Barry S. Payne

The effects of intermittent exposure to suspended solids and turbulence on three species of freshwater mussels

A laboratory experiment was performed to evaluate the effects of intermittent suspended solids exposure on the unionid clams Quadrula pustolosa, Fusconaia cerina and Pleurobema beadleanum. Intermittent impacts of this type are important effects of commercial navigation traffic in freshwater. Clams were cyclically exposed to turbulence alone or accompanied by 600-750 mg litre(-1) of suspended inorganic solids for 9 days. Clams exposed to suspended solids every 3 h reduced their metabolic rate but did not shift from the mainly protein based catabolism of controls. Feeding impairment was apparently compensated for by a reduction in metabolic demand. Conversely, clams exposed every 0.5 h to suspended solids shifted to virtually complete reliance on non-protein body stores as indicated by O:N values averaging 197.

Qualitative versus Quantitative Sampling to Evaluate Population and Community Characteristics at a Large-River Mussel Bed

-Quantitative and qualitative sampling methods were used to study community characteristics, density, recruitment rates and population demography of abundant species of freshwater mussels (Family: Unionidae), at Ohio River Miles 444.2-445.6 in July 1989 and September 1990. Mean unionid densities (?SD) based on 100, 0.25-sq m total substratum samples at four sites ranged from 4.4 ? 6.8 to 52.4 ? 13.9 individuals/ sq m. Mean densities of Corbicula fluminea ranged from 66.8 ? 67.7 to 1352.8 ? 96.1 individuals/sq m. Shannon-Weaver species diversity log23026 (2.32 to 2.50) and evenness (0.76 to 0.90) at these sites indicated an equitable distribution of species within the community. Individuals of two abundant species, Quadrula pustulosa pustulosa and Pleurobema cordatum, were represented by most size classes, indicating generally sustained recruitment with some annual variation. Both sampling methods provided similar estimates of community composition, species richness, diversity and evenness. A comparison of these results with those from a previous survey at this bed indicates no major changes in biotic conditions between 1984 and 1989-1990.

Recruitment of Fusconaia ebena (Bivalvia: Unionidae) in relation to discharge of the lower Ohio River.

Abstract Demographically complete sampling of a large population of Fusconaia ebena (Lea) in a mainstream shoal in the lower Ohio River (LOR) from 1983 through 1998 revealed two extremely successful recruitment years—1981 and 1990. Dominance of the 1981 and 1990 cohorts allowed length-to-age relationships to be estimated directly from length-frequency histograms. Two linear relationships adequately described growth rates from age 2 through 17 y. The first model applied to ages 2 through 10 y when annual growth averaged 6.1mm. The second model applied to ages 10 through 17 y when annual growth averaged only 1.1 mm. A survivorship curve was based on density of the 1981 cohort from age 2 through 17 y. During that period a constant proportion (17%) of the cohort died each year. Only 9% of the 1981 cohort alive in 1983 were still alive in 1998. In both 1981 and 1990 rapid and large spring rises in LOR discharge were immediately followed by rapid and large declines. These rises coincided with the expected spawning peak of Alosa chrysochloris, the only known fish host for F. ebena glochidia. The rapid return to low flow and depositional conditions was appropriately timed to enhance successful settlement of juvenile F. ebena after their parasitic stage on A. chrysochloris gills.

Growth and Survival of Recent Recruits to a Population of Fusconaia ebena (Bivalvia: Unionidae) in the Lower Ohio River

-Demographically complete sampling of a large population of Fusconaia ebena (Lea) in a mainstream shoal in the lower Ohio River from 1983 through 1987 revealed extensive annual variation in recruitment. Survival and early growth rate were assessed by monitoring size increase and relative abundance of an exceptionally abundant, and therefore distinct, cohort of recent recruits. Individuals recruited to the population in 1981 comprised approximately 70% of the entire population throughout the study period, indicating both negligible mortality of this successfully settled cohort as well as lack of subsequent strong recruitment. Shell length of F. ebena increased at a linear rate throughout the 1st 6 years of life. The annual growth increment was approximately 8 mm. Biomass increased exponentially over the same age range. Longevity of F. ebena at this location was estimated to range from 11 to 18 years. First reproduction was estimated to occur at an age of 6 years and at a tissue mass equal to only 14% of that of the oldest adults in the population. A long reproductive lifespan is required to maintain this population, which is characterized by extensive annual variation in recruitment success.

Effects of disturbances on large-river mussel assemblages

Data from more than 10 years of quantitative sampling from stable gravel shoals in large rivers of the central US were used to test effects of specific disturbances (passage of commercial navigation vessels, the flood of 1993, and introduction of Corbicula fluminea) on native freshwater mussels (Family: Unionidae). Although many lotic species of Unionidae have been eliminated from large rivers because of degraded water quality, poor land use practices, and large-scale navigation projects, the resulting fauna appears to tolerate many disturbances. For example, high density populations of C.fluminea had no effect on unionid density at two shoals in the lower Ohio River. The record flood of 1993 in the upper Mississippi River had no measurable effect on mussels at three locations; species richness (22–25), density (45.3–60.3), and percentage of juveniles (11–26%) varied among years but showed no temporal trend. In a barge turning basin that was dredged in 1976, density of recently recruited Amblema plicata plicata was not significantly different from density at a reference site for six of nine study years indicating that recruitment is proceeding at a similar rate regardless of current traffic levels. The mussel fauna now inhabiting large rivers, dominated by thick-shelled species tolerant of reduced water velocity and increased sedimentation, appears to be quite resilient to many natural and man-induced disturbances.

