Title : Ecosystem Characterization of a Wet-land Pond with Imaging Sonar
Abstract:
An acoustical-based procedure which incorporating truly synoptic measurements with quasicontinuous sampling of spatial-temporal fish information and benthic morphological characteristics was developed for observing, assessing, monitoring, and understanding aquatic ecosystems. In the current investigation, an isolated wet-land pond with dimensions of 40x40x2m for the purpose of sewage purification was selected for the verification and demonstration of this recently developed procedure. The procedure consisted three major components, which incorporated a synoptic image acquisition component with a mechanically scanned imaging sonar, a cumulative inversion processes for fish quantification, and a modeling technique (i.e., spatial statistics and phenomenological evaluations) for ecosystem characterization. Derived information of the individually detected fish includes: position, orientation and acoustic length. From the spatial-temporal-fish-morphology information system collected, ecosystem related information of the fish in the pond, such as abundance, distribution pattern, taxonomic groups,
prominent length(s), movement and activity pattern, predator-prey interactions, bio-physical interaction as well as food web dynamics, were derived. In this specific pond, three trophic levels were identified andconcluded, which include 1. Plankton (primary production), 2. tilapia (238 individuals, 20cm and 30cm in length), 3. snakehead fish (45 individuals, 60cm, 70cm and 90m in length). A stable ecosystem with prominent diffusion-advection movement pattern for forging activity characteristics and saturated environmental carrying capacity were concluded. The recently developed procedure was proved efficient for the quantification of ecosystem characteristics of underwater environment for both isolated as well as extended areas. This procedure can be directly and strictly applied to the normal sized aquacultural pond for the quantification of fish/shrimp abundance, prominent length as well as behavior characteristics.
