Backwater Lakes Research Articles

Optimizing the conditions of - amylase by an Esturian strain of Aspergillus spp

Water samples and sediments were collected from waterways in between two back water lakes namely Vambanad and Asthamudi, in Alukadavu, Kollam along the west coast of Kerala, India. 20 fungal species were isolated and identified by lacto phenol cotton blue staining method. From this, Aspergillus flavus was selected for starch hydrolysis Agar Medium for amylase activity under submerged fermentation for amylase production. The effect of different carbon source, nitrogen source, heavy metals, amino acids, dry biomass was studied and enzyme was optimized by using different physico-chemical parameters. The purity of enzyme was analyzed by thin layer chromatography. Minimal medium with starch has produced high amylase enzyme and soluble protein dry biomass with a temperature of 30°C and pH of 6, which includes 256.2 and 108 µg/ml, respectively. Key words: Amylase enzyme, back water fungi, Aspergillus flavus, submerged fermentation, SDS-PAGE, Ion exchange chromatography.

Observations of Silver Carp (Hypophthalmichthys molitrix) Planktivory in a Floodplain Lake of the Lower Mississippi River Basin

ABSTRACT The invasive silver carp (Hypophthalmichthys molitrix) has become pervasive in much of the Mississippi River, its tributaries, and in connected lakes and wetlands. As an increasingly abundant planktivore, it competes directly for food with native fishes. Its greatest impact may be in connected backwater lakes and wetlands, which due to their high primary production serve as critical sites for feeding and growth of many fishes. To assess the impact that silver carp may have on one such system, we examined the composition of plankton samples and of alimentary tract (gut) contents of collected from an oxbow lake in Mississippi, Forest Home Chute. Through an occasional connection to the Mississippi River, Forest Home Chute was invaded by silver in winter 2005, after which the river and lake became disconnected for about two years. In the water-column, the most common types of phytoplankton were euglenoid algae, cyanobacteria, and diatoms. The vast majority of zooplankton was rotifers with densities sometimes exceeding 7,000 organisms per liter. Very high concentrations of phytoplankton in the gut, relative to in the water-column, indicate substantial consumption of phytoplankton production. In October 2006, euglenoid phytoplankters were a much greater, and cyanobacteria a much lesser, proportion of prey in the fish gut compared to their proportions in the water-column. In December, however, there was no evidence of selective consumption by the silver carp population. Some of the phytoplankters observed in the lowest portion of the gut, including pinnate diatoms and euglenoid algae, were motile, indicating they had survived transit through the 5 to 7-m long gut tract. There was no evidence of rotifer survival of gut passage. By its high consumption of plankton, possible selective planktivory, and differential digestion of consumed phytoplankton and zooplankton, the silver may be altering the food web structure of these important connected lakes.

Exploring riverine zooplankton in three habitats of the Illinois River ecosystem: Where do they come from?

We sampled three habitats (main channel, side channels, and backwater lakes) during 2 yr along 32 km of the Illinois River to compare zooplankton distribution and dynamics, as well as evaluate the possible effects of hydrology on taxonomic abundance and distribution. Zooplankton assemblages displayed both spatial and temporal variation. Whereas the riverine zooplankton assemblage was dominated by rotifers, the backwater lake assemblage was dominated by copepods. Zooplankton densities in the main channel peaked earlier in the season in both years than the backwater lake habitats. To determine if these patterns were caused by fluvial exchanges occurring between habitats during flooding, we sampled the connections between the backwater lake and main channel habitats and found that large numbers of zooplankton entered the main channel via these connections. Further, calculations of main channel population growth, birth, and death rates showed that population growth rates most commonly exceeded birth rates during the flooding period. Seasonal inoculums from off‐channel habitats could play an important role in riverine zooplankton dynamics. However, for the main channel to achieve the measured zooplankton densities, ~400,000 backwater lakes would be required and zooplankton would need to travel an unrealistic number of days and distance based on estimated growth rates. Thus, other mechanisms (hatching of resting eggs or in situ reproduction) are likely responsible for zooplankton abundances.

