Download Appendix: How to Sample Streams for Bio

ZO 403 Invertebrate Zoology lab
Spring 2002
Stream Bio-Indicators
Introduction
Background on Rocky Branch
For this lab we will identify invertebrates collected from two first-order
streams. This is part of a continuing effort in support of an extensive ecosystem
restoration effort for Rocky Branch by
several groups associated with the University, led by Barbara Doll who spoke to
us at our last meeting.
Background: Rocky Branch is a
first-order stream draining most of North
Campus between Hillsborough Street and
Western Boulevard. It arises at the extreme southwestern corner of the Meredith College campus and the I-440 Hillsborough Street intersection, and is
tributary to Walnut Creek near where
Fayetteville Street crosses I-40. Before
it comes into campus it passes behind
several businesses, and warehouses, and
right through a lawn care company,
apartments parking lot and several yards
of older houses. It enters campus by
passing under Gorman Street and immediately receives drainage from the N. C.
State Physical Plant nursery/recycling
center/waste transfer dock. Below the
bridge to Motor Pool lot, Rocky Branch
receives several culverts which drain
Hillsborough Street, a C. P. & L. transformer pad and a commercial laundry.
Then come culverts from N. C. State
parking lots, the Food Service Center
and, among many other University buildings, Schaub, Weaver, and Grinnells
Halls, University Graphics, Central
Stores, the Human Resources Building
and the new Public Safety complex. At
Dan Allen, culverts bring in drainage
from all of Dan Allen and Hillsborough
Street between Gregory Poole construction equipment and repair and Nelson
Hall. After passing behind the gym and
athletic fields, Rocky Branch passes under Pullen Road and though the city’s
Pullen Park, Dix Hospital, and Boylan
Heights. The catchment is relatively
narrow, and the stream drains an unusually large area to be only first order because there are no obvious lateral tributaries.
Lab Activity
Assigned teams of students will identify and count all specimens collected
from Mill Creek and Rocky Branch by
taxonomic categories listed in the Stream
Data Sheets that will be provided in lab.
Results will be posted on the blackboard
before the end of class. Each student
must compose a report based on this information and turn it in on April 12.
Report
Use the simplified bioindicator index
(Resh's Family-Based Index) to calculate
indices of water quality for each collection. Discuss your own observations
about the differences in conditions in the
two streams. Choose one of the types of
animals that was present in Mill Creek
and look up its diet, habitat requirements,
and environmental tolerances. This animal should not be one of those in your
Voucher Collection, but it may be one for
which you write a notebook record.
Based at least partly on what you find
out about that animal, discuss the factors
that probably enhanced the biodiversity
of macroinvertebrates in Mill Creek.
1
ZO 403 Invertebrate Zoology lab
Very little historical research has been
done on Rocky Branch, but much can be
extrapolated from the history of a typical
forest stream in our eastern Piedmont and
the known effects of settlement, agriculture, and urbanization.
Rocky Branch must once have been a
picturesque woodland stream, cascading
over bedrock outcrops between low
banks. The landscape must have been
forested with oaks and hickories and
shaded overhead by dogwoods, elms,
sycamores, and tulip poplars. Gravely
riffles and sandy pools would create an
abundance of refuges and habitats. Old
beaver dams, small seepage springs and
intermittent tributaries would have
formed low, mucky marshes along the
banks.
It must have overflowed every winter
into pools which supported a variety of
amphibians, fairy shrimp, crayfish, isopods, amphipods, diving beetles, and
fingernail clams. Raccoons, otters, wild
turkeys, black bears, foxes, and deer
would have visited frequently. Many
species of salamanders, turtles, snakes,
crayfish, darters and minnows would
breed in the main channel, floodplain
pools, and beaver ponds. The gravelly
riffles must have harbored a diverse mix
of stoneflies, caddisflies, mayflies, dragonflies, beetle larvae, and hellgrammites.
When the land was cleared for agriculture in the early 1800’s, both soil erosion and peak runoff increased greatly.
