title: Evaluation of environmental levels and biological impact of TBT in Malta (central Mediterranean).
abstract: Chemical monitoring for butyltins in bulk seawater, surface microlayer and superficial sediments determined that the two main local sources of marine contamination by tributyltin (TBT) compounds in Malta are ship-repairing dockyards and marinas. In bulk seawater, TBT values ranged from below the detection limit of 5 ng Sn l(-1) to 300 ng Sn l(-1); in sediments derived from the most polluted areas, TBT concentrations as high as 1500 ng Sn g(-1) were measured. At TBT levels found in local harbours, several sublethal biological responses are possible and were observed, including a significant reduction in MFO enzyme system activities of fish; digestive cell atrophy in the oyster Ostrea edulis; and induction of imposex in the snail Hexaplex trunculus. The latter two responses are evident at TBT concentrations below the environmental quality standard (20 ng TBT l(-1)). The ecological implications of these results are discussed and it is concluded that exposure of marine organisms to TBT in local harbours may be expected to lead to a reduction in the long-term survival of a number of such organisms. For these reasons, both the use of TBT-based antifouling paints for pleasure boats as well as drydock practices need to be controlled by appropriate regulations and their enforcement.
authors.affiliation: Department of Biology, University of Malta, Msida. vaxi1@um.edu.mt
authors.forename: V
authors.initials: V
authors.lastname: Axiak
authors.forename: A J
authors.initials: AJ
authors.lastname: Vella
authors.forename: D
authors.initials: D
authors.lastname: Agius
authors.forename: P
authors.initials: P
authors.lastname: Bonnici
authors.forename: G
authors.initials: G
authors.lastname: Cassar
authors.forename: R
authors.initials: R
authors.lastname: Casson
authors.forename: P
authors.initials: P
authors.lastname: Chircop
authors.forename: D
authors.initials: D
authors.lastname: Micallef
authors.forename: B
authors.initials: B
authors.lastname: Mintoff
authors.forename: M
authors.initials: M
authors.lastname: Sammut
mesh_terms: D000818:Animals; D004784:Environmental Monitoring; D056890:Eukaryota; D005399:Fishes / Q000502:physiology; D006066:Gonads / Q000002:abnormalities; D010125:Ostreidae / Q000033:anatomy & histology / Q000187:drug effects; D010150:Paint; D012767:Ships; D012908:Snails / Q000033:anatomy & histology / Q000187:drug effects; D014220:Trialkyltin Compounds / Q000009:adverse effects* / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000009:adverse effects* / Q000032:analysis
chemical_list: D014220:Trialkyltin Compounds; D014874:Water Pollutants, Chemical; C011559:tributyltin