Format

Send to:

Choose Destination
See comment in PubMed Commons below
Aquat Toxicol. 2003 Jul 16;64(2):201-13.

Physiological responses of Gracilariopsis longissima (S.G. Gmelin) Steentoft, L.M. Irvine and Farnham (Rhodophyceae) to sub-lethal copper concentrations.

Author information

  • 1School of Biological Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK. mtbrown@plymouth.ac.uk

Abstract

Through a series of comparative experiments the relative effects of copper (Cu) exposure on the growth and physiology (chlorophyll fluorescence, ion leakage, O(2) evolution and pigmentation) of the red seaweed Gracilariopsis longissima was investigated. Of the various physiological end-points measured, growth proved to be the most sensitive with reductions in relative growth rate (RGR) observed at a concentration of 12.5 microg l(-1) Cu, with zero growth above about 300 microg l(-1). A significant increase in ion leakage and reduction in phycobiliprotein concentrations were evident, but only at the highest concentration tested (500 microg l(-1)), at which point shrinkage of apical tips also occurred. Photosynthetic rates, as measured by chlorophyll fluorescence and oxygen evolution, were first impaired at 250 microg l(-1), with a 30% reduction in photosynthetic efficiency (F(v)/F(m)) and a 60% reduction in oxygen evolution. There were no discernible effects on respiration rates or chlorophyll a and beta-carotene content over this concentration range. It was hypothesised that the observed uncoupling of growth and photosynthesis at low Cu concentrations might be explained by the release of dissolved organic matter (DOC), resulting in less available energy for growth. No such increase in DOC was apparent. Alternative explanations to account for the uncoupling, including the diversion of energy for maintenance of cell integrity and induction of protective mechanisms, are discussed.

PMID:
12799112
[PubMed - indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Elsevier Science
    Loading ...
    Write to the Help Desk