Challenges in merging fisheries research and management: the Upper Mississippi River experience

The Upper Mississippi River System (UMRS) is a geographically diverse basin extending 10° north temperate latitude that has produced fishes for humans for millennia. During European colonization through the present, the UMRS has been modified to meet multiple demands such as navigation and flood control. Invasive species, notably the common carp, have dominated fisheries in both positive and negative ways. Through time, environmental decline plus reduced economic incentives have degraded opportunities for fishery production. A renewed focus on fisheries in the UMRS may be dawning. Commercial harvest and corresponding economic value of native and non-native species along the river corridor fluctuates but appears to be increasing. Recreational use will depend on access and societal perceptions of the river. Interactions (e.g., disease and invasive species transmission) among fish assemblages within the UMRS, the Great Lakes, and other lakes and rivers are rising. Data collection for fisheries has varied in intensity and contiguousness through time, although resources for research and management may be growing. As fisheries production likely relies on the interconnectivity of fish populations and associated ecosystem processes among river reaches (e.g., between the pooled and unpooled UMRS), species-level processes such as genetics, life-history interactions, and migratory behavior need to be placed in the context of broad ecosystem- and landscape-scale restoration. Formal communication among a diverse group of researchers, managers, and public stakeholders crossing geographic and disciplinary boundaries is necessary through peer-reviewed publications, moderated interactions, and the embrace of emerging information technologies.     

Upper Mississippi River: seasonal and floodplain forest influences on organic matter transport

Seasonal influences and the role of floodplain forest as source or sink of organic matter is relatively unknown for 3arge, temperate rivers. Discharge and fine-particulate (FPOC), dissolved (DOC), and total organic carbon concentrations (TOC) were measured during five sampling periods from November, 1984, to August, 1985, above and below the floodplain-forested area (1054 ha) of Burlington Island in navigation Pool 19, upper Mississippi River. Sampling coincided with autumnal leaf fall of the floodplain forest, peak flood and falling spring flood, and low-flow conditions prior to and during phytoplankton bloom. Greatest TOC transport occurred during peak flood (8.84 × 10⁶ Kg/day) and leaf fall (7.79 × 10⁶ Kg/day). Peak flood transport was dominated by FPOC associated with flushing of material from upland areas. Transport during autumnal leaf fall was predominantly DOC attributed to litter leaching. Seasonal DOC loads generally increased downstream except during the phytoplankton bloom when a decrease was associated with increased microbial metabolic activity. Downstream decline in FPOC and increasing DOC loads during peak flood characterized the mechanism of deposition and processing of FPOC on the floodplain. FPOC concentration was significantly correlated to discharge and DOC concentrations were higher than FPOC except for peak flood. Significant downstream changes in TOC load suggests the importance of riparian vegetation as an influence on organic matter transport in large rivers.     

Translational science: past, present, and future

The concept of translational science is at least 15 years old. However, in its most recent incarnation, it represents the identification of a funding category designed to encourage academic participation in a critical stage of the drug discovery and product development process. It is hoped that this will make the process both shorter and more efficient. In this review, the author first considers the historical development of the pharmaceutical R&D process. The place of translational science in the process, the scientific techniques involved, and aspects of the business environment necessary for its success are then considered. Translational science does not displace preclinical development. Both concepts are relevant to the paramount importance of successfully and expeditiously bridging the gap between preclinical science and clinical testing, "from bench to bedside." Translational science is particularly likely to stimulate biomarker research in the universities and related business community and will probably give a modest boost to early clinical testing and commercialization of discoveries within the academic setting. Whether there will be a consequent improvement in the quality and efficiency of the overall process remains to be seen.     

