Zooplankton density in the Gouin reservoir, Quebec (1996)

Zooplankton density (ind./m3) and water quality were assessed in 20 reference lakes, nine logged-watershed lakes, and nine burnedwatershed lakes during three summers following watershed disturbances by logging or wildfires during june, july and september 1996.

Personne(s) ayant accès aux données

Personne(s) ayant collecté les données

Autres institutions

We thank E. Mangas and G. Méthot for taxonomic identification of zooplankton, Y. Barthélémy, C. Bouffard, P. Lafrance, P. D’Arcy and I. Saint-Onge for help during sampling and limnoplankton analyses, and A. Ghadouani, S. Lamontagne, M. Norton, Y. Prairie, and C. Vis for helpful comments. R. Carignan (Département de sciences biologiques, Université de Montréal) provided data on lake and catchment morphometry and water quality. We thank him for having shared his data.

Personne en chare des données

Audrey Lafrenaye

Source(s) de financement

This research was supported by grants from the SFM Centre of Excellence and the Natural Sciences and Engineering Council of Canada (NSERC) to BPA and the Fonds pour la Formation de chercheurs et l’aide à la recherche (FCAR) to A. Patoine. E. Prepas acted as a cosupervisor during the PhD Thesis. This paper is a contribution of the SFM Centre of Excellence and the Groupe de Recherche Interuniversitaire en Limnologie et en Environnement Aquatique (GRIL).

Format du jeu de données

Excel documents.

Nombre de sites

38

Description du site

STUDY LAKES AND SAMPLING DESIGN: The study region consists of roughly 30 000 km2 of boreal forest on the Canadian Shield (47°52’-48°60’N, 73°19’-76°43’W) in Québec, around the Gouin reservoir. The only environmental perturbations affecting the region are wildfires, forestry activities and defoliating insects. Lakes were selected to have three groups with different catchment conditions (unperturbed, logged, burnt), but otherwise similar in their morphometric characteristics. The reference group was comprised of 20 lakes with catchments free of any kind of perturbation for the past 70 years. The ‘logged lakes’ group consisted of nine lakes with catchments clear-cut during the summer of 1995. Cut blocks size generally ranged from 5 to 50 ha, but occasionally reached 200 ha. When expressed as a percentage, logging affected between 9 and 73% of a lake’s catchment area. Twenty metres buffer strips of unharvested vegetation were left fringing lakes, streams and wetlands. Clearcuts of the CPRS type (cut with protection of regeneration and soils) were performed with fuller-buncher machines. Felled trees were skidded to roadsides by grapple and line skidders. Mechanical de-limbers stripped off the branches and trimmed the trees. Slash debris were piled up along the periphery of the cut blocks, no closer than 30 m from any stream or lake. Roads were built to support eight axle double trailer logging trucks, and retain along their sides a 30-m wide strip of unharvested vegetation. The ‘burnt lakes’ group consisted of nine lakes whose catchments had burnt during the summer of 1995. The proportion of catchment area burnt varied between 50 and 100%. The 38 lakes were selected so as to minimise differences in lake morphometry and catchment physiography among the three groups.

Habitat

The forest is mainly composed of black spruce (Picea mariana (Mill.) BSP), balsam fir (Abies balsamea (L.) Mill.), jack pine (Pinus divaricata (Ait.) Dumont), white birch (Betula papyrifera Marsh.) and trembling aspen (Populus tremuloides Michx.). Lakes of the region are remote and can only be accessed by hydroplane or, in the case of logged catchment lakes, by logging roads.

Environnement

Aquatique

Taxa étudiés

Zooplankton

Information taxonomique

Crustacées, Animaux invertébrés autre qu'arthropodes.

