*********** +++++++++++++++++++++ 032095B.BIO + Source: ONR Asia + *********** +++++++++++++++++++++ Contributory Categories: ENG,ENV,OAC Country: India From: Workshop on Marine Bio-Acoustics Techniques and Their Applications 11-15 March 1996 National Institute of Oceanography Goa, India KEYWORDS: India; Bioacoustics, +++++ Part I/IV Items 1-2 Item 1 APPLICATIONS OF UNDERWATER ACOUSTICS ECOLOGY Stephen B. Brandt Great Lakes Center, 1300 Elmwood Avenue, Buffalo, New York, USA 14222-1095, 716-8784329 Underwater acoustics is an essential tool in fisheries management and biological oceanography and is widely used to measure the abundances, distributions and sizes of pelagic organisms in marine and freshwater systems. It is also useful for understanding the patchy distributions of organisms that are characteristic of aquatic environments. Recent research in underwater acoustics has further emphasized improved sensor development and deployment technology. However, advances in hardware technology may have outpaced our ability to use the fine-scale spatial and temporal information inherent in acoustic data and to convey this information in a useful and meaningful way to our colleagues. We have recently developed new procedures to examine the spatial ecology and production of pelagic organisms in aquatic environments that make better use of the spatial information in acoustic data. Our approach uses the acoustic data as a template for ecological modelling. We combine the strengths of underwater acoustics to measure fish abundances and sizes at high spatial resolution, bioenergetic models to measure fish consumption and growth, and spatial modelling to define the relationship between observed distribution patterns and causative processes. In our applications of spatially-explicit modelling, the aquatic habitat is modeled as an explicit feature of the environment by subdividing the pelagic habitat into small homogeneous units. Each unit represents I a small volume of water that is described by a set of characteristics (prey density, prey size, water temperature, dissolved oxygen, etc.) that have been measured in the field. Process-oriented simulation models of foraging and growth, parameterized according to the conditions of each cell and the specific size and species of fish being modeled, are run in each cell. These spatial models have allowed us to evaluate how the spatial patterning of environmental characteristics (prey density, prey size, water temperature, dissolved oxygen, etc.) affect the feeding ecology, growth and production of fishes. We employ advanced data visualization, spatial modeling and geographic information systems to map fish habitat quality. The MAVAIR (Multifrequency Acoustic Visualation And Information Retrieval) system is a Unix-based workstation that can process and manage very large, multidimensional data sets, and includes user-defined algorithms for acoustic data analyses and data interpola@tion, statistical analyses and interactive data visualization. Biological and physical data (eg. acoustic data on fish abundances and sizes, temperature profiles) measured at different spatial resolutions can be fully integrated using MAVIAR. The MAVIAR system is analogous to Geographic Information System (GIS) software but has many additional features that increase system flexibility for ecological modelling. The software is written in IDL (Interactive Data Language) which is specifically designed to handle large dimensional arrays. Examples from the Chesapeake Bay and the Great Lakes will be used to illustrate how biological processes interact with spatial/temporal heterogeneity in the physical habitat to affect predator-prey interactions, fish growth rates, and ultimately, fish production. It is argued that direct integration of acoustic data with ecological modelling can help in managing fisheries, studying predator-prey interaction, evaluating potential species introductions, measuring ecological efficiency of a species, and assessing how changes in environmental conditions can affect fish growth rates. +++++ End Item 1 +++++ Item 2 INDIAN OCEAN ECOSYSTEMS: A REVIEW OF PRESENT KNOWLEDGE, INFORMATION GAPS AND FUTURE DIRECTIONS A.H. Parulekar National Institute of Oceanography, Dona Paula, Goa - 403004, India The Indian Ocean, as a biological environment, is a converging point for three zoogeographic provinces. A major problem in studying such an expansive and equally diverse biotope is the inability to understand and predict spatial and temporal variability in ecology and biological productivity. So far, the mechanism responsible for such unpredictable variability, remains less understood. As many marine species, directly or indirectly comprise the food supply and are extremely sensitive to effects and impacts of environmental and man-made changes, the causes and predictability of variability in biological processes are both of societal and scientific concern. The ecological concept that the critical processes regulating and controlling the structure, function, scale and magnitude of biological populations can best be addressed on a regional basis, is relevant to studies and understanding of the Indian Ocean. Most practised protocol to study the biological processes is through investigations on different link and/or trophic levels of the marine f6od chain. However, no great success in predicting fish yield based on food chain studies, has been achieved. Rather, a good fit for understanding biological processes, its variability, resource potential, sustainable yield and ecological quality of a large oceanic space, like 74 million sq. km expanse of the Indian Ocean, is through a Large Marine