BULLETIN OF MARINE SCIENCE, 56(1): 319-329, 1995 REEF PAPER

EXPERIMENTAL MANIPULATIONS OF A SOLITARY CORAL (FUNGI A, ) WITH EMPHASIS ON THE EFFECTS OF LIGHT

Helen T. Yap, A. Rex F. Montebon, f.-A. von Oertzen and Romeo M. Dizon

ABSTRACT The metabolic rate per unit area of the solitary scleractinian coral Fungia (Danafungia) horrida did not vary significantly within a size range of 5-14 cm (diameter), Likewise. maintenance time in the laboratory up to a period of 1 week did not appear to influence metabolic performance. Gross photosynthetic rates, when measured under similar light inten- sities, did not differ significantly between in the field and in the laboratory. Significant variations in photosynthetic response to light occurred. Combined data for this and other species of the Fungia from the same reef flat were used to generate light response curves which showed I, to be about 800 microEinsteins m-2 S-I, as determined from the hyperbolic tangent formulation. Theoretical maximum gross primary production was about 2 I 250 fJ.g O2 cm- h- •

Primary production and respiration rates in scleractinian corals have not been measured previously in the Philippines, although a large body of literature on the subject exists for many geographic locations (reviewed in McCloskey et aI., 1978; Gladfelter, 1985; Sebens, 1987). Laboratory experiments on corals have dealt mostly with responses of various species to light. Examples are the investigations of Zvalinskii et aI. (1980), Chalker et aI. (1983), Kinzie and Hunter (1987), Den- nison and Barnes (1988), Edmunds and Davies (1988, 1989), and Newton and Atkinson (1991). Knowledge of light responses of corals is crucial in the interpretation of data which are eventually used in energy budgets. The coral-zooxanthellae complex responds instantly to changes in light intensity. There are particular ranges of light intensity which are optimal for primary production for each species (Sebens, 1987). Below such ranges, gross photosynthetic rate decreases and is eventually exceeded by respiration. Above optimal light intensities, the photosynthetic ma- chinery becomes saturated. Light saturation curves are especially useful for the investigation of such responses (Zvalinskii et aI., 1980; Chalker, 1980, 1981; Wyman et aI., 1987). One such curve is constructed here for the genus Fungia. There appears to be a dearth of studies to date on the effects of maintenance time, size, and physical transfer to the laboratory on coral metabolic rates. Because of logistic constraints that often arise, a number of metabolic experi- ments are done in the laboratory, and their results extrapolated to in situ condi- tions. Or at least, such results are presumed to apply to in situ conditions. It is with these constraints in mind that the effects of transfer to the laboratory and of maintenance time there are examined in this study. Finally, the question of size as it influences metabolic activity is still an open question for many organisms, including corals. Growth, for example, may be faster in smaller colonies (Bud- demeier and Kinzie, 1976; Yap et aI., 1992), although this appears not to be a general rule (Maragos, 1978; Kinzie and Sarmiento, 1986). In a review of coelen- terate biology, Sebens (1987) reports that weight-specific oxygen consumption decreases with increasing individual size, although his data are compiled mostly from studies on sea anemones. In the case of scleractinian corals, size is probably

319 320 BULLETIN OF MARINE SCIENCE. VOL. 56, NO. I. 1995 a factor that influences metabolic rates. This, again, has implications for conclu- sions that are drawn, i.e., the resulting energy budgets may be valid for only a particular size range of the organisms in question. In this paper, the results of experiments on various aspects of metabolism are described. These experiments address the following questions: ]) Are there sig- nificant changes in metabolic rate with respect to length of time maintained in the laboratory (from collection in the field) up to a period of 1 week? 2) Are there significant differences in metabolic rates with respect to size (within a certain range) of the corallum? 3) What is the photosynthetic response of the coral- zooxanthellae complex to light intensity within the range of natural daylight en- countered? 4) Are there significant differences between metabolic rates measured in situ and in the :laboratory? Metabolic rates here are expressed per unit surface area of the corallum which is a relatively useful standard (McCloskey and Muscatine, 1984). "Production" as used in the text refers to gross primary production or gross photosynthesis, except where light saturation curves were generated, in which case net primary production or net photosynthesis was used instead (Chalker et aI., 1983).

