Medidas de Gestao das Pescarias Marinhas e Aquicultura 2019 The State of World Fisheries and Aquaculture 2018 | Page 148

PART 3 HIGHLIGHTS OF ONGOING STUDIES
BOX 16
PREDICTING CHANGES IN SPECIES DISTRIBUTIONS
It is now known with high confidence that climate change
is producing shifts in the distribution of aquatic species
and that this trend is to continue. Marine species have
been expanding the leading edges of their distributions,
generally poleward, by 72 km per decade on average,
while the arrival of spring conditions in marine habitats
has been advancing by 4.4 days per decade
(Poloczanska et al., 2013; Pinsky et al., 2013). These
trends are consistent with species keeping to their thermal
or related ecological preferences. The concern is that
these shifts will affect biological interactions, and by
consequence the functioning of marine ecosystems. As a
result, climate change could substantially alter the
provision of the goods and services obtained from marine
ecosystems.
Recent evidence indicates that poleward expansion
will result in a net local increase in species richness in
most places, except in tropical regions, where strong
decreases in richness are expected (Molinos et al., 2016)
(Figure 38), although the patterns in species richness are
ultimately determined by multiple local drivers in addition
to temperature change (Batt et al., 2017).
While advancements in modelling suggest that range
shifts will continue (Cheung et al., 2016), not all shifts will
be predictable. The rate and direction of change in
temperature, known as climate velocity, shifts over space
and time (Pinsky et al., 2013; Burrows et al., 2014). The
nature, direction and speed of change will be determined
by how species and communities interact with climate
shifts, how tolerant they are to thermal changes, their
dependency on specific habitats, the length of their life
cycle and their interactions with other species. The
vulnerability of species to the indirect effects of climate
change – such as changes in dissolved oxygen levels,
ocean acidification (Branch et al., 2013), precipitation
and river discharges – further complicates these
predictions (Poloczanska et al., 2013), as does fishing
pressure, which can amplify or dampen climate impacts.
Distributional shifts can have managerial,
jurisdictional and/or operational implications. Research
will be needed on strategies for allowing both fisheries
and the species they exploit to adapt smoothly to global
climate change, particularly in light of possible feedback
between them.
FIGURE 38
DIFFERENCE BETWEEN PROJECTED (2100) AND CURRENT (2006) SPECIES RICHNESS FOR LOW (TOP)
AND HIGH (BOTTOM) GREENHOUSE GAS EMISSION PATHWAYS
REPRESENTATIVE CONCENTRATION PATHWAY (RCP) 4.5
90° N
70° N
50° N
30° N
10° N
10° S
30° S
50° S
70° S
90° S
NO. OF SPECIES
RCP 8.5
90° N
∆ RICHNESS
70° N
< −1 000
−1 000 to −500
−500 to −250
−250 to −50
−50 to −1
0
1 to 50
50 to 250
250 to 500
500 to 1 000
1 000 to 2 000
2 000 to 3 000
> 3 000
50° N
30° N
10° N
10° S
30° S
50° S
70° S
SOURCE: Adapted from Molinos et al., 2016
90° S
NO. OF SPECIES
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