This is a general session covering topics in River and Stream Ecology.
Lead Organizer: Jim Hood, Ohio State University (hood.211@osu.edu)
Presentations
09:00 AM
INVESTIGATING THE IMPACTS OF SOLID PHASE EXTRACTION ON DISSOLVED ORGANIC MATTER OPTICAL SIGNATURES AND THE PAIRING WITH HIGH-RESOLUTION MASS SPECTROMENTRY DATA (7852)
Primary Presenter: Alan Roebuck, Pacific Northwest National Laboratory (alan.roebuck@pnnl.gov)
Advancing our understanding of dissolved organic matter (DOM) in aquatic systems requires cross-platform integration of data streams. Recent studies have shown interest in pairing high resolution molecular data with optical data, an approach that would increase the information capacity of optical data with potential utility in sensor networks. However, solid phase extraction (SPE) pretreatments that accompany high resolution molecular analyses can bias the measured signals, leading to concerns over the ability to adequately derive linkages across platforms. We address this concern by assessing the impact of SPE on the pairing of high-resolution data with optical signatures for 47 samples collected from stream network of varying DOM sources. Pre- and post-SPE samples were characterized by excitation-emission fluorescence with parallel factor analysis (PARAFAC). PARAFAC models were then coupled with complimentary Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) data. A comparison of PARAFAC models revealed no systematic qualitative differences in the DOM composition, although quantitative biases were observed post-SPE due to a better recovery of “humic-like” signatures. Despite the observed quantitative differences, the molecular fingerprint associated with pre- and post-SPE fluorescence components were consistent suggesting that broad-scale linkages could be inferred reliably across FTICR-MS and optical platforms. This work represents a key step forward in the evaluation of cross platform linkages for the characterization of DOM in freshwater systems.
09:15 AM
FLOW ALTERATION IMPACTS RIVER METABOLISM: CAPTURING VARIABILITY AT HABITAT AND REACH SCALES WITHIN A REGULATED TEMPERATE RIVER ECOSYSTEM (7862)
Primary Presenter: Tara McKinnon, University of Nevada, Reno (taramckinnon@unr.edu)
Flow alterations caused by the damming and diverting of rivers and streams have led to notable changes in geomorphology, community composition, and nutrient cycling within these ecosystems. We quantified the metabolic impacts of a water diversion on the reach scale and in individual hydrologic units (riffles and pools) on the Shasta River California USA. We evaluated the river above and below the diversion using chamber incubations to quantify differences across unit types and Bayesian modeling to estimate reach scale metabolism. The below diversion pool unit demonstrated significantly higher rates of respiration, gross primary production, and net primary production (mean change±SD, 0.16±0.01 O2 g/m2, 0.67±0.03 O2 g/m2, 0.04±0.03 O2 g/m2, respectively). The below diversion riffle unit was only significantly different in net primary production, which increased by 0.32±0.08O2 g/m2. When biomass-corrected metabolic rates were considered, only the riffle unit remained significantly increased by the diversion. Reach scale net ecosystem production below the diversion was 27% of ecosystem production above the diversion, indicating a potential increase in CO2 flux out of the river. Our findings indicate that water diversions impact pool and riffle hydrological units differently and may significantly influence reach scale metabolism. Globally, there are many rivers affected by diversions and while our findings are limited to one river, we suggest future research should examine the role of water diversions and their effects on ecosystem metabolism and reach-level function.