MATERIALS AND METHODS

Study Sile.-The study site is a 0.5 lan-wide reef flat on the western side of Santiago Island in Bolinao, Pangasinan in the northwestern Philippines at approximately 16°24'41"N lat and 119°54'25"E long. Water depth averages about 1 m. A sea grass zone stretches from the shore about halfway across the flat, where it ends abruptly and gives way to a sand-rubble substrate. This second zone is dominated by large microatolls of Porites. Specimens of the solitary coral Fungia (Danafungia) horrida were collected from this area. The reason fungiids were ~;elected for study is that they consist of a single with relatively few endoliths, rendering the interpretation of physiological results easier. In addition to the coral itself and the symbiotic zooxanthellae, coral colonies, in contrast, are inhabited by a variety of com- mensal or parasitic plants and which also contribute to the observed oxygen changes. Mea- surements from a single polyp such as F. (Danafungia) horrida or other similar species of Fungia are therefore more straightforward, and can readily be attributed mainly to the coraI-zooxanthellae com- plex. Metabolic Experiments.-The metabolic experiments performed in this study made use of the oxygen technique (Zeitzschel, 1981). Primary production and respiration were measured by the degree of oxygen evolution or consumption, respectively. Metabolic rates are expressed per unit surface area of the coral. More specifically, projected surface area was used (Yap et aI., 1992). This was obtained by measuring the perceived longest dimension of the coral through the center (length, L) with a caliper calibrated in millimeters, and then taking the perceived longest dimension normal to L (width, W). Projected area, A, was computed by using the formula:

