NU Water-Related Research in Lancaster County

Phenological* change of plants is an indication of local and regional climate change, independent of the instrumentation records and associated bias/error. Although some phenological changes have been identified for native and perennial species and used to infer climate change in various regions of the world, little has been known for changes in agricultural plants/crops. This study examined change in the heading or flowering date of a winter wheat cultivar, Kharkof, over 70 years at six locations in the U.S. Great Plains, including Lincoln, Nebraska.

Results showed that the heading or flowering date of the Kharkof occurred 6-10 days earlier in 2004 than in 1948. Because the heading or flowering date of winter wheat is primarily a function of spring temperatures (Xue et al., 2004), the earlier heading or flowering dates indicate warmer spring season temperatures in the region. Further analysis of temperatures showed that this heading or flowering date shift to earlier time is significantly correlated with the increase in spring season (March-May) daily minimum temperatures. Although this signal of warmer spring daily minimum temperatures is obtained from the instrumental records, the confirmation of this signal by changes in the heading or flowering date offers independent evidence for the temperature change, free of possible instrumentation biases or errors. This warming temperature signal is further supported by the result showing a trivial relationship between the heading or flowering dates and winter and spring precipitation at all the study locations. This trivial correlation with precipitation (Q. Hu et al. / Agricultural and Forest Meteorology 135 (2005) 284-290 289) points to rising minimum daily temperatures as the sole explanation of the earlier winter wheat heading dates.

*Phenology is the science dealing with the influence of climate on the recurrence of such annual phenomena of animal and plant life as budding and bird migrations.

Paul Hanson, School of Natural Resources / Conservation and Survey Division, phanson2@unl.edu; Sue Lackey, School of Natural Resources / Conservation and Survey Divison, slackey1@unl.edu; Matt Marxsen, School of Natural Resources / Conservation and Survey Division, mmarxsen2@unl.edu

Dana Divine, ENWRA Project Coordinator, ddivine@lpsnrd.org

Visit the Nebraska Maps and More website (http://nebraskamaps.unl.edu/home.asp) to order an excellent publication that describes this project more in-depth, Bulletin 1: Eastern Nebraska Water Resources Assessment (ENWRA) Introduction to a Hydrogeological Study.

Eastern Nebraska contains 70% of the state's population, but is most limited in terms of the state's groundwater supplies. The population in this region is expected to increase; thus the need for reliable water supplies is paramount. Natural resources districts (NRDs), charged with ground water management in Nebraska, seek to improve their management plans in response to growing populations, hydrologic drought, and new conjunctive management laws. Detailed mapping and characterization is necessary to delineate aquifers, assess their degree of hydrologic connection with streams and other aquifers, and better predict water quality and quantity.

In a collaborative effort between local, state, and federal agencies, the ENWRA project has been initiated to gain a clearer understanding of the region's groundwater and interconnected surface water resources. These resources can be difficult to characterize because of the complex geology created by past glaciations. Acquiring geologic and hydrologic data in the eastern, or glaciated, part of Nebraska requires the use of multiple, innovative techniques. Currently, little is known about which techniques are most effective and feasible. Once identified, the most effective and feasible tools will be used to provide data, interpretations, and models for improved water resources management.

The ENWRA group has established three pilot test sites for intensive study using a variety of investigative techniques. The goal of the initial work being done at the three pilot test sites is to determine the location, extent, and connectivity of aquifers with surface waters, with the hope of expanding these investigative techniques across other portions of eastern Nebraska. The pilot test sites are located near Oakland, Ashland, and Firth with each site exhibiting differing geologic conditions. The techniques that will be utilized in the study include: 1) helicopter electromagnetic (HEM) surveys; 2) ground-based geophysical surveys; 3) test hole drilling; and 4) geochemical analysis, just to name a few. So far HEM surveys were completed over approximately one township at each site. Other techniques were used to provide "ground truth" data to support the HEM interpretations.