Ecosystem (LME) approach, being characterised by distinct bathymetry, hydrography, productivity and trophically dependent populations. As a result of continuing oceanographic investigations, lot of information on environment and biology of the Indian Ocean, has been generated over the last 35 years. Especially in the last two decades, more emphasis has been on quantifying the biological processes and trophic dynamics of ecosystems. Some of the finer aspects related to picco- and nanno-plankton, in terms of contribution to productivity; role of microzooplankton in secondary production; rate and magnitude of ext@Oellular production; biodegradation kinetics; grazing rate and conversion effrciency/equivalent; fluxes of calorific' energy; compartmental ecosystem models, have not only 'given an insight but has greatly helped in realistic evaluation of harvestable yields and biological quality of Indian Ocean ecosystems. By now, quite a substantial information is available on an "ecosystem-biota" basis for primary, secondary, benthic and tertiary production in the Indian Ocean. Estimates for primar production of the Indian Ocean ecosystems has been computed to be 0.8 x 10^9 tonnes and 2.8 x 10^9 tonnes for shelf and offshore ecosystems, respectively, with large magnitude of variability between LNE'S. Earlier, it was deduced that phytoplankton have specific growth rates and hence primary production should be much higher than estimates based on C14 techniques. This needs to be authenticated. With due consideration to the data of IIOE and post-IIOE, the zooplankton biomass production is projected to be 0.1 x 10^9 and 0.48 x 10^9 tonnes, for shelf and offshore, respectively. In terms of organic carbon, the secondary production is estimated as 0.0035 x 10^9 and 0.0129 x l0^9 tonnes, for shelf and offshore, respectively. The benthic production for shelf and offshore ecosystems, is estimated as 0.64 x l0^9 and 0.95 x 109 tonnes, respectively. The biomass in terms of organic carbon production for benthic realm in the Indian Ocean works out to be 0.005 x 10^9 and 0.007 x 10^9 tonnes for shelf and offshore, respectively. In case of microbial production, efforts and methods, so far being practised, are too inadequate to generate any reliable and large scale information. Fishery potential estimates have a low of 10.2 and a high of 45 million tonnes/year, as against the present yield of 5.0 million tonnes per year. An inference that emerges from the available fishery resource estimates bring to light discrepanr- ies in the reliability of potential resources and sustainable yields. Marine fish production system is generally described as an ecosystem with linear transfer of energy from phytoplankton- zooplankton-fish. However, in nature, apparently it does not happen. Further, the estimates differ primarily in the productivity weightages assigned to various trophic levels and the yield ratio of carbon to fish. A gist of findings and information gaps, are: o evidently there is a close coupling of physical forcing and biological productivity processes in the LME's of the Indian Ocean; o as mechanism of generation of nutrients and its availability in euphotic zone still remains far from being explained, it is imperative to differentiate between recurring and new production: o better insight into the dynamics of transport of high coastal production to subsurface water is a foremost pre-requisite; o magnitude of secondary production, rates of grazing and predation, faecal pellet production and its utihsation/fate, is an imminent information gap; o lack of information about the role of microbes in the formation of acute oxygen depletion of mid-depth waters, is a stumbling block in understanding and quantifying the biological processes in the Indian Ocean; o inadequacy of using calibrated methods for production estimates has generated incomparable, and at times, unrealistic projections about potential and sustainable marine living resources. Some of the shortcomings in the evaluation of biological variability, potential/harvestable resource and environmental quality of the Indian Ocean can more realistically be resolved through application of new and precise tools, like, molecular and biochemical techniques, satellite imaging and hydroacoustics. Use of molecular biological techniques for species and stock identification alongwith. laboratory studies will allow for more efficient biological sampling designs and processing of samples at sea and in the laboratory. Biological processes of the large marine ecosystems can be studied from a combination of satellites and surveys using colour scanning and other photo-optical sensors for measuring productivity, standing stock and energy fluxes. Similarly, techniques in hydroacoustics can beneficially be deployed, on case to case basis, to deal with certain problems in biological oceanographic sampling. Inspite of inherent defects, if any, these new tools, as elsewhere may pave a way for tackling nagging problems in estimating the biological variability of the Indian Ocean. +++++ End Item 2 +++++ CMR Disclaimer================================================== This document could contain information all or part of which is or may be copyrighted in a number of countries. Therefore, commercial copying and/or further dissemination of this text is expressly prohibited without obtaining the permission of the copyright owner(s) except in the United States and other countries for certain personal and educational uses as prescribed by the "fair copy" provisions of that countries Copyright Statues. ================================================================ ************** END Msg. B.BIO **************