Plymouth Field Trip 2019 - Group 1

On the 6th of July 2019, group 1 went out into Plymouth sound on EchoSound with the aim to examine and characterise the sea floor to the north east of the breakwater. This area is of particular interest due to its surprising range of habitats within the Plymouth sound including fine sediment, rocky outcrops, artificial reef environments including wrecks and sub-littoral mixed sediment areas which accommodates for some of Europe’s most threatened species. The particular area surveyed is a special area of conservation (SAC) but Plymouth sound also hosts special protection areas and marine conservation zones (Plymouth-MPA, 2014). Habitat mapping is an important component of today research into conservation and ecology (Hewitt et al 2005). Ultimately, higher biodiverse systems are better at coping with external stresses such as climate, and are better at recovering from stresses (Tilman and Downing 1994).

Geophysics - Habitat Mapping

Figure 28: a map of designations in the Plymouth Sound & Tamar Estuaries; © Plymouth City Council

A side scan SONAR ‘towfish’ was used to map a small section of the sea floor by going along the four transects. This creates a high-resolution image track plot which is used to distinguish boundaries which suggest a change in habitat or substrate.

Secondly, deployment of the video recorder was undertaken at two different place that were identified as areas of interest while on the side scan SONAR transects. The video recordings were helpful in order to identify species present. A start point for the recordings was adhered to and the boat was allowed to drift during recording.

To finalise, a ground truthing process took place in which we collected bed sediment via the Van Veen grab.

Figure 27: an enlarged image with added  legend of Figure 3 from the poster below.

Please  click the image below to view an enlarged version of our poster.

Introduction and Aims

Methods

Our survey showed a uniform benthic environment, with fine sand with the occasional rocky outcrop found on both sites surveyed with the  ground truthing and grabs.  The video showed the sediment included many apparent polycheate burrows,  which were then confirmed by the grab. Species ID validated that the  species found were expected in the areas. The  ID can be seen on the poster below. The sidescan SONAR showed some distinguishable artifacts on the sea bed, including a shipwreck  as seen on Figure 27.

Results

Figure 29: scientific poster displaying our habitat mapping findings.