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A winter dinoflagellate bloom drives high rates of primary production in a Patagonian fjord ecosystem

A winter dinoflagellate bloom drives high rates of primary production in a Patagonian fjord ecosystem
A winter dinoflagellate bloom drives high rates of primary production in a Patagonian fjord ecosystem
A dense winter bloom of the dinoflagellate Heterocapsa triquetra was observed at a fixed station (44°35.3′S; 72°43.6′W) in the Puyuhuapi Fjord in Chilean Patagonia during July 2015. H. triquetra dominated the phytoplankton community in the surface waters between 2 and 15 m (13–58 × 109 cell m−2), with abundances some 3 to 15 times higher than the total abundance of the diatom assemblage, which was dominated by Skeletonema spp. The high abundance of dinoflagellates was reflected in high rates of gross primary production (GPP; 0.6–1.6 g C m−2 d−1) and chlorophyll-a concentration (Chl-a; 70–199.2 mg m−2) that are comparable to levels reported in spring diatom blooms in similar Patagonian fjords. We identify the main forcing factors behind a pulse of organic matter production during the non-productive winter season, and test the hypothesis that low irradiance levels are a key factor limiting phytoplankton blooms and subsequent productivity during winter.Principal Component Analysis (PCA) indicated that GPP rates were significantly correlated (r = −0.8, p < 0.05) with a decrease in salinity/temperature and the presence of the Heterocapsa bloom. The bloom occurred under low surface irradiance levels characteristic of austral winter and was accompanied by strong northern winds, associated with the passage of a low-pressure system, and a water column dominated by double diffusive layering. To our knowledge, this is the first report of a dense dinoflagellate bloom during deep austral winter in a Patagonian fjord, and our data challenge the paradigm of light limitation as a factor controlling phytoplankton blooms in this region in winter
Primary production; , Mixing, Winter dinoflagellate blooms, Patagonian fjord
105-116
Montero, P.
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Pérez-Santos, I.
388b7bdf-a5ff-451f-a842-3d4aac01f8c9
Daneri, G.
bf7cd327-bc8b-4193-9d6a-c28a8e41b6de
Gutierrez, M.H.
31473a4a-4914-4ab2-a7e4-6253b85373f6
Igor, G.
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Seguel, R.
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Purdie, D.
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Crawford, D.W.
1625e56b-d0c8-4c45-b519-094d0e928a63
Montero, P.
7b9195b3-b778-43f2-9377-515c9bb34f73
Pérez-Santos, I.
388b7bdf-a5ff-451f-a842-3d4aac01f8c9
Daneri, G.
bf7cd327-bc8b-4193-9d6a-c28a8e41b6de
Gutierrez, M.H.
31473a4a-4914-4ab2-a7e4-6253b85373f6
Igor, G.
0c40f2e6-eecc-431e-8996-bc835b7932b8
Seguel, R.
1ba5009c-5271-4475-bcf6-18b193eccdf1
Purdie, D.
18820b32-185a-467a-8019-01f245191cd8
Crawford, D.W.
1625e56b-d0c8-4c45-b519-094d0e928a63

Montero, P., Pérez-Santos, I., Daneri, G., Gutierrez, M.H., Igor, G., Seguel, R., Purdie, D. and Crawford, D.W. (2017) A winter dinoflagellate bloom drives high rates of primary production in a Patagonian fjord ecosystem. Estuarine, Coastal and Shelf Science, 199, 105-116. (doi:10.1016/j.ecss.2017.09.027).

Record type: Article

Abstract

A dense winter bloom of the dinoflagellate Heterocapsa triquetra was observed at a fixed station (44°35.3′S; 72°43.6′W) in the Puyuhuapi Fjord in Chilean Patagonia during July 2015. H. triquetra dominated the phytoplankton community in the surface waters between 2 and 15 m (13–58 × 109 cell m−2), with abundances some 3 to 15 times higher than the total abundance of the diatom assemblage, which was dominated by Skeletonema spp. The high abundance of dinoflagellates was reflected in high rates of gross primary production (GPP; 0.6–1.6 g C m−2 d−1) and chlorophyll-a concentration (Chl-a; 70–199.2 mg m−2) that are comparable to levels reported in spring diatom blooms in similar Patagonian fjords. We identify the main forcing factors behind a pulse of organic matter production during the non-productive winter season, and test the hypothesis that low irradiance levels are a key factor limiting phytoplankton blooms and subsequent productivity during winter.Principal Component Analysis (PCA) indicated that GPP rates were significantly correlated (r = −0.8, p < 0.05) with a decrease in salinity/temperature and the presence of the Heterocapsa bloom. The bloom occurred under low surface irradiance levels characteristic of austral winter and was accompanied by strong northern winds, associated with the passage of a low-pressure system, and a water column dominated by double diffusive layering. To our knowledge, this is the first report of a dense dinoflagellate bloom during deep austral winter in a Patagonian fjord, and our data challenge the paradigm of light limitation as a factor controlling phytoplankton blooms in this region in winter

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1-s2.0-S0272771416308058-main - Accepted Manuscript
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Accepted/In Press date: 28 September 2017
e-pub ahead of print date: 28 September 2017
Published date: 5 December 2017
Keywords: Primary production; , Mixing, Winter dinoflagellate blooms, Patagonian fjord

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Local EPrints ID: 414475
URI: https://eprints.soton.ac.uk/id/eprint/414475
PURE UUID: 82cd51d2-a467-4b43-a546-a325be68e8ec

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Date deposited: 02 Oct 2017 16:30
Last modified: 10 Dec 2019 05:47

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