7797

• UCREFRP Catalog Number: 7797
• Author: Collins, K.
• Title: Conceptual Management Plan for Razorback Sucker Habitat Enhancement in Flooded Bottomlands Scott M. Matheson Wetland Preserve Moab, Utah.
• USFW Year: 1994.
• Copyright Material: NO

A. Relation of Nutrients, Sunlight Penetration and Warm Water
Temperatures to Phytoplankton Production. Phytoplankton
productivity provides the basis for development of a food web.
Phytoplankton production and standing crops increase in concert
with increases in annual input of nutrients regardless of
latitude. Carbon, nitrogen, and phosphorus are key elements for
phytoplankton production. Phosphorus is perhaps most limiting in
north temperate and subarctic climates (Schindler 1978).
Nitrogen is the most abundant element in the atmosphere and is
generally not limiting. Also, abundant carbon dioxide in the
atmosphere provides the necessary carbon. Therefore,
phytoplankton production and standing crop in north temperate
freshwaters is generally proportional to the phosphorus input.
Particulate phosphorus, either chemically desorbed or actively
mobilized by microbiota, is not readily available in rivers with
a high sediment load because most of the phosphorus is bound to
the sediments (Ellis and Stanford 1988). Watts and Lamarra
(1983) determined that between 21% and 49% of the total
phosphorus in Colorado River water at the bridge upstream from
Moab, Utah in September and October 1978 was bioavailable with
most of the extractable element in the form of calcium-bound
phosphorus. Therefore, Watts and Lamarra (1983) concluded that
algae production was not nutrient limited in this reach of the
Colorado River but that primary production was inversely related
to the turbidity of the riverine environment.
The rivers of the Upper Colorado River Basin are turbid and
contain large expanses of sand substrate. Production of
Phytoplankton and zooplankton that form the basis for a food
pyramid are extremely low in the these rivers (Grabowski and
Hiebert 1989; Cooper and Severn 1994 a, b, c, and d; Mabey and
Schiozawa 1993). High turbidity obstructs the penetration of
sunlight that is needed for phytoplankton production. Backwaters
and embayments along the main river channels and flooded
bottomlands in off-channel areas provide favorable conditions for
phytoplankton production. Sediments deposited in these areas
where the water velocity is decreased provide nutrients and
sunlight penetrates the clearer water that allows phytoplankton
to flourish as primary producers and to stimulate production of
the food chain. Low velocity off-channel habitats become warmer
than the riverine environment in the upper basin (Kaeding and
Osmundson 1988; Osmundson and Kaeding 1989). The combination of
nutrients, sunlight penetration of the water column, and warmer
water temperatures in low velocity habitats provide the best
conditions for phytoplankton production in the upper basin.
B. Importance of Low Velocity Habitats to Zooplankton
Production. The importance of low velocity habitats to the
production of zooplankton for fish in riverine environments has
not been documented very well. Most riverine studies have
concentrated on macroinvertebrates occurring in the drift (Waters
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