Field measurements of metabolic rates made use of a Plexiglas cylinder (volume = approx. 9 liters) bolted onto an acrylic platform on which the specimen was placed, forming a watertight enclosure. The top end of the cylinder was fitted with a dissolved oxygen probe (Nester Instruments model 8500X) and a battery-operated bilge pump for stirring the enclosed water (turn-over rate of the pump was about 400 gallons per hour). Prior to a series of measurements during a day, the probe was air calibrated according to the manufacturer's instructions. Respiration was measured first by covering the set-up with a black canvass material to exclude light and, hence, prevent photosynthesis. Production was then measured with the cover removed. Starting with the dark incubation reduced oxygen levels, thus avoiding supersaturation during photosynthetic measurements. For both production and respiration, changes in oxygen were recorded every minute until enough data points were obtained to produce a significant regression. Typically, measurement runs lasted lO- IS min, and took place: between 0900-1500. Temperature inside the chamber was monitored during the entire incubation by the probe's temper- ature sensor. This was compared with temperature outside the chamber which was measured with a YAP ET AL.: EXPERIMENTAL MANIPULATIONS OF A SOLITARY CORAL 321 mereury thermometer against which the probe sensor had been ealibrated in the laboratory. In general, internal chamber temperatures were higher than external temperatures by less than 1°C. Light values within the photosynthetically active range of radiation were registered simultaneously by aLI-COR 1935A spherical quantum sensor attached to a data logger. The sensor was mounted onto a tripod support and was situated about I m below the water surface. A spherical type was selected for purposes of measuring ambient light from all directions as a coral would typically receive it. Several light readings were averaged per minute for the entire duration of a production run, yielding a mean light intensity corresponding to a particular photosynthetic rate. A similar procedure was followed in the laboratory. The same enclosure and D.O. meter as in the field experiments were used for "Large" specimens (see explanation of size below). For "Small" and "Medium" corals, the incubation chamber was an acrylic cylinder (Strathkelvin Instruments RC400) with a volume of approximately 750 ml. Stirring was accomplished by means of a magnetic stir bar on the bottom. Dissolved oxygen was measured using a Strathkelvin D.O. meter (Model 781b) fitted with a Clarke-type microelectrode and connected to a stripchart recorder. Prior to a series of mea- surements, the electrode was calibrated as follows: the zero setting was determined after immersing the probe in a sodium borate/sodium sulfite solution to eliminate oxygen. The 100% oxygen saturation level was set by vigorously aerating seawater for at least 20 min, and then immersing the probe in this after thorough rinsing with distilled water. The temperature and salinity of the medium in both types of enclosures were kept at the average levels characterizing field conditions during most of the year. Salinity was 34%0, and temperature was fixed at about 28°C. Light intensity in the laboratory was regulated by a fluorescent light bank which could attain intensities of up to 400 microEinsteins m-2 s-'. A pair of halogen lamps (1,000 W each) was used to achieve intensities up to 750 f1E m-2 s-' which more elosely approximated field conditions during most daylight hours. Effect of Maintenance Time in the Laboratory.-In February 1990, a total of three small and three medium-sized (see explanation below) specimens of Fungia horrida were collected and immediately brought to the laboratory for metabolic measurements on the same day of collection (Day 0). Pro- duction and respiration were measured again the following day (Day I), and after 6 days (Day 6) to check for possible effects of maintenance time in the laboratory. In between measurements, the corals were kept in aerated aquaria with temperature and salinity approximating field values. Natural room light reaching the corals was about 25 f1Em-2 s-'. Sea water in the aquaria was renewed once a day. The number of replicates used (N = 3) was dictated by the length of time it took to finish all metabolic measurements within a day, so as to be able to compare maintenance time in terms of days. Effect of Size.- The following size categories were compared (figures in parentheses are the average long diameters in cm ± SO, and the number of specimens, N): Small (5.5 ± 0.5, N = 3), Medium (8.9 ± 0.9, N = 3) and Large (14.1 ± 1.0, N = 6). Designations of size were arbitrary, depending on the availability of representative specimens from the natural population. In the same experiment in February 1990 described above, the gross primary production of small and medium corals was compared at the following light intensities: 80, 140 and 350 f1Em-2 S-I. This was repeated for Days 0, 1 and 6. Initial respiration rates in the dark were also measured for both sizes. In March 1990, the metabolism of the small and medium corals was measured in the field (about 2 weeks after they were returned from the laboratory). Large fungiids (N = 6) were measured under the same environmental conditions in August 1990, and their metabolic rates compared with those of the other two size categories. Light intensity in all cases (March and August) averaged 2,000 /JoEm-2 s-'. All corals were from the same reef flat and were thus exposed to the same environmental conditions. It was assumed that differences in metabolism, if registered, would be due mainly to size differences. Responses of Primary Production to Light Intensity.-As described above, small and medium corals were illuminated at 80, 140, 350 (in the laboratory) and 2,000 /JoEm-2 S-I (in situ), and their primary production rates under these intensities measured. Large fungiids, on the other hand, were exposed to intensities of 2,000 (in situ) and 750 /JoEm-2 s-' (in the laboratory a day later; see following section). For each light level, the results for all size categories were pooled (after analyses demonstrated no effects of size on metabolism-see Results). Primary production with increasing light intensity was then assessed. The values so obtained were used to construct a light saturation curve for the species using the hyperbolic tangent function (Jassby and Platt, 1976; Chalker, 1980, 1981; Wyman et aI., 1987). To verify the light response trend indicated by results of the controlled experiments, a second light saturation curve was generated from data gathered monthly for corals of the genus Fungia from the same site over a 2-year period commencing in October 1989 (Yap et aI., in press). Methods and times of measurements (0900-1500) were exactly as described for this study. Replicate measurements of 322 BULLETIN OF MARINE SCIENCE, VOL. 56, NO.1, 1995

