Environmental Engineering Reference
In-Depth Information
Spatial scale
km
μm
Air temperature
Atmospheric pressure
Solar radiation - UV
Greenhouse gases
Global
climate
Interdecadal
variability
Precipitation
Winds - storms
Temperature
Cloudiness
Regional/local
climate
Interannual
variability
Temperature, salinity, pH
Estratification/mix
Light availability/turbidity
Dissolved nutrients, oxygen
Seasonality
Water column
Behaviour
Physiology
Life cycles (phenology)
Ecological niches
Species interactions
Cell size, methabolism
Phytoplankton
Fig. 1.
Cascading climate-related changes throughout the atmosphere-sea interfaces, the pelagic
environment and phytoplankton. Hydroclimatic variability from the large-scale and long-
term to the local and short-term scales affects water properties and consequently the ecology
of microalgae which follow the biophysical rules. Modifi cations in species physiology and
behavior (e.g., ecological traits and trade-off) may restructure the phytoplankton community
composition. These changes can alter the seasonal timing of blooms and eventually can result
in shifts of interannual and/or interdecadal biomass patterns.
Climate-driven Abiotic Changes in Marine Ecosystems
Rise in atmospheric carbon dioxide and ocean acidifi cation
Atmospheric carbon dioxide levels (CO
2
) have increased from pre-
industrial levels by nearly 40%, from circa 280 ppmv to nearly 384 ppmv
in 2007 (Solomon et al. 2007). Such rate of increase is of pressing concern,
as it is at least one order of magnitude faster than the rate observed over
the past centuries. Rising atmospheric CO
2
is tempered by ocean uptake;
however the diffusion into the water causes major impact on C chemistry,
as dissolved CO
2
reacts with H
2
O molecules to form carbonic acid (H
2
CO
3
),
which dissociates into bicarbonate (HCO
3
-
), releasing a proton H
+
and
reducing pH levels. These chemical processes are collectively known as
ocean acidifi cation and cause a decrease in the concentration of carbonate
ions (CO
3
2-
), increasing the solubility of calcium carbonate (CaCO
3
) (Caldeira
and Wickett 2003, Doney et al. 2009). Ocean acidifi cation has decreased the
pH of surface waters by ~0.1 units over the last two centuries to a present
pH average of 8.1 (Orr et al. 2005), and the projected concentrations of CO
2
