Integrating Hydrology and Ecology for Watershed Research II
Presiding: E Romanowicz, Plattsburgh State University; T Mihuc, Plattsburgh State University
NB52B-01 INVITED 10:30h
Quantifying Hydrologic Parameters in Basin-Scale Ecosystem Research: the Adirondack Story
How does one quantify hydrologic processes related to open channel flow and basin drainage at spatial and temporal scales suitable for ecosystem research? This is a very important question as more and more research brings together the disciplines of hydrology and ecology. Differences in the types of parameters measured, spatial and temporal variations of these parameters and the nature of field procedures between hydrological and ecological research results in different scales of study. Linkages between hydrology, geomorphology and ecology are easily identified. Ecological communities in streams are affected in part by the following stream characteristics: depth, water velocity, ponding and water quality. These stream characteristics are affected by processes or characteristics occurring at very different scales (e.g. bedrock, soils, soil depth, stream bed material, channel morphology, vegetation, topography, and climate). How do we apply these different processes and scales to extrapolate hydrologic data from specific points to a basin scale? As part of an NSF funded research project (DEB 022165) to study the effects of land use policy on hydrologic, ecologic and water quality indicators of watershed integrity we instrumented 22 basins in the eastern Adirondack Mountains (New York) to monitor water stage, water temperature and air temperature. Stage recorders with temperature sensors were installed in stilling wells adjacent to natural stream channels. Stage-discharge rating curves were developed for each site to estimate stream discharge as a function of stage. Streams in the Adirondacks tend to very flashy due to low infiltration capacity in the drainage basins. Consequently, streams respond quickly to storm events, making it difficult to quantify discharges at peak flows. The rating curves are better at predicting base flow discharge, however, there is insufficient data to estimate peak discharge from stage data. In this presentation we will discuss the issue of different spatial and temporal scales in hydrology and ecology. We will address specifically how one may extrapolate hydrologic data from open channel flow and basins to study ecological connections at different scales.
NB52B-02 INVITED 10:45h
Effects of Logging on Macroinvertebrate Responses to Watershed- and Patch-Scale Habitat Characteristics in the Adirondack Uplands
Watershed characteristics and land use practices can affect stream habitats at a variety of scales. A suite of variables describing watershed geomorphology (area, circularity, slope, elevation, aspect, soil depth, surficial geology), surface water hydrology (drainage density, baseflow discharge, `flashiness', groundwater influx, water velocity), and channel habitat (slope, width, depth, substrate particle size, stored and transported organic matter, transported sediment) were determined using GIS and field surveys in 19 upland Adirondack (New York) watersheds with differing land use. Watershed geomorphology was similar between land use types. However, Forest Preserve streams tended to have deeper and wider channels, despite steeper channel slopes, while streams in logged watersheds had more stored organic matter and finer substrate. 177 macroinvertebrate taxa were recorded in the streams, and taxa richness was significantly reduced in managed watersheds (p=0.006). 27 taxa showed a bias toward Preserve sites, while 9 were more common in managed streams (chi-square, p<0.10). Distributions of these taxa were related to channel geomorphology and particle size at the patch scale, and watershed circularity, ground and surface water drainage patterns, and inorganic sediment load at the watershed scale. Invertebrate distributions were affected both by land use patterns and watershed-scale geomorphologic variables.
NB52B-03 11:00h
Influence of Geology on Benthic Macroinvertebrate Assemblages: a Field Experiment Examining Differences in Fitness With Water Hardness
The composition of benthic macroinvertebrate assemblages is associated with catchment geology, with soft-water streams having restricted fauna and hard-water streams having greater diversity and abundance. We hypothesized that these patterns arise because of differences between taxa in osmoregulatory ability, with taxa found primarily in hard water having lower fitness in soft water, and taxa found in soft water having similar fitness in both types of water. To test this hypothesis, we exposed 13 taxa found across a range of water hardness to naturally occurring soft and hard water in streamside microcosms for three months. For each taxon, we measured 3 components of fitness (survival, growth rates, and adult emergence success). Responses of most species were consistent with our hypothesis. However, the hard-water taxon Hydroptila had equal survival between treatments and 50% greater emergence success in soft water. In this case, we suspect that osmoregulatory effects on fitness occur in earlier instars than used in this experiment. Although more information is needed to conclude osmoregulation limits the distribution of taxa, the direct effect of water chemistry on fitness provides a mechanism for the influence of catchment geology on stream invertebrate taxa.