production and respiration were made on six corals chosen at random for each monthly visit. Because of a scarcity of specimens of a particular species, individuals from more than one species of Fungia were used, For purposes of generating the lower end of the light saturation curve from the field data, an experiment was conducted in situ in July 1991 in which ambient light reaching a coral was system- atically reduced by means of shading with a series of black nylon screens. Six light intensities were achieved as follows: 1,90, 130,200,300 and 1,200 ""E m-2 S-I. Two specimens were measured per light level. Comparison of In Situ and Laboratory Rates.-As described in the experiment above conducted in August 1990, the metabolism of the large fungiids was measured in the field at a light intensity of approximately 2,000 ""E m-2 S-I. The corals were then transported to the laboratory on the same day where they were mainlained overnight in aerated aquaria at in situ temperature and salinity. Their respiration and then production were measured the following day at a light intensity of 750 ""E m-2 S-I (the maximum attainable in the laboratory). For purposes of comparison, data were collected on the primary production and respiration of other large fungiids (N = 9) measured on various dates in the field under a narrow range of light intensities averaging 750 ""E m-2 5-1• These data were gathered in the course of the 2-year monitoring program of the reef flat mentioned above. Effect of Light on Respiration.-In the February 1990 experiment, small and medium specimens (N = 3) were measured for respiration in the laboratory, then illuminated at 350 ""E m-2 S-1 for a few minutes, after which respiration was immediately measured again. Respiration rates before and after illumination were then compared. Before this experiment, the corals had been maintained in aquaria under natural room lighting as described above. Statistical Analyses.-Inferential statistics were employed where it was considered appropriate (Sokal and Rohlf, 1981; Zar, 1984). In such cases, data were log- or square-root transformed to meet the assumptions of normality and homoscedasticity, and the Analysis of Yariance (ANOYA) was applied to test for significant differences among treatments.

RESULTS Effect of Maintenance Time in the Laboratory on Coral Metabolism.-Figure 1 shows the initial respiration, then production of corals on the day of collection (Day 0), the following day (Day 1) and 6 days after collection (Day 6). As can be seen from the figure, there were no significant differences in metabolic rates due to length of time the corals were held in the laboratory before measurement. Statistical tests (Table 1) confirmed these results. Effect of Size.-Figure 1 also presents comparisons of metabolic rates in corals of 2 different sizes, small and medium, in the laboratory. Figure 2 compares production and respiration of all three size categories (small, medium, and large) in the field at a light intensity of about 2,000 fLEm-2 S-I. In both experimental set-ups, no significant differences in metabolic rate with respect to size were detected (Table 1). This finding was used to justify pooling of all sizes in some of the subsequent experiments in order to increase the number of replicates. Responses of Primary Production to Light Intensity.-In Figure 1, the responses of small and medium corals to the following light intensities are depicted: 80, 140 and 350 fLEm-2 S-I. The results for the two size categories are pooled and presented along with those for the large ones in Figure 3. The data for 750 fLE m-2 S-I represent only large corals, while values for 2,000 fLEm-2 S-1 are for all three sizes pooled. The data in Figure 3 are used to generate a light saturation curve using the hyperbolic tangent function. The Ik value for the species is indicated to be about 800 fLEm-2 S-I, and theoretical maximum gross primary production (Pm.x) about 2 1 250 fLgO2 cm- h- • The error terms of the parameters are given in the caption to the figure. YAP ET AL.: EXPERIMENTAL MANIPULATIONS OF A SOLITARY CORAL 323

SMALL DAY 0 MEDIUM 200

100

0 Z 0- -100 ~ a: SMALL DAY 1 MEDIUM 200 -Q. •...•..- CJ) ••.c W ·s 100 a: () 0(11 Z - CIl 0 0 ~ ~ - 0 -100 ::) C SMALL DAY 6 MEDIUM 0 200 a: Q. 100

0

·100 o 80 140 350 o 80 140 350

-2 -1 ()JElnsteins m sec ) LIGHT INTENSITY

Figure 1. Gross primary production and respiration of two size classes of Fungia (Danafungia) horrida under three different light intensities in the laboratory, and at three different acclimation periods (see text for details). Standard deviations indicated.

