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The northern coast of the state of Rio de Janeiro, eastern Brazil, is an important nesting ground for loggerhead turtles (Caretta caretta), with about 1500 nests laid annually (Lima et al. 2012). It also hosts foraging grounds for juvenile green turtles (Chelonia mydas) and serves as a migration corridor (and possibly provides foraging habitat) for olive ridley turtles (Lepidochelys olivacea) (Reis et al. 2010; TAMAR - Brazilian Sea Turtle Conservation Program database, unpublished data) and leatherback (Dermochelys coriacea) turtles (López-Mendilaharsu et al. 2009).
Despite the high importance of the area for sea turtles, construction began in 2008 for a large, private mixed-use port complex, named Açu Superport. This enterprise, which is the largest port-industry facility in South America, is located at 21.8157°S, 41.0060°W (Fig. 1), just south of the city of São João da Barra and about 260 km (geodesic distance) from the city of Rio de Janeiro (Barreto & Quinto Junior 2012). The port complex, now in operation, is equipped with two sets of terminals, one offshore and the other onshore, which together have 17 km of wharves accommodating up to 47 vessels (Ditty & Rezende 2014). Here we provide an account of sea turtle mortalities observed in the region that appear to be the result of dredging operations during both port construction and operation.
Since the beginning of construction in 2008, hopper dredges have been used for clearing and maintaining access channels, a turning basin, and a harbor basin, all to facilitate navigation of vessels using the port. In 2012, additional hopper dredges entered into operation for the construction of a new terminal and shipyard. Because the port complex is situated in a high-energy coastal zone, maintenance dredging of constructed channels is regularly required to remove sediments that build up after being transported and deposited by currents.
Hopper dredging was first identified as a source of turtle mortality in 1980, when 71 turtle interactions with hopper dredges were recorded over a period of five months in Canaveral Channel, Florida (NMFS 1991; Dickerson et al. 2004). Subsequently, between 1980 and 2003, 508 turtles have been impacted by dredgers from 38 different locations throughout the southeastern United States (Dickerson et al. 2004). Hopper dredges remove bottom sediments through articulated suction pipes, discharging it into a...