Climate change impacts and vulnerability in Europe 2016

Climate change impacts on environmental systems
Box 4.3
Examples of observed changes in species phenology in Europe's seas
The timing of spawning of sole in the Irish Sea and parts of the Greater North Sea has shifted to earlier in the year, at a rate
of 1.5 weeks per decade since 1970, in response to increasing sea surface temperature (MCCIP, 2013).
Long-term changes in the phytoplankton communities in the northern Baltic Sea and the Gulf of Finland have occurred over
the past 30 years. This can be seen in a decline in the spring bloom but an increase in the phytoplankton biomass during
summer in this period. These changes appear to reflect both climate-induced changes and the eutrophication process.
A change in the annual timing of peak seasonal abundance of decapoda larvae from 1958 to 2009 in the central North Sea
has been observed. Since the 1990s, the seasonal development of decapoda larvae has occurred four to six weeks earlier
than the long-term average. This trend towards an earlier seasonal appearance of decapoda larvae during the 1990s was
correlated with sea surface temperature rise. These phenological shifts are a response at the species level, and not simply
different seasonal timings by different species (Lindley and Kirby, 2010).
copepod species has changed considerably over time
(Figure 4.5). While C. helgolandicus is becoming more
abundant in the North Sea, the overall Calanus biomass
has declined by 70 % since the 1960s (Edwards et al.,
2016). Such rapid shifts in distribution range can
reorganise marine species communities and have an
impact on human communities that depend on them.
For example, it has been shown that occurrences
of European sprat are positively correlated with C.
finmarchicus, while species such as Atlantic horse
mackerel are positively correlated with C. helgolandicus
(Montero-Serra et al., 2015).
Figure 4.5
2010
2005
2000
Ratio of Calanus species in the Greater
North Sea
Calanus helgolandicus/Calanus finmarchicus ratio
0.9
0.8
0.7
0.6
0.5
Benthic invertebrates are also shifting their
distribution range as temperatures change in the
Greater North Sea, but their response lags behind
the temperature increase. Unless the individual
species are able to withstand a change in thermal
regime, this mismatch could lead to a drop in benthic
diversity (Hiddink et al., 2015). Such reorganisation
will have an impact upon human communities and
challenge traditional approaches to management of,
for example fisheries, which have to consider species
responses to temperature when planning future fishing
opportunities (Rutterford et al., 2015).
1995
1990
1985
1980
1975
1970
0.4
0.3
0.2
0.1
Very fast rates of northwards movement were
observed in the coastal waters of southern Norway
from 1997 and 2010. About 1 600 benthic marine
species were found, and of these 565 species had
expanded their distribution northwards along the
coast, at rates of 500–800 km per decade (Brattegard,
2011). Phytoplankton and highly mobile pelagic species
are the fastest migrating organisms; their migration
rate can be an order of magnitude faster than those of
terrestrial species (Poloczanska et al., 2013).
Note:
Source:
1965
1960
2 4 6 8 10
Month
Temporal and seasonal distribution of the ratio of Calanus
species from 1958 to 2014.
Edwards et al., 2016. © 2016 Sir Alister Hardy Foundation
for Ocean Science (SAHFOS). Reproduced with permission.
116 Climate change, impacts and vulnerability in Europe 2016 | An indicator-based report