Stable isotopes in recent larger foraminifera

Palaeogeography, Palaeoclimatology, Palaeoecology, 33 (1981) : 253--270

253

Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherlands

STABLE ISOTOPES IN RECENT LARGER F O R A M I N I F E R A

GEROLD WEFER 1, JOHN S. KILLINGLEY 2 and G E R H A R D F. LUTZE 1

l Geologisches Institut, Universitiit Kiel, 2300 Kiel (F.R.G.) ~Seripps Institution of Oceanography, La Jolla, Calif. 92093 (U.S.A.) (Received and accepted July 23, 1980)

ABSTRACT Wefer, G., Killingley, J. S. and Lutze, G. F., 1981. Stable isotopes in Recent larger foraminifera. Palaeogeogr., Palaeoclimatol., Palaeoecol., 33 : 253--270. Oxygen and carbon isotope analyses have been made on large benthic foraminifera from Bermuda, the Persian Gulf, and the Philippines. The foraminifera belong to the two suborders Rotaliina and Miliolina. Life spans range between one season to more than two years. Shells contain information about seasonal temperature ranges and life-history stages, recorded as fluctuations of oxygen and carbon isotopic values within the shell material. Almost all specimens studied showed the expected variations in 518 O with respect to ambient conditions (water isotopic composition and seasonal temperature fluctuations). The specimens from Bermuda seemed enriched in 1~O, whereas all specimens from the Philippines, independent of their taxonomic position, seemed to be depleted in 180 with respect to calcite equilibrium. Specimens from the same species showed about the same level and range of 5 ~ O values. The miliolid species Marginopora vertebralis, Cyclorbiculina compressa, Archaias angulatus, Peneroplis proteus, and Praesorites orbitolitoides cf. monensis commonly show carbon isotope values up to 2.5%0 lighter than expected equilibrium values independent of sample locality. The rotaliid species Heterostegina depressa, Operculina sp., and Calcarina spengleri show carbon isotope values more than 2%o lighter than expected equilibrium values, also independent of sample locality. All analyzed miliolid species show a tendency, with age, towards lighter-than-equilibrium 5~3C values. The analyzed rotaliid species showed the reverse, that is, shells tend toward increased 513 values with age. INTRODUCTION

Larger foraminifera are important producers of carbonate (Maxwell, 1968; Lutze et al., 1971; RSttger, 1972; Muller, 1974; Erez and Gill, 1977; Ross, 1977) in tropical and subtropical shallow-water areas. Also, they are important producers of organic matter (Sournia, 1977). Commonly, these foraminifera are associated with algal symbionts (Lee et al., 1979), which allows rapid growth (50--100 times that of most temperate species). A life span of one to sever.al years appears to be characteristic of most large to very large foraminifera (Ross, 1974, 1979). Wefer and Berger (1980) showed that in the shells of these larger foraminifera, the oxygen isotope signal records the seasons, and the carbon isotope 0031-0182/81/0000--0000/$02.50 © 1981 Elsevier Scientific Publishing Company

254 signal reflects the metabolic activities of the organisms in the seasonal progression. Thus, the variations in the stable isotopes in individual shells of a given species can be used: (1) for age and growth rate determinations, which has implications for c o m m u n i t y structure and carbonate production; (2) as a recording device for environmental fluctuations, including Comparisons between open ocean and enclosed bays; and (if the shells are well preserved) (3) for palaeontological implications such as yearly temperature and salinity ranges or for estimating the role of symbionts in the accumulation of carbonate in ancient rocks. We report here the stable isotope composition of several Recent larger foraminifera: Marginopora vertebralis, Cyclorbiculina compressa, Archaias

angulatus, Peneroplis proteus, Praesorites orbitolitoides cf. monensis, Heterostegina depressa, Calcarina spengleri, and Operculina sp. These species belong to two different suborders: Rotaliina and Miliolina. (For t a x o n o m y of P.

