SIBER SPIS sept 2011.pdf - IMBER

SIBER
Science Plan and Implementation Strategy
In addition to basic survey work on stocks and biomass distributions, physiological studies need
to be undertaken for converting measured concentrations into rates. The sampling strategy for
carrying out physiological studies is very different from surveys because specimens need to be
captured and brought back alive to either shipboard or land-based laboratories. Mesopelagic
species pose handling challenges due to the elevated pressures of their natural environs; both
temperature and pressure must be maintained when deep-living organisms are collected and
transported to the laboratory. Some physiological studies can be focused on surface-collected
animals, where night sampling can be employed to take advantage of vertical migrations to
the upper ocean undertaken by a number of species. However, not all myctophid species, for
example, are diel migrants, so this strategy will not work for studying all species of interest or for
investigating rates under ambient conditions at depth. Physiological rate measurements might
also be made in mid-depth traps, e.g. traps deployed in situ that measure O 2 consumption
of captured fish. But there are also challenges associated with making such measurements
in the OMZ realm, since determining small O 2 changes under conditions where the ambient
concentrations approach anoxia is problematic.
In addition to crustacean zooplankton and fish, other forms that need to be sampled and
considered are the gelatinous taxa (e.g. tunicates, coelenterates, cnidarians). Presumably,
these are important components of the epipelagic and mesopelagic food webs, yet very
little is known about the ecological function of these organisms in the food webs of the IO.
In extensive cruises during the NEM and SIM (Spring Intermonsoon) of 1980 and 1990 in
the open AS, tunicates and coelenterates contributed 36% and 14%, respectively, of the
identifiable macroplankton species in mid-water trawls with 0.9 and 1.4 mm mesh in the cod
ends. In addition, remains of gelatinous forms made up between 20-50% of the total wet weight
(Ignatiev, 2006). Since trawl samples with large catches of jellies are often discarded, a first
step would involve keeping such net collections, and then estimating the volume of jellyfish
sampled. Contributions of shrimp to the pelagic food web also need to be considered and can
nominally be assessed using trawl sampling surveys. Data mining efforts must be undertaken
to extract existing observation data sets of pelagic shrimp and other species as has already
been done with myctophids. The end-to-end food web modeling approaches described earlier
could also be employed as a means of assessing the biogeochemical roles of jellyfish, shrimp
and other species in the IO.
Acoustic sensors can now also be employed on gliders for autonomous deployment. These
glider-deployed sensors could be very powerful for carrying out epipelagic and mesopelagic
regional surveys. The caveat with this technology is that actual samples are needed in order to
interpret the acoustic information, so glider surveys have to be validated by ship-based trawl
surveys. Novel combinations of new and old sampling technologies should be actively studied
and pursued in any programs motivated under SIBER.
Finally, it should be noted that the mapping of temporal changes in biodiversity is a targeted
outcome of the Census of Marine Life (CoML). Identification of key species and their distribution
and abundance has been undertaken as part of this effort. With the exception of the central
eastern IO and ITF regions, the IO regional node of the CoML (IO-CoML) encompasses most of
the IO domain being targeted by SIBER. Effort should be made to coordinate SIBER activities
with the products and outcomes derived from the CoML. Guidance from CoML participants
has to how SIBER can best leverage their complementary efforts should be sought, potentially
in the form of organized collaborative workshop(s).
Shi p av a i l a b i l i t y
The establishment of the NIO time series station and the IndOOS and IMOS programs have
been hampered by limited ship time. It is crucial that ship availability for maintaining time
series and carrying out process studies is secured. There are several vessels that are or
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