Diet overlap among two Asian carp and three native fishes in backwater lakes on the Illinois and Mississippi rivers

Bighead and silver carp are well established in the Mississippi River basin following their accidental introduction in the 1980s. Referred to collectively as Asian carp, these species are filter feeders consuming phytoplankton and zooplankton. We examined diet overlap and electivity of Asian carp and three native filter feeding fishes, bigmouth buffalo, gizzard shad, and paddlefish, in backwater lakes of the Illinois and Mississippi rivers. Rotifers, Keratella spp., Brachionus spp., and Trichocerca spp., were the most common prey items consumed by Asian carp and gizzard shad, whereas crustacean zooplankton were the preferred prey of paddlefish. Bigmouth buffalo diet was broad, including both rotifers and crustacean zooplankton. Dietary overlap with Asian carp was greatest for gizzard shad followed by bigmouth buffalo, but we found little diet overlap for paddlefish. Diet similarity based on taxonomy correlated strongly with diet similarity based on size suggesting filtration efficiency influenced the overlap patterns we observed. Although rotifers were the most common prey item consumed by both bighead and silver carp, we found a negative relation between silver carp CPUE and cladoceran density. The competitive effect of Asian carp on native fishes may be forestalled because of the high productivity of Illinois and Mississippi river habitats, yet the potential for negative consequences of Asian carp in less productive ecosystems, including Lake Michigan, should not be underestimated.

Metal impacts on microbial biomass in the anoxic sediments of a contaminated lake

Little is known about the long‐term impacts of metal contamination on the microbiota of anoxic lake sediments. In this study, we examined microbial biomass and metals (arsenic, cadmium, chromium, copper, iron, lead, manganese, and zinc) in the sediments of Lake DePue, a backwater lake located near a former zinc smelter. Sediment core samples were examined using two independent measures for microbial biomass (total microscopic counts and total phospholipid phosphate concentrations) and for various fractions of each metal (pore water extracts, sequential extractions, and total extracts of all studied metals and zinc speciation by X‐ray absorption fine structure). Zinc concentrations were up to 1000 times higher than reported for sediments in the adjacent Illinois River and ranged from 21,400 mg/kg near the source to 1,680 mg/kg near the river. However, solid metal fractions were not well correlated with pore water concentrations and were not good predictors of biomass concentrations. Instead, biomass, which varied among sites by as much as 2 times, was inversely correlated with concentrations of pore water zinc and arsenic as established by multiple linear regression. Monitoring of other parameters known to naturally influence biomass in sediments (e.g., organic carbon concentrations, nitrogen concentrations, pH, sediment texture, and macrophytes) revealed no differences that could explain observed biomass trends. This study provides strong support for control of microbial abundance by pore water metal concentrations in contaminated freshwater sediments.

Seasonal changes and species composition of phytoplankton in oxbow and backwater lakes in Central Kalimantan, Indonesia

Seasonal changes and species composition of phytoplankton in oxbow and backwater lakes in Central Kalimantan, Indonesia

Assessment of soil microbial communities in surface applied mixtures of Illinois River sediments and biosolids

Restoration of the Illinois River and its backwater lakes involves the dredging of millions of cubic meters of sediment, and the relocation of this dredged sediment is a significant challenge. Beneficial use of sediment as landscaping soil on brownfields, strip mines, highway borders and other areas is a potential use for large quantities of this material, as sediments have desirable soil characteristics, including a favorable texture for plant growth and good water holding capacity. The addition of biosolids to Illinois River sediments has the potential to increase the organic and nutrient content of the sediments and thus to make these sediments more useful for the reclamation of damaged soils. The goal of the current study was to assess the impacts of biosolids additions on the physical/chemical characteristics and microbial communities of surface applied river sediments. Field plots containing various sediment/biosolids mixture were established and examined 1 year after application. Results indicated that biosolids addition had significant positive effects on soil organic carbon, total Kjeldahl nitrogen, total phosphorous, and microbial biomass and activity. In addition, the sediment/biosolids mixtures showed lower salinity and lower concentrations of copper, lead and zinc than the pure biosolids. PLFA analysis revealed that biosolids addition resulted in shifts in microbial community composition, with relative increases in Gram negative bacteria and relative decreases in Gram positive bacteria, fungi, and actinomycetes. These data suggest that a mixture of sediment and biosolids is preferable to either sediment or biosolids alone.

