Biology Reference
In-Depth Information
2
C depending on location and duration of time series within the last decades
(e.g., California: Sagarin et al.
1999
, Portugal: Lima et al.
2007
, North Sea:
Wiltshire et al.
2008
, Baltic: Andersen et al.
2011
, Australia: Poloczanska et al.
2011
). Current warming is larger over landmasses than over the open ocean and is
larger in higher latitudes than in the tropical region. In the Equatorial Tropical
Atlantic and the Western Equatorial Pacific (WEP), the SST increase between 2001
and 2005 relative to 1870-1900 was 0.5-1
C, while the Eastern Equatorial Pacific
(EEP) did not show any temperature increase (Hansen et al.
2006
). Whether the
increased temperature difference between the near-equatorial WEP and EEP may
be responsible for dampening or enhancing the frequency of El Ni˜o-Southern
Oscillation (ENSO) activity is still in debate (e.g., Hansen et al.
2006
; Collins et al.
2010
). The two most pronounced ENSO events in the last 100 years took place in
1983 and 1998 accompanied by an unprecedented warming in the EEP (Hansen
et al.
2006
).
Within the last two decades, there have been many attempts to develop
predictive modeling approaches to project present-day biogeographical distribu-
tion patterns into the future. Principally, two different directions have been
followed: (1) the “bioclimate envelope” models correlate species distributions
with climate variables including the knowledge about the physiological responses
of species to climate change (Pearson and Dawson
2003
and references therein).
A special form of these models is niche modeling which correlates the
macroecological preferences of a species at sample locations (e.g., demands for
temperature, substrate, light, etc.) with their distributional records. Niche models
predict potentially suitable habitats and the fundamental biogeographical niche
(Guisan and Thuiller
2005
;Grahametal.
2007
;Verbruggenetal.
2009
). (2) On
the other hand, marine ecologists stressed the importance to also consider the
variety of biotic interactions between species which are mostly responsible for
shaping the realized niche. A recent review extensively summarizes possible
consequences of both the abiotic and biotic environment and their interactions
in coastal marine environments with respect to climate change (Harley et al.
2006
). Although biotic interactions locally shape communities, they do not
explain global biogeographical patterns (Santelices et al.
2009
). Recently, Muller
et al. (
2009
,
2011
) presented a new bioclimate envelope model comparing
observed winter and summer SSTs of 1980-1999 to model SSTs of 2080-2099
based on a moderate greenhouse gas emission scenario in order to predict future
distributional range shifts of selected polar and cold-temperate seaweed species of
both hemispheres. Here, we use the same approach providing a macroecological
view on seaweed distribution based on a worldwide model of present and future
oceanic isotherms, carving out the resulting changes in spatial extent of major
biogeographical coastal regions (after Briggs
1995
) due to temperature change
and discussing expected changes of seaweed floras on a worldwide scale for the
end of the century.
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