Best management practices (BMPs) are widely promoted in agricultural watersheds as a means of improving water quality and ameliorating altered hydrology. We used a paired watershed approach to evaluate whether focused outreach could increase BMP implementation rates and whether BMPs could induce watershed-scale (4000 ha) changes in nutrients, suspended sediment concentrations, or hydrology in an agricultural watershed in central Illinois. Land use was >90% row crop agriculture with extensive subsurface tile drainage. Outreach successfully increased BMP implementation rates for grassed waterways, stream buff ers, and strip-tillage within the treatment watershed, which are designed to reduce surface runoff and soil erosion. No signifi cant changes in nitrate-nitrogen (NO 3 − -N), total phosphorus (TP), dissolved reactive phosphorus, total suspended sediment (TSS), or hydrology were observed after implementation of these BMPs over 7 yr of monitoring. Annual NO 3 − -N export (39-299 Mg) in the two watersheds was equally exported during basefl ow and stormfl ow. Mean annual TP export was similar between the watersheds (3.8 Mg) and was greater for TSS in the treatment (1626 ± 497 Mg) than in the reference (940 ± 327 Mg) watershed. Export of TP and TSS was primarily due to stormfl ow (>85%). Results suggest that the BMPs established during this study were not adequate to override nutrient export from subsurface drainage tiles. Conservation planning in tile-drained agricultural watersheds will require a combination of surface-water BMPs and conservation practices that intercept and retain subsurface agricultural runoff . Our study emphasizes the need to measure conservation outcomes and not just implementation rates of conservation practices.
SUMMARY 1. Growth, reproduction and life‐history parameters were measured for three cladoceran species from a small south‐eastern wetland, U.S.A. Simocephalus serrulatus, Diaphanosoma brachyurum and Scapholeberis mucronata juveniles were reared at temperatures between 10 and 25 °C on natural food resources. 2. Growth rate increased with temperature and decreased with individual size for all three species. Maximum somatic growth rate was higher for Simocephalus (49–72% day−1) and Diaphanosoma (21–91% day−1) than for Scapholeberis (11–45% day−1). Multiple regression equations were developed which predict temperature‐ and mass‐specific growth rates for each species. 3. Scapholeberis egg production was positively related to temperature; however, maximum egg production occurred at intermediate temperatures for Simocephalus and Diaphanosoma. Mean cumulative egg production was higher for Scapholeberis (28–92 eggs per female) than for Simocephalus (18–25 eggs per female) and Diaphanosoma (1–41 eggs per female), and was related to differences in reproductive strategy and survival. 4. Survival was inversely related to temperature in most cases. For all three cladocerans, the intrinsic rate of increase (r) and net reproductive rate (R0) increased with temperature, whereas generation time (G) decreased. Greater egg production by Scapholeberis compared with the other two cladocerans was consistent with higher R0 values for Scapholeberis at any given temperature. Although r was very similar among species, G was typically longer for Scapholeberis than for Simocephalus and Diaphanosoma. 5. This analysis provides basic information about the population parameters of these coexisting wetland species, and the growth rate models can be applied to field data to determine production dynamics.
Increased awareness of the contributions of nonpoint source runoff to the degradation of water quality in the Mississippi River and Gulf of Mexico emphasizes the need to increase conservation practices that reduce nutrient export from agricultural lands. To achieve long-term conservation goals in agricultural landscapes, it is important to understand farmers' perspectives on what practices are effective, practical, and economically attainable. We conducted a series of surveys, interspersed with focused outreach, of farmers in two agricultural watersheds in central Illinois in an attempt to better understand how outreach influenced their views on and adoption of conservation practices. Programs differed between the two watersheds in terms of the levels of intensity at which outreach efforts were conducted. Survey results suggest that more intensive outreach efforts, such as one-on-one landowner visits, localized workshops, and tours, can increase adoption of conservation practices associated with cost-share programs. Technical and financial assistance provided in a timely manner that did not interfere with planting and harvesting were major incentives among farmers in both watersheds to participate in cost-share conservation programs. Primary disincentives among farmers to enroll in cost-share programs were associated with multiple programmatic changes and complex application processes. Results indicate that there remains a need for outreach that increases awareness and implementation of conservation and best management practices specific to reducing agricultural runoff from tile-drained sources. Mitigation of nonpoint runoff will also require more effective management of nitrogen application rates and timing in order to conserve freshwater resources in Midwest agricultural landscapes and downstream waters. Integrated outreach teams comprised of stakeholders and local conservation agencies may lead to successful outreach efforts and reduce demands on limited conservation agency staff time. Key words: agriculture-best management practices-nitrogen-outreach effectiveness-streamThroughout the Midwest United States, there is increasing pressure to alter agricultural practices in ways that reduce nutrient exports to the Mississippi River and the Gulf of Mexico. Although numerous state, federal, and nongovernmental agencies are working with landowners and farmers to address nutrient reduction, nonpoint source runoff from agricultural lands remains a major source of water quality impairment to freshwater (USEPA 2000) and marine (Turner and Rabalais 1994; Goolsby et al. 1999;Raloff 2004) (Lutz et al. 1984;Napier 2001;Wossink and Osmond 2002;Baerenklau 2005;Doll and Jackson 2009). This perspective posits that farmers are unlikely to adopt conservation production practices that have potential to reduce farm profit without adequate compensatory incentive payments. Collectively, these studies highlight the need to target soil and water conservation efforts that are tailored to reflect the farm economics and enviro...
