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Notes 1779
well as Jokiel and Morrissey (1993), Doty used
insufficient volume of bulk solution into which
clod cards could dissolve. We recommend generating
calibration curves for cards under forced
convection conditions by using a rotating arm
in a tank or a current meter. If a rotating arm
in a tank is used, one must take into account
the effect of induced water motion in the tank.
Care must be taken that CaSO, does not accumulate
in the tank; water should be changed
every 2-3 runs if the tank is of limited volume.
A standard curve relating water motion to
clod card weight loss should accompany each
report of a field study that uses the cards to
quantify water motion. Water motion should
be reported in velocity units under specified
measurement conditions. Variations in temperature
between field readings and standardization
runs can be corrected using Fig. 4.
In many instances, it is not possible to anticipate
all conditions of temperature and water
composition that may be encountered in
the field; in such cases, Eq. 11 may allow a free
convection test to be used to replace the forced
convection calibration under field conditions.
Freshwater produced lower dissolution rates
than brackish or seawater (as expected on theoretical
grounds), but over 20-40%, changes
should be low. We do not anticipate large errors
associated with water chemistry in practical
applications of clod cards to marine systems.
Although ice-cube trays were convenient
molds, in theory a spherical shape would be
more desirable because it would project the
same surface area in all directions. Properly
calibrated clod cards should find wide application
in biological investigations in aquatic
environments.
Environmental Research Laboratory
University of Arizona
Tucson 85706-6985
References
T. Lewis Thompson
Edward P. Glenn
CHURCHILL, S. W. 1977. A comprehensive correlating
equation for laminar, assisting, forced and free convection.
AIChE J. 23: 10-l 6.
CUSSLER, E. L. 1984. Diffusion: Mass transfer in fluid
systems. Cambridge.
DICKSON, A. G., AND M. WHITFIELD. 1981. An ion-as-
sociation model for estimating acidity constants (at
25°C and 1 atm. total pressure) in electrolyte mixtures
related to seawater (ionic strength < 1 mole/kg H,O).
Mar. Chem. 10: 315-333.
Dorv, M. S. 1971. Measurement of water movement in
reference to benthic algal growth. Bot. Mar. 14: 32-
35.
-, J. R. FISHER, E. K. ZABLACKIS, B. J. COOK, AND I.
A. LEVINE. 1986. Experiments with Gracilaria in
Hawaii, 1983-1985: A raw data tabulation. Univ.
Hawaii Bot. Sci. Pap. 46. 486 p.
GLENN, E. P., AND M. S. DO-I-Y. 1992. Water motion
affects the growth rates of Kappaphycus alvarezii and
related red seaweeds. Aquaculture 108: 233-246.
HANSSON, I. 1973. A new set of pH-scales and standard
buffers for sea water. Deep-Sea Res. 20: 479-491.
HOWERTON, R. D., AND C. E. BOYD. 1992. Measurement
of water circulation in ponds with gypsum blocks.
Aquaculture Eng. 11: 141-155.
JOIUEL, P. L., AND J. I. MORRISSEY. 1986. Influence of
size on primary production in the reef coral Pocillopora
damicornis and the macroalga Acanthophora spiczjka.
Mar. Biol. 91: 15-26.
-, AND -. 1993. Water motion on coral reefs:
Evaluation of the clod card technique. Mar. Ecol. Prog.
Ser. 93: 175-181.
LAWS, E. A. 1975. The importance of respiration losses
in controlling the size distribution of marine phytoplankton.
Ecology 56: 419-426.
MARSHALL, W. L., AND R. SLUSHER. 1968. Aqueous systems
at high temperatures: Solubility to 200°C of calcium
sulfate and its hydrates in sea water and saline
water concentrates, and temperature-concentration
limits. J. Chem. Eng. Data 13: 83-93.
MATHIESON, A. C., E. T-R, M. DALY, AND J. HOWARD.
1977. Marine algal ecology in a New Hampshire tidal
rapid. Bot. Mar. 20: 277-290.
Mws, B. J. 1968. Field measuring “exposure” by means
of plaster balls-a preliminary account. Sarsia 34: 6 l-
68.
PASTERNAK, I. S., AND W. H. GAUVIN. 1960. Turbulent
heat and mass transfer from stationary particles. Can.
J. Chem. Eng. 38: 3542.
PA-N, M. R. 1992. A mass transfer explanation of
metabolic sealing relations in some aquatic invertebrates
and algae. Science 255: 1421-1423.
PEI, D. C. T. 1985. Heat transfer from spheres under
combined forced and natural convection. Chem. Eng.
Prog. Symp. Ser. 61: 57-63.
PERRY, R. H., AND C. H. CHILTON [eds.]. 1973. Chemical
engineers handbook, 5th ed. McGraw-Hill.
REID, R. C., AND T. K. SHERWOOD. 1966. The properties
of gases and liquids, 2nd ed. McGraw-Hill.
RILEY, J. P., AND G. SKIRROW [eds.]. 1975. Chemical
oceanography, 2nd ed. V. 1. Academic.
SHERWOOD, T. K., R. L. PIGFORD, AND C. R. WILKE. 1975.
Mass transfer. McGraw-Hill.
SKELLAND, A. H. P. 1974. Diffusional mass transfer. Wiley.
Submitted: 1.5 September 1993
Accepted: 21 March 1994
Amended: 19 April 1994