orbitolitoides cf. monensis see Seiglie et al., 1976.) The presence of symbionts in these foraminifera is a central aspect of growth history. Different types of symbionts have been reported. Lee et al. (1979) summarized the present knowledge of symbiosis in larger benthic foraminifera. The symbionts in H. depressa are diatoms (Dietz-Elbr~chter, 1971; Schmaljohann and RSttger, 1976). Diatoms may also be present in Operculina ammonoides (Leutenegger, 1977). The symbionts in Marginopora vertebralis (Ross, 1972) are dinoflagellates, while two different chlorophytes seem to be the algal symbionts in Archaias angulatus and Cyclorbiculina compressa (Lee et al., 1974; Mfiller-Merz and Lee, 1976). Fine-structure studies suggests that the symbiont within Peneroplis planatus is a rhodophycean (Leutenegger, 1977). The symbionts in Calcarina and in Praesorites have not been described. MATERIALS AND METHODS The specimens analyzed were collected from Bermuda (Harrington Sound), the Persian Gulf, and the Philippines (off Mactan, Cebu) (Fig.l), and with the exception of Opereulina, all foraminifera were taken alive. Detailed information on the sampling localities and data on the stable isotopic composition of the subsamples are given in the Appendix. The species of Archaias, Cyclorbiculina, Marginopora, Praesorites, and Peneroplis belong to the suborder Miliolina because of their (post-embryonic) porcellaneous, imperforate test. Heterostegina, Operculina, and Calcarina have a perforate wall and belong to the suborder Rotaliina (Table I). All specimens here analyzed were larger than the population average. The specimens of Marginopora and Cyclorbiculina had undergone asexual reproduction, and the adult test contained little or no protoplasm. The protoplasm was concentrated in the two-chambered embryos present within the reproduction chambers rimming the tests. The data on the reproduction chambers are marked with an R in the figures. After collection, the specimens were

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either fixed with ethanol or dried in the sun. Rose Bengal stain was used to d e t ect protoplasm if its presence was not already obvious. Specimens were subsampled, using a scalpel or needles to separate individual chambers from each test. Depending on their size, one to ten chambers were used for each analysis. It is k n o w n t hat for rotaliid species the addition of new chambers is accompanied by a c o n c u r r e n t strengthening of existing chambers with extra veneers of calcite. We a t t e m p t e d t o make allowance for this by scraping off the surface layers before removing material for analysis. To remove the organic m a t t e r attached to the test, each subsample was soaked in 10% aqueous solution of H202 for one-half hour. Subsequently, it was washed five times with deionized water, dried at 60°C and heated for 30 min at 300°C in vacuum. Analytical procedures are described by Berger and Killingley (1977). Analytical precision was f o u n d to be 0.1°/00 (one standard deviation)• T h e ~ 8 0 and 513C variations are given as deviation from PDB, in per mil. At the Bermuda location, temperatures varied between 16°C and 29.5 ° C, with the m a x i m u m in August and the minimum in February, and the average salinity was 36.1%o, with a range o f 0.7%o (B. yon Bodungen, pers. comm.). At the sampling site in the Philippines, the t e m p e r a t u r e varied between 26 and 30 ° C, with the m i ni m um in Febr ua r y and the m a x i m u m in July, and the average salinity was 34.5%o, with a yearly range of 0.7%o (N. Ran, pers. comm•). At the sampling site in the Persian Gulf, the t em perat ure (April) was 22.1°C in 15 m and 20.5°C in 30 m water depth. The salinity was 38.3%0 in 15 m and 39.3%0 in 30 m water depth (Brettschneider et al., 1970). E m e r y (1956) r e por t ed a t e m p e r a t u r e of 33°C and a salinity of 38%o in August at a p p r o x i m a t e l y the same sampling site. T herefore, we expect a yearly t e m p e r a t u r e range of about 11--13°C and a yearly salinity range o f less than 1%o.

