title: Are intertidal soft sediment assemblages affected by repeated oil spill events? A field-based experimental approach.
abstract: This study investigates the impact of repeated diesel spills on the structure of intertidal macrofaunal assemblages of a subtropical estuary. Three frequencies of exposure events were compared against two dosages of oil in a factorial experiment with asymmetrical controls. Hypotheses were tested to distinguish between (i) the overall effect of oil spills, (ii) the effect of diesel dosage via different exposure regimes, and (iii) the effect of time since last spill. Repeated oil spills dramatically altered the overall structure of assemblages and reduced the total density of macrofauna and densities of dominant taxa. Increasing the frequency of oil spills negatively affected macrofauna. In general, frequent low-dosage oil spills were more deleterious than infrequent high-dosage ones. However, increases in densities of some taxa, mainly the gastropod Heleobia australis, were observed in response to infrequent spills. Our results highlight the importance of repeated exposure events in determining the extent of oil impacts.
authors.affiliation: Centro de Estudos do Mar, Universidade Federal do Paraná, Av. Beira Mar s/n, PO Box 61, Pontal do Paraná 83255-976, Paraná, Brazil. Electronic address: leonardosandrini@gmail.com.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Sandrini-Neto
authors.affiliation: Centro de Estudos do Mar, Universidade Federal do Paraná, Av. Beira Mar s/n, PO Box 61, Pontal do Paraná 83255-976, Paraná, Brazil. Electronic address: ccmart@ufpr.br.
authors.forename: César C
authors.initials: CC
authors.lastname: Martins
authors.affiliation: Centro de Estudos do Mar, Universidade Federal do Paraná, Av. Beira Mar s/n, PO Box 61, Pontal do Paraná 83255-976, Paraná, Brazil.
authors.forename: Paulo C
authors.initials: PC
authors.lastname: Lana
mesh_terms: D001938:Brazil; D004784:Environmental Monitoring / Q000379:methods*; D063366:Estuaries; D005742:Gasoline / Q000009:adverse effects* / Q000032:analysis*; D019015:Geologic Sediments / Q000737:chemistry*; D059392:Petroleum Pollution / Q000009:adverse effects*; D012989:Soil Pollutants / Q000032:analysis*
chemical_list: D005742:Gasoline; D012989:Soil Pollutants
keywords: Field experiment; Frequency; Macrofauna; Oil exposure; Paranaguá Bay