Stave River Water Use Plan - BC Hydro

Stave River Water Use Plan
Monitoring Terms of Reference June 13, 2005
be collected at the same time of year, preferable during late summer when the when
reservoir levels are consistent between years due to recreational constraints. The data
will be used to test hypothesis H08 of the monitor.
Chlorophyll
In addition to the phytoplankton counts, water samples will be collected to
estimate chlorophyll a concentration, an indicator of phytoplankton standing crop. At
each station, 500 ml water samples will be collected at 1, 3, and 5 m below surface, and
mixed together in a large dark glass bottle to yield a single depth integrated sample.
Starting with 500 ml of the mixed epilimnetic water, field-filter the sub-sample using a
47 mm filtering manifold with a 0.45 µm Millipore HA filter. Should the filter become
plugged, discard the sub-sample and re-start the filtering process with a new 250 ml
sub-sample. At no time should the vacuum pressure of the filtering mechanism exceed
20 cm Hg. When dry, the filter should be folded, placed in small round aluminium
dishes, and kept frozen until analysed.
During phase 1 of the monitor, Chlorophyll samples will be collected every 4 to 6
weeks to capture annual trends in phytoplankton standing crop. In Phase 2, the level of
sampling effort will be reduced to 4 times per year (every 8 weeks between May and
November). All samples will be to be sent immediately to the Department of Fisheries
and Oceans chemistry lab in Cultus Lake for analysis. The data obtained from this
analysis will be used to test hypotheses H05 and H07 in Section 1.3.
Zooplankton
Zooplankton samples will be collected by Wisconsin vertical trawl hauls at each
sample station (Figure 2). The Wisconsin trawl net, which should not have a mesh size
greater than 80 µm and a throat diameter of 50 cm, will be lowered to a depth of 30 m
and hauled up at a speed of 0.5 m·s -1 . Once out of the water, the net should be rinsed
with a wash bottle to ensure that all organisms are in the collecting cup (cod-end). The
contents of the collecting cup are then washed into a plastic storage bottle to which
ethanol has been added as a preservative.
Prior to enumeration, the total volume of the sample will be stirred and split with a
Folsom splitter to a volume that contains at least 100 post nauplii stages of the most
abundant taxa. Enumeration will be done on a gridded petri-dish using a stereo
microscope under suitable magnification. Taxonomic identification will be taken to the
species level. Body length of individuals will be measured to the nearest 0.1mm, and
then using published length weight relationships (McCauley 1984) assign an
approximate dry weight (µg). The resulting data will then be used to determine species
density (No·L -1 ) and biomass (µg·L -1 ), as well as overall length distributions. These data
will then be used to test hypothesis H09.
During phase 1 of the monitor, zooplankton enumeration will be carried out every
4 to 6 weeks each year to capture seasonal and annual trends. In phase 2 of the
monitor, zooplankton sampling effort will be reduced to just one sample per year, and
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