256

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257 The 5~80 values for the surface water were calculated using 5'SO/salinity relationships of Craig and Gordon (1965). Seasonal variations in seawater 5'sO were small at all locations: approximately 0.3%o or less, possibly slightly greater in the Persian Gulf locations, although with limited salinity data, this is not well established. The expected ~ ' 8 0 variations within the shells for the different localities and ambient temperature variations were calculated using the equation of Epstein et al. (1953). Values of near-surface bicarbonate 5'3C were obtained from Kroopnick et al. (1970, 1972, 1977) and from Duplessy (1978). From these data, we calculated the calcite equilibrium 5'3C values using relationships published by Emrich et al. (1970). In Table II, we list data on the isotopic composition of the water with their sources. RESULTS AND DISCUSSION

Variations in 5'sO Bermuda (Fig.2a). We analyzed only miliolid species from Bermuda, and their 51sO range is close to that expected from ambient temperature variations. However, the actual 51sO values are heavier than those calculated from the Epstein et al. (1953) equation using known temperatures and determined 5'80 (water) values. All three specimens of Cyclorbiculina compressa are comparatively light in 6 ' s o in their central regions (summer), become heavier in the middle of the test (winter), and again lighter towards the margin. The data indicate a growth period of one year, with reproduction in the spring. No significant differences in isotopic fractionation between individuals is indicated from the C. compressa data. All values are between 1.5 and --1.0%o, and all three specimens have the heaviest values near 1.5%o. The marginal 8 ' 8 0 values for C. compressa II are heavier than those of the other specimens, but this may be due to absence of growth in spring for this individual. Archaias angulatus becomes lighter in 5'sO with age. If we expect a reproduction mechanism similar to that of C. compressa (both species have about the same size and belong to the same subfamily), then the analysed specimen shows reproduction in early spring, with buildup of the entire test between spring and summer. The sampling date was early August 1978. Persian Gulf (Fig.2b). Heterostegina depressa was sampled in April, which is in agreement with the heavier 51sO values in the marginal area of the test. The inner part of the test is about 1.6%o lighter, representing 8°C temperature difference (if the salinity is constant), indicating a reproduction time in early summer. The lifetime should be between one-half and one year. The 5'sO variations in Operculina sp. are smaller than those of H. depressa. The range of values is 1.1%o, representing about 5°C temperature difference. The values are light in the youngest four chambers (subsample No.8) and are heavier in the middle part of the test. The 5 'sO values again become lighter

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Fig.2. Top. a 180 variations of subsamples (reproduction chambers marked R) from foraminifera taken: (a) in Harrington Sound, Bermuda: Archaias angulatus, Cyclorbiculina compressa; (b) in the Persian Gulf: Heterostegina depressa, Operculina sp. Bottom. 6~3C variations of foraminifera from Bermuda (c), and the Persian Gulf (d). The drawings of the foraminifera show the characteristic shapes of the analyzed specimens. The horizontal axes in b and d show breaks because the growth sequence of H. depressa changes direction after the individuals obtain a certain size.

260 towards the center, suggesting reproduction in late fall and a lifetime of less than one year for this specimen.

