IC6_I

State of the art
The increasing anthropogenic impact on coastal ecosystems in the last decades emphasizes the need for a profound understanding of the consequences of disturbance events on ecosystem processes and functioning. The benthic macrofauna (organisms retained in a 1 mm mesh) is an important component in marine ecosystems, playing a vital role in nutrient cycling, detrital decomposition and as food source for higher trophic levels. Macrobenthic species are sensitive indicators of changes in the marine environment caused by anthropogenic and natural disturbances.
In recent years remote sensing technologies have been used more and more frequently to determine not only sediment types and bed morphology, but also macrofaunal distribution patterns. The combination of hydroacoustic methods and investigations of macrofaunal patterns will gain insight into the consequences of changes in hydrodynamics and sediment structure on benthic dynamics.
Beside abiotic factors, biological relations can influence the dispersal of macrofauna species. Numerous studies about adult-juvenile interactions in the field produced contrasting outcomes, but there is a lack of explicit results under controlled conditions.

Project description
The main focus of my PhD project is based on an interdisciplinary approach to study benthic habitat dynamics by analysing patterns of macrofauna communities integrated with an interpretation of multibeam and sidescan sonar bathymetric data and associated geoscientific information (linked to IC5).
Our study area was close to the JadeWeserPort, the deepwater harbour in the Inner Jade in the Southern North Sea (Germany). After completion in 2012, the new 18 m deep navigation channel enabled landing of large containerships with draught up to 16.5 m tide independently. The construction works involved changes in the spatial distribution of sediments and bedforms due to dredging and dumping activities, enhanced by modified hydrodynamic conditions.

First chapter: Introduction to my research questions
The biological objectives are to study assemblages of macrofauna benthic species in response to physical changes in the bathymetry and the sediment distribution caused by the construction works for the JadeWeserPort, and to classify and map the benthic habitats in this disturbed area. Additionally, the effect of biological disturbance (presence of adults) was investigated regarding their influence on distributional patterns using the example of two benthic species.

Second chapter: "Macrofauna and sediment dynamis in a construction area"
We documented the physical disturbance caused by the dumping and dredging activities for the construction of the JadeWeserPort. The early impact of the ongoing dredging activities on the dynamics of sediments and macrofauna were analysed, in order to evaluate the successional stages of the macrofauna communities. Data on the status of the ecosystem before the construction works of the Jade Weser Port has started were available (from BIOCONSULT) for comparison with the sampling campaign carried out with RV “Senckenberg” in May 2010. The results are pooled in a paper, which is close to submission.

Third chapter: "Comparison of macrofauna, sediment and hydroacoustic patterns in a highly disturbed construction area"
The completed analysis of the small scale distribution of the macrofauna communities in May 2010 will be compared with the hydroacoustic data, which were collected during the same survey in the Inner Jade. Areas representing different levels of physical disturbance will be related to the established habitat classification. We will discuss the technical limits of hydroacoustics for Benthic Habitat Mapping in a disturbed study site. The draft of this second paper is in preparation.

Forth chapter: "Adult-juvenile interactions of the bivalves Macomono liliana and Austrovenus stutchburyi"
The dispersal potential of benthic species is a key parameter for recolonisation processes in disturbed habitats. Therefore, I studied the post-settlement dispersal abilities of two benthic species in an experimental approach at the University of Waikato in New Zealand. In the flume lab in Hamilton I investigated adult-juvenile interactions of Macomona liliana and Austrovenus stutchburyi. These two bivalve species were collected from Tuapiro Point in the Bay of Plenty, where they showed inexplicable distributional patterns on the sheltered sand flat. The preliminary data analysis implicated no clear impact of the presence of adults on the post-settlement dispersal of the juveniles. Nevertheless, a draft of these results is in preparation.

Fifth chapter: "Simultaneous multi-device hydroacoustic mapping of highly impacted areas (JadeWeserPort, Wadden Sea, Germany: a geological and biological approach"
The analysis of the macrofauna communities in July 2010 from the second sampling campaign with RV “Senckenberg” in the Inner Jade is completed. Ruggero Capperucci (IC5) will be the first author of the paper, which deals with the comparison of different hydroacoustic techniques, regarding the mapping of seabed roughness and patchiness of sediment samples. The macrofauna data will be used to explain the acoustic classification.

Each chapter of my thesis provides a data basis, which can be used for the improvement of species distribution models, and will include a well-founded interpretation of the used methods, in order to give a motivation for further studies.