An annual energy budget is presented for Bear Brook, a small undisturbed second-order stream in northeastern United States. The ecosystem approach, in which all input and output fluxes of potential energy as organic matter are considered, is used to describe the dynamics of energy flow in a 1,700-m segment of the stream. The annual input of energy to the system is 6,039 Kcal/m2. Over 99% of this is allochthonous, from the surrounding forested watershed or from upstream areas. Autochthonous primary production by mosses accounts for less than 1% of the total energy available to the ecosystem. Algae and vascular hydrophytes are absent from the stream. Meteorologic inputs (litter and throughfall) from the adjacent forest account for 44% of annual energy input. Most of this is in particulate form. The remaining 56% of input enters by geologic vectors (inflowing surface and subsurface waters). Eighty-three per cent of the geologic input and 47% of the total input of energy occur as dissolved organic matter. Approximately 4,730 Kcal/m2 of organic detritus, nearly equally divided between leaves and branches, is stored within the system. The size of this detritus reservoir is stable from year to year. The turnover time of the branch compartment is about 4.2 years; of the leaf compartment, about 1 year. Although much of the annual input of energy is in a dissolved state, dissolved organic matter does not tend to accumulate in the system and displays a very rapid rate of turnover. Sixty-six per cent of annual energy input is exported to downstream areas in stream water. The remaining 34% is lost as heat through consumer activity. Bear Brook is a strongly heterotrophic steady-state system in which import and export of organic matter play a significant role. A conceptual scheme is presented by which import, export, photosynthesis, and respiration may be used to describe the functional dynamics and developmental processes of ecosystems.

https://www.jstor.org/stable/pdfplus/1942301.pdf

Energy Flow in Bear Brook, New Hampshire: An Integrative Approach to Stream Ecosystem Metabolism

Preface. Selected Atomic Weights. Customary Metric Conversion Factors. 1. Water Quality and Aquaculture: Preliminary Considerations. 2. Ecology of Aquaculture Ponds. 3. Water Quality Requirements. 4. Water Use. 5. Liming. 6. Fertilization. 7. Aeration. 8. Water Circulation. 9. Turbidity and Appearance of Water. 10. Aquatic Weed Control. 11. Off-Flavors and Harmful Algae. 12. Pollution. 13. Chemical, Physical, and Biological Treatments. 14. Waste Management. 15. Measurement of Water Quality. 16. Sustainability and Environmental Issues. References. Index.

Pond aquaculture water quality management

The bluegill sunfish (Lepomis macrochirus) undergoes several habitat shifts between the littoral and pelagic zones of small lakes during its life history. After hatching in the littoral zone, bluegill fry migrate to the pelagic zone to feed on zooplankton. In this study the fry then returned to the littoral zone in four different lakes at a relatively constant size of 12.5 mm standard length. Several years are spent feeding in the littoral zone vegetation before the bluegill again shifts to feeding on zooplankton, first in the water column above littoral vegetation and subsequently in the true pelagic zone. This shift to feeding on zooplankton occurred at a specific body size within a lake, but the size ranged from 50 to 83 mm among five different lakes. The size at which the shift occurred was directly correlated with the density of the major predator of the bluegill in these lakes, the largemouth bass (Micropterus salmoides). We demonstrate that the bluegill is faced with a growth (or feeding) rate-predation risk trade-off in making these habitat shifts. Analyses of stomach contents, the growth of small fish caged in the pelagic zone, and predictions of foraging rates in both habitats all indicate that the pelagic zone is the more profitable habitat for all size classes of the bluegill. Through a series of pond experiments we further show that risk of predation by largemouth bass was 40-80 times as great for small bluegills in the open water as for those in the vegetation. We interpret the patterns of habitat use by the bluegill in terms of a model that explicitly weights the costs (predation) and benefits (growth) of making a size-specific habitat shift to the pelagic. Finally, we discuss evidence that the bluegill can facultatively respond to changes in feeding rates and predation risk, and the consequences of such ontogenetic habitat shifts to community dynamics.

https://www.jstor.org/stable/pdfplus/1941633.pdf

Ontogenetic Habitat Shifts in Bluegill: The Foraging Rate‐Predation Risk Trade‐off