Philippines (Figs.3a, b). In Fig.3a miliolid, and in Fig.3b rotaliid foraminifera are included. Specimens of both groups precipitate carbonate within the same general isotopic range. Marginopora vertebralis II (Fig.3a) shows a lifetime of two years. This record was described in detail by Wefer and Berger (1980). The other M. vertebralis analyzed shows a similar signal. The juveniles of M. vertebralis I show especially light 5lsO values, which are not in agreement with the water temperature of 26.5°C recorded when sampled in January 1979. The other species analyzed from the Philippines (Praesorites orbitolitoides cf. monensis, Peneroplis proteus, Calcarina spengleri, and H. depressa) do n o t show such distinct seasonal variations in 5180 as M. vertebralis. By comparison with the M. vertebralis curves, it appears that each specimen grew to an adult size within one or two seasons. In the case of C. spengleri, it probably did so in summer, P. orb. cf. monensis through summer and fall, H. depressa from spring to fall, and P. proteus grew to maturity through, fall to early winter. C. spengleri seems to be offset to lighter values by a few tenths of per mil compared to the other Philippine species. Almost all specimens show the expected variations in 6180 with respect to ambient conditions (water isotopic composition and seasonal temperature fluctuations). From Bermuda, where the yearly temperature variations are 13.5°C, specimens show differences in 5180 of up to 2.4%o within a single test (Fig.2a). The maximum variation of ~ 1sO in specimens from the Philippines was 1.4%o (Fig.3a, b), corresponding to a yearly temperature difference of up to 4 ° C. Temperature ranges calculated from isotopic values of the two species from the Persian Gulf, H. depressa and Operculina sp. (Fig.2b) were 8°C and 5°C, respectively. Although no detailed seasonal data are available from the Gulf sampling sites, these temperature ranges are in general agreement with the expected yearly temperature variations. We therefore conclude that the ~180 c o m p o s i t i o n of living benthic larger foraminifera is a function chiefly of surface water temperature and, as such, records the seasonal temperature cycle. Williams et al. (1979) likewise found a good agreement between the seasonal range in isotopic composition of living planktonic foraminifera from oceanic waters off Bermuda and temperature variations. Their results are based on whole-shell analysis. All specimens analyzed from Bermuda seem enriched in ' 8 0 , whereas all specimens from the Philippines, independent of their taxonomic position, seem to be depleted in 1sO. While depletion in 1sO is not unusual in benthic foraminifera (Buchardt and Hansen, 1977; Erez, 1978) and has been ascribed to the use of metabolic CO2 in test construction (Duplessy et al., 1970), enrichment in 1sO is unexpected. The fact that the shell material consists of Mg-rich calcite may play a role. The miliolid foraminifera Marginopora, Peneroplis, and Archaias contain 15--18 mol percent MgCO3, and the rotaliid foraminifera Operculina and Heterostegina 12--13 mol percent MgCO3,

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Fig.3. Top. 6'80 variations of subsamples (reproduction chambers marked R) from foraminifera taken near Cebu, Philippines: (a) Miliolina: Marginopora vertebralis, Peneroplis proteous, and Praesorites orbitolitoides cf monensis; (b) Rotaliina: Heterostegina depressa and Calcarina spengleri. Bottom. ~ '3C variations of foraminifera from the Philippines: Miliolina (c) and Rotaliina (d). The drawings of the foraminifera show the characteristic shapes of the analyzed specimens.

according to Blackmond and T o d d (1959), For an increase in 5'sO of 0.6%o for each mol percent MgCO3 (Tarutani et al., 1969), an increase in 5 ' 8 0 of a b o u t 1%o for the miliolid species and a b o u t 0.75%o for the rotaliid species (with respect to pure calcite) would be expected. If this calculation is correct,

262 all species are actually depleted in 180. It follows that the miliolids should be 0.25%o heavier in 5180 than the rotaliids. This is possibly true in the C. spengleri specimen, but is not clear in the case of H. depressa. Any such Mgrelated fractionation effect is probably obscured b y differential vital fractionation effects between species. Vinot-Bertouille and Duplessy (1973) found no correlation between Mg-content and isotopic equilibrium. Wefer and Berger (1980) showed that life spans estimated from oxygen variations within single tests are in good agreement with direct observations by Ross (1972) on M. vertebralis and Lutze and Wefer (1980) on C. compressa. Another species where data on growth rates are available is H. depressa. Lutze et al. (1971) estimated a lifetime of not more than one year from growth curves of 11. depressa from the Persian Gulf. RSttger (1976) found that within 41A months, specimens from Hawaii grown in the laboratory under optimal light conditions increased in average size from 0.3 mm to 1.8 mm and that within the following months very little growth occurred. Our data indicate a growth period of one-half to one year for the 8.2-mm H. depressa from the Persian Gulf (Fig.2b) and of ca. one year for the 5.3-mm specimen from the Philippines (Fig.3b), a lifespan which is comparable or somewhat shorter than that observed in the laboratory. For the other species, no field and laboratory data on growth rates are available. Vinot-Bertouille and Duplessy. (1973) have reported large differences (more than 2%o) in isotopic composition between individual benthic foraminifera of the same species, presumably precipitated under similar conditions. We did not observe such dispersion between our three analyzed C. compressa (Fig.2a) and two M. vertebralis (Fig.3a) (each specimen of the species sampled from the same locality at about the same time). Both species showed a b o u t the same level and range of 5~80 values. For the t w o species studied, it does not seem to be necessary to analyse a large number of individuals to determine characteristic fractionation values for each species, as suggested by Vinot-Bertouille and Duplessy (1973).

