Mark S. Pearson

A bioassessment approach for mid-continent great rivers: the Upper Mississippi, Missouri, and Ohio (USA)

The objectives of the Environmental Monitoring and Assessment Program for Great River Ecosystems (EMAP-GRE) are to (1) develop and demonstrate, in collaboration with states, an assessment program yielding spatially unbiased estimates of the condition of mid-continent great rivers; (2) evaluate environmental indicators for assessing great rivers; and (3) assess the current condition of selected great river resources. The purpose of this paper is to describe EMAP-GRE using examples based on data collected in 2004–006 with emphasis on an approach to determining reference conditions. EMAP-GRE includes the Upper Mississippi River, the Missouri River, and the Ohio River. Indicators include biotic assemblages (fish, macroinvertebrates, plankton, algae), water chemistry, and aquatic and riparian physical habitat. Reference strata (river reaches for which a single reference expectation is appropriate) were determined by ordination of the fish assemblage and examination of spatial variation in environmental variables. Least disturbed condition of fish assemblages for reference strata was determined by empirical modeling in which we related fish assemblage metrics to a multimetric stressor gradient. We inferred least disturbed condition from the y-intercept, the predicted condition when stress was least. Thresholds for dividing the resource into management-relevant condition classes for biotic indicators were derived using predicted least disturbed condition to set the upper bound on the least disturbed condition class. Also discussed are the outputs of EMAP-GRE, including the assessment document, multimetric indices of condition, and unbiased data supporting state and tribal Clean Water Act reporting, adaptive management, and river restoration.

Multimetric macroinvertebrate indices for mid-continent US great rivers

Abstract We developed a set of great-river macroinvertebrate indices of condition (GRMINs) for the littoral benthos of mid-continent great rivers in the US (Missouri, Upper Mississippi, and Ohio). We used a multiscale (site, reach, landscape), multimetric abiotic stressor gradient to select macroinvertebrate assemblage metrics sensitive to human disturbance. We used the same stressor gradient to derive reference expectations by empirical modeling. We developed GRMINs for each of 5 reaches: the upper Missouri River, the lower Missouri River, the unimpounded Upper Mississippi River, the impounded Upper Mississippi River, and the Ohio River. We created 2 versions of each index. One version was based on the absolute value (AV) of the correlation between invertebrate metrics and the stressor gradient and potentially included all types of metrics (e.g., diversity, composition, tolerance to pollution, feeding guild). The second version included no tolerance-value-based metrics (NTV). Each index included up to 10 metrics. The indices were reliable for general assessment of great-river aquatic conditions except in the unimpounded Upper Mississippi River. The AV and NTV versions of the GRMIN were highly correlated (r  =  0.94). The indices revealed longitudinal variation in condition on great-river reaches and among-river variation in relative condition. No sites near or <100 km downriver of Kansas City, Missouri, on the Missouri River or Minneapolis–St. Paul, Minnesota, on the Upper Mississippi River were in least-disturbed condition. GRMIN indices are an indicator of biotic response to general human disturbance. They are appropriate for local and regional-scale ecological assessments and long-term monitoring.

Multispatial-scale variation in benthic and snag-surface macroinvertebrate assemblages in mid-continent US great rivers

Abstract We sampled macroinvertebrate assemblages in the littoral benthos and on the surface of snags in the Upper Mississippi, Missouri, and Ohio rivers. Snag assemblages differed from benthic assemblages. Tubificids, Caenis, Tanytarsus, Cryptochironomus, Limnodrilus, and Chironomini were consistently more abundant in the benthos; Nais, Cricotopus/Orthocladius, Nematoda, and Rheotanytarsus were consistently more abundant on snags. Filterers were more abundant and gatherers were less abundant on snags than in the benthos. Snag assemblages differed among rivers and among reaches within rivers. Variation among reaches was the result of direct and indirect effects of high-dam reservoir impoundments (upper vs lower Missouri River) and low-dam impoundment for navigation (impounded vs free-flowing Upper Mississippi River). The maximum relative abundance of filterers in the lower Missouri River, which was the only long unregulated reach we studied, was related to particulate organic C and sestonic chlorophyll a concentration, which increased with distance downriver from the lowest main-stem dam. Snag diameter, snag-surface characteristics, and water depth did not affect the composition of snag assemblages, but the dominant taxa on snags in fast-velocity locations were different from the dominant taxa on snags in slow-velocity locations. Relatively few taxa showed strong longitudinal patterns in relative abundance within a reach, and only on the Missouri River. We hypothesize that the many navigation dams on the Ohio and Upper Mississippi rivers suppress the development of environmental gradients and inhibit the formation of longitudinal patterns in macroinvertebrate assemblages. Snag assemblages were dominated by a few taxa (genus-level and higher), a characteristic that might constrain the sensitivity of the assemblages to some human impacts. Sampling snag assemblages has potential for great-river bioassessment, but further research is necessary on sampling methods and sensitivity of assemblages to stressors.