ECONOMIC ANALYSIS OF WETLAND RESTORATION ALONG THE ILLINOIS RIVER1

ABSTRACT:Creating and restoring wetland and riparian ecosystems between farms and adjacent streams and rivers in the Upper Mississippi River Basin would reduce nitrogen loads and hypoxia in the Gulf of Mexico and increase local environmental benefits. Economic efficiency and economic impacts of the Hennepin and Hopper Lakes Restoration Project in Illinois were evaluated. The project converted 999 ha of cropland to bottomland forest, backwater lakes, and flood‐plain wetland habitat. Project benefits were estimated by summing the economic values of wetlands estimated in other studies. Project costs were estimated by the loss in the gross value of agricultural production from the conversion of corn and soybean acreage to wetlands. Estimated annual net benefit of wetland restoration in the project area amounted to US$1,827 per ha of restored wetland or US$1.83 million for the project area, indicating that the project is economically efficient. Impacts of the project on the regional economy were estimated (using IMPLAN) in terms of changes in total output, household income, and employment. The project is estimated to increase total output by US$2,028,576, household income by US$1,379,676, and employment by 56 persons, indicating that it has positive net economic impacts on the regional economy.

Sediment quality and quantity issues related to the restoration of backwater lakes along the Illinois River waterway

Sedimentation has severely impacted backwater lakes along the Illinois River. The State of Illinois and the US Army Corps of Engineers are currently involved in a joint effort to address ecosystem degradation within the Illinois River Basin, and excessive sedimentation of backwater lakes and side channels is a primary cause of that degradation. Necessary parts of the overall restoration effort are to adequately characterize both the quality and quantity of backwater lake sediments prior to implementing any restoration efforts, and to identify potential beneficial reuses of dredged sediments. This paper summarizes some of our efforts in these areas with an emphasis on Peoria Lake which has received the most attention to date. Sediment characterization has included detailed bathymetric surveys, sediment dating with 137Cs, chemical and mineralogical characterization of sediments to three meters depth, analysis of recent sediments (to 30 cm depth) for acid-volatile sulfide and simultaneously extracted metals, and analysis of ammonia and toxic metals in sediment pore waters. Dredged sediments have also been used in various trial projects to demonstrate potential handling and beneficial reuse strategies. Some significant findings of these studies are: 1) Long-term sedimentation rates are high, and average 1–3 cm y−1; 2) total concentrations of several trace metals (e.g., Pb, Cd, Ni) and PAH compounds sometimes exceed consensus-based probable effect levels for sensitive sediment-dwelling organisms; 3) pore water dissolved ammonia concentrations in Peoria Lake are potentially toxic to sensitive sediment-dwelling species; and 4) weathered sediments can make productive agricultural soils.

Siltation and hydrologic regime determine species composition in herbaceous floodplain communities

Interest in the restoration of riparian habitat is increasing. However, little is known about factors responsible for riparian communities, especially grasslands. In order to construct plant communities for a restoration project in the floodplain of a large river in the Midwestern United States, we sampled four floodplains with various disturbance regimes located in Illinois and Missouri. They were chosen to be representative of different plant communities of floodplains, with a focus on herbaceous communities. The areas included backwater lakes, alluvial fans, groundwater seep marshes, oxbow marshes, seasonally inundated grassland, and non-inundated grassland. Vegetation, soils and groundwater or standing water depth were measured at various intervals along transects. Communities were produced using TWINSPAN and tested for differences in environmental factors. The soil morphology, taxonomic classification, and fertility parameters were similar among sites. Environmental factors influencing community composition were the presence of permanent water and silt deposition. We conclude that water depth determines species composition in permanently wet areas. Silt deposition determines composition in seasonally inundated grassland. Where silt deposition is high enough to inhibit seedling emergence, dominance is attained by plants able to reproduce vegetatively by rhizomes. Such a reproductive process leads to nearly monotypic stands produced by large clones. Results are discussed in relation to models of riparian processes and succession.

