Richard V. Anderson

Bioconcentration patterns of zinc, copper, cadmium and lead in selected fish species from the Fox river, Illinois

This study was conducted to determine if bioconcentration patterns were similar between four common essential and nonessential trace elements. The whole body concentrations of Zn, Cu, Cd and Pb were related to the whole body dry weights of blue-gill (Lepomis macrochirus), black crappie (Pomoxis nigromaculatus), black bullhead (Ictalurus melas), and yellow perch (Perca flavescens). Zinc, Cu, Cd, and Pb were selected because most studies of heavy metal concentrations in fish have examined one or more of these elements. These metals are often closely associated with each other as natural impurities or as alloys. Zinc and Cu are essential components of metallo-enzymes. Cadmium and Pb have not been shown to have essential functions in fishes, but rather inhibit biological systems and competitively interfere with Zn and Cu. The fish species were chosen on the basis of their importance as recreational and food species and their frequent use in both field and laboratory studies. Patterns of metal bioconcentrations with fish size were determined by simple linear regression.

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.

Predictive quality of macroinvertebrate — habitat associations in lower navigation pools of the Mississippi River

Macroinvertebrate community structure was compared between habitat types within a navigation pool and between navigation pools of the Upper Mississippi River. Bottom samples were taken using a grab or Wilding sampler from 40 and 14 stations on Pool 19 and 26, respectively. In both Pools, distinct communities developed based on substrate type or the presence of aquatic macrophytes rather than specific habitats as defined by river morphometry. Areas with sand substrates usually had communities of low density and diversity. Communities of the highest density, including Hexagenia or Musculium or both, occurred in habitats with silt-sand substrates. However, these areas were low in diversity. High diversity was found in both vegetated areas and habitats with coarse substrates, the latter dominated by net-spinning caddisfly larvae. Due to pool age and longitudinal distribution of species, community similarity between Pools 19 and 26 was not significant, p < 0.05, but functional feeding similarities occurred between communities from the same type of substrate.

Turtle Habitat Use in a Reach of the Upper Mississippi River

Abstract Turtle community composition was determined in three habitats—open river, slough, and backwater—of the Mississippi River near Hamilton, Illinois. While seven species of turtles were collected during the study, distinct communities were found in each of the habitats. The open river site was dominated by female smooth softshell turtles, Apalone muticas, which made up approximately 80% of the community in this habitat. While turtles were abundant in the backwater habitat, only three species, red-eared slider (Trachemys scripta), common snapping turtle (Chelydra serpentina), and painted turtle (Chrysemys picta), were collected. Though all three species were common in the backwater, the red-eared slider was the most abundant. The habitat with the most abundant and diverse turtle community was the slough. In addition to red-eared sliders, the most abundant species collected, common snapping turtles, painted turtles, smooth softshell turtles, spiny softshell turtles (Apalone spinifera), common map turtles (Graptemys geographica), and false map turtles (G. pseudogeographica), were also collected in this habitat. The slough habitat had permanent water with low current velocities and abundant basking and refuge sites, which provide the best conditions for most of the turtle species collected.

Declining populations of the fingernail clam Musculium transversum in the upper Mississippi River

We examined recent temporal trends in the abundance of fingernial clamsMusculium transversum (formerlySphaerium transversum) in the upper Mississippi River. Historical data on densities of fingernail clams were obtained from regional scientists and published literature. We also sampled benthos in six navigation pools in summer 1991, finding very few fingernail clams. The combined data set, including historical data and sampling results, extended from 1973 to 1992 and was sufficient to statistically evaluate trends in densities of fingernail clams in eight pools. Populations of fingernail clams declined significantly in five of the eight pools examined (Pools 2, 5, 7, 9, and 19), which spanned a 700-km reach of river from St. Paul, Minnesota, to Keokuk, Iowa. Densities in Pool 19, which had the longest historical record on fingernail clam abundance, averaged 30 000 m−2 in 1985 and progressively declined to zero in 1990. Combined data from all eight pools showed a significant decline in abundance of fingernail clams. An evaluation of potential causal factors led us to hypothesize that the population declines in Pools 2 to 9 were linked to point-source pollution rather than to dredging activity or commercial navigation traffic. In Pool 19, the declines of fingernail clams may have resulted from low-flow conditions during drought periods, but the causal mechanisms by which low flow influences fingernail clam abundance are unclear. The decrease in fingernail clam populations may adversely affect certain fish and wildlife, such as migrating lesser scaupAythya affinis, which feed heavily on the small mollusk. Moreover, the decreases in populations of this pollution-sensitive mollusk may signal a large-scale deterioration in the health of this riverine ecosystem.

