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Long-term effects of bottom trawling on large sponges in the Gulf of Alaska



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  • Journal Title:
    Continental Shelf Research
  • Personal Author:
  • NOAA Program & Office:
  • Description:
    Manipulative studies that characterize short-term effects of bottom trawls on seafloor habitats are numerous, but studies that examine long-term effects are rare. The long-term (13 years) effects of a single bottom trawl on large (>20 cm) erect sponges were investigated by revisiting the site of prior experimental trawling studies. In prior studies, large sponges were assessed immediately after trawling and 1 yr post-trawling. Thirteen years post-trawling, the average density of large sponges was 31.7% lower (range 1.5–53.0%) and the incidence of sponge damage (torn, necrotic, missing tissue, prone) was 58.8% higher within strip transects in trawled versus untrawled reference areas. For all sponge species combined, the mean density of large sponges was 3.19 individuals 100 m−2 in trawled areas and 4.67 individuals 100 m−2 in reference areas. The most abundant sponge species in both trawled and reference areas was Rhabdocalyptus dawsoni. Mean density of this species differed greatly between trawled (1.57 individuals 100 m−2) and reference areas (2.91 individuals 100 m−2). Thirteen years after trawling, the mean percentage of damaged sponges on strip transects was 15.3% in trawled areas and 6.3% in reference areas. The rate of damage in trawled areas was less than that observed both immediately after trawling and 1 year later. The persistence of damage (lower sponge densities and higher rates of injury in trawled areas) and the potential resultant changes to benthic communities where deepwater habitat-forming biota, such as large erect sponges, are present provide rationale for cautious management of the long term effects of bottom trawling.
  • Keywords:
  • Source:
    Continental Shelf Research, 150, 18-26
  • DOI:
  • ISSN:
    0278-4343
  • Format:
    PDF
  • Publisher:
    Elsevier BV
  • Document Type:
    Journal Article
  • Rights Information:
    Accepted Manuscript
  • Compliance:
    Library
  • Main Document Checksum:
    urn:sha-512:5cc707b3c4dcf73a59791e22083f3f08a3ba4b71580278f0c4faaad83242828609c4fbe824b2c0a47e64c41540ef9620b70d8487b42b130acaf3366ad3669050
  • Download URL:
  • File Type:
    Filetype[PDF - 761.29 KB ]
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