Date of Award:

5-1958

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Watershed Sciences

Department name when degree awarded

Fishery Ecology

Committee Chair(s)

William F. Sigler

Committee

William F. Sigler

Abstract

Investigation of primary production in streams and rivers has lagged behind similar investigations in marine and lacustrine environments. Recently, however, Odum (1956) has demonstrated methods that allow the estimation of productivity of most moving waters. For reasons discussed later in this paper, Odum's method is not satisfactory for shallow, very rapid rivers as typified by Logan River. The present investigation then was primarily an exploration of a method possibly applicable to measurement of productivity in shallow rapid rivers.

Investigations of phases of the ecology and distribution of the main contributors to primary production, the benthic algae, was a necessary corollary to intelligent measurement of primary production in Logan River. A recent review of the knowledge of ecology of river algae (Blum, 1956) summarizes this topic.

Most quantitative investigations of river algae have been directly or indirectly concerned with indices of pollution rather than productivity (Jones, 1951) (Reese, 1937) (Patrick, 1949) (Butcher, 1932, 1940, 1945, and 1947). The growth of algae on slides has been a frequently used method of quantitative study, but it is difficult to relate values attained in this fashion to total productivity or standing crop. Statements concerning algal succession and seasonal variation based on counts of algae growing on glass slides in very rapid water appear questionable.

The concepts of productivity measurement basic to methods used in this investigation are little different than those pertaining to marine and lacustrine environments. The distribution and quantity of chlorophyll in the plankton of lakes was intensively studied by Kosminski (1938) who also foresaw the relation between chlorophyll and lake productivity. Further development of this concept occurred during work by Manning, Juday, and Wolf (1938) and Manning and Juday (1941). Much knowledge of the relation between chlorophyll and productivity has accumulated since these investigations. Ryther (1956) concludes that with knowledge of chlorophyll based rates of photosynthesis, distribution and quantity of chlorophyll and available light one may estimate the primary production of an entire body of water. Edmondson (1955) gives evidence of the usefulness of chlorophyll measurements in making plankton productivity estimates regardless of the taxonomic groups of chlorophyll bearers represented. The relationship of light to aquatic photosynthesis as well as the quantity and quality of light available is summarized by Edmondson (1956). A concise review of the current knowledge of algal photosynthesis is given by Krauss (1956).

The importance of short-term algal photosynthesis in rapid rivers is more obvious than it is in other aquatic habitats. Recycling of fixed energy by the reuse of algal decomposition products in the growth of other algae or aquatic plants is at a minimum in Logan River. Brief pseudo-plankton measurements suggest that a large percentage of the net product of photosynthesis is lost downstream. Nowhere on the bed of Logan River is there evidence of important conservation of organic matter in the form of muck or plant detritus. Although quantities of leaves fall into the river, contributions from terrestrial plants are actually unimportant. Little of the foreign plant material reaching Logan River is accumulated until it arrives at the impoundments.

The food habits of the dominant fish indicate a complete dependence on aquatic insect larvae (Fleener, 1951) (Zarbock, 1951) (Sigler, 1951). Although the food of North American stream insects has not been intensively investigated, work on the food habits of closely allied insects from British streams shows that algae are the most important food (Badcock, 1949) (Jones and Erichsen, 1949, 1950).

The importance of the benthic algae in Logan River may then be summarized: for practical purposes the entire diet of the terminal consumers (trout, whitefish, sculpins) consists of aquatic insect larvae (diptera, ephemeroptera, trichoptera, and plecoptera) which depend almost entirely for their sustenance on the living, standing crop of benthic algae or freshly fragmented portions of it in the stream drift. The energy transfers implicit in this statement involve solar energy that was probably fixed in carbon compounds by algae within the previous few months only.

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