Variations in 6~3C Bermuda (Fig.2c). The four specimens analyzed, which all belong to the suborder Miliolina, have 513C values between about 1.3 and 4.0%0, showing a much wider range than the expected equilibrium values for calcite (4.1-3.3%o). Values become progressively lighter towards the margin of each test. The rate at which 6'3C decreases with increasing size (age) is similar in all three C. compressa. A. angulatus shows especially light 5~3C values in the last-formed part of the test. The earlier part of the test in this species has values near calcite equilibrium. Persian Gulf (Fig.2d). The 51~C values in H. depressa become heavier towards the margin (from a b o u t --1.7 to 1.3) with the exception of the last two subsamples, which again show lighter values. In Operculina sp., the 613C values vary only between 0.1 and --0.6%0, with slight tendency to become lighter towards the margin of the test.

263

Philippines (Fig.3c, d). The miliolid specimens (M. vertebralis, P. orb. cf. monensis and P. proteus, Fig.3c) show ~13C values between 0.8 and 4.0%o. They are close to or lighter than expected equilibrium values. All specimens analysed show a tendency, with age, towards lighter than equilibrium values. In one of the two M. vertebralis, it can only be seen in their two-chambered juveniles. One M. vertebralis shows an overall positive, the other a negative correlation between oxygen and carbon values (Fig.3a, c). The t w o rotaliid species, C. spengleri and H. depressa (Fig.3d), have ~13C values b e t w e e n - - 1 . 5 and 0.5%0, which are several per mil lighter than calculated equilbrium values, Both specimens become heavier in 6~3C with age, and the variation within each test and between tests are less than in the miliolid specimens. The carbon isotopic composition of Recent foraminifera has received much less study than the oxygen isotopic composition, although a number of reports are now available with carbon isotope data on b o t h planktonic (Savin and Douglas, 1973; Weiner, 1975; Vergnaud-Grazzini, 1976; Williams et al., 1977; Berger et al., 1978a, b; Shackleton and Vincent, 1978; Kahn, 1979) and benthic species (Vinot-Bertouille and Duplessy, 1973; Burchardt and Hansen, 1977; Shackleton, 1977; Erez, 1978; Wefer and Berger, 1980). While for oxygen isotopes the main cause of variation appears to be temperature (with the average level pegged by water composition and any more or less constant vital effect), no such simple cause has been identified for carbon isotope variations. Our results (Figs.2c, d and 3c, d) may be summarized as follows: (1) For the miliolid species (M. vertebralis, C. cornpressa, A. angulatus, Peneroplis proteus, and Praesorites orb. cf. monensis, independent of sample locality, carbon isotope values are close to or as much as 2.5%o lighter than expected equilibrium values (3.3--4.1°/00). (2) For the rotaliid species (H. depressa, Operculina sp., and C. spengleri), independent of sample locality, carbon isotope values are more than 2%o lighter than expected equilibrium values. (3) There is a tendency, with age, towards lighter 6~3C values in all miliolid species analyzed and towards heavier 513C values in the rotaliid species (except Operculina sp.). The total range in 5~3C values is moderate compared with that found in certain corals (Land et al., 1975, 1977; Emiliani et al., 1978) and algae (LSwenstam and Epstein, 1957). These observations may be interpreted as follows. The distinct difference in the level of 513C values between miliolid and rotaliid foraminifera indicates different amounts of metabolic CO2 used for shell construction. Erez (1978) showed that with increasing photosynthesis, more metabolic CO2 is incorporated in the skeleton of similar benthic foraminifera a n d hermatypic corals, and the carbon isotopic composition becomes lighter. The difference in absolute values between the two suborders would suggest, therefore, that the rotaliid foraminifera have greater photosynthetic rates than the miliolids, since the 5~3C values in rotaliids are