The stream's rocky riffles were smothered
with mud and sand. Devegetated banks
caved in, adding more sediment to the
channel. Alluvial fans of gravel and silt
spread over the floodplain above obstructions. Wastes from animals and outhouses and excess fertilizer began to pollute the stream with nutrients, stimulating
Spring 2002
algal and bacterial growth and reducing
oxygen levels in the sediments.
As the city of Raleigh grew out past
campus, increasing areas of streets and
roofs drained rapidly down into the
stream channel in every storm. The
rushing waters began to scour the channel, both downward and outward, removing increasingly valuable land surfaces from the campus. From the 1950’s
and continuing through the present, more
and more parking lots, apartments,
buildings, and roads were added to the
catchment, mainly by the University.
The banks of Rocky Branch were channelized and hardened with gravel, concrete block walls and asphalt rubble to
stop the loss of land from athletic fields
and parking lots. Former floodplains
were buried under landfill. A section of
about 100 m was enclosed in a culvert
behind Carmichael Gym. Waste asphalt
and concrete were dumped down the ravine sides. Later, granite riprap and
culverts were added to reduce caving of
the banks.
These changes greatly increased the
proportion of impervious surface in the
catchment, causing even higher flows
during rainstorms, and much lower flows
in between rains. The combination of
high storm flows and bank stabilization
caused the channel to erode downward to
bedrock and leave a deep ravine below
Dan Allen Drive. Most recently (about
1993), Gorman Drive was widened and
built up to a high causeway, confining the
stream into a long, narrow culvert.
Rocky Branch has been treated like a
drainage ditch by the University and upstream urban and suburban areas for
decades. The headwaters are not on
campus, and include a long reach of rail2
ZO 403 Invertebrate Zoology lab
Spring 2002
road, the Hillsborough-Beltline intersection, two lawn care companies, and a
suburban area where residents sometimes
discard trash into the stream. Eroded silt
and clay, toxic chemicals and garbage
washed from construction sites, waste
handling facilities, street surfaces and
building drains, and even direct sewage
discharges continue to contaminate the
water.
odonates in 1991, but neither was found
there in 1996. The only organisms classes have found regularly in segments of
Rocky Branch on the N. C. State campus
are midgefly and cranefly larvae, water
striders, crayfish, and aquatic earthworms, and at one site, salamanders.
That relatively rich site was totally restructured by the recent channel restoration project.
Previous Surveys
All animals collected in Rocky
Branch since that 1978 visit are relatively
insensitive to poor water quality and habitat disturbance. In one or two studies,
small populations of green sunfish, hydropsychid caddisfly and calopterygid
damselfly larvae were found, but there
was no trend for improvement until about
1998. Part of the reason for this low diversity was a scarcity of important natural
habitats such as clean gravel and
leafpacks. Frequent scouring by high
flows had flushed out what little organic
detritus might have fallen into the stream.
In 1978, the newly formed Biological
Monitoring Group of the N. C. Division
of Environmental Management sampled
Rocky Branch in a preliminary comparison of urban and rural streams. The results were shocking - they found nothing
but midgefly larvae and aquatic earthworms. This was the lowest biodiversity
and poorest bioindication of water quality
of any stream they sampled.
N. C. State student organizations and
aquatic ecology classes have been surveying Rocky Branch for about 12 years.
A survey involves sampling with kickscreens and dipnets to retrieve as many
different kinds of larger invertebrates as
possible. The numbers and identity of
the animals we catch enable a comparison
with general biomonitoring assessment
standards and through an increasing span
of years, to determine whether conditions
for the biological communities of Rocky
Branch are declining, improving or remaining the same. You are now part of
that ongoing effort.
'Restoration Efforts
In the early 1990's, students began an
effort to restore and protect the water
quality and habitats of Rocky Branch.
The early efforts of the old Student Environmental Action Coalition around
1989 have been continued by the current
Lorax club. We have benefited over that
entire period from the leadership of Ms.