The light saturation curve based on field data gathered monthly over 2 yr for various members of the genus Fungia (Fig. 4) yields strikingly similar parameters, 2 1 particularly for Ik and Pmax. The respiration value of 86 /-LgO2 cm- h- , on the other hand, is about twice that estimated from the preceding curve of 47 /-LgO2 cm-2 h-1• See the caption for the error terms. During the 2-year monitoring period, water temperature fluctuated over a 10° range in the reef flat, with a maximum temperature of 33°C during the summer months of April-August, and a minimum of 23°C in December. Salinity, measured with a refractometer, exhibited a range of 5%0, with a minimum value of 29%0 reached during the peak of the rainy season in October. For the rest of the year (roughly November-June, approximately 8 mo), salinity was relatively stable at 34%0. 324 BULLETIN OF MARINE SCIENCE. VOL. 56. NO. I, 1995

Table 1. Results of AI'iOVA tests for significant effects of various experimental manipulations on gross primary production (P) and respiration of Fungia (Danafungia) horrida

Factor D.F. F-ratio Prob.

Maintenance time Small corals Respiration 2,6 0.780 N.S. Pat 80 j.LE m-2 sec-I 2,6 0.079 N.S. P at 140 j.LE m-2 sec-1 2,6 0.212 N.S. P at 350 j.LE m-2 sec-1 2,6 1.156 N.S. Medium corals Respiration 2,6 0.297 N.S. P at 80 j.LE m-2 sec-1 2,6 0.048 N.S. Pat 140 j.LE m-2 sec-I 2,6 0.175 N.S. Pat 350 j.LE m-2 sec-1 2,6 0.134 N.S.

Size Laboratory*b p at 80 •.•.E m-2 sec-I 1,16 0.280 N.S. Pat 140 j.LE m-2 sec-1 1,16 0.103 N.S. Pat 350 j.LE m-2 sec-1 1,16 0.458 N.S. In situ' Respiration 2,8 0.863 N.S. P at 2000 j.LE m-2 sec-1 1,9 2.360 N.S. Before and after illumination at 350 j.LE m -2 sec-1 in the laboratory* ** Respiration 1,4 2.581 N.S. In situ vs. labe Production 1,14 0.197 N.S. Respiration 1,14 3.879 N.S.

* Maintenance times pooled . •.••Maintenance times and size classes pooled. *** Size classes pooled. a S vs. M vs. L. bS vs. M. 'L only.

Comparison of In Situ and Laboratory Rates.-Production and respiration rates of fungiids measured in the field and in the laboratory under the same light intensities (750 ~E m-2 S-I) were not significantly different (Fig. 5, Table 1). Respiration Before and After Exposure to More Intense Light.-In Figure 6, the respiration of corals, after being maintained at natural room lighting (25 ~E m-2 S-I), and prior to exposure to 350 f.LE m-2 S-I, is compared with respiration after illumination at the latter light intensity. An increase in post-illumination respira- tion is apparent. This difference was not significant, however, presumably because of the small sample size used (N = 3).

DISCUSSION The absence of a size effect in the metabolism of Fungia (Danafungia) horrida, at least within the range studied (diameters of 5-14 cm), is contrary to some findings that smaller individuals metabolize faster than larger ones (Sebens, 1987). It also makes it less complicated to extrapolate values taken from a small group of individuals to a larger group with a broader range of sizes, or even a population. The results on maintenance time in the laboratory are also encouraging. They YAP ET AL.: EXPERIMENTAL MANIPULATIONS OF A SOLITARY CORAL 325

SMALL MEDIUM LARGE 300 Z 0 ~ a: •...- 200 11. ' •.. (fJ J: W 1'1 a: 'E u 100 Z-- 0 01'1 i= aI 0 ::s.. ::;) 0 C -- 0 a: 11. -100

Figure 2. Comparison of three size classes of Fungia (Danafungia) horrida in terms of gross primary production and respiration. Standard deviations indicated. Only field measurements are used (mea- surements are from different dates). Light intensity averaged 2,000 fLE m-2 S-I.