NB52B-04 INVITED 11:15h
Hydrological disturbance benefits native fish at the expense of exotic fish
Many of New Zealand's native fish do not coexist with introduced salmonids. Previous studies of disjunct distributions of exotic brown trout and native galaxiids in the Taieri River demonstrated native extirpation except where major waterfalls prevented trout upstream migration. In the nearby Manuherikia River, waterfalls are not significant and we predicted water abstraction for irrigation might mediate non-overlapping distributions. We used multivariate analyses to test for differences in environmental conditions (catchment and instream scales) in sympatry and allopatry, and a supervised artificial neural network to identify factors mediating non-overlapping distributions (139 sites). Brown trout are capable of reaching most locations in the Manuherikia catchment, and often occur upstream of Galaxias anomalus. In this river, their largely disjunct distributions are mediated by water abstraction for irrigation, together with pool habitat and valley slope. Brown trout are more susceptible than the natives to stresses associated with low flows and high temperatures and it seems trout are prevented from eliminating galaxiid populations from sites in low gradient streams where there is a high level of water abstraction. In contrast to many reports in the literature, hydrological disturbance associated with human activity benefits native fish at the expense of exotics in the Manuherikia River.
NB52B-05 11:30h
Segment and Reach Scale Geomorphology and Associated Fish Assemblages in the Cheyenne River Basin
We used bankfull width, maximum bankfull depth, reach slope, and median substrate particle size to characterize 58 stream reaches in the Cheyenne River Basin, South Dakota including the mainstem Belle Fourche and Cheyenne rivers and their tributaries. We collected fishes from all reaches to investigate correspondence between geomorphology and fish assemblage composition. Cluster analysis grouped 56 reaches into medium-river, small-river, flat-stream, and steep-stream groups. Small- and medium-river reaches were sequential along the lower mainstem Belle Fourche and Cheyenne rivers. Flat- and steep-stream reaches were intermixed among tributary streams and the upper mainstems. We collected a total of 38 fish species. Ten favored riverine reaches and 10 others favored flat- or steep-stream reaches. Species richness and faunal similarity (Morisita's Index) were highest in small-river reaches and lowest in flat- and steep-stream reaches. Small-river reaches had the most distinct fish assemblage with relatively high species richness and faunal similarity. Environmental harshness and isolation from stable (source) fish assemblages apparently reduced richness and faunal similarity among flat- and steep-stream fish assemblages. This suggests faunal composition of stream reaches would be difficult to predict despite habitat similarity.
NB52B-06 INVITED 11:45h
Macroinvertebrate Responses to Wetland Hydrogeomorphic Classes in the Laurentian Great Lakes
As part of a larger research project on Great Lakes coastal wetlands, we investigated whether macroinvertebrate assemblages differ with varying amounts of lake and river influence. Wetlands were classified as open lacustrine (most exposed to wave action, no significant river influence; n=29), protected (little exposure to either wave or river influence; n=22), or riverine (influenced by a second order or larger stream, varying exposure to wave action; n=30). Macroinvertebrates were collected using dip nets in 2002 and 2003. Indirect gradient analyses revealed differences in macroinvertebrate assemblages related both to wetland type and to ecological province. Open lacustrine wetlands (characterized by larger average particle sizes, less soft sediment, and more open water) had the lowest macroinvertebrate diversity. Riverine wetlands contained more rheophilic taxa and had the highest invertebrate and vegetative diversity. Protected wetlands had intermediate invertebrate and vegetative diversity. We propose that wave action creates a harsher physical environment and limits fine sediment and organic matter accumulation, all leading to lower invertebrate diversity. Invertebrate and vegetative diversity are maximized by sediment and organic matter deposition and flow heterogeneity from connected streams. Ecoprovincal differences in macroinvertebrate assemblages may reflect regional patterns of anthropogenic activity in addition to biogeographic patterns.
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