Exploiting new wideband echo sounder technology for zooplankton characterization, sizing and abundance estimation

Marine zooplankton functions at many levels in ocean food webs, as consumers, producers and prey. They are major contributors to elemental cycling and vertical fluxes. Despite their central role and more than 100 year of research on these organisms, the M arine Zooplankton Colloquium 2(2001) concluded that our knowledge of their ecological function in their natural environment has increased only modestly. According to this group of scientists, there is not so much a lack of ideas, but inadequate methodolog ies and instrumentation that limits the pace of advances in understanding marine zooplankton. Our ability to predict abundances and distribution is still at an early stage. Yet, the need for such information is increasing as we enter the age of ecosystem- based management and as carbon cycling in the ocean is becoming of major relevance related to climate change. The proposed application plans to use freshly developed wideband echo sounder technology, which is actually a side-product of a modern multi-bea m sonar development and apply this for targeting zooplankton applications. Covering a band of 50 to 500 kHz, the existing equipment does not cover the entire spectrum needed for the very smallest size groups, but certainly most zooplankton sizes. Further expansions are defined outside the project as now due to the limitations of the call. The combination of split beam and wideband methods is new, and represents a simplification of the fairly complicated calibration of a wideband system, but also allows fo r spectrum analysis of single targets. The proposed project work is a mixture of software development for the transceiver and data presentations, calibration methodology, inversion methods for zooplankton sizing, ex situ experiments and trial surveys. R eference: Marine Zooplankton Colloquium 2 (2001): Future marine zooplankton research: a perspective. Mar Ecol Prog Ser 222: 297-308