8092

• UCREFRP Catalog Number: 8092
• Author: U.S. Department of the Interior.
• Title: Proceedings of the Symposium on Restoration Planning for the Rivers of the Mississippi River Ecosystem.
• USFW Year: 1993.
• USFW - Doc Type: Washington, D.C.
• Copyright Material: NO

12 BIOLOGICAL REPoRT 19

build in some replication; however, the time and
cost were prohibitive.

Level N

This component involves using infrared aerial
photography on the same 10 watersheds examined
in Level II. Aerial infrared photos were taken in
spring 1992 before leaves were present. Ground
photos were taken concurrently to aid in aerial
photo interpretation. A mosaic of all aerial photos
will be made; landscape features will be identified,
mapped on mylar sheets, and recorded in digitized
fonn. We hope this level of assessment will prove
as reliable as and more economical than Levels II
and IlL

Biological Monitoring
Subcommittee

Sediment Chemistry

During the last 15 years, total suspended solids
in the lower Minnesota River have been six times
greater than those in the Mississippi River at their
confluence (MPCAfiles). Contaminants such as
heavy metals and PCB's often associate with
smaller particles in suspended solids and sedi-
ments (Oliver 1989).
Suspended solids, sediments, sediment pore
water, and mussels were collected at four main-
stem and five tributary sites once during spring
and once during summer 1990. Suspended solids
were analyzed for pH, percent organic matter,
nickel, cadmium, lead, copper, zinc, and chro-
mium. Zinc was the most abundant of the heavy
metals found, and cadmium was the least abun-
dant.

Ambient Toxicity

Toxicity tests frequently show good correlation
with elevated instream pollutants and down-
stream persistence (Ankley et al. 1990). The objec-
tive of this component of the study is to determine
if ambient toxicity can be demonstrated in Minne-
sota River surface water and sediments. Thirteen
mainstem sites, eight tributary sites, and four
reservoir sites were selected. These sites were cho-
sen based on the following criteria: good road ac-
cessibility and availability of stream sediment,
area to launch a small boat, and proximity to
physical and chemical subcommittee monitoring
sites.

Ambient water and sediment samples were col-
lected in midchannel to avoid shoreline distur-
bances. Samples were collected during five periods
in 1989 and 1990 to cover all four seasons and to
coincide with other sampling activities. Anion and
cation concentrations were determined for each of
the samples.
Two standardized test procedures were applied
to the surface water and sediment pore water.
Ceriodaphnia, a microcrustacean. and Selanas-
trom, a green alga, were the test organisms. Ceri-
odaphnia test procedures are described by Horn-
ing and Weber (1985), and Selanastrom test
procedures are described by the U.S. Environ-
mental Protection Agency (1989).
Toxicity to Ceriodaphnia was found at 5 of the
25 sampled sites. The most highly toxic sites were
found near the mouth of the Minnesota River and
in Lac Qui Parle Reservoir. Mainstem locations
upstream from rkm. 17 and the eight tributary
locations were nontoxic, but three of the four res-
ervoir sites were toxic.
Toxicity to Selanastrom was found at 8 of the 15
sampled locations. Toxicity was found at all sites
in the mainstem between rkm. 336 and the mouth
and at both sampled reservoir sites. None of the
five sampled tributaries was toxic. The most toxic
site to Selanastrom was found in Lac Qui Parle
Reservoir.
Reservoir sites had higher concentrations of to..
tal nutrients in sediment pore water, mainstem
sites showed higher concentrations of nitrite, and
tributary sites had higher concentrations of ni-
trate. Four locations-two mainstem (Fort
Snelling and I -35W Bridge) and two reservoirs
(Rapidan and Lac Qui Parle)-had the highest
concentrations of ammonia and total phosphate.
Three mainstem locations (I-35W Bridge, Judson,
and Courtland) had nitrite levels more than 100
times higher than the other sites. Four tributary
locations (Le Sueur, Blue Earth, Watonwan, and
Rush rivers) had sediment nitrate concentrations
2-10 times greater than the other locations. Am-
monia, nitrate, total phosphate, and iron showed a
progressive increase in downstream mainstem lo-
cations.

Algal Communities

The composition and abundance of algal com-
munities in streams reflect characteristics of the
sUlTOunding watershed, riparian zone, and chan-
nel morphology. These features influence the
physicochemical conditions of water and substrate