Warsha Singh1, Erla B. Örnólfsdóttir2,Gunnar Stefánsson1

Application of an Autonomous Underwater Vehicle
(AUV) to study macrobenthic organisms
Warsha Singh , Erla B. Örnólfsdóttir ,Gunnar Stefánsson
1
1
2
2
1
University of Iceland
Vör Marine Research Center at Breiðafjörður
Project Details
Control module
Antenna tower
Propulsion module
• Species of interest: Iceland scallop (Chlamys islandica).
• Study site: Breiðafjörður, West Iceland.
DVL INS module
Goals
Battery module
Nosecone
Side scan sonar transducer
• Estimate abundance of scallops from AUV photographs
(Figure 1), through image analysis techniques.
• Classify habitats from sonar images (and photographs),
through classification algorithms.
• Establish the use of an AUV for stock assessment surveys.
AUV survey technique is:
Camera
Figure 1: The University of Iceland & Vör Marine Research Center at Breiðafjörður
jointly own an AUV. This Gavia AUV, approximately 2.2 m in length, has a downward
facing digital camera (800 x 600 x 24 resolution) and a side-scan sonar (marine sonic
dual frequency 600 / 1200 kHz). The antenna tower has GPS, Iridium, wireless LAN
antennas and visual beacon. (Photo by Halldór Pálmar Halldórsson, insert by Teledyne Gavia ehf)
Pilot survey
Figure 2: Survey locations in
Breiðafjörður, West and South West
of Stykkishólmur in september 2010.
Areas covered were previously known
scallop dredging sites.
• time and cost effective.
• not destructive to the marine environment.
• repeatable, therefore can improve variance estimates.
• Conducted September 7-9, 2010 (Figure 2).
• Photos gave a rough indication of the scallop distribution
and habitat type (Figure 3).
• Size of the scallops could be estimated (Figure 3a).
The area photographed can be determined based on the
field of view of the camera (45 degrees) and the height
of the AUV above the bottom.
(a)
• Live and dead scallops could be differentiated because
the dead shells decolorize (Figure 3a).
(b)
• Relatively more scallops were seen at sites 7 & 8 together
with mussels and molluscs (Figure 3b).
• Photos taken at 1 - 2 m from the bottom were of highest
clarity.
• In turbid waters the clarity of the photos was low at > 2.5 m
from the bottom.
Figure 3: Photographs from Breiðafjörður (site 5 in Fig. 2) obtained with a black and white
gavia camera; (a) shows a live scallop (bottom left) and a dead scallop (top right) enlarged,
and two starfish, also given is an indication of the size scale, photo was taken at 1.34 m
above the bottom & 31.55 m depth; (b) photo from site 7, taken at 1.79 m above the bottom
and 42.56 m depth showing scallop and mussel dominated bed.
(a)
(b)
• Scallop habitat was mainly flat with occasional rough bottom
and some rocks present (Figure 4).
• Coloured photos from the gavia (slightly lower resolution)
will also be used in this project (Figure 5).
(c)
Figure 5: Scallops photographed with
a gavia colour camera at 1.94 m
above the bottom, from the water
surface (0.29 m depth). The scallops
were planted along the Álftanes
inter-tidal zone as part of a trial run
conducted before the pilot survey.
Figure 4: Low frequency (30 m range) side-scan sonar images from Breiðafjörður (site 5); (a)
shows a flat habitat with some rocks, a shoal of fish can also be seen in the upper left corner;
(b) and (c) show rough and wavy bottom respectively.
Acknowledgements
To Símon Már Sturluson, Richard Yeo & Heimir Kristinsson for most valuable support in data collection,
and United Nations University - Fisheries Training Programme for partially funding this work.
Contact: [email protected]