Adaptations of the surfgrass phyllospadix to hard marine substrates: tests of anatomical differentiation and carbon isotope fractionation hypotheses

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Show simple item record Cooper, Lee W. 2015-02-19T00:36:15Z 2015-02-19T00:36:15Z 1987-05
dc.description Thesis (Ph.D.) University of Alaska Fairbanks, 1987 en_US
dc.description.abstract The study examined adaptation in the seagrass genus Phyllospadix to rocky substrates, habitats not generally exploited by seagrasses. One hypothesis tested whether the genus exhibits anatomical features distinguishing it from other seagrasses. A corollary predicted that individual Phyllospadix species show additional specialization, based on observations that three species are distinctly zoned where they occur together. A second hypothesis tested a model of carbon assimilation that predicts that submerged aquatic plants growing on hard substrates, such as Phyllospadix species and most marine algae, experience less transport resistances to inorganic carbon uptake than rooted and rhizoidal plants. As a consequence, it was predicted that Phyllospadix species would show enzymatic discrimination against carbon-13 similar to marine algae and dissimilar to other seagrasses. Carbon isotopic variability in Phyllospadix serrulatus and Phyllospadix torreyi was compared with that of the algae Egregia menziesii and Halosaccion amerlcanum growing at the same location. Carbon isotopic variability in eelgrass. Zostera marina, was also examined to provide a basis of comparison to sediment rooted seagrasses. Comparison with Z. marina was useful in defining anatomical features in Phyllospadix that are adaptations to rocky littoral environments. These features include greater hypodermal fiber and roothair development, thickened rhizomes, and smaller lacunae. Comparison among Phyllospadix spp. for microhabitat adaptations was less fruitful. Phyllospadix spp. show carbon isotopic discriminatory patterns distinct from Z. marina and marine algae. Although marine algae and Phyllospadix spp. overlapped isotopically, only the seagrasses became isotopically lighter with increasing intertidal height, probably through atmospheric carbon dioxide incorporation. Carbon isotope ratios in submerged seagrasses did not appear to be affected by water motion, as predicted by boundary layer considerations. An observed correlation between leaf thickness and leaf isotopic ratios also indicated complications to simple models of carbon assimilation in submerged aquatic plants. en_US
dc.language.iso en_US en_US
dc.title Adaptations of the surfgrass phyllospadix to hard marine substrates: tests of anatomical differentiation and carbon isotope fractionation hypotheses en_US
dc.type Thesis en_US phd en_US
dc.identifier.department Oceanography
dc.contributor.chair Chapin, F. Stuart
dc.contributor.chair McRoy, C. Peter
dc.contributor.committee Cooney, Robert T.
dc.contributor.committee Kipphut, George W.

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