264 lighter than in miliolids. There is independent evidence that this is indeed so. It seems probable that the zooxanthellae in the rotaliid H. depressa provide essential nutrients for the host. When the host is kept in the dark, the animals do n o t grow, even if they are offered food (Dietz-Elbr~ichter, 1971). RSttger (1972) showed that starved foraminifera survive for as long as 4 months in the dark. In optimal light (600 lux), growth is relatively rapid (RSttger, 1976), even without external food supply. Apparently, primary production by the symbionts is b y far the most important source of nutrition for H. depressa. The miliolid Sorites marginalis (belonging to the same subfamily as Cyclorbiculina and A. angulatus), the feeding rates are generally several orders of magnitude greater (~>10:1) than photosynthetic rates (Lee and Bock, 1976). Furthermore, in this species light apparently does not enhance the rate of calcification under experimental in situ conditions (Lee and Bock, 1976). In contrast, A. angulatus showed in laboratory studies a calcification rate which was 2--3 times higher in the light than in the dark (Lee and Zucker, 1969; Duguay and Taylor, 1978}. Thus, photosynthesis also is important for calcification in this miliolid. However, the evidence favors the suggestion that the relative importance of photosynthetic rates, compared with feeding rates, is much greater in the rotaliid H. depressa than in the miliolids Sorites and Archaias. Also, Erez (1978, fig.2c) showed higher photosynthetic rates for Heterostegina and Amphistegina (rotaliids) and lower rates for Amphisorus and Borelis (miliolids). It is possible that the hyaline and more transparent walls of the rotaliid species, as compared with miliolid species, reflect this difference in adaptation; it would appear that more light is available for photosynthesis by symbionts in the rotaliid foraminifera. If the conclusion is valid that ~ 13C indicates the role of symbionts in the incorporation of carbon in carbonates, then Calcarina and Operculina should have symbiont relationships similar to those of H. depressa, because both show a similar 5~3C value. Furthermore, it would follow that ~13C values from shell material can be used to predict levels of photosynthetic rates in other foraminiferal species and that we have here a tool in estimating the role of symbionts in the deposition of ancient rocks and in the evolution of larger foraminifera, a question recently discussed by Ross (1974) and Lee et al. (1979}. The tendency towards lighter carbon values with increasing age, observed in the miliolid species, is unexpected because the opposite has been found in planktonic foraminifera (Vergnaud-Grazzini, 1976; Berger et al., 1978b), where ~ 3 C becomes heavier with size (and age). The tendency towards lighter values could be caused by: (1) a continuing increase in dependency on symbiontic algae during growth, parallel to increased exposure of the plasma to light with increasing size, (2) an increase in growth rate with age. While we have no evidence for the first possible cause, we do see increasing growth combined with especially light 5'3C values in the case of C. compressa

