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Nuig biogeoscience research group

marine study – methods

• Sediment cores collected from the Galway Bay area will be used to understand the past history of sedimentation providing clues to past climatic conditions.
• Multibeam swath acoustic and airborne lidar data collected by INFOMAR [ see example below ] will be incorporated in hydrodynamic and sediment transport models of Galway Bay to understand water circulation patterns and sediment movement in the area.

• Computer programs will be developed to utilize backscatter and sub-bottom seismic reflection data for the classification, composition and sub-seafloor structure of sediments.

• GIS, bathymetry, and remotely operated vehicles (ROVs) will be used to identify cold-water coral habitats and understand the ecology of the seabed. [ see example below ]

• Observations of water and flow properties will be used to analyse variability patterns and to validate results from hydrodynamic models.

• Hydrodynamic models will be combined with these (and other) environmental data to provide input into ecological modelling programs.

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Example of technique: Multibeam swath acoustic and airborne lidar data

Bathymetry of Galway Bay revealed by shipborne multibeam sonar and airborne LIDAR. The bulk of the surveying was done in 2007 by the Celtic Voyager's SIMRAD EM1002 with LIDAR utilised in shallow coastal areas. Tidal reduction and cleaning of multibeam was conducted by INFOMAR personnel. LIDAR processing was conducted by an external contractor. Coverage of Galway Bay was completed in 2008 with LIDAR surveys flown along the south Connemara coast and the west cost of Co. Clare; this data is not publicly available as yet and is not shown. More information can be found on the INFOMAR website.

A glance at the bathymetry reveals some interesting features: bedded limestone outcrops north and north-east of the Aran Islands; an unusual network of interconnected scour-like features around bedrock outcrops; long, low eastward-trending ridges of sediment that originate at outcrops in the centre of the Bay.

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Example of technique: Understanding seabed ecology

Remotely Operated Vehicles will be used to look at the ecology of deep water corals off the coast of Galway Bay.  With the exception of the MAXENT model, the results shown below are from Janine Guinan, a former PhD student of Dr. Anthony Grehan and Prof. Colin Brown.  The results have been published in Ecological Informatics (Guinan, J.C., Brown, C., Dolan, M.F.J. & Grehan, A.J., 2009. Ecological niche modelling of the distribution of cold-water coral habitat using underwater remote sensing data. Ecological Informatics, 4, 83-92. 10.1016/j.ecoin f.2009.01.004).  The MAXENT model results shown below have been compiled by Anna Rengstorf a current PhD candidate within the Biogeoscience group.

Explanation of the images: Top Row: A) The Bathysaurus ROV (Remotely Operated Vehicle). B) Bathymetry map of a study area on the Western margin of the Porcupine bank showing the track of ROV-based video data. C) ROV-based stills showing healthy cold water coral colonies of Lophelia pertusa (L) and Madrepora oculata (M.) Associated fauna within the coral reef ecosystem include the purple octocoral Anthotela sp. (O) and glass sponges Aphrocallistes sp. (S). Images © Ifremer/AWI Bottow Row: Habitat suitability maps for cold water corals based on terrain parameters of rugosity, slope and aspect and an analysis scale of 90 meters. Maps show the percentage probability of occurrence of Lophelia pertusa. Red areas reflect high probability of occurrence, green areas are considered unsuitable for the species. A range of modelling techniques are evaluated: D) ENFA- Environmental Niche Factor Analysis (Hirzel et al. 2002); E) GARP - Genetic Algorithm for Rule-Set Prediction (Stockwell and Noble, 1991); F) MAXENT – Maximum Entropy (Philipps et al. 2006).

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