300

.-.. -' .. ..c: ~8 o 0•..•

bl) :l. '-'

-100 P = 258 tanh (1/823) - 47 n

-200 o 500 1000 1500 2000 2500

-2 -1 (J.l.Einsteins m sec )

LIGHT INTENSITY

Figure 3. Light saturation curve (fitted line) superimposed on net primary production and respiration of Fungia (Danafungia) horrida with increasing light intensity. Triangles represent values for small and medium size classes; the circle represents the large size class; and the square depicts all sizes pooled. Bars are standard deviations. Light saturation curve estimates ± SE are as follows: P max = 2 1 2 I 257.7 ± 19.56 fJ-g O2 cm- h- , ex = 0.00]2]5 ± 0.0002062, R =0 -47.03 ± 10.75 fLg O2 cm- h- • 326 BULLETIN OF MARINE SCIENCE, VOL. 56, NO. I, 1995

Z 300 a....•

~ 200 ....•~ ll.. Cf.l ....---- III 'I-< o ~ ..l:l 100 -.... N Z 'S a u ....• N E-< a 0 u tall ;::l :t Cl '-' a -100 P = 258 tanh (I/820) - 86 ~ n ll..

-200 0 500 1000 1500 2000 2500

·2 ·1 (~Einsteins m sec )

LIGHT INTENSITY

Figure 4. Light saturation curve generated from data from monthly monitoring of various members of the genus Fungia over a 2-yr period, Light saturation curve estimates ± SE are as follows: Pmox = 2 l 2 257,55 ± 17.46 I-l-gO2 cm- h- , ('t = 0,00122 ± 0,00018. R = -85,99 ± 1.816 I-l-gO2 cm- hi. Each data point represents an individual measurement.

30

Z 0 20 ~ ~ a:: ~ •• - .c ~N 'E 10 :aII: •.• N --Z 0 0 01 j:: :t 0 0 ;:) Q 0 II: ~ ·10

·20 FIELD LABORATORY -2 ., (750 I-£Elnat.lna m He )

Figure 5. Comparison of field and laboratory measurements of gross primary production and respi- ration of Fungia (Danafungia) horrida at 750 Jl.Em-2 S-l. Standard deviations indicated. YAP ET AL.: EXPERIMENTAL MANIPULATIONS OF A SOLITARY CORAL 327

