Abundance of a chlorophyll a precursor and the oxidation product hydroxychlorophyll a during seasonal phytoplankton community progression in the Western English Channel. (September 2015)

• Record Type: Journal Article
• Authors: Steele, Deborah J.; Tarran, Glen A.; Widdicombe, Claire E.; Woodward, E. Malcolm S.; Kimmance, Susan A.; Franklin, Daniel J.; Airs, Ruth L.
• Is Part Of: Progress in oceanography. Volume 137:Part B(2015:Sep.)
• Page Start: 434
• Page End: 445
• Publication Date: 2015-09
• Subjects: PAR photosynthetically active radiation -- WCO Western Channel Observatory -- chl-a chlorophyll a -- HO-chl-a 132-hydroxychlorophyll a -- chl-aP276 chlorophyll aP276 -- HPLC high performance liquid chromatography; Oceanography -- Periodicals; 551.4605
• DOI: 10.1016/j.pocean.2015.04.021
• Languages: English
• ISSNs: 0079-6611

Abstract

Highlights: First measurement of hydroxychlorophyll a and chl- a P276 over an annual cycle. Hydroxychlorophyll a was produced primarily during bloom decline. Pelagic particulate hydroxychlorophyll a correlated with Phaeocystis spp. abundance. The ratio of the precursor chl- a P276 to chl- a increased during high chl- a concentration. Abstract: This study presents the first in-situ measurements of the chlorophyll a oxidation product, hydroxychlorophyll a as well as the chlorophyll a precursor, chlorophyll a P276 conducted over an annual cycle. Chlorophyll a oxidation products, such as hydroxychlorophyll a may be associated with the decline of algal populations and can act as an initial step in the degradation of chlorophyll a into products which can be found in the geochemical record, important for studying past climate change events. Here, hydroxychlorophyll a and chlorophyll a P276 were measured at the long-term monitoring station L4, Western Channel Observatory (UK, www.westernchannelobservatory.org ) over an annual cycle (2012). Weekly measurements of phytoplankton species composition and abundance enabled detailed analysis of possible sources of hydroxychlorophyll a . Dinoflagellates, 2 diatom species, the prymnesiophyte Phaeocystis spp. and the coccolithophorid Emiliania huxleyi were all associated with hydroxychlorophyll a occurrence. However, during alternate peaks in abundance of the diatoms, no association with hydroxychlorophyll a occurred, indicating that the oxidation of chlorophyll a was dependant not only on species but also on additional factors such as the mode of mortality, growth limiting factor (i.e. nutrient concentration) or phenotypic plasticity. Surface sediment samples contained 10 times more hydroxychlorophyll a (relative to chlorophyll a ) than pelagic particulate samples, indicating that more chlorophyll a oxidation occurred during sedimentation or at the sediment–water interface, than in the pelagic environment. In addition, chlorophyll a P276 correlated with chl- a concentration, thus supporting its assignment as a chl- a precursor.