PRACTICUM 4
ROOM 219
October 1, 2013
LOTIC ECOSYSTEMS: MACROINVERTEBRATE AND DIATOM IDENTIFICATION
AND QUANTIFICATION
A. MACROINVERTEBRATE IDENTIFICATION AND ENUMERATION
1. Using a transfer pipette, decant off as much ethanol as possible. Retain enough to
make a slurry.
2. Pour the sample into a few petri dishes. You must keep the organisms wet while
identifying them, but do not retain so much fluid that they float all over the dish. Use
as many petri dishes as needed.
3. Sort the macroinvertebrates by eye into similar looking organisms; segregate these
within and among different petri dishes.
4. Identify under a dissecting microscope and record the lowest possible taxonomic
designation for each organism using the ID guides provided. Until you get the hang
of identifying macroinvertebrates, identifications should be confirmed by the
instructor.
5. Please write environmental and macroinvertebrate data in the sheets provided below.
Do not leave without allowing me to make a copy for my records.
B. I will compile all of the abiotic and biotic data for both segments of the Bushkill Creek into
an Excel spreadsheet and post it to Moodle. You can use these data to complete the
calculations and answer the questions below in your field journal.
DATA SHEET
Please turn in one completed data sheet per group before leaving lab. Data from all 5 replicates
at both sampling stations will be compiled and made available on Moodle.
Bushkill Creek under 13th Street Bridge, Easton, PA
Sampling site mean current velocity: __________ Depth: __________
Physicochemical characteristics of Bushkill Creek under 13th St. bridge.
Temperature (˚C)
pH
Dissolved oxygen (mg/L)
Conductivity
(uS/cm)
Table 1. Macroinvertebrates identified in Bushkill Creek under 13th St. bridge.
Macroinvertebrate Order/Family/Genus
Tally
Alkalinity
(mg/L as
CaCO3)
DATA SHEET
Please turn in one completed data sheet per group before leaving lab. Data from all 3 replicates
at both sampling stations will be compiled and made available on Moodle.
Bushkill Creek within Henry’s Woods
Sampling site mean current velocity: __________ Depth: __________
Physicochemical characteristics of Bushkill Creek within Henry’s Woods.
Temperature (˚C)
pH
Dissolved oxygen (mg/L)
Conductivity
(uS/cm)
Table 2. Macroinvertebrates identified in Bushkill Creek within Henry’s Woods.
Macroinvertebrate Order/Family/Genus
Tally
Alkalinity
(mg/L as
CaCO3)
FIELD JOURNAL
Figures, tables, and calculations to include:
1. Copy or cut and paste Tables 1 and 2 (above) into your journal.
Questions to consider:
1. What is the total species richness and Simpson biodiversity for Bushkill Creek
macroinvertebrates at the 13th Street bridge location?
2. What is the total species richness and Simpson biodiversity for Bushkill Creek
macroinvertebrates at the Henry’s Woods location?
3. EPT Taxa Richness is the number of Ephemeroptera (mayfly), Plecoptera (stonefly), and
Trichopera (caddisfly) taxa in a sample. Values range from 0 to 12, with low values
indicating more organic pollution (from nutrients found in fertilizers, sewage, and other
sources). As organic pollution continues to increase, some pollution tolerant
macroinvertebrates will become dominant and will be able to support large populations
within the stream, while pollution sensitive or semi-sensitive organisms will be unable to
survive. EPT are most diverse in natural streams and decline with increasing watershed
disturbance. How does the EPT Taxa Richness compare between the 13th Street bridge
site and the Henry’s Woods site?
4. Based on your calculations of biodiversity and the EPT values above, do either of these
locations along the Bushkill Creek seem to be showing signs of stress? Use the chart
below as a guide.
Water Quality
Excellent
Good
Fair
Poor
Very Poor
Taxa Richness
≥ 14
12-13
9-11
7-8
≤6
EPT Taxa Richness
≥5
4
3
2
0-1
5. Next, you will need to calculate the Family Biotic Index (FBI). In the tables below (i.e.,
use one for the 13th Street bridge site and the other for the Henry’s Woods site), list the
names of the macroinvertebrate families collected and the number of individuals in each
family in the sample. Look up the tolerance score (Appendix 1) for each family or higher
taxon and write it next to the column; multiply the values in the number column by the
tolerance score for that row. Sum the resulting numbers, and then divide this sum by the
total number of individuals. The equation below is used to calculate the FBI (Hilsenhoff
1988).
Table 3. FBI calculation for the Bushkill stream at the 13th St. bridge.
Table 4. FBI calculation for the Bushkill stream at Henry’s Woods.
6. If you indicated above that water quality in either or both of these locations is less than
good quality, what are some activities within the Bushkill Creek watershed that may be
contributing to this decline?
APPENDIX 1. Tolerance values for macroionvertebrates (Hilsenhoff 1988)