Chlorophyll-a transformations associated with sinking diatoms during termination of a north atlantic spring bloom

Nicole J. Bale; Ruth L. Airs; Patrick Martin; Richard S. Lampitt; Carole A. Llewellyn

doi:10.1016/j.marchem.2015.03.005

Chlorophyll-a transformations associated with sinking diatoms during termination of a north atlantic spring bloom

Nicole J. Bale^*, Ruth L. Airs, Patrick Martin, Richard S. Lampitt, Carole A. Llewellyn

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

8 Citations (Scopus)

Abstract

A research cruise in the North Atlantic during the annual diatom bloom provided an ideal platform to study chlorophyll-a (chl-a) transformations associated with a large scale diatom bloom and export below the photic zone. On one deployment, Lagrangian sediment traps captured a significant flux of aggregated diatom cells produced during the termination of the main bloom. We examined the distribution of chl-a transformation products in sinking particles from the sediment traps and in suspended particles from the water column using high-resolution HPLC with multistage mass spectrometry (LC-MSⁿ). There was a dramatic change in the distribution of chl-a and its transformation products between the pre-sinking period, when the average chl-a concentration integrated over the upper 50m was 68±36mgm^-2, and the post-sinking period, when it was 30±11mgm^-2. Before the diatom bloom left the euphotic zone (pre-sinking), suspended particles contained a considerably higher percentage of pheophorbide-a and other chl-a transformation products (27%) than during the post-sinking period (10%). Despite high levels of spatial variability in the chl-a concentration, and despite sampling from both within and outside a main bloom patch, the chl-a transformation products in suspended particles did not exhibit spatial variability. Sinking particles associated with the diatom bloom export had low POC:chl-a ratios (52-97), suggesting undegraded phytoplankton cells. However, the samples with especially low POC:chl-a ratios exhibited similar distributions of chl-a transformation products to those with a higher ratio. The proportions of demetalated and de-esterified transformation products increased with depth of suspended particles, although significant levels of these products were also found in the uppermost 20m during the bloom. This suggests processes in both surface waters and through the water column led to the formation of these products.

Original language	English
Pages (from-to)	23-33
Number of pages	11
Journal	Marine Chemistry
Volume	172
DOIs	https://doi.org/10.1016/j.marchem.2015.03.005
Publication status	Published - May 1 2015
Externally published	Yes

Bibliographical note

Publisher Copyright:
© 2015 Elsevier B.V.

ASJC Scopus Subject Areas

Oceanography
General Chemistry
Environmental Chemistry
Water Science and Technology

Keywords

Bloom termination
Chlorophyll-a transformation products
Diatom bloom
North atlantic
Sinking particles
Suspended particles

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10.1016/j.marchem.2015.03.005

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title = "Chlorophyll-a transformations associated with sinking diatoms during termination of a north atlantic spring bloom",

abstract = "A research cruise in the North Atlantic during the annual diatom bloom provided an ideal platform to study chlorophyll-a (chl-a) transformations associated with a large scale diatom bloom and export below the photic zone. On one deployment, Lagrangian sediment traps captured a significant flux of aggregated diatom cells produced during the termination of the main bloom. We examined the distribution of chl-a transformation products in sinking particles from the sediment traps and in suspended particles from the water column using high-resolution HPLC with multistage mass spectrometry (LC-MSn). There was a dramatic change in the distribution of chl-a and its transformation products between the pre-sinking period, when the average chl-a concentration integrated over the upper 50m was 68±36mgm-2, and the post-sinking period, when it was 30±11mgm-2. Before the diatom bloom left the euphotic zone (pre-sinking), suspended particles contained a considerably higher percentage of pheophorbide-a and other chl-a transformation products (27%) than during the post-sinking period (10%). Despite high levels of spatial variability in the chl-a concentration, and despite sampling from both within and outside a main bloom patch, the chl-a transformation products in suspended particles did not exhibit spatial variability. Sinking particles associated with the diatom bloom export had low POC:chl-a ratios (52-97), suggesting undegraded phytoplankton cells. However, the samples with especially low POC:chl-a ratios exhibited similar distributions of chl-a transformation products to those with a higher ratio. The proportions of demetalated and de-esterified transformation products increased with depth of suspended particles, although significant levels of these products were also found in the uppermost 20m during the bloom. This suggests processes in both surface waters and through the water column led to the formation of these products.",

keywords = "Bloom termination, Chlorophyll-a transformation products, Diatom bloom, North atlantic, Sinking particles, Suspended particles",

author = "Bale, {Nicole J.} and Airs, {Ruth L.} and Patrick Martin and Lampitt, {Richard S.} and Llewellyn, {Carole A.}",

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T1 - Chlorophyll-a transformations associated with sinking diatoms during termination of a north atlantic spring bloom

AU - Bale, Nicole J.

