Basic HTML Version
Ref. No. [UMCES]CBL 12-005
8
4.4. Zooplankton >50 µm
The data below describes the numbers of zooplankton in both the ambient challenge
water and after the BOLL filter water during all trials. Size-class distinctions or measures are
determined by considering the greatest available measure among the x, y, and z body axis,
exclusive of appendages such as legs, swimming appendages, sensory apparatus, or other fine
appendages.
The zooplankton communities found during trials 1, 2, and 3 were primarily composed of
the calanoid copepod
Eurytemora affinis
in its various life stages. Size class one (>75µm to
<120µm) contained the eggs and nauplii, which primarily passed through the filter. While eggs
were usually encountered singly, egg clusters when present, were also counted as single objects.
Size class two (around 1mm) organisms were largely adult
Eurytemora affinis
. The filter
appeared to stop adult calanoid copepods effectively with the exception of run 3 when
effectiveness dropped. In addition, barnacle nauplii, rotifers, and several other rare taxa were
present in lessor abundance.
The zooplankton communities found during trials 4 and 5 were primarily size class one
(>75µm to <120µm) organisms, which were found in both pre- and post-sieve samples in near
equal numbers. The dominant species were primarily small rotifers identified as
Brachionus
calyciflorus
and
Trichocercas rousseleti.
Although rotifers were nearly as abundant after the
filter, many experienced visible damage and may not have survived. Small nauplii of copepods
were also found to be abundant in both pre and post sieve samples, even though adult copepods
were rare. Bivalve larvae were present in moderate numbers and often passed the filter. The filter
generally stopped adult copepods, although some Harpacticoids (smaller than the Calanoids in
our samples) were observed in the post filter samples.
BOLL-1
March 16, 2011
Time point
Size Class 1
>75 µm to <120µm
(#/m
3
)
Size Class 2
Around 1 mm
(#/m
3
)
Total
>50-µm
(#/m
3
)
T-0 Initial
Ambient
143,000
12,000
155,000
Post 40 µm
114,333
0
114,333
T-1 Mid
Ambient
201,000
8,000
209,000
Post 40 µm
153,333
0
153,333
T-2 Final
Ambient
205,000
13,000
218,000
Post 40 µm
132,000
333
132,333