Biological field and laboratory methods for measuring the quality of ...
Biological field and laboratory methods for measuring the quality of ...
Biological field and laboratory methods for measuring the quality of ...
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BIOLOGICAL METHODS<br />
Calculate <strong>the</strong> chlorophyll a <strong>and</strong> pheophytin a<br />
as follows:<br />
Chlorophyll a (mg/m 3 ) =26.7 (663b -663 a ) X E<br />
VXL<br />
Pheophytin a (mg/m 3 ) = 26.7 (1.7 X 663a - 663b) X E<br />
VXL<br />
where 663b is <strong>the</strong> I-em corrected 00 663 be<strong>for</strong>e<br />
acidification; 663a is <strong>the</strong> 00 663 after acidification;<br />
E <strong>the</strong> volume <strong>of</strong> acetone used <strong>for</strong> <strong>the</strong><br />
extraction (m}); V <strong>the</strong> volume <strong>of</strong> water filtered<br />
(liters); <strong>and</strong> L <strong>the</strong> path length <strong>of</strong> <strong>the</strong> cuvette<br />
(em).<br />
5.3 Cell Volume<br />
5.3.1 Microscopic (algae <strong>and</strong> bacteria)<br />
Concentrate an aliquot <strong>of</strong> sample by settling<br />
or centrifugation, <strong>and</strong> examine wet at a 1000X<br />
magnification with a microscope equipped with<br />
a calibrated ocular micrometer. Higher magnification<br />
may be necessary <strong>for</strong> small algae <strong>and</strong> <strong>the</strong><br />
bacteria. Make optical measurements <strong>and</strong><br />
determine <strong>the</strong> volume <strong>of</strong> 20 representative<br />
individuals <strong>of</strong> each major species. Determine <strong>the</strong><br />
average volume (cubic microns), <strong>and</strong> multiply by<br />
number <strong>of</strong> organisms per milliliter.<br />
5.3.2 Displacement (zooplankton)<br />
Separate sample from preservative by pouring<br />
through a piece <strong>of</strong> No. 20 mesh nylon bolting<br />
cloth placed in <strong>the</strong> bottom <strong>of</strong> a small glass<br />
funnel. To hasten evaporation, wash sample with<br />
a small amount <strong>of</strong> 50 percent ethanol to remove<br />
excess interstitial fluid <strong>and</strong> place on a piece <strong>of</strong><br />
filter or blotting paper. Place <strong>the</strong> drained plankton<br />
in a 25-, 50-, or 100-ml (depending on<br />
sample size) graduated cylinder, <strong>and</strong> add a<br />
known volume <strong>of</strong> water from a burette. Read<br />
<strong>the</strong> water level in <strong>the</strong> graduated cylinder. The<br />
difference between <strong>the</strong> volume <strong>of</strong> <strong>the</strong> zooplankton<br />
plus <strong>the</strong> added water <strong>and</strong> <strong>the</strong> volume <strong>of</strong> <strong>the</strong><br />
water alone is <strong>the</strong> displacement volume <strong>and</strong>,<br />
<strong>the</strong>re<strong>for</strong>e, <strong>the</strong> volume <strong>of</strong> <strong>the</strong> total amount <strong>of</strong><br />
zooplankton in <strong>the</strong> sample.<br />
5.4 Cell Surface Area <strong>of</strong> Phytoplankton<br />
Measure <strong>the</strong> dimensions <strong>of</strong> several representative<br />
individuals <strong>of</strong> each major species with a<br />
16<br />
microscope. Assume <strong>the</strong> cells to be spherical<br />
cylindrical, rectangular, etc., <strong>and</strong> from <strong>the</strong> linear<br />
dimensions, compute <strong>the</strong> average surface area<br />
(p.2) per species. Multiply by <strong>the</strong> number <strong>of</strong><br />
organisms per milliliter (Welch, 1948, lists<br />
ma<strong>the</strong>matical <strong>for</strong>mulas <strong>for</strong> computing surface<br />
area).<br />
6.0 PHYTOPLANKTON PRODUCTIVITY<br />
Phytoplankton productivity measurements<br />
indicate <strong>the</strong> rate <strong>of</strong> uptake <strong>of</strong> inorganic carbon<br />
by phytoplankton during photosyn<strong>the</strong>sis <strong>and</strong> are<br />
useful in determining <strong>the</strong> effects <strong>of</strong> pollutants<br />
<strong>and</strong> nutrients on <strong>the</strong> aquatic community.<br />
Several different <strong>methods</strong> have been used to<br />
measure phytoplankton productivity. Diurnal<br />
curve techniques, involving pH <strong>and</strong> dissolved<br />
oxygen measurements, have been used in natural<br />
aquatic communities by a number <strong>of</strong> investigators.<br />
Westlake, Owens, <strong>and</strong> TaIling (1969)<br />
present an excellent discussion concerning <strong>the</strong><br />
limitations, advantages, <strong>and</strong> disadvantages <strong>of</strong><br />
diurnal curve techniques as applied to nonisolated<br />
natural communities. The oxygen<br />
method <strong>of</strong> Gaarder <strong>and</strong> Gran (1927) <strong>and</strong> <strong>the</strong><br />
carbon-14 method <strong>of</strong> Steeman-Neilson (1952)<br />
are techniques <strong>for</strong> <strong>measuring</strong> in situ phytoplankton<br />
productivity. TaIling <strong>and</strong> Fogg (1959)<br />
discussed <strong>the</strong> relationship between <strong>the</strong> oxygen<br />
<strong>and</strong> carbon-14 <strong>methods</strong>, <strong>and</strong> <strong>the</strong> limitations <strong>of</strong><br />
both <strong>methods</strong>. A number <strong>of</strong> physiological<br />
factors must be considered in <strong>the</strong> interpretation<br />
<strong>of</strong> <strong>the</strong> carbon-14 method <strong>for</strong> measurement <strong>of</strong><br />
phytoplankton productivity. Specialized applications<br />
<strong>of</strong> <strong>the</strong> carbon-14 method include bioassay<br />
<strong>of</strong> nutrient limiting factors <strong>and</strong> measurement<br />
<strong>of</strong> <strong>the</strong> potential <strong>for</strong> algal growth.<br />
The carbon-14 method <strong>and</strong> <strong>the</strong> oxygen<br />
method have <strong>the</strong> widest use, <strong>and</strong> <strong>the</strong> following<br />
procedures are presented <strong>for</strong> <strong>the</strong> in situ <strong>field</strong><br />
measurement <strong>of</strong> inorganic carbon uptake by<br />
<strong>the</strong>se <strong>methods</strong>.<br />
6.1 Oxygen Method<br />
General directions <strong>for</strong> <strong>the</strong> oxygen method are<br />
found in: St<strong>and</strong>ard Methods <strong>for</strong> <strong>the</strong> Examination<br />
<strong>of</strong> Water <strong>and</strong> Wastewater, 13th Edition,<br />
pp. 738-739 <strong>and</strong> 750-751.