IC5_II

The building of marine infrastructures, land reclamation, capital and maintenance dredging cause significant changes in hydrodynamic and sedimentary regimes that often lead to modification or loss of habitat in coastal marine areas. This is particularly true for tidal environments where tidal and wave processes govern the delicate erosion-deposition equilibrium. The Environmental management of marine tidal inlets requires quali- and quantitative knowledge of the distribution of physical and biological habitats, along with an understanding of the natural processes and of the short- to long-term impacts caused by anthropogenic activities on habitat dynamics. Acoustic remote sensing techniques may be very effective in providing estimates of sediment size distribution, porosity and seabed processes which are one of the key elements controlling the distribution of benthic environments (Kenny et al., 2003). Particularly over the last 15 years, acoustic classification coupled with ground-truth techniques were efficiently used for the quantitative definition of seabed feature at different scales (Kenny et al., 2003; Pauly et al., 2002; Pikitch et al., 2004; Bartholomä, 2006). The advantage of this methodological approach is the achievement of continuous spatial observations over large areas and time-efficient surveys when compared to conventional monitoring methodologies.
The purpose of this research study are (1) to characterize spatial sediment-benthic-roughness threshold values and habitat patchiness changes over time in human-impacted in tidal environments; (2) to analyze spatial distribution patterns of hydro-acoustic remote sensing seafloor classification maps; (3) to define system-related limitations and resolutions for habitat patchiness recognition.
This will be done by integrating and comparing the results obtained from different acoustic systems such as vertical beam (subbottom profilers), sidescan and multibeam profiler. The vertical and horizontal variability that affect the backscatter signal will be assessed. Data will be interpreted manually or by means of automated image-processing algorithms.
In particular, time-series and historical data on biological, textural and lithological information will be interpreted together to quantify changes along long temporal scales in response to sea level changes, physico-chemical, geological and climatic conditions. In doing so, different classification tools and statistical techniques, for temporal and spatial trends detection, will be assessed. In addition, procedures to consistently integrate interdisciplinary information will be investigated. Specific question to be addressed in order to fulfill the above stated objectives are:

The study will focus on the investigation of different target locations found in the two areas of the Jade Bay (German North Sea coast) and the Tauranga Harbor (Northern Island, New Zealand). Background information for the two study sites has been collected and data inventory conducted. To be able to employ the same methodological approach and conduct site-specific research, sub-bottom profiler surveys will have to be carried out in Jade Bay area, whereas acoustic biological and sediment time-series are already available for both the Tauranga Harbour.
The Jade Channel is a tide dominated system located on the southeastern North Sea. The channel hosts one of the largest port construction project ever realized in Germany over the last 50 years; this was designed to receive mega-container vessels. The enlargement of the Jade Weser Port on the western bank of the channel was started in 2008 and is now presently finalized. After an investment of 950 million euros, 360 ha of land were reclaimed (http://www.jadeweserport.de). Dredging and land reclamation for the Jade Weser Port are causing changes in tidal channel architecture and hydrology (Kubicki and Bartholomä, 2011). For this particular area I will be mainly focusing on biological, sediment can acoustic data collected in the Jade Bay. The study of the inner Jade Bay will involve dense cooperation with IC 6. Here, side scan sonar imagery is available for the subtidal zone. The characterization and the modelling of the distribution of marine benthic species will be one of the main objectives of the IC6 INTERCOAST project. Observation from the IC5 and IC6 will be valuable to both project and will opportunity for collaboration and joint data analysis.
The Tauranga Harbour is located along the Bay of Plenty and is one of the largest tidal estuaries of the New Zealand territory (Lawrie, 2006). During the last century a growing economic development was accompanied by land reclamation, urbanization and infrastructure construction (http://www.marinelibrary.co.nz), making Tauranga Harbour the largest New Zealand port for gross export tonnage (http://www.port-tauranga.co.nz/). The Harbour is also acknowledged for being a site of great value in terms of natural habitats. In 1992 the channel was deepened to ensure safe navigation, maintenance dredging operation have also been increased to counteract sand accumulation along the southeastern border of the entrance channel (Spiers et al., 2009). Human intervention was proved to cause local changes in hydrodynamics and sedimentary processes (Spiers and Healy, 2007; Spiers et al., 2009). Presently acoustic surveys are being carried out in the area to map the distribution of benthic communities, data will be interpreted and used to detect spatial and temporal changes.