2. Methods
Ship-board observers made the first surveys of the last seas to be
surveyed for plastics at sea. Areas as far south as 74S and from 60
to 170E and 57 to 120W were surveyed by observers on the MV
Esoperanza and RRS James Clark Ross. The regions surveyed were
parts of the Scotia, Bellingshausen, Amundsen, Durmot D’Urville,
Davis and the edge of the Cosmonaut seas. They used high-powered
binoculars for an hour each day to scan and identify floating items
(other than ice). The details of these were recorded together with
geographic position, environmental and ship information (such as
speed and heading). Even with experienced observers, ideally
marine debris surveys would be much more rigorous with dedicated
towed collection apparatus, slower transit speeds (both
vessels were travelling at 8e10 knots for many of the observations)
and repeat sampling in areas of poor sea conditions. However
pragmatic approaches are needed as justification of ship use for
dedicated debris surveys of remote areas such as the Southern
Ocean are unlikely given the long transits, large ship sizes, rising
fuel costs and realisation of environmental impact (carbon footprint)
involved.
Benthic towed apparatus (Agassiz trawl [mesh size 1 1 cm]
and Epibenthic sledge [mesh size 300 mm]) were deployed from the
RRS James Clark Ross in the southern Bellingshausen and eastern
Amundsen seas (see Supplementary materials for tow durations
and positions). Trawled material was transferred to precooled 100%
ethanol for fixation for 24 h. Fixed samples were then sorted and
examined using stereomicroscopy.