265 in the very rapid buildup of reproductive chambers (Wefer and Berger, 1980; see Fig.2c). The tendency toward heavier carbon values during growth, as f o u n d in the rotaliid species of Heterostegina and Calcarina, corresponds to a decrease in the degree of disequilibrium in the shell precipitation of aged organisms, as described in planktonic foraminifera (Vergnaud-Grazzini, 1976; Berger et al., 1978b), and corals (Emiliani et al., 1978). We follow the consensus in suggesting that the decrease in disequilibrium is caused by the slowdown of growth rate with age. Stable isotope values in a Nautilus pompilius shell (Eichler and Ristedt, 1966) also show enrichment in heavy isotopes with age, and crowding of septa (slowing of growth) is associated with unusually heavy carbon values. The fact that M. vertebralis shows both a positive and a negative correlation between oxygen and carbon is intriguing. In the other species, no general correspondence between ~13 C and ~ls O is obvious. A positive correlation of 5~3C and 5~sO values in the calcareous hard parts of the same organism has been noted previously for ahermatypic coral (Land et al., 1977; Emiliani et al., 1978) and for the otoliths of a rat-tail fish (Mulcahy et al., 1979). The data of Emiliani et al. (1978) on a deep-sea coral show a striking correlation between 5 ~sO and 513 C over an unusually wide range of values. In that case, both seasonal effects and symbiotic effects are excluded as possible factors. Clearly, the correlation is mainly due to parallel disequilibrium for oxygen and carbon, in this case. In other instances, a high rate of growth may be linked to high temperatures (and irradiation). When nutrient supply is strongly limiting, a reverse correlation might be expected, since cold water is associated with nutrients. Killingley and Berger (1979) showed that carbon isotope values in a California mussel fluctuated seasonally, with 13C depletion during periods of upwelling and growth. Hence the 513C fluctuations were phase-shifted with respect to the oxygen isotope (temperature) signal. If oxygen and carbon isotopic values vary in response to seasons, therefore, their correlation will depend on the size of the phase shift, which depends on regional conditions (Fairbanks and Dodge, 1979). ACKNOWLEDGEMENTS Supported by Deutsche Forschungsgemeinschaft (SFB 95, Contribution No.259), Deutscher Akademischer Austauschdienst and by the U.S. National Science Foundation (Ocean Sciences Div. Grant No. OCE78-25587). G. W. thanks the staff of the Geological Research Division for facilitating his extended sojourn at SI0, during the 79/80 academic year. He also thanks R. Dunbar for occasional assistance on the mass spectrometer. We are grateful to W. H. Berger for valuable discussions and a critical reading of the manuscript. We thank B. von Bodungen and N. Rau for kindly providing unpublished environmental data for the sampling locations on Bermuda and in the Philippines. We also t h a n k A. Miiller for foraminifera samples from the Philippines. Contribution Bermuda Biological Station No. 827.

266

APPENDIX Locality, samples

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Distance from test center (ram)

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3 juvenile, 51So (PDB)

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Cyclorbiculina compressa I (Bermuda, HarrLngton Sound, Old Shoals, 10 m, April 1978)

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2.27 2.73

0.85 0.42

2.57 2.05

1 2 3 4 5

0.62 0.96 1.28 1,60 1.92

0.58 0,73 0.82 1.24 1.10

3.75 3.58 3.32 3.33 3.08

6 7 8

2.52 3.01 3.36

1.43 1.07 1.13

3.25 2.17 2.88

C y c l o r b i c u U n a c o m p r e s s a III

R

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with the isotope

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61BO (PDB)

61~C (PDB)

O p e r c u l i n a sp. (Persian Gulf, 30 m, April 1965)

C y c l o r b i c u l i n a c o m p r e s s a II

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R = reproduction

i 2 3 4

0 0.33 0.5 0.65

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--0.03 0.09 ---0.16 --0.06

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0.83 1.00 1.28 1.83

0.13 0.17 0.37 ---0.70

--0.32 -0.23 -0.03 -0.63

0.11 0.39 -0.63 --0.61 --0.94

3.70 4.06 3.55 3.73 1.27

--1.60 --1.26 --1.63 --1.50 --1.42 --1.47 --1.58 --1.61 --1.31 --0.60 -0.66 -0.73 -0.15 -0.69 -0.02 -0.06

--1.76 --0.44 --0.11 --0.51 0.42 --0.04 --0.17 0.17 -0.12 0.60 0.71 0.22 0.67 1.34 0.48 -0.04

A r c h a i s angulatus (Bermuda, Harrington Sound, Old Shoals, 10 m, August 1978)

1 2 3 4 5

0 0.44 0.72 1.12 1.39

Heteros~egina depressa (Persian Gulf, 15 m, April 1965)

1 2 3 4 5 6 7 8 9

0.4 0.74 0.98 1.17 1.42 1.68 1.82 2.16 2.55

---0.49 --0.94 -0.42 --0.40 0.73 0.88 0.68 1.48 1.10

3.45 3.14 3.07 2.61 2.77 2.72 2.75 2.65 2.53

10 11 12

2.94 3.82 4.5

0.50 0.46 --0.19

1.89 1.75 1.37

10j 11j 12j

2.94 3.82 4.5

0.31 0.36 -0.18

2.30 1.69 2.01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

0 0.56 0.83 1.12 1.22 1.39 1.78 2.22 2.5 2.78 3.06 1.67 1.94 2.22 2.50 2.78

267 APPENDIX (continued) Subsample No.

Distance f r o m test c e n t e r ( r a m )

