Detecting human mitigation intervention: Effects of sewage treatment upgrade on rocky macrofaunal assemblages

• Published in: Marine environmental research 2012-09, Vol.80, p.27-37
• Main Authors: Bustamante, María, Bevilacqua, Stanislao, Tajadura, Javier, Terlizzi, Antonio, Saiz-Salinas, José Ignacio
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Animals; Applied sciences; BACI designs; Biodiversity; Biological and medical sciences; Disturbance; Environment; Environmental Monitoring; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Hard substrata; Invertebrates; Invertebrates - physiology; Pollution; Recovery; Sea water ecosystems; Sewage; Synecology; Taxonomic diversity; Time Factors; Wastewaters; Water Purification; Water treatment and pollution
• ISSN: 0141-1136; 1879-0291
• DOI: 10.1016/j.marenvres.2012.06.007

The effectiveness of secondary vs primary treatments of wastewaters in mitigating the effects of sewage discharge on the multivariate structure and diversity of rocky invertebrate assemblages was assessed over a nine-year period through a beyond-BACI experimental design. Assemblages from different tidal levels (i.e. mid-shore, low-shore, 3 m and 8 m subtidal) were sampled at the impact location (I) and three control locations (Cs) at a hierarchy of spatial scales. The improvement in water treatment significantly changed the structure, diversity and cover of low intertidal assemblages. Faunal cover at 8 m subtidal increased significantly after the treatment upgrade at I. The secondary treatment also affected patterns of spatial heterogeneity between I and Cs for mid-shore and 3 m subtidal assemblages. This study demonstrates that powerful experimental designs combined with univariate and multivariate analytical approaches are fundamental in distinguishing the subtle effects of human impact from those of natural processes. ► This study represents one of the first attempts to apply a beyond-BACI design in environmental impact assessment. ► We examine the effectiveness of secondary vs primary wastewater treatment over nine years at four different tidal levels. ► Improvement of treatment changed structure, diversity, abundance or spatial heterogeneity depending on the tidal level. ► Powerful sampling designs, univariate and multivariate analytical approaches are fundamental in detecting human impacts.