Hydrology,hydraulics, and geomorphology of the Upper Mississippi River system

The Upper Mississippi River system has been modified with locks, dams, dikes, bank revetments, channel modifications, and dredging to provide a nine-foot navigation channel. These activities have changed the river's characteristics. The historical changes in the hydrologic, hydraulic, and geomorphic characteristics were assessed and related to navigational development and maintenance activities in the Upper Mississippi River system. The hydrologic, hydraulic, and geomorphic features studied include river discharges, stages, sediment transport, river position, river surface area, island surface area, and river bed elevation. Water and sediment transport effects on dredging were also estimated. It was found that the general position of the Upper Mississippi River system has remained essentially unchanged in the last 150 years except for specific man-made developments in the river basin. The stage, velocity, sediment transport, and river and island areas were altered by development of the 2.75-m navigation system. Dredging requirements are strongly related to mean annual water discharge. Years in which water discharges were great were generally the years during which large volumes of sediment needed to be dredged from the channel. The backwater areas are experiencing some deposition. With implementation of erosion-control measures in major tributaries and upland areas, better confinement of disposed dredged materials, and better maintenance practices, the sedimentation and pertinent problems in the main channel, as well as in the backwater areas, may be reduced with time.     

An assessment of the aquatic and wetland vegetation of the Upper Mississippi River

Illinois, Iowa, Minnesota, Missouri, and Wisconsin have strong botanical traditions that have resulted in a macrophyte literature which documents the identity, taxonomy, floristics, and ecology of aquatic macrophytes and wetland vegetation of the Upper Mississippi River and its floodplain. These findings are reviewed with respect to floristics, vegetation dynamics (patterns, history, production and management), and environmental changes that impact vegetation. Aspects requiring future study are noted to direct subsequent investigations.     

Our current understanding of the Upper Mississippi River System floodplain forest

The silver maple-American elm floodplain forest spans throughout the floodplains of the Upper Mississippi River System (UMRS). These forests of the UMRS today are less diverse than those of pre-European expansion (ca. early 1800s). Scientists and land managers are concerned about loss of species diversity including mast species such as pin oak (Quercus palustris Muenchh.), swamp white oak (Quercus bicolor Willd.), bur oak (Quercus macrocarpa Michx. Q), pecan (Carya illinoinensis (Wangenh.) K. Koch), and other hickories. The Great Midwest Flood of 1993 maintained species diversity in the lower, unimpounded region of the Upper Mississippi River, providing an opportunity for eastern cottonwood and black willow to regenerate in this portion of the Mississippi River. However, throughout the entire region, floodplain forests of the Upper Mississippi River have become less diverse, and have become dominated by the flood-tolerant and shade-tolerant silver maple (Acer saccharinum L.). The imminent loss of green ash (Fraxinus pennsylvanica Marsh.) to the Emerald Ash Borer (Agrilus planipennis Fairmaire) follows an already changing forest structure due to a disease-related shift of American elm (Ulmus americana L.) from the overstory to the midstory strata. Another invasive, reed canary grass (Phalaris arundinaceae L.), interferes with evolved mechanisms for establishment as it outcompetes trees of the early successional floodplain forest. Further research is needed to create and maintain diverse floodplain forest communities that have been lost under current conditions. Returning flood-prone agricultural lands within the floodplain to the floodplain forest will improve the health and connectivity of the river system, increase the diversity of habitats, and provide flood relief for communities of the Upper Mississippi River.     

Flow cytometry of bacteria: glimpses from the past with a view to the future

Measurement of bacteria and other microorganisms at the level of single cells has progressed enormously over the last couple of decades. Up to the late 1970s, there were no other means than microscopy for observation of single microorganisms, making any type of measurement very cumbersome and tedious, at best. Today, we measure several parameters simultaneously with a precision of a few per cent, and at a rate of 1000 cells per second. The first papers on the use of flow cytometry to measure bacteria appeared only in 1977, although the method had proved highly successful in studies of mammalian cells for almost a decade. There were several reasons for this relatively late introduction, including technical limitations, problems with adequate staining, and, not least, the human factor. Today, flow cytometry has a wide range of microbiological applications, ranging from studies of the bacterial cell cycle and many other cellular characteristics to assessment of antibiotic susceptibility of clinical samples, and monitoring of bacteria and other microorganisms in anything from sewage to sea water. Still, the potential of flow cytometry in microbiology is far from fully utilised. Better instruments and new stains will provide new opportunities to understand, control and exploit this vital part of the biosphere.     

