SIBER SPIS sept 2011.pdf - IMBER

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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 66
SIBER Science Plan and Implementation Strategy could be used for SIBER-related studies: The NIO has a new 80m vessel with adequate stern working area for carrying out a wide variety of oceanographic and fisheries-oriented studies. The Indian Ministry of Earth Sciences (MOES) has a ship that surveyed the Indian EEZ out of Kochi which is capable of mid-water trawling. The ASCLME operates the 57m Dr. Fridtjof Nanse Norwegian oceanographic research vessel in the western IO approximately 300 days per year. Its 23 berths could accommodate scientists focusing on SIBER-related activities, e.g. RAMA mooring and biogeochemical sensor deployment. However, additional vessels that have long-range, open ocean sampling capabilities are needed and these will have to be contributed by other countries (e.g. Japan, China, France, Germany, the U.K. and the U.S.A.). To address this need, the Indian Ocean Panel has established the IndOOS Resources Forum (IRF) to assist IndOOS/RAMA, IOGOOS and SIBER in securing ship time for mooring support/ maintenance and sampling. Opportunity may also exist to piggyback nutrient determinations and bioassays on major large-scale survey cruises that are being carried out under WOCE and GEOTRACES. Such measurements could help to better characterize basinwide nutrient distributions and provide information on dissolved iron concentrations and limitation patterns. Discussions should be initiated with these programs to find ways to leverage SIBER-relevant biogeochemical and ecological observations. Pir a c y Piracy has become an increasingly significant problem in the western equatorial IO over the last decade, particularly in the Gulf of Aden and the coastal and open ocean waters off Somalia. As a result, many countries do not allow research vessel operations in this region at present. The National Science Foundation (NSF) cancelled a research project in the AS and ASCLME efforts to deploy RAMA moorings with biogeochemical sensors in the western IO were also cancelled due to piracy concerns. The piracy issue must be considered when developing any SIBER-related programs in the western IO and the AS for the foreseeable future. Alternative sampling methods using, for example, gliders are being considered by the IOP as a means to obtain data from the western equatorial IO where it is currently unsafe to deploy and retrieve RAMA moorings. This approach should also be considered for biogeochemical and ecological sampling in these waters. For additional details on piracy impacts in the western IO, see Appendix V (Regional Piracy Update). 67
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