▪ Abstract Local habitat and biological diversity of streams and rivers are strongly influenced by landform and land use within the surrounding valley at multiple scales. However, empirical associations between land use and stream response only varyingly succeed in implicating pathways of influence. This is the case for a number of reasons, including (a) covariation of anthropogenic and natural gradients in the landscape; (b) the existence of multiple, scale-dependent mechanisms; (c) nonlinear responses; and (d) the difficulties of separating present-day from historical influences. Further research is needed that examines responses to land use under different management strategies and that employs response variables that have greater diagnostic value than many of the aggregated measures in current use. In every respect, the valley rules the stream.      H.B.N. Hynes (1975)

http://deq.idaho.gov/media/525804-Landscapes_Riverscapes_Influence_landuse_stream_ecosystems_Allan_2004.pdf

Landscapes and Riverscapes: The Influence of Land Use on Stream Ecosystems

The statistical analysis of compositional data

Aim We surveyed the empirical literature to determine how well six diversity hypotheses account for spatial patterns in species richness across varying scales of grain and extent. Location Worldwide. Methods We identified 393 analyses (‘cases’) in 297 publications meeting our criteria. These criteria included the requirement that more than one diversity hypothesis was tested for its relationship with species richness. We grouped variables representing the hypotheses into the following ‘correlate types’: climate/ productivity, environmental heterogeneity, edaphics/nutrients, area, biotic interactions and dispersal/history (colonization limitation or other historical or evolutionary effect). For each case we determined the ‘primary’ variable: the one most strongly correlated with taxon richness. We defined ‘primacy’ as the proportion of cases in which each correlate type was represented by the primary variable, relative to the number of times it was studied. We tested for differences in both primacy and mean coefficient of determination of the primary variable between the hypotheses and between categories of five grouping variables: grain, extent, taxon (animal vs. plant), habitat medium (land vs. water) and insularity (insular vs. connected). Results Climate/productivity had the highest overall primacy, and environmental heterogeneity and dispersal/history had the lowest. Primacy of climate/ productivity was much higher in large-grain and large-extent studies than at smaller scales. It was also higher on land than in water, and much higher in connected systems than in insular ones. For other hypotheses, differences were less pronounced. Throughout, studies on plants and animals showed similar patterns. Coefficients of determination of the primary variables differed little between hypotheses and across the grouping variables, the strongest effects being low means in the smallest grain class and for edaphics/nutrients variables, and a higher mean for water than for land in connected systems but vice versa in insular systems. We highlight areas of data deficiency. Main conclusions Our results support the notion that climate and productivity play an important role in determining species richness at large scales, particularly for non-insular, terrestrial habitats. At smaller extents and grain sizes, the primacy of the different types of correlates appears to differ little from null expectation. In our analysis, dispersal/history is rarely the best correlate of species richness, but this may reflect the difficulty of incorporating historical factors into regression models, and the collinearity between past and current climates. Our findings are consistent with the view that climate determines the capacity for species richness. However, its influence is less evident at smaller spatial scales, probably because (1) studies small in extent tend to sample little climatic range, and (2) at large

ARTICLE Spatial species-richness gradients across scales: a meta-analysis

https://ir.library.oregonstate.edu/downloads/n870zs617

Assessing and addressing the re-eutrophication of Lake Erie: Central basin hypoxia

Diatom ecological guilds display distinct and predictable behavior along nutrient and disturbance gradients in running waters

Introduction Assessments of environmental conditions in rivers and streams with diatoms have a long history, which has resulted in the development of the two basic conceptual and analytical approaches used today. First, based on the work of Kolkwitz and Marsson (1908), autecological indices were developed to infer levels of pollution based on the species composition of assemblages and the ecological preferences and tolerances of taxa (e.g., Butcher, 1947; Fjerdingstad, 1950; Zelinka & Marvan, 1961; Lowe, 1974; Lange-Bertalot, 1979). Second, Patrick's early monitoring studies (Patrick, 1949; Patrick et al ., 1954; Patrick & Strawbridge, 1963) relied primarily on diatom diversity as a general indicator of river health (i.e., ecological integrity), because species composition of assemblages varied seasonally and species richness varied less. Thus, the concepts and tools for assessing ecosystem health and diagnosing causes of impairment in aquatic habitats, particularly rivers and streams, were established and developed between 50 and 100 years ago. The many advances in the use of diatoms and other algae for monitoring stream and river quality have been reviewed by Patrick (1973) and, more recently, by Stevenson and Lowe (1986), Round (1991), Whitton et al . (1991), Coste et al . (1991), Whitton and Kelly (1995), Rosen (1995), and Lowe and Pan (1996). There are three major objectives for this chapter. First, we emphasize the importance of designing environmental assessments so that many approaches are used and results are based on rigorous statistical testing of hypotheses. Second, we review the many characteristics of diatom assemblages that could be used in assessments and the methods and indices of assessment.