Free-Living Nematode Associations in Pool 19, Mississippi River

ABSTRACT Nematodes were sampled in Pool 19 of the Mississippi River in several habitat types along a latitudinal transects and within the same habitat type for the entire length of the pool. While bacterial-feeding nematodes, particularly Tobrilus, dominated the community in most habitat types, plant-feeding nematodes produced distinct communities in vegetated areas. Density changed over the length of the pool, but taxonomic composition did not. Current velocity and its effect on substrate type and organic matter content of the substrate appear to be important habitat characteristics which affect nematode communities.

Improved Measurement of the Organic Carbon Content of Various River Components

ABSTRACT Using a coulometric titration technique, carbon content was determined in biotic and abiotic samples collected in Pool 19 of the upper Mississippi River. With the exception of waterfowl tissue, biotic samples contained substantially less organic carbon than the 50% assumed a priori. Inorganic carbon in soft tissues of biota was not quantitatively significant. Organic carbon content in substratum samples varied among habitats from which the samples were collected.

Longitudinal Variation in Zooplankton Populations in Pool 19, Upper Mississippi River

ABSTRACT Zooplankton samples were collected in main channel and adjacent channel border habitat at eight transects in navigation Pool 19, Mississippi River. Rotifers dominated the system with the most abundant organism being Brachionus calyciflorus. Zooplankton densities were statistically higher at both the upper and lower ends of the pool. The lower end of the pool was lacustrine in nature, thus supporting higher zooplankton densities. These high densities are transferred to the upper part of the succeeding pool Such a sequence of populations may be typical of pool systems that result from navigation structures such as those on the upper Mississippi River.

Chaetogaster Iimnaei (Oligochaeta: Naididae) Infesting Unionid Mollusks (Pelecypoda: Unionidae) and Corbicula fluminea (Pelecypoda: Corbiculidae) in Pool 19, Mississippi River

ABSTRACT A population of the Asiatic clam, Corbicula fluminea, and eight species of cohabiting unionid mollusks were examined for the presence of the oligochaete, Chaetogaster limnaei. The mollusks were collected in navigation Pool 19, upper Mississippi River. Infestation of C. limnaei in the Asiatic clam was significantly greater than in unionids. A decline in occurrence and abundance of C. limnaei infesting the Asiatic clam was found in the winter when the Asiatic clam population also declined. Of the unionid mollusks, Leptodea fragilis had the highest rate of infestation and the highest number of C. fluminea per individual.

The Development of an Aquatic Vegetation Community in Pool 19, Upper Mississippi River

ABSTRACT Sediments have accumulated in the main channel border area upstream of Lock and Dam 19 on the upper Mississippi River to the extent that water depth has decreased from 11.5 m to less than 2 m. Beginning in the 1950s, aquatic vegetation became established in the lower 3 km of the pool; community development through 1983 was primarily submersed vegetation (Potamogeton spp. and Vallisneria americana). Aerial photographs were used to document the expansion of plant beds from 19 ha (1956) to 80 ha (1978). In 1984, Nelumbo lutea invaded the plant bed and by 1987 occupied 26 of the 110 vegetated ha. Standing crop estimates showed that where N. lutea was present, standing crop biomass of V. americana was reduced by an average of 56%. Using existing conceptual models and estimated sedimentation rates, we predict that the study area will become a naturally leveed floodplain dominated by immersed vegetation. Species composition of the community will depend on elevation, nutrient status of the soils, and th...