25

BEFORE AFTER

-50

Figure 6. Respiration of Fungia (Danafungia) horrida before and after illumination at 350 j.LE m-2 S-I in the laboratory (size classes pooled). Standard deviations indicated. indicate that metabolic rates do not change even after a week in the laboratory under minimal maintenance. With this knowledge, it becomes possible to design relatively long-term experiments in the laboratory and reasonably assume that responses would remain relatively stable provided that the physico-chemical en- vironment is controlled accordingly. Corals measured in the field and in the laboratory under the same irradiance values had similar photosynthetic rates. This similarity in rates under the same light intensities could indicate the absence of stress in corals transferred from the field to the laboratory. Considerable care was taken in transport, with natural temperature and salinity and constant aeration maintained at all times. Further- more, transport time was only about 15 min. There were indications of a difference in respiration before and after illumi- nation at 350 J-LEm-2 S-I. Edmunds and Davies (1988) found that respiration of the coral Porites porites increased after exposure to higher light intensities be- cause these brought about increased production of organic substrates for respi- ration. Similarly, Porter et a!. (1984) measured a significantly higher nocturnal respiration for corals growing in the light as compared to shade-adapted speci- mens. Results of this study show significant responses of photosynthesis to increasing light intensity, with Ik estimated to be about 800 J..LEm-2 S-I. The light saturation curve generated on the basis of results of monthly measurements made in situ on various members of the genus Fungia over a period of 2 yr was similar to the curve produced from data from controlled laboratory experiments on Fungia (Danafungia) horrida. Some scatter in the data was to be expected probably due to the fact that field measurements of photosynthesis and respiration against light were made at different temperatures and salinities, and because different species were involved. The variations in the data, however, did not obscure the general response pattern to light. The field measurements were thus seen to confirm the laboratory results. The value of Ik of about 800 f.1E m-2 S-1 is higher than that found for many other species of corals growing at various depths in different habitats (Zvalinskii et a!., 1980; Chalker et a!., 1983; Porter et a!., 1984; Gattuso, 1985). This is most probably a function of depth and latitudinal location, both of which determine the 328 BULLETIN OF MARINE SCIENCE, VOL. 56, NO, I, 1995 degree of light adaptation of a particular coral. An Ik value of 800 /J.Em--2 S-1 may be considered to be at the high end of the observed spectrum. This means that the genus Fungia, growing at relatively shallow depths close to the equator, has adapted to the naturally intense light regime occurring here. Such an adap- tation also explains the relatively high photosynthetic rates measured in the study. It must be noted, however, that light saturation curves are usually generated employing one value for respiration. A constant rate is used despite increasing light intensity, which represents an erroneous assumption. There is a need for new models that would take light-dependent respiration into account. In applying results of this study to corals in general, attention must be paid to the fact that Fungia is a solitary coral consisting of a single polyp. However, because of its basic coral physiology, and its complement of symbiotic zooxan- thellae typical of most stony corals, the metabolic responses described here are presumed to be indicative of trends for other members of the Scleractinia. Pro- duction and respiration rates measured in this study for various species of the fell within the same range as that determined for different species of colonial corals [reviewed in McCloskey et aI., 1978; see also discussion in Yap et al. (1994)].

ACKNOWLEDGMENTS

H. M. E. Nacorda provided valuable assistance in the field. This study was funded through a grant from the Australian International Development Assistance Bureau under the ASEAN-Australia Eco- nomic Cooperation Program Marine Science Project "Living Coastal Resources." This is contribution No. 237 of the Marine Science Institute.