Experimental manipulations of fish in a Northern California river during summer base flow reveal that they have large effects on predators, herbivores, and plants in river food webs. California roach and juvenile steelhead consume predatory insects and fish fry, which feed on algivorous chironomid larvae. In the presence of fish, filamentous green algae are reduced to low, prostrate webs, infested with chironomids. When the absence of large fish releases smaller predators that suppress chironomids, algal biomass is higher, and tall upright algal turfs become covered with diatoms and cyanobacteria. These manipulations provide evidence that the Hairston, Smith, Slobodkin–Fretwell theory of trophic control, which predicts that plants will be alternately limited by resources or herbivores in food webs with odd and even numbers of trophic levels, has application to river communitics.

https://science.sciencemag.org/content/sci/250/4982/811.full.pdf

Effects of Fish in River Food Webs

Bioaccumulation of persistent organic chemicals: mechanisms and models

The dynamics of DDT in lentic environments were studied in a farm pond and four artificial pools. A hypothesis that biological magnification of pesticides was dependent on passage of the residues through a food chain was rejected and a hypothesis that accumulation depends on adsorption and solubility differences was proposed. The mechanism proposed is based on the principle that compounds are exchanged between water and fats. Exchange in fish passes through two stages, from water to blood and from blood to fats, permitting a high degree of magnification in fish. The proposed mechanism accounts for the reported observations that pesticides are excreted by fish, that body load of pesticides increases as the fat content of fish increases, that pesticide magnification by fish is inverse to the water solubility of the compounds and that pesticides persist longer in oligotrophic than eutrophic lentic ecosystems.

A Proposal: Exchange Equilibria Control the Degree Chlorinated Hydrocarbons are Biologically Magnified in Lentic Environments

Blood characteristics and mortality were compared between rainbow trout which were captured by (1) angling with artificial lures, (2) electroshocking, and (3) seining. The hemoglobin concentration, erythrocyte sizes, plasma protein concentrations, and plasma protein fractions varied according to the method of capture. Mortality was negligible in the shocked and seined lots, but was above 85% in the hooked fish group. Mortality was delayed and the symptoms suggest progressive shock. Definite differences in behavior were noticed in the postcapture fish and included prolonged fasting (shocked and hooked fish), hyperexcitability (shocked fish), and lethargy (hooked fish). The authors believe that presently used methods of capturing and handling fish should be re-evaluated, particularly if the fish are to be used in toxicological or management studies.

Influence of Capture Methods on Blood Characteristics and Mortality in the Rainbow Trout (Salmo gairdneri)

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1965.10.1.0074

Primary productivity and energy relationships in artificial streams1

https://aslopubs.onlinelibrary.wiley.com/doi/epdf/10.4319/lo.1956.1.3.0162

Benthic Productivity as Influenced by Fish Predation

Almost all of the macroscopic aquatic organisms can serve as food for fishes under certain conditions and the many quantitative and qualitative studies of the standing crops of fish-food animals have been of value in estimating the capacity of a body of water to produce fish. While investigations of the production of fish-food animals are numerous, the majority of these studies are based upon summer season collections only. A very few of the workers have made estimates of production of invertebrates (Lundbeck 1926; Miller 1941). Ricker (1946) presented an analysis and review of the literature with a discussion of certain problems of the dynamics of production and also delineated the fundamental concepts of productivity which have an ecological application. Clarke (1946) has outlined concepts of productivity in a marine area. Certain of the interrelationships of a fish population and the invertebrate fauna in one of Michigan's lakes have been considered by Ball (1948). The present report is concerned with a study, in this same lake, first, of the composition of the invertebrate fish-food population for a period of three years and, second, of the responses of these organisms to the removal of the fish population.

Robert C. Ball

Papers

A Proposal: Exchange Equilibria Control the Degree Chlorinated Hydrocarbons are Biologically Magnified in Lentic Environments

Influence of Capture Methods on Blood Characteristics and Mortality in the Rainbow Trout (Salmo gairdneri)

Primary productivity and energy relationships in artificial streams1

Benthic Productivity as Influenced by Fish Predation

Effects of the Removal of the Fish Population on the Fish-Food Organisms of a Lake