Document 6532972

334
NOTES
AN1 D COMMENT
tures, there was no loss of orthophosphate
after 24 hr of refrigeration,
but freezing
caused the release of 0.02 mg P per 40
fronds (less than 5 mg dry weight).
The luxury-consumed
phosphorous of
algae is apparently released as orthophosphate with any of the methods used to
kill the algae. This indicates that this phosphorus must be in highly labile forms that
readily revert to orthophosphate when the
algae die.
The data indicate that significant quantities of orthophosphate and probably three
to four times as much total phosphorus
(Fitzgerald and Nelson 1966) will be released from algae if they are killed in water
samples preserved for future analyses. Both
freezing and the addition of chloroform
appear to kill the algae and aquatic weed
tested. The quantity of phosphorus released
from algae in water samples will be dependent on the degree of killing (20% of
Chlorella cells survived freezing at -15C
Fitzgerald 1964b ) and the amount of surplus or stored phosphorus in the cell (Fitzgerald and Nelson 1966). In the fertile
areas of the midwestern United States, algal
blooms frequently amount to 10 mg dry
weight/liter
or more and the subsequent
release of 0.02 to 0.06 mg of orthophosphate
per liter may be a significant source of
error for water analyses.
Therefore, water samples to be preserved for future analyses by methods other
SKILL
IN
THE
USE
OF
than refrigeration should be filtered
move any algae before preserving.
G. P. FITZGERALD
S. L. FAUST
Water Chemistry Laboratory,
Unitiersit y of Wisconsin,
Madison, Wisconsin
53706.
REFERENCES
ALLEN, M. B. 1952. The cultivation
of Myxophyceae.
Arch. Mikrobiol.,
17: 34-53.
AMERICAN PUBLIC HEALTH ASSOCIATION. 1960.
Standard
methods for the examination
of
water and wastewater,
11th ed. APHA, New
York, N.Y. 626 p.
FITZGFCMLD, G. P. 1964a.
Factors in the testing
and application
of algicides. Appl. Microbial.,
-.
12: 247-253.
1964b.
The effect of algae on BOD
measurements.
J. Water
Pollution
Control
Federation,
36:
1524-1542.
-,
AND S. L. FAUST.
1963. Bioassay for
algicidal
versus algistatic
chemicals.
Water
Sewage Works, 110: 296-298.
-,
AND T. C. NELSON. 1966. Extractive
and enzymatic analyses for limiting or surplus
phosphorus in algae.
J. Phycol., 2: 32-37.
HUGHES, E. O., P. R. GORJXAM, AND A. ZEHNDER.
1958. Toxicity
of a unialgal
culture
of
Microcystzk
aeruginosa.
Can. J. ?rIicrobiol.,
4: 225-236.
RAINWATER, F. H., AND L. L. THATCHER.
1960.
Methods for collection
and analysis of water
samples. U.S. Govt. Printing
Office, Washington, D.C. 30 p,
STRICKLAND, J. D. H., AND T. R. PARSONS. 1960.
A manual of sea water analysis, p. 9 and 42.
Bull. Fisheries Res. Board Can. 125.
FOLSOM'S PLANKTON
We have found that the Folsom plankton
splitter sometimes gives poor replication
when it is used to remove small aliquots
from plankton samples by repeated halving
of the sample; this has been particularly
noticeable when aliquoting has been carried to the %2 or ?& level. The statistical
analysis of the operation of Folsom’s splitter
( McEwen, Johnson, and Folsom 1954) had
l This investigation
was part of the Scripps
Tuna Oceanography
Research Program and was
supported by U.S. Bureau of Commercial Fisheries
Contract
No. 14-17-0007-458.
to re-
SAMPLE
SPLITTERI
led us to believe that the splitter was more
satisfactory than a Stempel pipette for extracting a subsample.
It is obvious that splitting is uneven when
the plankton forms clumps, as it usually
does when a relatively small amount of
plankton is suspended in a relatively large
volume of preservative. The statistical tests
referred to above, however, appear to have
been carried out on samples in which the
concentration of plankton organisms in the
preserving fluid was relatively high. Both
high and low concentrations are encountered
when dealing with survey samples from
NOTES
TABLE
1.
variation
AND
Standard deviations
SD, coefficients
of
C and mean value of x2 for six replicate
tests as described in the text
Tests
Deviations
After
standard
mixing
c
Using
operator
judgment
C
Using
air-mixing
device
SD
X2
SD
x2
SD
C
X’
Calanus
Euphausia
Sagitta
8.09
24.67
1.89
5.96
94.15
5.04
1.47
30.43
0.41
5.56
15.96
1.32
1.95
28.52
0.61
3.15
52.27
0.47
3.87
11.61
0.58
0.44
7.31
0.15
2.21
24.09
0.38
areas with different standing stocks, even
though collected in a standard manner.
Experience has shown that a careful technician, when taking aliquots with this apparatus,
soon abandons the objective
method of splitting after a standard number of oscillations in favor of visually judging a favorable moment to split, that is,
when the plankton is apparently homogeneously distributed over the floor of the
splitter. To increase the homogeneity of
the dispersion of the sample, we have modified our splitter by the addition of an air
inlet manifold which has many pin-holes
through which air under slight pressure
passes into the unsplit sample, stirring it
vigorously. This seems to be the simplest
of several possible methods of stirring the
sample without damaging it.
We made up a small artificial plankton
335
ZOMMENT
sample of 500 adult Calanus helgolandicus,
100 Euphausiu eximia, and 100 subadult
Sagitta euneritica and carried out some
simple tests with it. It was split to the %s
aliquot six times by each of the following
methods: 1) after six standard oscillations,
2) at the moment when the operator judged
it to be evenly dispersed, and 3) after six
standard oscillations during which air bubbles were used to stir the sample. The results (Table 1) suggest that these three
techniques produce progressively
better
replication and that there is an element
of skill in operating the unmodified splitter
with meager samples. The improvement
was less with Sagitta than with crustaceans,
which would be expected because they
tend to clump less than crustaceans. This
supports the suggestion that clumping is
responsible for poor performance of the
Folsom splitter. Thus, a degree of caution
is advised in applying the original statistical tests to all applications in which the
splitter is useful.
ALAN
R. LONGHURST
DON
L. R. SEIBERT
Scripps Institution
of Oceanography,
La Jolla, California
92038
REFERENCE
Y~CEWEN,
G.
FOLSOM.
F., M. W. JOHNSON, AND T. R.
1954. A statistical analysis of the
Folsom sample splitter based upon test observations.
Arch
Meteorol.
Geophys.
Bioklimatol.,
Ser. A, 6: 502-527.
A SPEcTRopHOToh~ETRIC METHOD FOR THE ESTIMATION
OF
PERCENTAGE
DEGRADATION OF CHLOROPHYLLS TO PHEO-PIGMENTS
IN EXTRACTS OF ALGAE
Estimation of algal standing crops from
photosynthetic
pigment content is now
widely used because such pigments are
specific to plant material and their spectrophotometric estimation is straightforward.
The presence of pigment degradation products having
visible
absorption
spectra
similar to those of chlorophylls is a possible
source of error.
According
to Strickland
and Parsons
( 1965), the presence of degradation prod-
ucts in surface waters of the open sea can
probably be ignored. In removing epipsammic (Round 1965), epiphytic, or epipelic
(Eaton and Moss 1966) algae from their
substrata, there is always the possibility of
contamination by decaying algal cells, and
phytoplankton
from small bodies of water
may be contaminated by suspended mud
containing pigment degradation products.
The method described here was evolved
for the monitoring of a large number of