The biological impact of overflowing sands around a marine aggregate extraction site: Dieppe (eastern English Channel)

Abstract

Desprez, M., Pearce, B., and Le Bot, S. 2010. The biological impact of overflowing sands around a marine aggregate extraction site: Dieppe (eastern English Channel). – ICES Journal of Marine Science, 67: 270–277. The study investigates the physical impact of sediment deposition associated with aggregate dredging at a site off Dieppe, and the consequences for benthic fauna. Sampling stations were sited across potential zones of impact classified as high, moderate, and low deposition, depending on their proximity to dredging activities and their position relative to the net sediment transport route. Samples were also taken west of the dredge site outside the zone of likely impact (no deposition). A strong gradient was observed from the sediments dominated by fine sands in the high and moderate deposition zones, through to coarse sands and gravels in the low and no deposition zones. The benthic fauna sampled from the deposits of fine sand in the high and moderate deposition zones were sparse compared with the coarser deposits sampled from the low and no deposition zones. There was a strong correspondence between the distribution of different sediment fractions and the associated benthic fauna, with a weighted Spearman rank correlation of 0.638, higher than reported in related studies. This suggests that in deposition areas such as this, biological interactions play a less important role in shaping communities than the changes in the physical environment, which may have a greater impact on the biological communities.

Sand, rarer than one thinks

“…Marine sand mining has had an impact on seabed flora and fauna (Krause et al, 2010). Dredging and extraction of aggregates from the benthic (sea bottom) zone destroys organisms, habitats and ecosystems and deeply affects the composition of biodiversity, usually leading to a net decline in faunal biomass and abundance (Desprez et al, 2010) or a shift in species composition. Long-term recovery can occur only where original sediment composition is being restored (Boyd et al, 2005).…”

“…Tourism may be affected through beach erosion (Kondolf, 1997), while fishing -both traditional and commercial -can be affected through destruction of benthic fauna (Cooper, 2013;Desprez et al, 2010). Agriculture could be affected through loss of agricultural land from river erosion (John, 2009) and the lowering of the water table (Kondolf, 1997).…”

Demand for and environmental impacts of sand mining

“…Damage is more severe in small river catchments. The same applies to threats to benthic ecosystems from marine extraction (Krause et al, 2010;Desprez et al, 2010;Boyd et al, 2005).…”

“…Marine sand mining has had an impact on seabed flora and fauna (Krause et al, 2010). Dredging and extraction of aggregates from the benthic (sea bottom) zone destroys organisms, habitats and ecosystems and deeply affects the composition of biodiversity, usually leading to a net decline in faunal biomass and abundance (Desprez et al, 2010) or a shift in species composition. Longterm recovery can occur only where original sediment composition is being restored (Boyd et al, 2005).…”

“…Tourism may be affected through beach erosion (Kondolf, 1997), while fishingboth traditional and commercial -can be affected through destruction of benthic fauna (Cooper, 2013;Desprez et al, 2010). Agriculture could be affected through loss of agricultural land from river erosion (John, 2009) and the lowering of the water table (Kondolf, 1997).…”