This discussion topic submitted by Margot Doremus (email@example.com) at 1:22 am on 8/2/99. Additions were last made on Wednesday, May 7, 2014.
I studied foraminifera. My objectives were as follows: 1. Recognize dominant species
2. Evaluate relationship between grain size and dominant species
3. Determine species richness
4. Examine species richness in terms of grain size
Some species I identified were: Archaias Angulatus, Archaias compressus, Amphistegina lessonii, Broeckina orbitolitoides, Clavulina tricarinata, Cruciloculina triangularis, Massilina protea, Nonion depressulum, Orbulina universa, Peneroplis bradyi, Peneroplis proteus, Pyrgo comata, Quinqueloculina horrida, Quinqueloculina sp, Quinqueloculina tenagos, Quinqueloculina tricarinata, Schlumbergina alveoliniformis, Sorites marginalis, Triloculina bassensis, Triloculina carinata, Triloculia fitteri, and Triloculina linneiana. The species Amphistegina lessonii can be found in seagrass, coral reef, or sediment, in temperatures of 25-26°C and greater than 39 parts per thousand salinity. The species Sorites marginalis can be found in Thalassia, from 18-26°C and greater than 37 parts per thousand salinity. So, this is evidence that could support the claim that the core was taken from an area of seagrass. Of course, one also has to realize that forams can easily be moved. I will reference this point later.
In the core, the species richness of the foraminifera piqued at sample number 1 and sample number 10, or near the surface and at about 191 cm down. This corresponded to apexes in the median grain size.
Of the grain sizes, most of the foraminifera were found in the .5mm to 1mm grain size. And, of the 4293 individuals counted, an overwhelming majority were Archaias angulatus. It would be interesting to conduct further study in different places to see if Archaias is dominant in many places.
Conclusions: 1. Molluscan community similarity and foraminiferan species richness coincide.
2. Molluscan species richness was greatest where the mean grain size was smallest, and the comparison of foraminiferan species richness to mean grain size had mixed results.
3. Over the last 6,000 years, seagrass has probably dominated this ecosystem
4.The Molluscan and Foraminiferal ecological records tell different stories.
The places on the Spearman rank correlation by sample of the molluscan death assemblage where the molluscan community was the most stable and least changing corresponded to the places in the foraminiferan record where species richness was the greatest. The species richness curves for both molluscs and forams followed a similar pattern, especially at samples 4, 5, and 6, which corresponded to a low point in median grain size. This could mean that the current was moving things around less at these points.
In terms of community reconstruction, the molluscan record and the sedimentology proved much more valuable and conclusive than the foraminiferal record. This could be because the foraminiferans are smaller and therefore more subject to movement.
Given the evidence of foraminiferans observed that thrive in seagrass, this area of the core sample could have been a place of dense seagrass.
Recommendations for further study: 1.Why, when the mollusk community is unchanging, is the foraminiferan species richness at its greatest?
2. Why does molluscan species richness correlate to mean grain size?
3. What processes are causing a dominance of right valves over left valves?
4. What causes change in species richness in the communities?
5. Is it possible to determine whether forams lived and died in the community or were moved there by taphonomic processes?
Albani, Alberto D. Recent Shallow Water Foraminifera From New South Wales. Austrailian Marine Sciences Association; Oct. 1979.
Bagg, Rufus Matthew Jr. Foraminifera Collected Near the Hawaiian Islands By the Steamer Albatross in 1902. Washington; Washington government Printing Office, 1908.
Boltovsky, Esteban and Ramil Wright. Recent Foraminifera. Dr W Junk b.v. Publishers, the Haugue, 1976.nbm
Cushman, Joseph A. Foraminifera: Their Classification and Economic Use. Harvard University Press; Boston, 1940.
Galloway, J. J. Manual of Foraminifera.Principia Press, W. M. Mitchell Printing Co; Greenfield, IN, 1933.
Murray, John W. Distribution and Ecology of Living Benthic Foraminiferids. Heinamann Educational Books Limited; London, Great Britain, 1973.
Poag, C. Wylie. Ecologic Atlas of Benthic Foraminifera of the Gulf of Mexico. Hutchinson Ross Publishing Company, 1981.
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