LITERATURE CITED

Buddemeier, R. W. and R. A. Kinzie III. 1976. Coral growth. Oceanogr. Mar. BioI. Ann. Rev. ]4: 183-225. Chalker, B. E. 1980. Modelling light saturation curves for photosynthesis: an exponential function. J. Theor. BioI. 84: 205-215. ---. 1981. Simulating light-saturation curves for photosynthesis and calcification by reef-building corals. Mar. BioI. 63: 135-141. ---, W. C. Dunlap and J. K. Oliver. 1983. Bathymetric adaptations of reef-building corals at Davies Reef, Great Barrier Reef, Australia. II. Light saturation curves for photosynthesis and respiration. J. Exp. Mar. BioI. Ecol. 73: 37-56. Dennison, W. C. and D. 1. Barnes. 1988. Effect of water motion on coral photosynthesis and calci- fication. J. Exp. Mar. BioI. Ecol. I IS: 67-77. Edmunds, I'. J. and I'. S. Davies. 1988. Post-illumination stimulation of respiration rate in the coral Porites porites. Coral Reefs 7: 7-9. --- and ---. 1989. An energy budget for Porites porites (Scleractinia), growing in a stressed environment. Coral Reefs 8: 37-43. Gattuso, J.-I'. 1985. Features of depth effects on Stylophora pistillata, an hermatypic coral in the Gulf of Aqaba (Jordan, Red Sea). Proc. 5th Int. Coral Reef Congo 6: 95-100. Gladfelter, E. H. 1985. Metabolism, calcification and carbon production. II. Organism-level studies. Proc. 5th Int. Coral Reef Congo 4: 527-539. Jassby, A. D. and T. Platt. 1976. Mathematical formulation of the relationship between photosynthesis and light for phytoplankton. Limnol. Oceanogr. 21: 540-547. Kinzie, R. A. III and T. Hunter. 1987. Effect of light quality on photosynthesis of the reef coral Montipora verrucosa. Mar. BioI. 94: 95-109. --- and T. Sarmiento. 1986. Linear extension rate is independent of colony size in the coral Pocillopora damicomis. Coral Reefs 4: 177-181. Maragos, J. E. 1978. Coral growth: geometrical relationships. Pages 543-550 in D. R. Stoddart and R. E. Johannes, eds. Coral reefs: research methods. Monographs on oceanographic methodology 5. UNESCO, Paris. McCloskey, L. R. and L. Muscatine. 1984. Production and respiration in the Red Sea coral Stylophora pistillata as a function of depth. Proc. R. Soc. Lond. B 222: 215-230. ---, D. S. Wethey and J. W. Porter. 1978. Measurement and interpretation of photosynthesis and YAP ET AL.: EXPERIMENTALMANIPULATIONSOF A SOLITARYCORAL 329

respiration in reef corals. Pages 379-396 in D. R. Stoddart and R. E. Johannes, eds. Monographs on oceanographic methodology 5. UNESCO, Paris. Newton, P A. and M. J. Atkinson. 1991. Kinetics of dark oxygen uptake of Pocil/opora damicornis. Pac. Sci. 45: 270-275. Porter, J. W., L. Muscatine, Z. Dubinsky and P G. Falkowski. 1984. Primary production and pho- toadaptation in light- and shade-adapted colonies of the symbiotic coral, Stylophora pistil/ata. Proc. R. Soc. Lond. B 222: 161-180. Sebens, K. P ] 987. Coelentcrata. Pages 55-120 in T. J. Pandian and E J. Vernberg, eds. Animal energetics. Academic Press, Inc., London. Sokal, R. R. and E J. Rohlf. 1981. Biometry, 2nd ed. W. H. Freeman and Co., New York. 859 pp. Wyman, K. D., Z. Dubinsky, J. W. Porter and P G. Falkowski. 1987. Light absorption and utilization among hermatypic corals: a study in Jamaica, West Indies. Mar. BioI. 96: 283-292. Yap, H. T., P M. Alino and E. D. Gomez. 1992. Trends in growth and mortality of three coral species (: Scleractinia), including effects of transplantation. Mar. Ecol. Prog. Ser. 83: 91-101. ---, A. R. E Montebon and R. M. Dizon. 1994. Energy flow and seasonality in a tropical coral reef flat. Mar. Ecol. Prog. Ser. 103: 35--43. Zar, J. H. 1984. Biostatistical analysis, 2nd ed. Prentice-Hall, Inc., Englewood Cliffs, New Jersey. 7]8 pp. Zeitzschel, B. 1981. Field experiments on benthic ecosystems. Pages 607-625 in A. R. Longhurst, ed. Analysis of marine ecosystems. Academic Press, London. Zvalinskii, V. I., V. A. Leletkin, E. A. Titlyanov and M. G. Shaposhnikova. 1980. Photosynthesis and adaptation of corals to irradiance 2. Oxygen exchange. Photosynthetica 14: 422--430.

DATE ACCEPTED: December ]6, 1994.

ADDRESSES: (H.T. Y., A.R.F.M. and R.M.D.) Marine Science Institute, University of the Philippines, Diliman, 1101 Quezon City, Philippines; (i.-A.a.) Department of Biology, University of Rostack, 7/8 Freiligrathstr., 2500 Rostock, Germany.