MEPS 227:125-133 (2002)  -  doi:10.3354/meps227125

Fish farming impacts in the Mediterranean studied through sediment profiling imagery

Ioannis Karakassis1,*, Manolis Tsapakis1, Christopher J. Smith1, Heye Rumohr2

1Institute of Marine Biology of Crete, PO Box 2214, 71003 Heraklion, Crete, Greece
2Institut für Meereskunde, Düsternbrooker Weg 20, 24105 Kiel, Germany

ABSTRACT: The sediment beneath and at various distances from the fish farm cages in Cephalonia bay (Eastern Mediterranean) was investigated seasonally through sediment profiling imagery (SPI) as well as through monitoring of geochemical variables and macrofaunal assemblages. The SPI images (SPI) repeatedly showed the same qualitative pattern along the benthic enrichment gradient with readily identifiable attributes such as depth of dark sediment, signs of outgassing and bioturbation marks. Quantitative comparisons showed that a large number of SPI attributes showed significant positive or negative correlation with geochemical and biological attributes describing the effect of fish farming on the seabed. All multivariate patterns obtained through the analysis of SPI attributes were highly correlated to those obtained from standard multivariate analysis of macrofauna during the respective seasons. It is argued that SPI provides an integrated assessment of the sedimentary conditions and therefore may be used as a complement of or even a substitute for standard sampling methods when mapping the effects of aquaculture on silty substrates.

KEY WORDS: Sediment profile imaging (SPI) · Benthic habitats · Impacts of aquaculture · Multivariate analysis · Mediterranean

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