Graduation Year

2004

Document Type

Thesis

Degree

M.S.

Degree Granting Department

Marine Science

Major Professor

Pamela Hallock Muller.

Keywords

Archaias, Cyclorbiculina, Amphistegina, metabolism, irradiance

Abstract

Oxygen production and consumption were measured in five species of benthic foraminifers using a "Clark-type" oxygen electrode. Net photosynthesis and respiration were calculated and normalized to both μg Chl a and mm² upper surface area for the chlorophyte-bearing soritid foraminifers, Archaias angulatus and Cyclorbiculina compressa, and the diatom-bearing amphisteginids, Amphistegina gibbosa, A. lessonii and A. radiata. Photosynthesis/Irradiance curves were generated by fitting data to the hyperbolic tangent equation P = Pmax tanh (α I/ Pmax). Derived photosynthetic parameters, Pmax, α, Ik were found to correspond to the general responses of the endosymbiont taxa. Chlorophyll concentration was found to be significantly lower in Cyclorbiculina compressa than in the other four species. Maximum O₂ production (Pmax) when normalized to Chl a was 3-4 times higher in soritid species than in amphisteginids.

Photosynthetic efficiency (α) was significantly higher in Amphistegina gibbosa and A. lessonii than in the soritids. Mean Ik, which indicates approaching light saturation, was 13 and 26 μmol photon m ⁻2sec⁻1 respectively for A. gibbosa and A. lessonii compared with 95 and 119 μmol photon m⁻2sec⁻1 respectively for Archaias and Cyclorbiculina. Calculated P/I data were to variable for Amphistegina radiata to estimate reliable α and Ik values. Factorial metabolic scope, which indicates potential for activity was only 2-6 for amphisteginids versus 9-16 for soritids. Annual primary production was estimated to be 285 mmoles O₂ m⁻2 of habitat for A. angulatus, 9.3 mmoles O₂ m⁻2 of habitat for C. compressa and 15.3 mmoles O₂ m⁻2 of habitat for Amphistegina lessonii. Pmax values for Amphistegina gibbosa fluctuated at the compensation point and did not indicate significant oxygen production.

Pmax values for Amphistegina radiata failed to reach the compensation point and net oxygen production was not recorded.

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