Environmental controls on the biogeography of diazotrophy and <i>Trichodesmium</i> in the Atlantic Ocean

Snow, JT, Schlosser, C, Woodward, EMS, Mills, MM, Achterberg, EP, Mahaffey, C ORCID: 0000-0002-4215-7271, Bibby, TS and Moore, CM (2015) Environmental controls on the biogeography of diazotrophy and <i>Trichodesmium</i> in the Atlantic Ocean. GLOBAL BIOGEOCHEMICAL CYCLES, 29 (6). pp. 865-884.

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Abstract

<jats:title>Abstract</jats:title><jats:p>The cyanobacterium <jats:italic>Trichodesmium</jats:italic> is responsible for a significant proportion of the annual “new” nitrogen introduced into the global ocean. Despite being arguably the best studied marine diazotroph, the factors controlling the distribution and growth of <jats:italic>Trichodesmium</jats:italic> remain a subject of debate, with sea surface temperature, the partial pressure of CO<jats:sub>2</jats:sub>, and nutrients including iron (Fe) and phosphorus (P), all suggested to be important. Synthesizing data from seven cruises collectively spanning large temporal and spatial scales across the Atlantic Ocean, including two previously unreported studies crossing the largely undersampled South Atlantic gyre, we assessed the relationship between proposed environmental drivers and both community N<jats:sub>2</jats:sub> fixation rates and the distribution of <jats:italic>Trichodesmium</jats:italic>. Simple linear regression analysis would suggest no relationship between any of the sampled environmental variables and N<jats:sub>2</jats:sub> fixation rates. However, considering the concentrations of iron and phosphorus together within a simplified resource‐ratio framework, illustrated using an idealized numerical model, indicates the combined effects these nutrients have on <jats:italic>Trichodesmium</jats:italic> and broader diazotroph biogeography, alongside the reciprocal maintenance of different biogeographic provinces of the (sub)tropical Atlantic in states of Fe or P oligotrophy by diazotrophy. The qualitative principles of the resource‐ratio framework are argued to be consistent with both the previously described North‐South Atlantic contrast in <jats:italic>Trichodesmium</jats:italic> abundance and the presence and consequence of a substantial non‐<jats:italic>Trichodesmium</jats:italic> diazotrophic community in the western South Atlantic subtropical gyre. A comprehensive, observation‐based explanation of the interactions between <jats:italic>Trichodesmium</jats:italic> and the wider diazotrophic community with iron and phosphorus in the Atlantic Ocean is thus revealed.</jats:p>

Item Type:	Article
Uncontrolled Keywords:	nitrogen fixation, trichodesmium, resource ratio, nutrient stress, iron, phosphorus
Subjects:	?? Q1 ??
Depositing User:	Symplectic Admin
Date Deposited:	22 Jul 2015 10:14
Last Modified:	31 Oct 2023 00:26
DOI:	10.1002/2015GB005090
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/2017163