SIBER SPIS sept 2011.pdf - IMBER

SIBER
Science Plan and Implementation Strategy
that chemical and biological factors are important (Piketh et al., 2000; Wiggert et al., 2006).
What combinations of factors control these sources and sinks of CO 2 in the IO, and how will
they respond to increasing nutrient inputs and global warming Regardless, the global trend of
increasing atmospheric and oceanic CO 2 concentrations will lead to lower pH and acidification
of the IO over the coming decades, with potential negative impacts on coral reefs and other
calcifying organisms (Doney, 2010). How will this alter biogeochemical cycles, ecosystems
and higher trophic levels in the IO What will the human impacts be
Because of its rapid warming (Alory and Meyers, 2009; Alory et al., 2007; International
CLIVAR Project Office, 2006) the IO may provide a preview of how climate change will affect
the biogeochemistry and ecology of other ocean basins and also human health. The SWM
appears to be intensifying as a result of warming and it has been suggested that this is driving
increased upwelling, primary production and ecosystem change in the AS (Goes et al., 2005;
Gomes et al., 2009). Changes in the strength and duration of the monsoons will impact vertical
mixing and freshwater and nutrient inputs in both the AS and the BoB and these in turn will
impact human populations, especially in coastal areas. Increasing temperatures will also have
direct impacts on marine ecosystems in the IO, likely altering food web dynamics, species
distributions and the incidence of disease (Hoegh-Guldberg and Bruno, 2010). Increased
frequency of coral bleaching events is also expected, which will lead to significant negative
socioeconomic impacts (Wilkinson et al., 1999).
Ro l e o f h i g h e r t r o p h i c l e v e l s in e c o l o g i c a l
p r o c e s s e s a n d b i o g e o c h e m i c a l c y c l e s
Finally, it is important to consider the role of higher trophic levels in ecological processes,
biogeochemical cycles and human health. The mesopelagic myctophid fish stocks in the AS
(Fig. 6) are of global significance, both economically and ecologically (Gjøsaeter, 1984). This
stock has been estimated at 100 million tons with a potential yield (harvest) of ~200,000 tons
per year. These biomass and yield estimates need to be better constrained, and their timespace
variability quantified. What role do these fish play in the ecological and biogeochemical
Fi g u r e 6 Myctophid fish caught by the fishing and oceanographic research vessel Sagar Sampada in
the Arabian Sea.
Photographs courtesy of P. K. Karuppasamy.
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