Denitrification in the Upper Mississippi River: rates, controls, and contribution to nitrate flux

We evaluated patterns of denitrification and factors effecting denitrification in the upper Mississippi River. Measurements were taken over 2 years, during which river discharge ranged from record flooding to base flow conditions. Over the period of study, average denitrification enzyme activity was highest in backwater lakes and lowest in the main channel. Throughout the study reach, highest denitrification enzyme activity occurred during fall and lowest occurred in winter. Rates during spring floods (2001) were only slightly higher than during the preceding winter. Mean unamended denitrification rates ranged from 0.02 (fall 2001 in backwaters) to 0.40 µg N·cm–2·h–1(spring 2001 in backwaters). Laboratory experiments showed that denitrification rates increased significantly with addition of NO3–regardless of sediment C content, while rates increased little with addition of labile C (glucose). Denitrification in this reach of the upper Mississippi River appears to be NO3–limited throughout the growing season and the delivery of NO3–is strongly controlled by river discharge and hydrologic connectivity across the floodplain. We estimate that denitrification removes 6939 t N·year–1or 6.9% of the total annual NO3–input to the reach. Hydrologic connectivity and resultant NO3–delivery to high-C sediments is a critical determinant of reach-scale processing of N in this floodplain system.

Trophic structure and energy flow in backwater lakes of two large floodplain rivers assessed using stable isotopes

Carbon and nitrogen stable isotopes (δ13C and δ15N, respectively) were measured for locally abundant primary producers, detritus, aquatic invertebrates, and fish in backwater lakes of two large floodplain rivers in an effort to understand patterns of energy dependence and trophic structure within these habitats. We observed trophic enrichment values for 15N that were within the ranges observed for other aquatic systems but were often considerably lower than the 3.4‰ typically assumed in stable isotope studies. Production based on benthic and terrestrial material, combined with planktonic production for larval fish, appears to be an important energy source supporting consumers in backwater lakes of large floodplain rivers. Our isotopic data challenge the conventional wisdom that macrophytes are centrally involved in supplying carbon to aquatic consumers in shallow lakes and that food webs in most lakes are sustained almost exclusively by carbon fixed by phytoplankton.

Life in the fast lane: fish and foodweb structure in the main channel of large rivers

We studied the main channel of the lower Illinois River and of the Mississippi River just upstream and downstream of its confluence with the Illinois River to describe the abundance, composition, and/or seasonal appearance of components of the main-channel community. Abundance of fishes in the main channel was high, especially adults. Most adult fishes were present in the main channel for either 3 or 4 seasons/y, indicating that fishes regularly reside in the main channel. We documented abundant zooplankton and benthic invertebrates in the main channel, and the presence of these food types in the diets of channel catfish and freshwater drum. All trophic levels were well represented in the main channel, indicating that the main channel supports a unique food web. The main channel also serves as an important energetic link with other riverine habitats (e.g., floodplains, secondary channels, backwater lakes) because of the mobility of resident fishes and because of the varied energy sources supplying this food web. It may be more realistic to view energy flow in large-river systems as a combination of 3 existing concepts, the river continuum concept (downstream transport), the flood pulse concept (lateral transport to the floodplain), and the riverine productivity model (autochthonous production). We urge additional research to quantify the links between the main channel and other habitat types in large rivers because of the apparent importance of main-channel processes in the overall structure and function of large-river ecosystems.

A proposed aquatic plant community biotic index for wisconsin lakes.

