Negative relationships between the nutrient and carbohydrate content of the seagrass Thalassia testudinum

Authors

Justin E. Campbell, Marine Science Program, Department of Biological Sciences and Southeast Environmental Research Center, Florida International UniversityFollow
Laura A. Yarbro, Florida Fish & Wildlife Commission, Fish & Wildlife Research Institute
James W. Fourqurean, Marine Sciences Program, Department of Biological Sciences and Southeast Environmental Research Center, Florida International University,Follow

Abstract

This study documents relationships between plant nutrient content and rhizome carbohydrate content of a widely distributed seagrass species, Thalassia testudinum, in Florida. Five distinct seagrass beds were sampled for leaf nitrogen, leaf phosphorus, and rhizome carbohydrate content from 1997 to 1999. All variables displayed marked intra- and inter- regional variation. Elemental ratios (mean N:P ± S.E.) were lowest for Charlotte Harbor (9.9 ± 0.2) and highest for Florida Bay (53.5 ± 0.9), indicating regional shifts in the nutrient content of plant material. Rhizome carbohydrate content (mean ± S.E.) was lowest for Anclote Keys (21.8 ± 1.6 mg g⁻¹ FM), and highest for Homosassa Bay (40.7 ± 1.7 mg g⁻¹ FM). Within each region, significant negative correlations between plant nutrient and rhizome carbohydrate content were detected; thus, nutrient-replete plants displayed low carbohydrate content, while nutrient-deplete plants displayed high carbohydrate content. Spearman's rank correlations between nutrient and carbohydrate content varied from a minimum in Tampa Bay (ρ = −0.2) to a maximum in Charlotte Harbor (ρ = −0.73). Linear regressions on log-transformed data revealed similar trends. This consistent trend across five distinct regions suggests that nutrient supply may play an important role in the regulation of carbon storage within seagrasses. Here we present a new hypothesis for studies which aim to explain the carbohydrate dynamics of benthic plants.

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Copyright © 2012 Elsevier.

The definitive publisher-authenticated version is available online at http://dx.doi.org/10.1016/j.aquabot.2012.02.002

This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DBI-0620409 and #DEB-9910514. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Recommended Citation

Campbell, J.E., L.A. Yarbro, J.W. Fourqurean. 2012. Negative relationships between the nutrient and carbohydrate content of the seagrass Thalassia testudinum. Aquatic Botany 99: 56-60.