[OANNES Foro] Defining isoscapes as an index of ocean productivity

[Mario Cabrejos]

Global Ecology and Biogeography

First published: 12 November 2019

 <https://doi.org/10.1111/geb.13022> https://doi.org/10.1111/geb.13022

Defining isoscapes in the Northeast Pacific as an index of ocean
productivity


<https://onlinelibrary.wiley.com/action/doSearch?ContribAuthorStored=Espinas
se%2C+Boris> Boris Espinasse
<https://onlinelibrary.wiley.com/action/doSearch?ContribAuthorStored=Hunt%2C
+Brian+P+V> Brian P. V. Hunt
<https://onlinelibrary.wiley.com/action/doSearch?ContribAuthorStored=Batten%
2C+Sonia+D> Sonia D. Batten
<https://onlinelibrary.wiley.com/action/doSearch?ContribAuthorStored=Pakhomo
v%2C+Evgeny+A> Evgeny A. Pakhomov

Abstract

Aim

We modelled isoscapes in the Northeast (NE) Pacific using satellite‐based
data, with the main objective of testing whether isoscapes defined by a few
key parameters can be used as a proxy for secondary productivity.

Location

Northeast Pacific; 46-60° N and 125-165° W.

Time period

>From 1998 to 2017 (ongoing).

Major taxa studied

Zooplankton, with a focus on large herbivores.

Methods

Approximately 280 summer zooplankton samples were analysed for carbon (δ
13C) and nitrogen (δ15N) stable isotope (SI) ratios. Environmental
conditions experienced by zooplankton organisms were extracted from
satellite, in situ sensor and model databases. A generalized additive model
approach was used to explain the spatial variability of δ13C and δ15N
values and to predict isoscapes.

Results

Sea surface temperature (SST), sea level anomaly (SLA) and chlorophyll‐a
concentration emerged as the significant SI predictors. Modelled isoscapes
reproduced patterns observed in δ13C and δ15N value distribution, such as
a decrease from the coast to offshore. The contribution of eddies in
enhancing local production in the open ocean was also well captured by the
models. In the central part of the NE Pacific, higher SI values were
correlated with higher large copepod biomass measured by the North Pacific
Continuous Plankton Recorder (CPR) survey. However, in the area off the
coast of British Columbia, high δ15N variability appeared to be associated
with episodic intrusions of coastal waters, demonstrating that caution is
needed when interpreting sharp changes in SI ratios.

Main conclusions

Although the mechanisms driving SI ratio variability are complex, we
demonstrate that a few parameters used as a proxy for some of these major
mechanisms are able to produce successful isoscape models. This approach was
proved useful to provide a qualitative estimate of secondary production,
which can be particularly valuable in a region where few data are available.



------------ pr?xima parte ------------
Se ha borrado un adjunto en formato HTML...
URL: <http://lista.oannes.org.pe/pipermail/oannes-oannes.org.pe/attachments/20191125/0b443642/attachment.html>