Patterns in habitat and fish assemblages within Great Lakes coastal wetlands and implications for sampling design

Discerning fish–habitat associations at a variety of spatial scales is relevant to evaluating biotic conditions and stressor responses in Great Lakes coastal wetlands. Ordination analyses identified strong, geographically organized associations among anthropogenic stressors and water clarity, vegetation structure, and fish composition at both whole-wetland and within-wetland spatial scales. Lacustrine-protected wetlands were generally internally homogeneous in fish composition, whereas riverine or barrier-beach lagoon wetlands could be more heterogeneous, especially if they had large tributaries and complex morphology or if the mouth area was more directly exposed to the adjacent lake than were other areas. A tendency towards more turbidity-tolerant fish but fewer vegetation spawners, nest guarders, or game and panfish differentiated both more-disturbed from less-disturbed wetlands and open-water from vegetated areas within wetlands. Variation in vegetation structure related to wetland hydromorphology and...

An assessment of stressor extent and biological condition in the North American mid-continent great rivers (USA)

We assessed the North American mid-continent great rivers (Upper Mississippi, Missouri, and Ohio). We estimated the extent of each river in most- (MDC) or least-disturbed condition (LDC) based on multiple biological response indicators: fish and macroinvertebrate, trophic state based on chlorophyll a, macrophyte cover, and exposure of fish-eating wildlife to toxic contaminants in fish tissue (Hg, total chlordane, total DDT, PCBs). We estimated the extent of stressors on each river including nutrients, suspended solids, sediment toxicity, invasive species, and land use (agriculture and impervious surface). All three rivers had a greater percent of their river length in MDC than in LDC based on fish assemblages. The Upper Mississippi River had the greatest percent of river length with eutrophic status. The Ohio River had the greatest percent of river length with fish with tissue contaminant levels toxic to wildlife. Overall, condition indices based on fish assemblages were more sensitive to stress than macroinvertebrate indices. Compared to the streams in its basin, more of the Upper Mississippi and Missouri Rivers were in MDC for nutrients than the Ohio River. Invasive species (Asian carp and Dreissenid mussels) were less widespread and less abundant on the Missouri River than on the other great rivers. The Ohio River had the most urbanized floodplains (greatest percent impervious surface). The Missouri River had the most floodplain agriculture. The effect of large urban areas on river condition was apparent for several indicators. Ecosystem condition based in fish assemblages, trophic state, and fish tissue contamination was related to land use on the floodplain and at the subcatchment scale. This is the first unbiased bioassessment of the mid-continent great rivers in the United States. The indicators, condition thresholds, results, and recommendations from this program are a starting point for improved future great river assessments.

Multimetric Fish Indices for Midcontinent (USA) Great Rivers

Abstract We developed fish assemblage–based multimetric indices as indicators of ecological conditions for the lower Missouri, impounded upper Mississippi, unimpounded upper Mississippi, and Ohio rivers. Using data from 475 daytime electrofishing samples, we calculated 81 candidate fish metrics. We screened these metrics for their range and their responsiveness to a multimetric stressor gradient that included water chemistry, human disturbance, and landscape-scale indicators of human disturbance and stress. Each reach-specific great-river fish index (GRFIn) included 8–10 nonredundant metrics scored on a continuous scale from 0 to 10 (10 = good). No metrics were common to all four GRFIns; one metric (the number of minnow species) was common to three GRFIns. We determined the least disturbed conditions from the y-intercepts of the quantile regressions between the GRFIn scores and the corresponding stressor gradients. Ecological condition as indicated by GRFIn score varied among reaches; 44 ± 8% (95% confide...

Spatial distributions of biophysical conditions on the Ohio River

We examined longitudinal and patchy distributions of water quality, fish assemblage, and land cover metrics from 59 sites on the Ohio River to determine if they were responses to geophysical, biological, and/or anthropogenic constraints. Conceptual models of river ecology hold that longitudinal trends are associated with river size and spatial heterogeneity or patchiness results from interactions between biology and hydromorphology, and in-channel and landscape process. Spatial autocorrelation was used to estimate patch length or the river distance between sites at which conditions are no longer spatially dependent. Significant linear (p 400 km). The exceptionally long patch length of silica suggests its distribution was constrained more by advection than biological assimilation like other nutrients. Turbidity, total suspended sediments, and Secchi depth had similar patch lengths. Their distributions were not related to the positions of dams or tributaries. The relatively small patch lengths for the proportion of fish with deformities or of native species, or of nonindigenous species contrasted with the large patch length for the proportion of detritivores. Patch length of riparian development was less than agriculture and forest suggesting that the distribution of development was relative more constrained by valley walls and vulnerability to flooding. Analyses of the spatial distributions offish, habitat, and water chemistry in large rivers can inform restoration and conservation decisions that maintain or increase biological diversity.