Barbara Doll of the U. N. C. Sea Grant
Program. Ms. Doll has won a grant to
finance the current restoration program.
Previous, smaller projects had already
resulted in stream bank plantings, channel
deflector posts, and increased protection
of the stream from on-campus wastes and
runoff. Most of those early efforts were
replaced by the current project.
Not surprisingly, their surveys have
revealed very low numbers and diversity
compared to less disturbed streams. At a
site above Gorman Street where Rocky
Branch flows under a street near the railroad track, we collected amphipod crustaceans (probably Crangonyx) and
3
ZO 403 Invertebrate Zoology lab
Those early efforts paid off when we
began to see limpets, mud snails, and two
kinds of mayfly larvae. In February
1997, Ms. Doll, a student, myself, and a
Physical Plant employee transported several tubs of leaf detritus, mud, twigs and
gravel from a similar-sized stream in a
wooded part of Centennial Campus and
put it in the stream near the Motor Pool
lot. Two months later, several species of
aquatic “true bugs,” beetles and dragonflies were collected, and the number of
baetid mayflies seemed higher in the
segment below the “seeding.”
Although most of those organisms
were found again in 1998 and 1999, there
have been no improvements in the area
downstream of Dan Allen Drive at all,
and no further additions of species to the
reach above Dan Allen. Some of the
animals found in 1999 have not been
collected since then. In recent years
student stream watchers have observed
discoloration, foam and crayfish kills in
Rocky Branch several times.
Appendix: How to Sample
Streams for Bio-Indicators
To compare selected stream segments, sample with dipnets, kickscreens,
pans, forceps and pipettes to get as many
different kinds of animals as possible.
Watch out for broken glass and rusty
metal as you sample and pick the material! Because of the possibility of bacterial contamination, wash your hands thoroughly before consuming any food or
drink after collecting in streams.
Remember that materials collected
with kickscreens and dipnets are best
examined in white pans in good light. It
is much harder to see the animals in the
nets and, if you spend most of your time
searching in a net, you are liable to con-
Spring 2002
clude that there are none present when in
fact there are quite a few. Each pan
should be searched for at least 3 minutes,
and 6 or 7 is better. Many animals do
not move immediately after a sample is
placed in a pan, but become active
enough to recognize and pick only after a
few minutes. This will require patience,
because only a few kinds of animals
move in the first minute or two.
Do not kill crayfish, fish, or salamanders. Their populations are less able
to intensive collection and they can often
be identified with experience better as
live specimens in the field than as preserved specimens in the lab. Whenever
possible, release them alive. Crayfish
cannot be identified as immature specimens, and the easiest adults to identify
are the actively breeding males. We only need to collect and preserve a few actively breeding males to document a
crayfish fauna.
Representative specimens of the medium and small invertebrates will be preserved for identification and evaluation in
a later lab meeting. Continue picking and
transferring the animals into labeled alcohol jars until you see no new kinds of
animals. Midgefly larvae and aquatic
oligochaetes are quite small and amazingly diverse in streams. Pick large numbers of them, even though they may not
appear to be different kinds, because even
sub-family level differences are hard to
recognize without a dissecting microscope. After the class has put 5 or 6 of
each of the other, recognizably different,
types of animal into the jars at any one
site, additional specimens should be returned alive to the stream.
Another useful collecting approach is
to grab a thicker leafpack and peel away
the leaves one at a time to find animals.
4
ZO 403 Invertebrate Zoology lab
Spring 2002
The older, more decayed leafpacks will
produce more animals than freshly
formed ones. Also, larger rocks and
woody debris, or even bottles and cans,
can be examined directly. Look with
special care for brownish or grayish,
small, inactive animals such as snails,
water pennies, and limpets, and minute
but active midgefly larvae and aquatic
earthworms.
Be sure that data on temperature, oxygen, turbidity, pH and water flow are
taken before the class leaves the sampling
area. All samples and data must be returned to the classroom, and there thoroughly and accurately labeled with date,
stream and location, well preserved with
alcohol, and left in the care of Ms. Austin.
5