Approche expérimentale

SAMPLING AND ZOOPLANKTON ANALYSES: The lakes were sampled in June, July and September of 1996, roughly 1 year after catchment perturbations. Zooplankton was sampled at the deepest point in the lakes, established by echosounding, with a 53-lmmesh cantilevering net from 1 m above the sediment to the lake surface. Filtered water volume varied between 80 and 1200 L dependingon lake depth. Zooplankton was narcotised in the field with carbonated water and preserved in 4% formaldehyde. In the laboratory, larvae of the dipteran Chaoborus were removed from the samples and counted. Taxonomic analyses were performed on 10 mL subsamples. Zooplankton was identified to the species level, following the keys of Brandlova, Brandl & Fernando (1972), Edmonson (1959) and Smith & Fernando (1978), and densities were expressed as ind.L-1.Naupliar and copepodite stages of calanoids were distinguished from those of cyclopoids. Integrated water samples for water quality, chlorophyll a and phytoplankton analyses were taken from the euphotic zone (1%of incident PAR) at the same site as zooplankton samples. Vertical oxygen profiles from the surface to the sediments allowed the calculation of average water column oxygen concentrations. SAMPLING AND CHEMISTRY : The lakes were sampled three times each year during the icefree season (a few days after ice-out in late May or early June, in mid-July, and in mid-September). Integrated water samples were taken from the euphotic zone (1% of incident PAR), filtered within 12 h when necessary, and stored at 4°C until analyzed (within 72 h). Samples for dissolved organic carbon (DOC) measurements and occasional colour (absorbance at 440 nm) measurements were filtered on washed Gelman Supor 0.45-mm membranes and kept at 4°C. DOC was measured (Shimadzu TOC-5000) within 72 h by infrared gas analysis after sample acidification and He sparging followed by Pt-catalyzed oxidation at 700°C. In these lakes, DOC concentrations measured with Supor 0.45-mm membranes are identical, within measurement precision, to those obtained with precombusted GF/C filters. Total phosphorus (TP) was measured using the molybdenum blue method after autoclaving 50-mL samples with 0.5 g of potassium persulfate for 1 h at 120°C. NO3 – and NH4 + were measured on filtered samples by automated flow injection analysis (Lachat methods 10-107-04-1-B and 10-107-06-1-F). Total nitrogen (TN) was measured as NO3 – after alkaline persulfate digestion of 50-mL samples at 120°C. TN was not measured in June and July of 1997. The ions Cl– , SO4 2–, Ca2+, Mg2+, Na+, and K+ were measured by ion chromatography (Dionex DX-500). Alkalinity was measured by Gran titration, pH and H+ (log(pH)) was measured in the laboratory with a double-junction electrode on air-equilibrated samples.

Statut de l'étude

Complété

Stratégie d'echantillonnage

Échantillonnage passif (e.g. trappe à insecte ou à animal)

Objectifs de l'étude

Niveau de la communauté (e.g. richesse, distribution, composition)

Types de données

Liste d'espèces, Abondance/abondance relative/fréquence

Fréquence d'échantillonnage

The lakes were sampled three times per year, in May–June, July, and September of 1996. All were sampled within 5 days between 06:00 and 15:00.

Première année de collecte de données

1996

Dernière année de collecte de données

1996

Patoine A., Pinel-Alloul B. and Prepas E. E. (2002) Effects of catchment perturbations by logging and wildfires on zooplankton species richness and composition in Boreal Shield lakes. Freshwater Biology, 47, 1996–2014

Carignan R., D’Arcy P. & Lamontagne S. (2000) Comparative impacts of fire and forest harvesting on water quality in Boreal Shield lakes. Canadian Journal of Fisheries and Aquatic Sciences, 57 (Suppl. 2), 105–117.

Patoine A., Pinel-Alloul B., Prepas E. E. A and Carignan R. (2000) Do logging and forest fires influence zooplankton biomass in canadian boreal shield lakes? Canadian Journal of Fisheries and Aquatic Sciences, 57 (Suppl. 2), 155–164

Pinel-Alloul B., Prepas E.E., Planas D., Steedman R. and Charrette T. (2002) Watershed Impacts of Logging and Wildfire: Case Studies in Canada. Lake and Reservoir Management, 18 (Suppl.4), 307-318

Données