10.5061/DRYAD.0P2NGF1XQ
Gray, Derek
0000-0001-7614-8296
Wilfrid Laurier University
Cohen, Rachel
Wilfrid Laurier University
Littoral macroinvertebrate and water quality data for 32 lakes across the
boreal-tundra transition in the Northwest Territories
Dryad
dataset
2020
Northwest Territories Cumulative Impact Monitoring Program*
CIMP197
Northwest Territories Cumulative Impact Monitoring Program
CIMP197
2020-12-31T00:00:00Z
2020-12-31T00:00:00Z
en
https://doi.org/10.5061/dryad.pk0p2ngk6
11317 bytes
3
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
This dataset includes macroinvertebrate and water quality data from 32
lakes sampled in the Northwest Territories, Canada, from the Dempster and
Inuvik-Tuktoyaktuk Highways during July and August of 2017 and 2018. It
was collected as part of a project to determine how physicochemical
variables affect macroinvertebrate and fish communities in small Arctic
lakes.
Study sites Our 32 study lakes were located within the boreal to tundra
transition area. Eight of the lakes were sampled in August 2017 in the
boreal forest region within the Gwich'in Settlement Area (GSA), and
24 of the lakes were sampled in August 2018 in the Inuvialuit Settlement
Region (ISR) where tundra vegetation dominates. Our selection of lakes was
not random, but was determined by a combination of logistical, licensing,
and scientific considerations. As our project included fish community
sampling, we had heavy gear, including gill nets and motorboats to
transport to each lake, limiting the distance we could travel from the
highway. Peat hummocks in the tundra and boggy terrain in the boreal
region made it especially difficult to traverse long distances carrying
heavy gear. Licenses were required for the research project as a whole
(Northwest Territories Scientific License), and for fish collection in
particular (Department of Fisheries and Oceans Scientific Collection
Permit). These licenses required community consultation in the choice of
lakes sampled so that lakes of cultural or recreational value to
communities could be excluded. Therefore, for logistical reasons we
considered all lakes within 300 m of the highways as possible sites. We
also included five sites further away from the highway (0.6-3.5 km from
the highway) that were accessible from the Trail Valley Creek Field
Station (68.741°N, -133.499°W) north of Inuvik. For licensing reasons, and
to respect the wishes of the communities, we excluded culturally
significant lakes such as the Husky Lakes near Tuktoyaktuk or Dolomite
Lake near Inuvik. Finally, for scientific reasons, we deliberately
attempted to select lakes that varied in latitude and surface area. Our
rationale was that we were hoping to examine environmental gradients, so
lakes at different latitudes and of different sizes would be likely to
vary in temperature, depth, fish presence/absence, and other important
environmental variables. Biological data We collected macroinvertebrate
samples using a modified version of the Ontario Benthic Biomonitoring
Network protocol (OBBN) (Jones et al. 2007). We collected three replicate
samples using a 500 μm D-net to kick and sweep macroinvertebrates. The
modifications to the original OBBN protocol were that each replicate was
collected over three minutes, and replicates were taken along parallel
transects from the shore until 1 m depth was reached. We used a
three-minute traveling kick and sweep per replicate rather than ten
minutes because of the abundance of organic matter on the lake bottom that
quickly clogged the D-net, preventing further sample collection. To
conduct a traveling kick and sweep, the researcher “vigorously kicks the
substrate to disturb it to a depth of ~5 cm” and sweeps the net “back and
forth and up and down” to capture disturbed invertebrates (Jones et al.
2007). We did not take replicates at random locations in the lake as in
the conventional OBBN protocol due to inaccessibility of different parts
of the shoreline. A boat was not always available when we were collecting
macroinvertebrate samples, and the boggy terrain often made it difficult
to walk the shoreline without sinking into the peat. We were able to
discern three types of substrate in our study lakes: mats of sphagnum
moss, sphagnum moss with floating and emergent vegetation, and mixed
gravel/cobble. For most lakes we visited, the littoral zone was quite
homogeneous, consisting primarily of sphagnum moss, below which was a
layer of fine silt. Many lakes also had floating vegetation, such as water
lilies, and emergent sedges or grasses nearshore. A smaller number of
lakes had cobble/gravel habitats in addition to sphagnum substrate. In
cases where there were no clear indications of differing habitat types
along the shore, we collected replicate samples at least 10 m apart. In
cases where obvious habitat heterogeneity existed (e.g. sphagnum bottom
versus rocky bottoms), we collected at least one sample in each habitat
type. Each sample was preserved in 95% ethanol and brought back to the
laboratory for identification. Using a 500 µm sieve and a dissecting
microscope, we identified macroinvertebrates to the order and family level
in the laboratory according to the OBBN tally sheet (Jones et al. 2007).
