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Linking a Latitudinal Gradient in Ocean Hydrography and Elemental Stoichiometry in the Eastern Pacific Ocean
Author(s) -
Lee Jenna A.,
Garcia Catherine A.,
Larkin Alyse A.,
Carter Brendan R.,
Martiny Adam C.
Publication year - 2021
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2020gb006622
Subject(s) - ocean gyre , redfield ratio , hydrography , oceanography , environmental science , plankton , nutrient , mesopelagic zone , deep sea , pacific ocean , remineralisation , subtropics , pelagic zone , geology , phytoplankton , chemistry , ecology , biology , inorganic chemistry , fluoride
Abstract A past global synthesis of marine particulate organic matter (POM) suggested latitudinal variation in the ratio of surface carbon (C): nitrogen (N): phosphorus (P). However, this synthesis relied on compiled datasets that may have biased the observed pattern. To demonstrate latitudinal shifts in surface C:N:P, we combined hydrographic and POM observations from 28°N to 69°S in the eastern Pacific Ocean (GO‐SHIP line P18). Both POM concentrations and ratios displayed distinct biome‐associated changes. Surface POM concentrations were relatively low in the North Pacific subtropical gyre, increased through the Equatorial Pacific, were lowest in the South Pacific subtropical gyre, and increased through the Southern Ocean. Stoichiometric elemental ratios were systematically above Redfield proportions in warmer regions. However, C:P and N:P gradually decreased across the Southern Ocean despite an abundance of macro‐nutrients. Here, a size‐fraction analysis of POM linked increases in the proportion of large plankton to declining ratios. Subsurface N* values support the hypothesis that accumulated remineralization products of low C:P and N:P exported POM helps maintain the Redfield Ratio of deep nutrients. We finally evaluated stoichiometric models against observations to assess predictive accuracy. We attributed the failure of all models to their inability to capture shifts in the specific nature of nutrient limitation. Our results point to more complex linkages between multinutrient limitation and cellular resource allocation than currently parameterized in models. These results suggest a greater importance of understanding the interaction between the type of nutrient limitation and plankton diversity for predicting the global variation in surface C:N:P.