The agencies involved in the ENWRA are:

• Lower Platte South Natural Resources District
• Lower Platte North Natural Resources District
• Papio Missouri River Natural Resources District
• Lower Elkhorn Natural Resources District
• Lewis and Clark Natural Resources District
• Nemaha Natural Resources District
• United States Geological Survey
• University of Nebraska Lincoln Conservation and Survey Division
• Nebraska Department of Natural Resources
• Nebraska Department of Environmental Quality

Remote sensing is a useful tool for providing regulatory officials with the data necessary to make decisions regarding recreational waters. In 2005, CALMIT scientists undertook a collaborative effort with the Nebraska Department of Environmental Quality aimed at developing a tool to identify lakes where blue-green algae populations are present. The overall purpose was to incorporate those affected lakes into a toxic-algae alert procedure to provide early warnings to the public about the potential danger. This project also served to promote coordination and information sharing about toxic-algae issues among local units of government, lake associations, lake owners, and the public.

Both in-situ (close-range) and remote techniques were employed to detect and quantify in real-time the algal phytoplankton pigment concentration and composition (i.e., chlorophyll-a and phycocyanin in the water column). Two criteria were used to identify lakes and reservoirs with high probability of toxic algae: 1) chlorophyll concentration above 50 mg/m3; and 2) existence of blue green algae (the phycocyanin absorption feature has been used to indicate remotely the presence of blue-green algae). These criteria were tested by analytical assessment of toxic algae and the tests were positive: when the sensor systems indicated high probability of toxins, they were found in water samples.

Reduction in range and abundance of shovelnose sturgeon Scaphirhynchus platorynchus over the past century has been primarily attributed to critical habitat loss, poor water quality, and overharvest. These declines have led to concerns about populations of this once ubiquitous sturgeon species in large rivers throughout their Mississippi River Basin-wide range. However, detailed analyses of shovelnose sturgeon populations do not exist in several potentially important portions of their range, such as the Platte River, Nebraska. Shovelnose sturgeon, for example have been documented in the Lower Platte River, Nebraska (i.e., Columbus, NE to Plattsmouth, NE), but little is known about their population dynamics. Additionally, indications that seasonal fishing pressure in the Lower Platte River may affect local abundances, growth and mortality rates, and age at maturity of shovelnose sturgeon create a need for obtaining more specific population information. Researchers have initiated a five year study of the shovelnose sturgeon population in the Lower Platte River to characterize the abundance, distribution, demography, population dynamics, and genetics of shovelnose sturgeon. For preliminary data from the first year of sampling, view the presentation via the website like below.

Click here to read Tara Anderson's Master's Thesis on Shovelnose Sturgeon Population Dynamics

This extensive research project intends to determine the reproductive habitat parameters and develop rearing procedures for the federally endangered Salt Creek Tiger Beetle (SCTB). The SCTB is endemic to the saline wetlands of Lancaster County, Nebraska and was first described in the early 1900s. Based on museum records, it was apparently abundant in its type locality of the Capital Beach area of Lincoln, Nebraska. However, by the late 1980s, surveys indicated a dramatic decline in beetle populations, following corresponding losses in saline habitats upon which the beetle depends. Currently, the majority of beetles are limited to a single area along the banks of Little Salt Creek in Lancaster County. This means that in order to successfully recover the SCTB, it will be necessary to reestablish populations at restored historic sites and at new sites. This will require data on the appropriate management of the sites to provide reproductive habitat.

Although the basic life history and habitat requirements of the SCTB is known, much detailed biological information on the SCTB biology is lacking, and this information is essential for developing appropriate conservation and recovery plans. A well-defined group of beetle species occur exclusively in saline wetlands; however, physiological basis for these habitat preferences are not known. Considerable speculation surrounds the association of soil salinity with SCTB oviposition (laying eggs).

Harvey and his students are conducting research to characterize the hydrogeology and hydrochemistry of the alluvial and bedrock aquifers beneath eastern Nebraska's saline wetlands. They are also attempting to quantify the mixing relationship between fresh surface and shallow groundwater, and the deeper saline groundwater that moves to the surface under artesian pressure Their research is aimed ultimately at assessing the impact of both spatial and temporal hydrological changes across the wetland on the SCTB.

Dr. Harvey's portion of the larger research project will contribute to the conservation of the SCTB by identifying suitable release sites and developing habitat management guidelines for existing and restored habitat sites. The project will also use existing information to further refine and develop practices and protocols in order to successfully and efficiently captive-rear the SCTB.

