Knowledge and implications of global change in the oceans for biology, ecology, and ecosystem services - Ocean Sustainability in the 21st Century - page 133

pacts on benthic communities by facilitating competitive exclusion, predation, and extinc-
tion(Agius, 2007 ).Planktonisaparticularly goodindicator ofclimate change,inparticular
on the shift of species distribution in relation to global warming (Hays et al., 2005 ) . Many
members of the genus Ceratium , important primary producers in tropical and temperate
waters, have expanded their range into warmer water. For example, before 1970, C. tricho-
ceros was only found south of the UK, but is now found off the west coast of Scotland and
in the northern North Sea. Dramatic biogeographical shifts have also been documented for
warm-water assemblages of calanoid copepod, which have moved 1000 km further north
in the north-east Atlantic over the past 40 years, with a concomitant retraction in the range
of cold-water assemblages (Hays et al., 2005 ) . Classical examples from the benthos are the
so-called Lessepsian migration of various Red Sea species through the Suez Canal to the
Mediterranean, the outbreak of the green algae Caulerpa taxifolia and Caulerpa racemosa
in the Mediterranean, the introduction of Ponto-Caspian species in the Baltic, and the ex-
pansionoftheJapanese oyster Crassostrea gigas intheWaddenSeaandalongthesouthern
North Sea coastline (Barange et al., 2011 ) . The effects of an increasing number of 'new'
species on existing communities are diverse, and often not well known. The role of alien
species should therefore be assessed in a more integrated and dynamic context of shifting
species' ranges and changing compositions and structures of communities (Walther et al.,
2009 ) .
Asynthesis ofthe various types ofimpacts onmarine biodiversity andthuspotentially
on related ecosystem services is reported in Figure 4.1 .
Figure 4.1
The effects of different drivers (including climate change as temperature rise, acidification and hypoxia)
on function of biodiversity and goods and services in different oceanic regions
(based on data from Costello et al ., 2010 ) .