09:30 AM
DRIVERS OF PHOSPHORUS SORPTION IN STREAMS ACROSS AN AGRICULTURAL WATERSHED DURING LOW AND HIGH FLOW (8078)
Primary Presenter: Devan Mathie, The Ohio State University (mathie.22@buckeyemail.osu.edu)
Excess dissolved phosphorus (P) exports from agriculturally dominated watersheds can contribute to harmful algal bloom (HAB) growth in lakes. To improve HABs management, we need a better understanding of the in-stream processes that shape dissolved P exports. Stream sediment can, depending upon environmental and sediment characteristics, sorb or desorb P, altering the bioavailability of P loads by altering the concentration of dissolved P. We hypothesized that sorption and desorption rates would differ between low and high flow because runoff delivers new sediment and increases stream water dissolved P. We also expected sorption rates to decline with stream size because sediment in larger streams can be more P saturated. To test these hypotheses, we conducted two surveys focused on P exchange during spring high flow events and summer low flow periods in the Maumee watershed, which plays an important role in shaping Lake Erie HABs. For both surveys, we sampled streams across a size gradient and measured rates of P sorption and desorption in sediment as well as aspects of sediment composition that likely influence exchange rates. Our results indicate that sediment sorbed P under both low flow and high flow. Under low flow, P sorption rate declined with stream size and was related to sediment organic matter and iron content. Under high flow, P sorption rate was not related to stream size or aspects of sediment composition. Our results help clarify factors influencing P sorption rates and could be used to identify streams that play an important role in shaping P exports.
09:45 AM
FINE SCALE MAPPING OF WATER QUALITY ALONG THE ILLINOIS WATERWAY REVEALS SHIFTING TEMPORAL AND SPATIAL GRADIENTS IN BIOGEOCHEMICAL CYCLING AND ECOSYSTEM DYNAMICS (7953)
Primary Presenter: Sophie LaFond-Hudson, USGS (slafond-hudson@usgs.gov)
Water quality in rivers is influenced by inputs from point and non-point sources and by effects of hydrologic and geomorphological features on biogeochemistry and primary production. To investigate temporal and spatial gradients of biogeochemically-active constituents, we used the Fast Limnological Automated Measurements (FLAMe) platform to collect high-resolution spatially continuous sensor data along 550 km of the Illinois Waterway and Chicago Area Waterway Systems from Chicago, IL to the confluence with the Mississippi River near Grafton, IL; five week-long trips were conducted over a 14-month period that spanned a variety of hydrological conditions. Water was pumped onboard a moving boat to a series of water quality sensors logging at 1 Hz, while traveling downriver and into select off-channel features (backwaters, tributaries). Distributions of nitrate, dissolved oxygen, and chlorophyll were analyzed for “hot spots” by comparing their skewness and kurtosis to normal distributions. These hot spot locations consistently occurred in off-channel features. Next, we compared concentration gradients from main channel into off-channel features to determine when and where steepest gradients occurred. For example, steep gradients regularly occurred in the backwater Hansen Lake; chlorophyll increased nearly 10x over 2 km during 4 of 5 campaigns while nitrate gradients ranged from +4 mg/L (spring) to -3 mg/L (late summer). Our results highlight the breadth of spatial gradients that can arise in off-channel features and their importance for understanding water quality in rivers.
10:00 AM
SEDIMENT DRIVES PHOSPHORUS STORAGE IN SMALL AGRICULTURAL STREAMS (8106)
Primary Presenter: Joseph Gentine, The Ohio State University (gentine.3@buckeyemail.osu.edu)
A major driver of eutrophication in aquatic ecosystems is phosphorus (P) pollution. While controlling P loss at its source is important, P export to lakes and estuaries may be influenced by P storage and transformation within lotic ecosystems. However, spatial patterns in P storage in different pools (plants, algae, and sediment) across watersheds has received little attention, but likely varies considerably with flow and stream size. We examined the form, quantity, and location of phosphorus stored in an agriculturally dominated small watershed (20 km2) in northwest Ohio, USA. We measured the P stored in sediment, plant, and algae pools in 15 reaches varying in size and flow regime from grassed waterways to a third order stream. Sediment-P dominated P-pools at all sites regardless of stream type or habitat. Variation in total sediment accounted for the largest amount in variation of total P among sites. The P content of sediment, algae, and plants were similar among pools and reaches. P concentration of plants and algae ranged from less than 1 to 3.5 times the P concentration in sediment. By contrast, sediment mass was 1.3-326 times larger than the plant mass across sites. At each site, more P was associated with sediment than all other pools combined. Additionally, measurements indicate that streambed sediments acted as a phosphorus sink across all sites sampled. In streams with high sediment loads, processes determining sediment stores along the stream reach also drive phosphorus storage.
CS20 - River and Stream Ecology
Description
Time: 9:00 AM
Date: 3/6/2024
Room: Hall of Ideas F