Hydraulic dredging targeting the bivalve Chamelea gallina in the northern and central Adriatic Sea has been taking place for over 30 years. In the period 20002001, 73 commercial dredgers harvested the resource within the sandy coastal area of the Ancona Maritime District (central Adriatic Sea). Despite this, no study aimed at investigating the impact of the fishery on the macrobenthic community of the area has ever been carried out. Sampling was done at 6 monthly intervals in an attempt to relate the impact of hydraulic dredging to different levels of fishing intensity. Data regarding two depth strata (46; 710 m) were analysed separately by means of permutational multivariate analysis of variance. The results revealed an overall condition of moderate disturbance within the benthic community, especially so within the 46 m depth stratum. The response of the benthic community to varying intensities of fishing activity was rapid, occurring within 6 months. Differences in the response of benthic community to differing intensities of fishing activity were found between the two depth strata considered. Significant differences in multivariate location of the benthic community were revealed between the three disturbance levels in both depth strata. Differences in multivariate dispersion were detected above a threshold level of fishing intensity, only within the shallow community. Differences were found between depth strata relating to species diversity and evenness, with significant differences between levels of fishing intensity being evident only within the 46 m depth stratum. The results emphasised that, even in a benthic community that is typical of a moderately disturbed environment, the effects of fishing on community structure were still discernible over and above the natural variation.
Medium-term impacts of hydraulic clam dredgers on a macrobentic community of the Adriatic Sea (Italy)
2006
Abstract
Hydraulic dredging targeting the bivalve Chamelea gallina in the northern and central Adriatic Sea has been taking place for over 30 years. In the period 20002001, 73 commercial dredgers harvested the resource within the sandy coastal area of the Ancona Maritime District (central Adriatic Sea). Despite this, no study aimed at investigating the impact of the fishery on the macrobenthic community of the area has ever been carried out. Sampling was done at 6 monthly intervals in an attempt to relate the impact of hydraulic dredging to different levels of fishing intensity. Data regarding two depth strata (46; 710 m) were analysed separately by means of permutational multivariate analysis of variance. The results revealed an overall condition of moderate disturbance within the benthic community, especially so within the 46 m depth stratum. The response of the benthic community to varying intensities of fishing activity was rapid, occurring within 6 months. Differences in the response of benthic community to differing intensities of fishing activity were found between the two depth strata considered. Significant differences in multivariate location of the benthic community were revealed between the three disturbance levels in both depth strata. Differences in multivariate dispersion were detected above a threshold level of fishing intensity, only within the shallow community. Differences were found between depth strata relating to species diversity and evenness, with significant differences between levels of fishing intensity being evident only within the 46 m depth stratum. The results emphasised that, even in a benthic community that is typical of a moderately disturbed environment, the effects of fishing on community structure were still discernible over and above the natural variation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
