Title: The Effect of Quartz versus Calcareous Sand on the Densities of Living Foraminifera
Abstract: To evaluate the effect of quartz versus calcareous sand on foraminiferal densities, the genera Quinqueloculina, Ammonia, Elphidium and Ammobaculites were monitored at Link Port, Florida. Observations were made over four to seven months in each of 1984, 1985, 1986 and 1987. Densities were analyzed for each year by two-way ANOVA's. Each year there was a significant periodicity, approximately synchronous across genera, in both substrates. Out of 16 trials only four indicated a significant difference between sediment type. The results lead to the conclusion that the mineralogy of the sediment is not important in regulating foraminiferal densities at Link Port. INTRODUCTION The availability of CaCO3 increases with increasing water temperature and salinity. Greiner (1974) reasoned that arenaceous species occupied low salinity areas in the Gulf of Mexico because of the lack of availability of CaCO3 for the secretion of calcareous tests. He believed hyaline tests need less availability of CaCO3 than porcelaneous ones due to the construction of their wall types. He envisioned a gradient from low availability of CaCO3 (arenaceous), intermediate availability (hyaline) to high availability (porcelaneous). The large size and thick walls of foraminifera in shallow tropical waters has also been attributed to CaCO3 availability (Boltovskoy and Wright 1976). The substantial contribution foraminifera make to carbonate production has received considerable attention (e.g. Hallock et al. 1986). No one, however, has tried to evaluate the significance of the carbonate substrate itself. Is the distinct Florida-Bahamas faunal province due in part to the calcareous sediment? The purpose of this study is to compare foraminiferal densities in quartz versus calcareous sand to find out if the mineralogy of the sand has an effect on benthic foraminiferal densities. Genera from porcelaneous, hyaline, and arenaceous foraminifera are used for the evaluation. They are Quinqueloculina (porcelaneous), Ammonia (hyaline), Elphidium (hyaline) and Ammobaculites (arenaceous). The genus Quinqueloculina is represented by the species Q. impressa and Q. seminula. The genus Ammonia is represented by the species A. beccarii. The genus Elphidium is represented by the species E. gunteri and E. mexicanum. The genus Ammobaculites is represented by the species A. exiguus. METHODS Quartz sand was obtained from a mud-free sand deposit near Link Port, Florida, and mud-free calcareous sand was obtained from a beach on San Salvador Island, Bahamas. Four windows (35 cm on a side) were cut into each of two large (166 liter) PVC trash cans. The windows were cut so that sediment could be added to the can to a depth of 15 cm. About 30 liters of sand was added to each can and the cans were placed in 15 cm deep holes dug on the bottom (1 m water depth) so that the sediment in the cans was approximately level with the natural sediment, which is 98% quartz sand and 2% mud. The water temperature at Link Port varies from 12?-32?C and the salinity from 20-38%o (Nelson et al. 1982). After one month, four replicate samples of 5 ml each were taken by inserting core liners into the sediment of each can. After washing over a 63 , sieve to remove any mud which might lower the pH or act as a chelating substance, samples were stored in 95% EtOH. Rose Bengal was added the day before enumeration so that the stain would have sufficient time to penetrate the protoplasm. The cans were sampled monthly during the duration of each experiment. The experiments ranged in duration from four to seven months per year (text-figs. 1-16), and were conducted in the years 1984, 1985, 1986 and 1987. The experiments were designed for analysis by two-way ANOVA's with interaction. Differences in observed densities are tested for by the hypotheses: time, sediment type and interaction (sediment types behave differently with time). The original counts were transformed to ln(x + 1) to make the data more normal and alleviate the problem of a zero count. RESULTS The mean number of individuals per 5 ml for the four taxa are shown in table 1. Sixteen two-way ANOVA's were calculated to analyze the data. Rather than presenting the traditional 16 ANOVA tables, the results are summarized by listing the probability of the F-ratios, p(F), for each hypothesis (table 2). In 1984 samples were taken each month from March through September. The time hypothesis was significant for all taxa (table 2). Text-figures 1-4 show why this is so. All the taxa had maximum densities in the warmer months. Note the scale on the ordinate is not the same for the taxa so that the maxima achieved by Ammobaculites in August and September only amounts to a few individuals, while the maxima for Quinqueloculina amount to changes in hundreds. The hymicropaleontology, vol. 35, no. 2, pp. 135-141, 1989 135 This content downloaded from 157.55.39.92 on Tue, 21 Jun 2016 05:14:54 UTC All use subject to http://about.jstor.org/terms M. A. Buzas: Effects of quartz vs. calcareous sand on livingforaminifera
Publication Year: 1989
Publication Date: 1989-01-01
Language: en
Type: article
Indexed In: ['crossref']
Access and Citation
Cited By Count: 6
AI Researcher Chatbot
Get quick answers to your questions about the article from our AI researcher chatbot