Assessing environmental conditions in rivers and streams with diatoms

Benthic diatoms and water chemistry were sampled from 49 stream sites in the Mid- Atlantic Highlands region of the United States to evaluate the use of diatoms as indicators of envi- ronmental conditions in streams across varying geographic and ecoregional areas. Diatom samples were collected from depositional and erosional habitats in a randomly selected reach in each stream site. Patterns of diatom species distributions in relation to environmental variables were determined using canonical correspondence analysis. Diatom species in both habitats were highly correlated with a pH gradient. A second gradient was correlated with variables that were commonly associated with agricultural runoff such as turbidity and total phosphorus. The relationship between diatoms and major environmental variables was quantified with regres- sion and calibration models. The correlation between diatom-inferred and observed pH was high (r2 = 0.90). Cross-validation with jackknifing showed that pH models were reasonably robust (r2 = 0.69 for depositional habitats, r2 = 0.67 for erosional habitats). The regression and calibration models for the depositional habitats had only slightly higher predictive powers than those of erosional habitats. The relationship between diatoms and important environmental variables was robust and quanti- fiable, and the sensitivity of diatom assemblages to environmental conditions did not differ between erosional and depositional habitats. Therefore we concluded that diatoms can be used as quantitative indicators of environmental conditions in lotic systems.

Using diatoms as indicators of ecological conditions in lotic systems: a regional assessment

22 – Benthic Algal Communities as Biological Monitors

We attempted to identify spatial patterns and determinants for benthic algal assemblages in Mid-Atlantic streams. Periphyton, water chemistry, stream physical habitat, riparian conditions, and land cover/use in watersheds were characterized at 89 randomly selected stream sites in the Mid-Atlantic region. Cluster analysis (TWINSPAN) partitioned all sites into six groups on the basis of diatom species composition. Stepwise discriminant function analysis indicated that these diatom groups can be best separated by watershed land cover/use (percentage forest cover), water temperature, and riparian conditions (riparian agricultural activities). However, the diatom-based stream classification did not correspond to Omernik’s ecoregional classification. Algal biomass measured as chl a can be related to nutrients in habitats where other factors do not constrain accumulation. A regression tree model indicated that chl a concentrations in the Mid-Atlantic streams can be best predicted by conductivity, stream slope, total phosphorus, total nitrogen, and riparian canopy coverage. Our data suggest that broad spatial patterns of benthic diatom assemblages can be predicted both by coarse-scale factors, such as land cover/use in watersheds, and by site-specific factors, such as riparian conditions. However, algal biomass measured as chl a was less predictable using a simple regression approach. The regression tree model was effective for showing that ecological determinants of chl a were hierarchical in the Mid-Atlantic streams.

Spatial patterns and ecological determinants of benthic algal assemblages in mid‐atlantic streams, usa

1US Environmental Protection Agency, National Center for Environmental Assessment, 26 W. Martin Luther King Dr., Cincinnati, Ohio 45268 USA 2Department of Zoology, Michigan State University, East Lansing, Michigan 48824 USA 3Environmental Sciences and Resources, Portland State University, Portland, Oregon 97207 USA 4Department of Fisheries and Wildlife, Oregon State University, c/o US Environmental Protection Agency, 200 SW 35th Street, Corvallis, Oregon 97333 USA 5US Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, 200 SW 35th Street, Corvallis, Oregon 97333 USA 6OAO Corporation, c/o US Environmental Protection Agency, 200 SW 35th Street, Corvallis, Oregon 97333 USA

Yangdong Pan

Papers

Assessing environmental conditions in rivers and streams with diatoms

Using diatoms as indicators of ecological conditions in lotic systems: a regional assessment

22 – Benthic Algal Communities as Biological Monitors

Spatial patterns and ecological determinants of benthic algal assemblages in mid‐atlantic streams, usa

Comparison of correlations between environmental characteristics and stream diatom assemblages characterized at genus and species levels