We performed quality assurance and quality control on taxonomic accuracy
and sorting efficiency following the Canadian Aquatic Biomonitoring
Network (CABIN) protocol (McDermott et al. 2014). We counted full samples
from the eight lakes collected in 2017 from the GSA, while we used
subsampling by weight for the 24 lakes sampled the next year in the ISR
due to large sample sizes and high abundances of macroinvertebrates. For
the ISR samples, we weighed an entire sample, and then weighed out a small
amount of sediment representing approximately 10% of the sample for
analysis. If we did not count at least 100 individuals in this subsample,
then we added more sediment until at least 100 individuals were identified
for that particular subsample. We counted two more subsamples for each
lake in the same manner, such that a minimum of 300 individuals were
identified from each lake. If fewer than 300 individuals were present in
the whole sample, we processed the entire sample. This methodology
resulted in a mean of 437 individuals identified for each ISR lake with a
standard deviation of 148. We conducted subsampling without replacement,
meaning that we did not return sediment to the sample after each
subsample. We collected fish community data in both sampling years. In
2017, we performed gillnetting according to the Ontario Broadscale
Monitoring (BsM) protocol (Sandstrom et al. 2013). In 2018, we modified
the BsM protocol in that we checked nets every 45-60 minutes and deployed
nets an average of 11 hours in small to medium lakes (<500 ha) and
37 hours in larger lakes (>500 ha). We changed the sampling
methodology to address community concerns regarding the more lethal method
of the BsM protocol where gillnets are left overnight (16-22 hours).
Because of differences in sampling between field seasons, we used the
occurrence of fish species instead of catch-per-unit-effort. In our
statistical analysis, we used occurrence data for the most common fish
that were caught, including whitefish (Coregonus clupeaformis or Coregonus
nasus), northern pike (Esox lucius) and least cisco (Coregonus
sardinella). Water quality and chemistry data We measured a suite of water
quality and chemistry parameters in lakes where macroinvertebrates were
sampled. We obtained water clarity measurements using a Secchi depth at
the deepest point of the lake by lowering the Secchi disk over the shady
side of the boat. We used a Eureka Manta multiparameter probe (Eureka
Water Probes) to take water quality measurements in the littoral zone at
the same locations where macroinvertebrates were collected. The
measurements were taken before collection of the invertebrates to avoid
changes that might result from disturbing the sediment. The probe measured
pH, conductivity, turbidity, and water temperature. Additionally, we
collected a nearshore water sample to measure total suspended solids
(TSS), chlorophyll-a¸ total phosphorus, total nitrogen, dissolved organic
carbon, and calcium. To measure TSS, we followed standard operation
procedures according to method 2540 D (Rice et al. 2017). We measured
chlorophyll-a concentrations by filtering 250 mL of each water sample
through Fisherbrand G4 glass fiber filters. We then used methanol to
extract the chlorophyll-a from the filters and measured the concentration
dissolved in the methanol using a fluorometer (Turner TD700) (Symons et
al. 2012). We used a Perkin Elmer Optima 8000 Inductively Coupled Plasma
Optical Emission Spectroscopy (ICP-OES) to measure calcium concentrations,
and a Shimadzu TOC-LCPH carbon and nitrogen analyzer (Shimadzu Corp.) to
measure dissolved organic carbon and total nitrogen. We measured total
phosphorus by first digesting a portion of the sample in an autoclave
using ammonium persulfate and sulfuric acid according to EPA method 365.1.
Then, we used a SEAL Continuous Segmented Flow Analyzer (SEAL Analytical,
Inc.) to measure total phosphorus colorimetrically. In addition to the
described water quality parameters, we collected sediments, as they have
been shown to be important in determining the structure of
macroinvertebrate communities in lakes (De Sousa et al. 2008; Namayandeh
and Quinlan 2011). We determined sediment size distribution by drying
sediment samples at 105 °C for eight hours and then using a sieve shaker
for ten minutes per sample to separate grain sizes using seven different
sieve sizes (4 mm, 2 mm, 1 mm, 500 µm, 250 µm, 125 µm, 63 µm). To
calculate % organic matter and % CaCO3 in sediments we used 5 g of
sediment from each sample that was <2 mm and followed the standard
operating procedure for loss on ignition (Santisteban et al. 2004).
References De Sousa, S., Pinel-Alloul, B., and Cattaneo, A. 2008. Response
of littoral macroinvertebrate communities on rocks and sediments to lake
residential development. Can. J. Fish. Aquat. Sci. 65(6): 1206–1216.
doi:10.1139/F08-031. Jones, F.C., Somers, K.M., Craig, B., and Reynoldson,
T.B. 2007. Ontario benthos biomonitoring network: protocol manual.
Available from
https://desc.ca/sites/default/files/OBBN2007finalapril18c.pdf. McDermott,
H., Paull, T., and Stachan, S. 2014. Canadian Aquatic Biomonitoring
Network (CABIN) laboratory methods: Processing, taxonomy, and quality
control of benthic macroinvertebrate samples. In Environment Canada.
doi:10.1089/dna.1998.17.321. Rice, E.W., Baird, R.B., and Eaton, A.D.
(Editors). 2017. Standard methods for the examination of water and
wastewater, 23rd edition. American Public Health Association, American
Water Works Association, Water Environment Federation, Washington, D.C.
Sandstrom, S., Rawson, M., and Lester, N. 2013. Manual of instructions for
broad-scale fish community monitoring; using North American (NA1) and
Ontario small mesh (ON2) gillnets. Ontario Minist. Nat. Resour.
Peterborough, Ontario. Version 2013.2 35 p. + Append. Symons, C.C.,
Arnott, S.E., and Sweetman, J.N. 2012. Grazing rates of crustacean
zooplankton communities on intact phytoplankton communities in Canadian
Subarctic lakes and ponds. Hydrobiologia 694(1): 131–141.
doi:10.1007/s10750-012-1137-6.