麻豆传媒

This thesis considers two separate problems: 1) taphonomic alterations in marsh foraminifera and 2) foraminiferal responses to a variety of industrial and domestic activities. The field areas were centered in two locations; Chezzetcook Inlet, Nova Scotia, and New Bedford Harbor, Massachusetts.

Marsh foraminiferal distributions from cores collected seasonally for a year at 4 sites along Chezzetcook Inlet, Nova Scotia suggest that living foraminifera do not migrate vertically within the core and that infaunal species do not affect the total population downcore. Also, there appears to be little to no taphonomic alteration of marsh foraminifera within these cores. The total species composition at the surface was very similar to that in the subsurface. There seemed to be little evidence that infaunal habitat or taphonomic biasing affected the total assemblage downcore in replotted data from Nanaimo, British Columbia; it appears that there are environmental changes and is amplified by coincident lithology changes. Assemblage changes throughout the core appear to be the result of changes in environmental conditions at the time of deposition. Consequently, the top 1 em of these cores is a representative aliquot and accurately reflects environmental conditions occurring at the time of deposition.

New Bedford Harbor has been affected by intense industrial activities over the last 50 to 60 years. This has led to heavy metal, PAH, PCB, and organic enrichment contamination of sediments. Foraminiferal distributions in surficial samples showed recovery in the lower part of the harbor as well as in some parts of the Upper Harbor where contamination of sediments was at its worst. The return of calcareous species such as Haynesina orbiculare and Elphidium spp. suggests recovery of the environment. Deformities of tests in foraminifera occurred in cores where PCB concentrations were highest suggesting that foraminifera are responding to increased levels of contamination. As concentrations of pollutants decreased toward the top of the core, deformities decreased to almost zero. The various foraminiferal responses reinforce the fact that foraminiferal assemblages are useful in detecting pollution changes through time and they can be applied to just about any marginal marine setting which makes them an excellent cost-effective tool as biomonitors for industrial and municipal pollution. XV

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Pages: 329
Supervisor: David Scott