroinvertebrates at 12 sites on black shale-draining streams (BLS) and four sites on a limestone-draining stream (LMS). Trace metal analysis of streamwater and sediments and rapid bioassessment of the macroinvertebrate communities followed US EPA methods and protocols. Concentrations of zinc, cadmium, copper, lead and nickel in BLS water and sediments were significantly (p<0.05) higher than in LMS water and sediments. Concentrations of copper, cadmium, arsenic and nickel in the BLS water exceeded slightly the acute aquatic-life standards. Similarly, concentrations of cadmium, arsenic, lead, zinc, and mercury in BLS sediments exceeded the Effect Range-Low values of the sediment quality guidelines. Total abundance, taxa richness, and percent EPT taxa, were significantly (p< 0.05) lower in the BLS than the LMS. The absence of pollution-sensitive Heptageniidae and Chloroperlidae in the BLS samples was associated with elevated metal concentrations in these sites, but not apart from observed hydrologic and habitat differences. Biological condition scores for BLS and LMS sites categorized the streams as slightly impaired and unimpaired, respectively. This study shows that trace metals released from natural sources such as black shales can cause structural alterations to benthic communities.
http://www.benthos.org
NB44A-06 16:45h
Ecological health monitoring of the Mekong River by using benthic algae in 2003-2004
The monitoring of ecological health of the Mekong River by using benthic algae was carried out from 2003 - 2004. Thirty sampling sites along the Mekong River and its tributaries were selected in Laos, Thailand, Cambodia and Veitnam. In this investigation, the distribution of some species of benthic algae in different environments revealed that there was a significant relationship in the presence of them to the water quality, and these species could be used as a potential biomonitor of water quality in the Mekong River. One hundred and eighty six species of benthic diatoms and 46 species of macroalgae were found. Some dominant species of benthic algae could be used as biomonitors to assess water quality. Hydrodictyon recticulatum and Microspora floccosa and indicated clean-moderate water quality; Audouinella cylindrica, Cladophora glomerata, Achnanthes inflate and Cymbella turgidula indicated moderate water quality; Stigeoclonium flagelliforum, Aulacoseira granulata and Cymbella tumida indicated moderate-polluted water quality and Caloglossa leprieurii, Gomphonema parvulum and Nitzschia clausii indicated polluted water quality. The ecological health assessment of the Mekong River by using the species of benthic algae as biomonitors reveled that in the upstream and tributaries revealed moderate water quality. In contrast, some sites in the lower Mekong showed moderate-polluted to polluted water quality.