Environmental Engineering Reference
In-Depth Information
ubiquitous in temperate coastal systems and are recognized as the most
constant interannual biomass events (Smayda 1998, Winder and Cloern
2010). A classic paradigm earlier advanced by Sverdrup (1953) explains the
annual recurrence of phytoplankton spring blooms, and has been used as
a baseline pattern to evaluate changes among ecosystems.
Over the last 50 years, reports on climate-related changes in marine
ecosystems have noticeably increased (Hays et al. 2005, Harley et al. 2006,
Parmesan 2006, Yang and Rudolf 2010). Phytoplankton responses to climate
variations have been examined at different spatiotemporal scales, both in
empirical (e.g., Feng et al. 2008, Huertas et al. 2012, Rossoll et al. 2012) and
fi eld investigations (e.g., Wiltshire et al. 2008, Guinder et al. 2010, Wetz et
al. 2011), as well as using modeling approaches (e.g., Sarmiento et al. 2004,
McNeil and Matear 2006, Boyce et al. 2010). Climate modifi cations, such
as the rise in atmospheric CO
2
and warming, affect the marine biosphere
through modifi cations in pH, carbonate availability, water column stability,
nutrient and light regimes. These changes directly impact small-sized
(
ca
. < 1 to > 100 µm) phytoplankton organisms, whose short-term life cycles
make them amenable to quickly respond to subtle environmental variations.
Therefore, tracking changes in the phytoplankton community structure
can be an accurate indicator of ecosystem perturbations (Beaugrand 2005,
Hays et al. 2005, Irwin et al. 2006). Modifi cations at the bottom of the food
web are likely to permeate the trophic network due to trophic amplifi cation
and the subsequent cascading effects (Fig. 1). Understanding how climate
interacts with the marine environment from global to local scales is therefore
critical to assess consequences on marine biota at all organization levels,
from individuals (e.g., physiology, growth rate and cell size) to communities
(e.g., structure and phenology).
In this chapter we review recent advances in the understanding of the
physical and chemical nature of ocean-climate change and the implications
for phytoplankton ecology. We fi rst introduce current global ocean threats,
i.e., ocean acidifi cation and warming. We address both direct and indirect
effects of these environmental changes on phytoplankton productivity and
provide examples of proximate impacts on individuals, populations and
communities by reviewing fi eld observations at different latitudes, empirical
approaches and data modeling. We further examine broader ecological
responses that emerge from these proximal impacts: alteration in the cycle
of elements and plankton stoichiometry, changes in food webs structure
and societal repercussions. We conclude by identifying future research
foci that might help gaining a thorough understanding of phytoplankton
responses to climate change.