AU - Airs, Ruth L.

AU - Martin, Patrick

AU - Lampitt, Richard S.

AU - Llewellyn, Carole A.

PY - 2015/5/1

Y1 - 2015/5/1

N2 - A research cruise in the North Atlantic during the annual diatom bloom provided an ideal platform to study chlorophyll-a (chl-a) transformations associated with a large scale diatom bloom and export below the photic zone. On one deployment, Lagrangian sediment traps captured a significant flux of aggregated diatom cells produced during the termination of the main bloom. We examined the distribution of chl-a transformation products in sinking particles from the sediment traps and in suspended particles from the water column using high-resolution HPLC with multistage mass spectrometry (LC-MSn). There was a dramatic change in the distribution of chl-a and its transformation products between the pre-sinking period, when the average chl-a concentration integrated over the upper 50m was 68±36mgm-2, and the post-sinking period, when it was 30±11mgm-2. Before the diatom bloom left the euphotic zone (pre-sinking), suspended particles contained a considerably higher percentage of pheophorbide-a and other chl-a transformation products (27%) than during the post-sinking period (10%). Despite high levels of spatial variability in the chl-a concentration, and despite sampling from both within and outside a main bloom patch, the chl-a transformation products in suspended particles did not exhibit spatial variability. Sinking particles associated with the diatom bloom export had low POC:chl-a ratios (52-97), suggesting undegraded phytoplankton cells. However, the samples with especially low POC:chl-a ratios exhibited similar distributions of chl-a transformation products to those with a higher ratio. The proportions of demetalated and de-esterified transformation products increased with depth of suspended particles, although significant levels of these products were also found in the uppermost 20m during the bloom. This suggests processes in both surface waters and through the water column led to the formation of these products.

AB - A research cruise in the North Atlantic during the annual diatom bloom provided an ideal platform to study chlorophyll-a (chl-a) transformations associated with a large scale diatom bloom and export below the photic zone. On one deployment, Lagrangian sediment traps captured a significant flux of aggregated diatom cells produced during the termination of the main bloom. We examined the distribution of chl-a transformation products in sinking particles from the sediment traps and in suspended particles from the water column using high-resolution HPLC with multistage mass spectrometry (LC-MSn). There was a dramatic change in the distribution of chl-a and its transformation products between the pre-sinking period, when the average chl-a concentration integrated over the upper 50m was 68±36mgm-2, and the post-sinking period, when it was 30±11mgm-2. Before the diatom bloom left the euphotic zone (pre-sinking), suspended particles contained a considerably higher percentage of pheophorbide-a and other chl-a transformation products (27%) than during the post-sinking period (10%). Despite high levels of spatial variability in the chl-a concentration, and despite sampling from both within and outside a main bloom patch, the chl-a transformation products in suspended particles did not exhibit spatial variability. Sinking particles associated with the diatom bloom export had low POC:chl-a ratios (52-97), suggesting undegraded phytoplankton cells. However, the samples with especially low POC:chl-a ratios exhibited similar distributions of chl-a transformation products to those with a higher ratio. The proportions of demetalated and de-esterified transformation products increased with depth of suspended particles, although significant levels of these products were also found in the uppermost 20m during the bloom. This suggests processes in both surface waters and through the water column led to the formation of these products.

KW - Bloom termination

KW - Chlorophyll-a transformation products

KW - Diatom bloom

KW - North atlantic

KW - Sinking particles

KW - Suspended particles

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JO - Marine Chemistry

JF - Marine Chemistry

ER -

Chlorophyll-a transformations associated with sinking diatoms during termination of a north atlantic spring bloom

Abstract

Bibliographical note

ASJC Scopus Subject Areas

Keywords

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