Thomas F. Waters

Secondary Production in Inland Waters 1

Publisher Summary The measurement of production is being employed as an indicator of the health of an ecosystem, assessing the effect of environmental pollution or other disturbance. Additionally, secondary production is of vital interest to natural resource administrators responsible for the management of wild populations utilized for both food and recreation and in inland waters, particularly for vertebrate fisheries. This chapter discusses a selected portion of aquatic production biology, secondary production in inland waters. The chapter focuses on three groups, fishes, zoobenthos, and zooplankton, which have received most attention, for which methodology has been best worked out, and which are of most immediate concern to man. The production of other secondary producers, including heterotrophic algae, bacteria and fungi, protozoans, amphibians, reptiles, and other aquatic vertebrates, such as some birds and mammals more commonly associated with the terrestrial environment, must await further advances and reviews by other specialists. The energy flow through these other groups may be extremely important.

Interpretation of Invertebrate Drift in Streams

Various experiments were conducted in a small Minnesota trout stream to determine if data on the drift of stream invertebrates obtained with stationary nets set in the stream, may be interpreted as indication of permanent downstream displacement. A mayfly, Baetis vagans McDunnough, and the scud, Gammarus limnaeus Smith, were the two species primarily involved in the drift. Drifting invertebrates were collected in arrays of several shallow nets stacked on their supporting rods to obtain the vertical distribution of the drift through the water column. Both species entered the drift nets, not only along the stream bottom, but in all water strata. A comparison of the standing crops with drift net accumulations indicated that the drift was too large to be supplied only by the standing crops in the vicinity of the drift nets and that the organisms must have drifted down from upstream areas. Measurement of the dispersal of organisms moving into a denuded stream bottom area, alternately open to movement from upstream and downstream, indicated that both species did so primarily at night and from upstream. Experimentally blocking the drift with nets set from bank to bank reduced daily drift rates downstream from the block position through a distance of 38 m, including two riffles and an intervening pool, indicating that the organisms normally drifted through at least this distance. In general, it appears that the accumulation of organisms in drift nets is the result of a permanent displacement of the organisms downstream, and not the result of nondirectional activity in the immediate vicinity of the nets.

Diurnal Periodicity in the Drift of Stream Invertebrates

Many aquatic animals exhibit diurnal periodicity in activity. In lakes the daily vertical migrations of crustaceans, rotifers, and the insect Chaoborus have been the subject of many studies (Bainbridge 1961, Pennak 1944, Berg 1937). Although similar phenomena might be expected in streams, little has been reported. Moon (1940), who studied the colonization by invertebrates of bottom materials set out in trays, reported greater activity at night than during the day in both a lake and a stream. It is reasonable to postulate that changes in activity among stream organisms would be manifested in changes in the drift rate (defined as the quantity of organisms drifting downstream per unit time per unit of stream width), but published studies on drift either have not undertaken measurement of drift rates during hours of darkness or have not distinguished between night and daytime drift rates (Needham 1928, Lennon 1941, Dendy 1944, Mullor 1954, Waters 1961). However, Lennon (personal communication) observed in his study greater activity of stream insects at night and believed that in his 24-hour drift samples the immatures were collected mostly at night. Also, in a personal communication, G. R. Alexander, Michigan Department of Conservation, stated that in his drift studies (as yet unpublished), there appeared to be peaks in drift rate in the evening and again in early morning. Prior to the present study, ecological investigations in the summer of 1959 included drift measurements out of an exclosure set into a stream bottom; much higher drift rates were observed at night than during daylight hours. Subsequent observations, both from an exclosure and in the open stream, confirmed the daily changes as regularly occurring events. The purpose of the present study was to document more intensively this phenomenon of diurnal periodicity in the drift rate. I would like to express appreciation to Robert J. Knapp for his conscientious assistance in the field; to many students, especially George A. Swanson, for the extensive work of sorting and analyzing the samples in the laboratory; and to Roy C. Arnold on whose property the field work was conducted, and who generously offered his cooperation and facilities. The study was assisted by National Science Foundation research grant No. F 9935.

ANNUAL PRODUCTION OF MACROINVERTEBRATES IN THREE STREAMS OF DIFFERENT WATER QUALITY

Macroinvertebrate annual production was estimated in three Minnesota streams that differed in watershed geologic origin and in total alkalinity. Annual mean alkalinities (as CaCOt) in the Caribou River, Blackhoof River, and North Branch Creek were 34, 83, and 245 mg/L, respectively. Annual production by herbivore-detritivore invertebrates was lowest in the Caribou River (wet mass: 27.0 g/m2), intermediate in the Blackhoof River (36.9 g/m2), and highest in North Branch Creek (I 19.6 g/m2). Estimates of annual production by invertebrate carnivores followed the same pattern: lowest in the Caribou River (5.5 g/m2, intermediate in the Blackhoof River (6.5 g/m2), and highest in North Branch Creek (12.8 g/m2). These estimates of annual production were positively associated with alkalinity, nitrates, and fish standing stocks.