5180 (PDB)

613C (PDB)

Praesorites orb. cf. m o n e n s i s (PhiliPpines, C e b u , M a e t a n , 1 m, January 1979) 1 2 3 4 5 6 7

0.33 0.5 0.72 0.89 1.06 1.17 1.36

--2.96 --2.96 --3.34 --3.15 --3.23 --3.14 --3,00

2.11 2.41 2.23 2.19 2.03 2.00 1.90

P e n e r o P l i s p r o teus (Philippines, C e b u , M a c t a n , 1 m, January 1979) 1 2 3 4 5 6

0.33 0.44 0.56 0.72 0.83 1.00

--3.27 --2.57 (--4.43) --2.68 --2.73 --2.65

4.03 2.98 3.07 3.71 3.04 2.23

M a r g i n o p o r a vertebralis I (Philippines, C e b u , M a c t a n , 1 m, January 1979)

R

Subsample No.

Distance f r o m test c e n t e r ( r a m )

0 1,5 2.5 3.5 4.5 5.5

--3.05 --2.35 --3.25 --3.08 --2.82 --3.04

2.01 2.77 2.32 2.03 2.98 2.42

7 8 9

6.5 7.25 8.1

--2.72 --2.73 --2,84

3,01 3,02 2,67

7j 9j

6.5 8.1

--3.10 --3.27

1.01 0.94

8 9 10 11 12 13 14 15 16 17

2,3 2.45 2.65 2.85 3.1 3.35 3.55 3.85 4.1 4.45

--3.35 --3.38 --3.42 --3.45 ---3.08 --3.08 --2.85 --2.90 --2,58 --2.75

2.65 1.72 2,19 1.78 2.36 2.08 3.04 2.60 3.12 2.20

18 19 R 20 21 22 23 24 18j 19j 20j 21j 22j

4.75 5.1 5.5 5.9 6.5 6.7 6.8 4.75 5.1 5.5 5.9 6.5

--2.71 --2.78 --2.70 --3.35 --3.19 --3.14 --3.44 --2.26 --2.68 --2.83 --2.60 --2.62

3.14 2.72 2.94 1.44 2.16 1.30 0.86 1.26 1.17 1.41 1.01 1.00

--3.20 --3.18 --3.03 --2.98 --2.96 --2.94 --2.92 --3.19 --2.93 --2.98 --2.88 --2.94 --3.17

--0.79 -0.82 -0.31 -0,28 -0.14 0.12 --0.03 0.08 0.28 0.19 0.35 0.46 0.19

1 2 3 4 5 6 7 8 9 10 11

M a r g i n o p o r a vertebralis II (Philippines, Cebu, M a c t a n , 1 m, January 1979) 0.3 0.5 0.8 1.15 1.5 1.8 2.05

51~C (PDB)

H e t e r o s t e g i n a depressa (Philippines, C e b u , M a c t a n , 1 m, October 1979)

1 2 3 4 5 6

1 2 3 4 5 6 7

51SO (PDB)

12 13

0.33 0.39 0.5 0.78 1.00 1.33 1.67 2.06 2.44 2.83 3.17 3.61 4.0

Calcarina spengleri (Philippines, C e b u , M a c t a n , 1 m, October 1979) --2.12 2.49 --2.57 --2.57 --2.47 --3.21 --3.23

3.93 3.00 3.48 2.77 2.81 3.36 2.22

1 2 3 4 5 6 7

0.28 0.33 0.89 1.12 1.15 1.22 1.33

--3.73 --3.73 --3.52 --3.38 --3.49 --3.61 --3.37

--1.50 --1.42 --1.35 --0.90 -0.97 -0.85 -0.72

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