The Aquatic Macrophyte Community Index (AMCI) is a multipurpose tool developed to assess the biological quality of aquatic plant communities in lakes. It can be used to specifically analyze aquatic plant communities or as part of a multimetric system to assess overall lake quality for regulatory, planning, management, educational, or research purposes. The components of the index are maximum depth of plant growth; percentage of the littoral zone vegetated; Simpson's diversity index; the relative frequencies of submersed, sensitive, and exotic species; and taxa number. Each parameter was scaled based on data distributions from a statewide database, and scaled values were totaled for the AMCI value. AMCI values were grouped and tested by ecoregion and lake type (natural lakes and impoundments) to define quality on a regional basis. This analysis suggested that aquatic plant communities are divided into four groups: (1) Northern Lakes and Forests lakes and impoundments, (2) North-Central Hardwood Forests lakes and impoundments, (3) Southeastern Wisconsin Till Plains lakes, and (4) Southeastern Wisconsin Till Plains impoundments, Driftless Area Lakes, and Mississippi River Backwater lakes. AMCI values decline from group 1 to group 4 and reflect general water quality and human use trends in Wisconsin. The upper quartile of AMCI values in any region are the highest quality or benchmark plant communities. The interquartile range consists of normally impacted communities for the region and the lower quartile contains severely impacted or degraded plant communities. When AMCI values were applied to case studies, the values reflected known impacts to the lakes. However, quality criteria cannot be used uncritically, especially in lakes that initially have low nutrient levels.

Floristic Quality Assessment of Wisconsin Lake Plant Communities with Example Applications

ABSTRACT Floristic quality is a rapid assessment metric designed to evaluate the closeness of the flora of an area to undisturbed conditions. To be useful for a variety of monitoring applications it has to be calibrated for local conditions. Based on data from 554 lakes, this paper develops a floristic quality metric for Wisconsin lake plant communities and calibrates it for ecoregional and lake type differences. The Northern Lakes and Forests ecoregion had the highest floristic quality with flowages having the highest number of species and lakes having the highest average coefficient of conservatism (Ȼ). Floristic quality in lakes and flowages in the North Central Hardwoods region and the Southeastern Till Plain region were not significantly different and were combined into a single group. Their floristic quality was intermediate between the Northern Lakes and Forest groups and the final group that was a combined Driftless Area and Mississippi River Backwater lake group. When applied to a limited number of examples the floristic quality index appears to give reasonable results but more trials of use under well documented disturbance conditions is needed to determine its sensitivity.

Nektonic Invertebrate Dynamics and Prolonged Summer Flooding on the Lower Illinois River

ABSTRACT Prolonged extreme flooding during mid-summer 1993 provided an opportunity to investigate nektonic invertebrate dynamics in lower Illinois River floodplains and backwater lakes. We used plankton nets to sample flooded grass shorelines, flooded forests, and open water habitats during rising and falling stages of the flood. Transects oriented perpendicular to shore were sampled to investigate community composition along the floodplain gradient extending riverward. Invertebrate densities differed between samples collected on the rising stage of the flood (mean = 11,584 individuals m−3) and on the falling stage of the flood (mean = 78 individuals m−3). Density estimates from samples collected at the shoreline of the rising flood waters exceeded estimates from open water and the falling flood shoreline by two orders of magnitude. Corixids were the most abundant taxa found (78%) at flooded shorelines. Densities were highest in inundated grass habitats at the rising edge of the flood. Flooded trees had the next highest densities, followed by floating macrophytes and open water. Our findings exemplify the flood pulse hypothesis in that productivity, as measured by invertebrate density, increased dramatically on the rising flood but then fell just as dramatically on the falling flood.

Estimating flow rates to optimize winter habitat for centrarchid fish in Mississippi River (USA) backwaters

The backwaters of large rivers provide winter refuge for many riverine fish, but they often exhibit low dissolved oxygen levels due to high biological oxygen demand and low flows. Introducing water from the main channel can increase oxygen levels in backwaters, but can also increase current velocity and reduce temperature during winter, which may reduce habitat suitability for fish. In 1993, culverts were installed to introduce flow to the Finger Lakes, a system of six backwater lakes on the Mississippi River, about 160 km downstream from Minneapolis, Minnesota. The goal was to improve habitat for bluegills and black crappies during winter by providing dissolved oxygen concentrations >3 mg/L, current velocities <1 cm/s, and temperatures >1°C. To achieve these conditions, we used data on lake volume and oxygen demand to estimate the minimum flow required to maintain 3 mg/L of dissolved oxygen in each lake. Estimated flows ranged from 0.02 to 0.14 m3/s among lakes. Data gathered in winter 1994 after the culverts were opened, indicated that the estimated flows met habitat goals, but that thermal stratification and lake morphometry can reduce the volume of optimal habitat created. This article is a U.S. Government publication and is in the public domain in the United States.

