RV Investigator voyage summary. Great Australian Bight deep-water pelagic and benthic ecosystem study

[摘要] Objectives and brief narrative of voyageThe voyage was designed to characterise deep-water pelagic and benthic community structure and identify key ecological processes in the central and eastern Great Australian Bight (GAB. This understanding of the structure and function of the ecosystem will be used to inform future integrated and sustainable ocean management, and assessment/mitigation of potential future impacts. An overarching objective of the voyage is to contribute to developing models of ecosystem-level structure and function for the GAB. The Great Australian Bight Research Program is a collaboration between BP, CSIRO, the South Australian Research and Development Institute (SARDI), the University of Adelaide, and Flinders University. The Program aims to provide a whole-of-system understanding of the environmental, economic and social values of the region; providing an information source for all to use.Scientific objectivesThe pelagic ecosystem structure in the eastern GAB, which is characterised by seasonal upwelling and a narrow continental slope, will be compared with the poorly sampled central GAB, where year-round downwelling is predicted and the shelf and slope are wider, with the following GAB Research Program objectives;1. Comparing the eastern and central GAB continental margin zooplankton and micronekton communities in terms of their species composition, size range, biomass, nutrient source/trophic pathways and habitat.2. Testing the hypothesis that the “microbial food web” is the dominant planktonic food web over the deep GAB continental margin, particularly in the central GAB where year-round downwelling is thought to be the prevailing cross-margin flow, and that the more efficient “classic food web” only dominates in the eastern GAB during periods of nutrient-rich upwelling.3. Describing the community structure, dynamics, biodiversity and endemism of microbes (i.e., viruses and bacteria), plankton (i.e., phytoplankton, zooplankton, ichthyoplankton) and micronekton (including squids, small pelagic and mesopelagic fish and gelatinous organisms).Benthic characterisation is important because there are virtually no existing benthic biological data beyond continental shelf depths (200 m); because conservation values attributed to Commonwealth Marine Reserves (CMR) spanning wide depth ranges are untested on the mid- and lower continental slope; and because oil and gas lease areas extend across the GAB Marine Park (GAB MP).Within the GAB Research Program, the Benthic Biodiversity project has the following objectives:1. Quantify spatial patterns in the physical environment, and composition and abundance of benthic fauna in BP leases and adjacent continental slope areas of the GAB to provide baseline metrics relevant to monitoring the potential future impacts of oil and gas exploration on benthic communities.2. Determine requirements (including identifying indicators and metrics), and identify suitable control sites, for future ecological monitoring in the GAB - especially to detect and quantify ecological impacts from oil and gas exploration on benthic communities of the GAB Marine Park.Voyage objectivesThe pelagic sampling objectives were:1. Collect and process a full set of water samples to characterize and quantify primary production, microbial communities (virus/bacteria/ picophytoplankton) and determine a variety of water column environmental and chemical parameters.2. Collect and process phytoplankton, zooplankton and micronekton samples from vertical tow, side, EZnet (LOPC) and IYGPT MIDOC tows during day and night. Opportunistically collect nekton (e.g. squids and tuna) for food web studies.3. Conduct experiments investigating microbial and planktonic physiology and productivity4. Collect and process profiling lagrangian acoustic, optical (PLAOS) measurements day and night.5. Collect and process underway pelagic acoustic measurements and target unique layers with TRIAXUS, ...

[发布日期] 2016-02-29 [发布机构] CSIRO

[学科分类] 地球科学(综合)