Three Master's theses have been completed and a third is in progress:

• Coke, Gordon R., (2008) Groundwater Dynamics Within the Saline Wetland Alluvium of the Little Salt Creek Valley, Lancaster County, Nebraska, MS Thesis, UNL School of Natural Resources. 79 p.
• Gilbert, James, (2008) Groundwater Mixing Dynamics in the Saline Wetlands of the Little Salt Creek Watershed, Lancaster County, Nebraska, MS Thesis, UNL School of Natural Resources, 148 p.
• Kelly, Bridget, (2011), Using Electrical Resistivity Imaging (ERI) to Map Saline Groundwater and Subaqueous Spring Discharge: An Example From the Saline Wetlands of Eastern Nebraska, MS Thesis, UNL Department of Earth and Atmospheric Sciences, 150 p.

Catfish angling is popular throughout the United States and catfish are the most sought after fish species in the Platte River. However, catfish management in the Platte River is minimal as little is known about current populations. The objective of this study was to determine the current status of channel catfish and flathead catfish populations in the central and lower Platte River. Specifically, the study evaluated population characteristics including relative abundance, size structure, condition, age, growth and mortality.

Channel catfish are much more abundant than flathead catfish in the Platte River. The current Platte River channel catfish population appears to be average, comparable to many Nebraska and Midwestern rivers. Population characteristics displayed considerable variation along the Platte River and some longitudinal patterns were evident. Channel catfish in the central Platte River had lower relative abundances, higher condition, greater size structure, faster growth and lower mortality compared to lower Platte River channel catfish. Key factors likely influencing differences in channel catfish population characteristics are prey availability, flow modifications, habitat characteristics, tributary inflows and angler exploitation. Water manipulations from the Loup River Power Canal were also identified as a possible negative influence on lower Platte River channel catfish populations because hydropeaking is likely creating a stressful environment. However, channel catfish in the central Platte River appear to have benefited from recent high flows that likely increased productivity and food availability in the central Platte River.

Tony Barada's Master's Thesis on Catfish Population Dynamics in the Platte River

Branched Oak and Pawnee reservoirs are two waterbodies in eastern Nebraska that provided important local fisheries for nearly half of Nebraska’s population. Littoral species of fish, such as black crappie, bluegill and largemouth bass, dominated the angler catch early in the life of these reservoirs. However, sedimentation and erosion have substantially altered the habitat of these reservoirs, which resulted in shift from clear-water littoral habitat to turbid-water limnetic habitat. These habitat changes caused a shift in the sportfish community from one dominated by shallow-water species such as black crappie, bluegill and largemouth bass, to one dominated by open-water species such as walleye and white bass. In addition to habitat changes, introductions of the white perch into these reservoirs have caused additional changes in the fish communities and their associated dynamics. Since their introduction, white perch numbers have increased precipitously over the last 15 years resulting in populations of stunted white perch. Elimination of the stunted status for these white perch populations through increased stocking of predators has been unsuccessful to date.

This study will provide an in depth analysis of the white perch populations in these two Nebraska reservoirs. Specifically, we will estimate the biomass of each white perch population and quantify the spatiotemporal (daily and seasonally) distribution of white perch in both reservoirs.

Habitat alterations and accidental introduction of white perch into Branched Oak Lake have shifted the fish community from one dominated by littoral (near-shore) species (e.g., largemouth bass and bluegill) to one dominated by pelagic (open-water) species (e.g., white perch and gizzard shad). Along with the change in the fish community, angler trips to Branched Oak Reservoir have declined by 85% over the last two decades. Further, the white perch population has become stunted, meaning there is a high density of slow growing individuals that mature at a small size. Like Branched Oak Lake, Pawnee Lake historically supported an active and diverse fishery, and has experienced similar habitat alterations and accidental introduction of white perch; however, unlike Branched Oak Lake, stunting has not yet occurred for the white perch population in Pawnee Lake.

Studies at both lakes enable researchers to examine white perch interactions with other fishes in two similar Nebraska reservoirs having different white perch population stages (i.e., stunted and non-stunted). Food habits and diet overlap among white perch, crappie, walleye, white bass, and channel catfish are being evaluated. To study diet, fish stomachs are pumped and the contents analyzed to understand which fish species prey on white perch. All stomach content samples are analyzed and data synthesized. Stable isotope analyses of stomach contents have been conducted and the results confirmed.

By documenting the potential competition bottlenecks that exist between white perch and other fish species of importance, management program may be developed to eliminate stunted status for the white perch population in Branched Oak Lake and to prevent stunting of the white perch population in Pawnee Lake.