Notes: Largemouth Bass Size Distributions under Varying Annual Hydrological Regimes in the Illinois River

Little is known about the population dynamics of largemouth bass Micropterus salmoides in temperate large river–floodplain ecosystems. However, the hydrological regimes in these systems are often similar to those of large reservoirs where fluctuating water levels during spawning have been shown to affect largemouth bass population dynamics. Most backwater lakes of the Illinois River have soft, silty substrates. These substrates are not conducive to nest building, so spawning centrarchids may use annual spring floods to access inundated terrestrial vegetation and previously dry, compacted substrates on the floodplain. We used electrofishing catch data from La Grange Reach of the Illinois River (1990–1995) to assess how spring and early-summer river levels influence the cohort strength of largemouth bass. Strong cohorts were produced during years with high spring floods (1990, 1993, and 1995) when largemouth bass could access the floodplain for spawning and nursery habitat. In both 1990 and 1993, fish had access to the floodplain for extended periods during spring and summer, which resulted in exceptionally strong cohorts. These cohorts probably benefitted from abundant forage and cover on the floodplain, which bolstered survival rates. Weak cohorts were produced in 1992 and 1994 when river levels were low and fluctuating during spawning and in 1991 when river levels declined dramatically during spawning. Length distributions of other centrarchids mirrored those of largemouth bass, indicating that river levels probably affected other nest-building species in La Grange Reach.

Within-Bed Distribution of Myriophyllum spicatum L. in Lake Onalaska, Upper Mississippi River

ABSTRACT The exotic species Myriophyllum spicatum L. has become a recent member of the submersed aquatic plant community within the upper Mississippi River system (UMRS). Notable for nuisance growth in many North American locations, its potential for creating problems in the river system is not known. To better understand its nuisance potential, within-bed-plant pattern and the relationship between plant biomass, water depth, sediment moisture, and sediment organic content were studied in Lake Onalaska, a backwater lake of UMRS Pool 7. These results were compared with studies of biomass distribution of M. spicatum in Lake Wingra, Wisconsin. Within-bed biomass from Lake Onalaska was not significantly correlated with depth, organic matter, or sediment moisture. Lake Onalaska milfoil beds produced biomass similar to other lakes in the region but were restricted to much shallower water depths. The shallow maximum growth depth is probably related to poor water clarity but the maximum growth depth could vary significantly from year to year because of the dynamic nature of water clarity in the UMRS. Because Mississippi River pools are shallow, the area occupied by milfoil could also vary considerably from year to year.

Patterns of foraging and distribution of bluegill sunfish in a Mississippi River backwater: influence of macrophytes and predation

Abstract— We studied the trophic interactions and spatial distributions of bluegills Lepomis macrochirus and largemouth bass Micropterus salmoides in a macrophyte bed in Lake Onalaska, a backwater lake in the upper Mississippi River. The diets of adult and age‐0 bluegills were similar and changed seasonally probably in response to changes in life stages of macroinvertebrates (i. e. emergence of winged adults). Diets and diel patterns of abundance of bluegill suggest that age‐O and adults were feeding in the vegetated, littoral zone. Predation by age‐O largemouth bass appears to influence use of vegetated habitat by age‐0 bluegills. In summer, when most age‐O bluegills were vulnerable to predation by age‐O largemouth bass, bluegill abundance was strongly correlated with vegetation biomass. In October and November, piscivory by age‐O largemouth bass was limited by gape. Consequently, the relationship between the abundance of age‐O bluegills and vegetation biomass was weakened because predation risk by age‐O largemouth bass was reduced.