The flood pulse drives primary productivity, biotic communities, and abiotic processes in large river systems; however, the effects of floods on restored floodplain lakes and associated wetlands are poorly understood. Record flooding of the Illinois River, Illinois, in 2013 reconnected two floodplain preserves under restoration that had been disconnected from the river by levees for[80 years. Differences in hydrological connections between sites created a natural experiment where field-based data collection could be employed to document flood effects. Levee failure and subsequent river connection at Merwin Preserve increased nutrient capture and floodwater retention, shifted microbial and invertebrate communities, increased fish species richness, spawning and nursery habitat, and stimulated production of moistsoil plant communities during summer drawdown that provided foraging habitat for spring-migrating waterfowl. However, increased hydrologic connectivity during the growing season resulted in loss of submersed vegetation and habitat for autumn-migrating waterfowl. In contrast, river water overtopped the levee at Emiquon Preserve during a 6-day event that resulted in marginal changes in the bacterial community and negligible changes in water quality and community diversity. Tradeoffs among ecological services should be carefully considered when Electronic supplementary material The online version of this article
1. In contrast to extensive studies of zooplankton in lakes, the role of microcrustaceans in wetlands is not well studied. In this study, spatial and temporal patterns of microcrustacean assemblage structure and secondary production were quantified over a 2-year period in a southeastern U.S.A. wetland. 2. Thirty-two species, including 19 cladocerans, 10 copepods and three ostracods, generated different temporal patterns of density and production between vegetated (Nymphaea) and non-vegetated (open-water) zones reflecting species-specific differences in life histories. 3. Summer assemblages were dominated by small, planktonic filter-feeders, typified by high annual production ⁄ biomass (P ⁄ B) and daily production. In contrast, winter assemblages were dominated by larger, epibenthic detritivores with low P ⁄ B and high biomass. Seasonal shifts in the relative importance of planktonic species in the warmer months to benthic and epiphytic species in the cooler months suggest that energy flow pathways through microcrustaceans may vary seasonally. 4. Total annual production was higher during both years in the Nymphaea zone (13.0 g and 13.6 g DM m )2 year )1 ) than the open-water (8.2 and 6.3 g DM m )2 year )1 ), and was similar between years for the entire wetland pond (12.3 and 12.2 g DM m )2 year )1 ). 5. Although wetland ecosystems have been the subject of considerable ecological research in the past 20 years, our study is one of the few to demonstrate a highly diverse and relatively productive microcrustacean assemblage. Such comprehensive production studies can be used to quantify the ecological importance of microcrustaceans in freshwater wetland ecosystems.
Daphnia lumholtzi comprises a substantial component of the zooplankton community during mid-to late-summer in Lake Chautauqua, a floodplain lake along the Illinois River near Havana, Illinois. In order to quantify the utilization of D. lumholtzi by juvenile fishes, diet analyses were conducted for seven juvenile fish species collected from Lake Chautauqua during the 2001 annual drawdown period. Freshwater drum Aplodinotus grunniens and emerald shiner Notropis atherinoides demonstrated negative selectivity for D. lumholtzi relative to native zooplankton species whereas four species of fish (bluegill Lepomis macrochirus, white bass Morone chrysops, white crappie Pomoxis annularis and black crappie Pomoxis nigromaculatus) consumed substantial amounts of D. lumholtzi. Although selectivity values for D. lumholtzi varied among these fish species, positive selection for D. lumholtzi increased similarly among larger size classes of each fish species, and corresponded with ontogenetic shifts in diet. Mean body length of D. lumholtzi consumed by 20-69 mm L T juvenile fishes ranged from 0Á75 to 0Á99 mm with a calculated total length range of 2Á0-2Á6 mm. Results from this study provide evidence that high abundances of D. lumholtzi in mid-to late-summer provide an additional food source for several juvenile fish species during a time when abundances of large native cladoceran species (i.e. Daphnia) are low, and juvenile fishes are searching for larger prey associated with ontogenetic shifts from zooplankton to macroinvertebrates and fishes. Because zooplankton production is typically lower in rivers than in lakes, survivorship of juvenile fishes produced in floodplain lakes may be higher in riverine systems if they are not reliant on zooplankton as a primary food resource. Therefore, high abundances of D. lumholtzi may benefit juvenile fishes in managed floodplain lakes, such as Lake Chautauqua, by increasing growth and facilitating the transition from zooplanktivory to insectivory or piscivory.
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