doi:10.1016/S0025-326X(03)00192-9
Copyright © 2003 Elsevier Ltd. All rights reserved.
Floating debris in the Ligurian Sea, north-western Mediterranean
a Sezione Oceanografia Fisica, Istituto Scienze del Mare, CNR, Forte di S. Teresa, 19036, Pozzuolo di Lerici (SP), Italy
b Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149-1098, USA
Available online 25 May 2003.
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Abstract
Results from visual sightings of large floating debris are presented, taken in the Ligurian Sea, a sub-basin of the north-western Mediterranean Sea which belongs to the recently stated “Cetacean Sanctuary”. Data have been collected during three oceanographic cruises, during the summer of 1997 and 2000. Results for the 1997 data suggest a debris density of the order of 15–25 objects km−2, while for the 2000 data, a lower density of the order of 3–1.5 objects km−2 is found. The difference between the two results appears statistically significant using simple tests. Possible reasons for the observed variability are discussed, including meteorological forcing, marine currents and debris input variability.
Author Keywords: Marine debris; Plastic; Pollution; Mediterranean sea; Monitoring; Meteorological forcing
Fig. 1. (a) Map of the Ligurian Sea showing the locations of debris sightings during transects and the locations of the fixed stations for the 1997 and 2000 cruises. Sightings (stations) are indicated as dots (triangles), white for 1997 and filled for 2000. For 1997 only one dot per three sightings is shown, due to the high sighting density; (b)–(d) show the magnified regions framed in (a), indicating the transect structure. Numbers (letters) indicate 1997 (2000) transects.
Fig. 2. Probability density function (pdf) of distance between consecutive sightings,
r, divided in classes of 1 km: (a) 1997 data; (b) 2000 data.
Fig. 3. Time series of ECMWF wind speed (stick diagram) at 43°N, 9°E for (a) June–July 1997; (b) August–September 2000.
Table 1. Transect charactersitics (see Fig. 1)

Lt indicates the transect length, and rt the average distance between consecutive sightings along the transect.
Table 2. Fixed station charactersitics

Table 3. Statistics computed from transect and station sightings based on: the whole 1997 data set; the whole 2000 data set; the Alliance data set only (2000)

Not-found indicates the average distance between consecutive sightings along transects; Not-founds indicates the average number of sightings at fixed stations; Dt and Ds indicate the average densities estimated from transect and station data, respectively.