Size‐Selective Predation on Gammarus Pseudolimnaeus by Trout and Sculpins

Length distributions of the stream amphipod Gammarus pseudolimnaeus were obtained from analysis of the stomach contents of age I and older brook (Salvelinus fontinalis), brown (Salmo trutta), and rainbow trout (S. gairdneri) collected from July 1979 to May 1980, and of sculpins (Cottus cognatus) and young—of—year trout. Length distributions of Gammarus in benthic and drift samples were also analyzed for comparison with stomach—content data. For all sample dates, length of Gammarus in the stomachs was significantly greater than in the benthic samples. Mean and median sizes in the drift were usually smaller than in the benthos, indicating that length distributions in the drift did not directly account for the length distributions of Gammarus in the stomachs. Age I and older trout generally consumed more Gammarus in the day than at night, and those consumed at night tended to be larger. The occurrence of larger Gammarus in the night drift than in the day drift and an observed lower exploitation rate at night support Allans drift/predation risk hypothesis. Size selective predation by sculpins and young—of—year trout was significant but less pronounced than in age I and older trout. Although there was seasonal differences in the lengths of Gamarus in fish stomachs as well as in the drift and benthos, size—selective predation occurred throughout the year. Size—selective predation may have its greatest impact on Gammarus populations in the winter, when density and growth rates are low.

Standing Crop and Drift of Stream Bottom Organisms

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Effects of Floods on Food Consumption and Production Rates of a Stream Brook Trout Population

Abstract Food consumption and production rates were estimated for a stream population of brook trout, Salvelinus fontinalis Mitchill, over a two-year period (1965–1966) in which four severe floods occurred. Two year classes were nearly eliminated as producing components of the population. Standing crops of older age groups were reduced as a result of a decrease in the streams carrying capacity after sand and debris carried into the stream by flood waters filled pools and blanketed riffle areas. Invertebrate populations were also severely damaged by floods, reducing the food supply and causing an apparent decrease in growth rates in 1965 when three of the four floods occurred. Results of laboratory feeding experiments at four different temperature-season combinations were used to estimate food consumption rates of the brook trout in their natural environment. Maintenance requirement increased with increasing temperature in the spring and summer and decreased with decreasing temperature in the fall and win...

Production Rate, Population Density, and Drift of a Stream Invertebrate

Production rates of the stream mayfly, Baetis vagans McDunnough (Ephemeroptera: Baetidae), were estimated by two different methods, compared, and related to population density and drift rate. In the year of study, this mayfly had two summer generations and one winter generation. The two production rate methods yielded estimates of 9.1 and 12.6 g/m2 year as the sum of the three generations, although both estimates were minimal. Production rates for the summer generations were higher than for the winter generation, although winter production was still at a significant level. The summer generations drifted in large quantities, up to about 22 g/day, but the winter generation appeared to drift little, if any, until near the end of the generation in early spring. The relation between annual production rate and mean population density, or turnover ratio, was 9.7, or 3.2 times the number of generations. See full-text article at JSTOR

Trout Production Dynamics and Water Quality in Minnesota Streams

Abstract We sampled fish assemblages and quantified production dynamics of brook trout Salvelinus fontinalis, brown trout Salmo trutta, and rainbow trout Oncorhynchus mykiss in 13 southeastern Minnesota streams during 1988–1990 to examine the influence of water quality on fish populations in fertile trout streams. Fish assemblages in 15 stream reaches were abundant, but low in diversity; 13 species were collected. Parameter means (ranges) over the reaches were species richness, 4.1 (1–8); density, 29,490 (1,247–110,602) fish/ha; and biomass, 253.5 (49.6–568.6) kg/ha. Means (ranges) for salmonids were annual mean density, 2,279 (343–8,096) fish/ha; annual mean biomass, 162.0 (32.5–355.5) kg/ha; and annual production, 155.6 (36.7–279.6) kg/ha. Salmonid production and mean biomass were greater during the spring-fall interval than during fall-spring; young cohorts (ages 0–1) contributed the greatest proportion to population biomass and production. Salmonid annual production-to-mean-biomass ratio (P/B) average...

EFFECTS OF SMALL IMPOUNDMENTS ON HYDROPSYCHID CADDISFLY PRODUCTION IN VALLEY CREEK, MINNESOTA'

Annual production by filter-feeding caddisfly larvae (Trichoptera: Hydropsychidae) was estimated by the size-frequency method and compared in riffles immediately above and below small (< 1 ha) impoundments or ponds at three sites in Valley Creek, Minnesota in 1982-1983. At all three sites, production was significantly higher below impoundments than above. At the most upstream site, annual production by Hydropsyche slossonae was 0.9 g/m2 (dry mass) in the upper riffle but was 40.0 g/m2 in the riffle located below inputs by ponds beside the main stream. At the middle site, production by H. slossonae and a small population of Cheumatopsyche pettiti was 16.2 g/m2 in the upper riffle, but was 31.7 g/m2 below two mainstream impoundments and a side pond. At the lowermost site, production by co-dominants H. slossonae and C. pettiti together with Hydropsyche riola totalled 5.8 g/m2 in the upper riffle but 34.9 g/m2 below a mainstream impoundment. Although the number of hydropsychid species increased at successive downstream sites, the proportionate representation of species in the upper riffle at a given site was almost identical to that in the lower riffle. The higher production in lower riffles was attributed to factors in pond or impoundment outflows that provided favorable conditions for species already established in the reach of creek containing the impoundment. The most likely factor was postulated to be an increase in abundance or quality of seston. Other factors were better growths of moss and filamentous algae, which provided attachment sites for retreat con- struction, and the absence of abrasive sand after deposition in impoundments.