Significance of instream autotrophs in trophic dynamics of the Upper Mississippi River

Trophic dynamics of large river–floodplain ecosystems are still not well understood despite development of several conceptual models over the last 25 years. To help resolve questions about the relative contribution of algal and detrital organic matter to food webs in the Upper Mississippi River, we (1) separated living and detrital components of ultrafine and fine transported organic matter (UTOM and FTOM, respectively) by colloidal silica centrifugation; (2) identified stable isotope signatures (δ¹³C and δ¹⁵N) for these two portions of transported organic matter and other potential organic matter sources; and (3) employed a multiple source, dual-isotope mixing model to determine the relative contribution of major energy sources to primary consumers and the potential contribution of basal sources to the biomass of secondary consumers. The δ¹³C and δ¹⁵N of living and detrital fractions of UTOM and FTOM were distinct, indicating clear differences in isotopic composition of the algal and detrital fractions of transported organic matter. Living and detrital transported organic matter also differed from other potential organic matter sources by either δ¹³C or δ¹⁵N. A six-source mixing model using both δ¹³C and δ¹⁵N indicated that algal transported organic matter was the major resource assimilated by primary consumers. The contribution of detrital transported organic matter was small in most cases, but there were a small number of taxa for which it could potentially contribute to more than half the assimilated diet. Colloidal dissolved organic matter, which includes heterotrophic bacteria, accounted for only a small fraction of the organic matter assimilated by most primary consumers, indicating that coupling between microbial processes and metazoan production is minimal. Terrestrial C₃ litter from the floodplain forest floor and aquatic macrophytes were also relatively unimportant to the assimilated diet of primary consumers. Application of the mixing model to compare basal source isotopic ratios to secondary consumers revealed that most organic matter moving from primary to secondary consumers originated from algal TOM. Our findings indicate that autochthonous organic matter is the major energy source supporting metazoan production in the main channel of this large river, at least during the summer. This study joins a number of other investigations performed globally that indicate organic matter originating from instream production of sestonic and benthic microalgae is a major driver in the trophic dynamics of large river ecosystems.     

Flood Reduction through Wetland Restoration: The Upper Mississippi River Basin as a Case History

Despite this nation's massive effort during the past 90 years to build levees throughout the upper Mississippi Basin, mean annual flood damage in the region has increased 140% during that time. These levees exacerbate the flood damage problem by increasing river stage and velocity. Thus, rather than continuing to rely on structural solutions for flood control, it is time to develop a comprehensive flood management strategy that includes using wetlands to intercept and hold precipitation where it falls and store flood waters where they occur. History testifies to the truth of this premise: it was the rampant drainage of wetlands in the nineteenth century that gave rise to many of today's water resources management problems. The 1993 flood verifies the need for additional wetlands: the amount of excess water that passed St. Louis during the 1993 flood would have covered a little more than 13 million acres —half of the wetland acreage drained since 1780 in the upper Mississippi Basin. By strategically placing at least 13 million acres of wetlands on hydric soils in the basin, we can solve the basin's flooding problems in an ecologically sound manner.     

Colonizing macroinvertebrates in the Upper Mississippi River with a comparison of basket and multiplate samplers *

SUMMARY. Colonizing aquatic macroinvertebrates were collected from two kinds of artificial substrate placed on wing dams in Pool 13 of the Upper Mississippi River in September 1978. Thirty-one taxa were collected from basket samplers containing cement spheres and twenty-one taxa from multiplate samplers constructed from tempered hardboard. Hydro-psychidae (Trichoptera), especially Cheumatopsyche sp., Potamyla flava and Hydropsyche sp., were the dominant macroinvertebrates which colonized both samplers. Basket samplers had a significantly greater macroinvertebrate density, biomass and number of taxa compared with multiplate samplers. Precision of the arithmetic mean for density, biomass and number of taxa was 19.9, 18.3 and 8.1% for basket samplers and 18.8, 18.7 and 8.5% for multiplate samplers. The number of sampling units required for a precision of 20% for macroinvertebrate density, biomass and number of taxa was 13, 11 and 2 for basket samplers and 11, 11 and 2 for multiplate samplers. Basket samplers with 7.5-cm cement spheres are recommended for use instead of multiplate samplers.     