Oxygen uptake and nitrogenous excretion rates during overwinter degrowth conditions in the pulmonate snail, Helisoma trivolvis☆

Abstract 1. 1. Unfed snails have oxygen uptake rates 45–55% lower than fed snails and, after 124 days starvation, unfed snails have NH3 excretion rates 67% lower than fed. 2. 2. In starved snails nonprotein carbon supplied 74–83% of total catabolic needs (which was 39–54% of fed snails total) during 124 days, while in fed snails it supplied 91–95%. 3. 3. Tissue degrowth provided approximately 26 and 18%, of the carbon catabolized by unfed and fed snails, respectively. 4. 4. Controlled differential catabolism of protein resources during degrowth is related to the actuarial bioenergetics of reproduction.

A Shell Gape Monitor to Study Effects of Physical Disturbance on Freshwater Mussels

ABSTRACT A bivalve shell gape monitor, previously used to detect toxic discharges in Europe, was used to measure response of the freshwater mussel Amblema plicata plicata (Say 1817) (Mollusca: Unionidae) to brief changes in water velocity. In the laboratory, overall behavior of eight A. p. plicata was virtually unaffected by exposure once every 2 hr to a 5-min pulse of high-velocity water (45 cm/s) created with a submersible pump. In the east channel of the upper Mississippi River near Prairie du Chen, WI, multiple passes of recreational craft reduced by only a few percent the total time that six A. p. plicata were opened during a 2-hr period. Only six of 42 events, caused by passage of a work boat or a 6.5-m-long skiff, caused a measurable response in mussel shell gape. It was concluded that A. p. plicata was not greatly affected by brief changes in ambient water velocity caused by vessel passage.

The Structure of Dominant Invertebrate Assemblages in a Small Southeastern Stream

ABSTRACT Invertebrates were collected following near-average extremely low, and above-average discharge in the winters of 1987, 1988, and 1989, respectively, in Luxapalila Creek, Mississippi and Alabama. Total invertebrate density was lower in pools (mean −7,364, range −5,427-12,561 individuals/sq m) than in riffles where it was also more variable (mean −15,964, range −9,662-28,820 individuals/sq m). There were no significant seasonal density differences among pools (p>0.05) In samples collected during the fall, total density in riffles was two times higher than in pools. Following high discharge in December-February 1988–89, there were no significant density differences between pools and riffles. Interhabitat differences in chironomid and oligochaete species composition existed in Luxapalila Creek; seasonal periods of high water had a greater effect on invertebrates in riffles than pools.

Effects of Forced Hot Air on Zebra Mussel (Dreissena polymorpha) Survival

Abstract Exposure of dewatered zebra mussels (Dreissena polymorpha) to forced (moving) air substantially increased mortality compared to that in still air. Estimated times to a 50% mortality in moving air were 32.7 h at 25°C, 4.6 h at 35°C, and 1.4 h at 45°C.

Life history and production of filter-feeding insects on stone dikes in the lower Mississippi River

Population and production dynamics of two filter-feeding macroinvertebrates, the caddisfly Hydropsyche orris and the midge Rheotanytarsus sp., were examined in the lower Mississippi River Miles 510–515. Samples were collected from September to November 1987, May to December 1988, and March to May 1989 from stone dikes that protrude into the river. Developmental synchrony was high among individuals in both populations, and seasonal changes in the relative abundance of instars indicated bivoltine and trivoltine life cycles for H. orris and Rheotanytarsus sp., respectively. The size frequency method was used to estimate production (P) and biomass (B) of each cohort in each population. P/B ratios for spring and fall cohorts of H. orris equaled 4.5 and 3.7. Spring, summer, and fall cohorts of Rheotanytarsus sp. had P/B ratios of 4.0, 4.7, and 4.1, respectively. Annual production, estimated as the sum of cohort production values, of the H. orris and Rheotanytarsus sp. population equaled 10.1 and 0.359 g m−2 (dry weight). Annual P/B ratios equaled 10.8 and 16.1 for the H. orris and Rheotanytarsus sp. populations, closely matching values expected for bivoltine and trivoltine populations, respectively. Annual production of H. orris is in the low end of the range of published estimates for other lotic hydropsychid populations inhabiting coarse substratum in warm, lowland rivers of medium size or small, trophically enriched streams. Annual production of Rheotanytarsus sp. is the first such estimate based on a simultaneous assessment of life cycle and production. Given the lack of naturally occurring gravel and cobble substrate in the lower Mississippi River, stone dikes are an especially important habitat for H. orris and Rheotanytarsus sp.