Contribution of sediment fluxes and transformations to the summer nitrogen budget of an Upper Mississippi River backwater system

Routing nitrate through backwaters of regulated floodplain rivers to increase retention could decrease loading to nitrogen (N)-sensitive coastal regions. Sediment core determinations of N flux were combined with inflow–outflow fluxes to develop mass balance approximations of N uptake and transformations in a flow-controlled backwater of the Upper Mississippi River (USA). Inflow was the dominant nitrate source (>95%) versus nitrification and varied as a function of source water concentration since flow was constant. Nitrate uptake length increased linearly, while uptake velocity decreased linearly, with increasing inflow concentration to 2 mg l⁻¹, indicating limitation of N uptake by loading. N saturation at higher inflow concentration coincided with maximum uptake capacity, 40% uptake efficiency, and an uptake length 2 times greater than the length of the backwater. Nitrate diffusion and denitrification in sediment accounted for 27% of the backwater nitrate retention, indicating that assimilation by other biota or denitrification on other substrates were the dominant uptake mechanisms. Ammonium export from the backwater was driven by diffusive efflux from the sediment. Ammonium increased from near zero at the inflow to a maximum mid-lake, then declined slightly toward the outflow due to uptake during transport. Ammonium export was small compared to nitrate retention. Handling editor: J. Padisak     

The evaluation of a rake method to quantify submersed vegetation in the Upper Mississippi River

A long-handled, double-headed garden rake was used to collect submersed aquatic vegetation (SAV) and compared to in-boat visual inspection to record species presence at 67 individual sites. Six rake subsamples were taken at each site and a rake density rating was given to each species collected in the subsamples. Presence at the site, frequency of occurrence in the six rake samples, and additive density rating (the sum of the six rake density ratings) were quantified for each species at each site. The validity of the indices was tested against biomass data collected by clipping all remaining vegetation from the 67 sites. In the turbid water of the Mississippi River, visual inspection of SAV from boats was ineffective with only 27% of the species detected, while raking retrieved on average 70% of the total number of submersed species in the 67 sites. Presence of species at individual sites was correlated with biomass from Stuckenia pectinata, while frequency of occurrence and additive density rating were correlated with biomass for species with greater than 21 g of total biomass from all sites. The efficiency of the rake to collect biomass varied among species; only 18% of total biomass was captured via raking the site six times. Additive density rating as an index of abundance can be used to detect temporal changes in the same water body; however, cross-species comparison is not encouraged unless the efficiency of the rake has been determined for each species being compared.     

River stage response to alteration of Upper Mississippi River channels,floodplains, and watersheds

The Upper Mississippi River System (UMRS) is a large and diverse river system that changes character along its 1,200 mile network of rivers and canals and 2.6 million acres of floodplain. It supports more than 30 million people in its watershed, a significant commercial waterway, more than a million acres of “floodplain” agriculture and about one-half million acres of river-floodplain managed for fish, wildlife, and recreation. Large-scale geomorphology and climate patterns largely determine the hydrologic characteristics of a nested hierarchy of UMRS river reaches. The human impacts above are also important drivers determining hydrologic characteristics within the hierarchy. Understanding the relationship among physical and chemical processes and ecological responses is critical to implement an adaptive management framework for UMRS ecosystem sustainability. Historic or contemporary data from 42 locations were used to examine changes in UMRS hydrology and to demonstrate the utility of a multiple reference condition analysis for river restoration. A multivariate mathematical framework was used to show how river stage hydrology can be characterized by the variability, predictability, seasonality, and rate of change. Large-scale “geomorphic reaches” have distinct hydrologic characteristics and response to development throughout the UMRS region, but within navigation pool hydrology is similar among all impounded reaches regardless of geomorphic reach. Reaches with hydrologic characteristics similar to historic reference conditions should be examined to determine whether those characteristics support desired management objectives. Water levels can be managed, within limits to support navigation and agriculture, to more closely resemble natural hydrology for the benefit of a variety of species, habitats, and ecological processes.