Publication Date:
2014-07-30
Description:
Artificial substrates are omnipresent today in most estuaries mostly in form of massive rip-rap used for
groynes and jetties. In the Weser estuary, Germany, 60% of the shoreline is covered with such artificial
substrates while, natural rocky substrate is lacking, as in all Wadden Sea estuaries. This large quantity of
artificial substrates may be colonized by a benthic hard-substrate community which differs from the
local natural soft-substrate assemblage. In this study we examined species compositions, abundances,
biomass, and numbers of species of subtidal benthic communities on groynes and in the natural habitat,
the sediment, along the salinity gradient of the Weser estuary. Species composition changed on both
substrates significantly with salinity and was also significantly different between the substrates. In a
comparison with the sediment, the groynes did not provide any benefit for non-indigenous nor for
endangered species in terms of abundance, biomass, and number of species, but represent habitats with
higher total abundances and biomass; though some non-indigenous species even occurred exclusively on
groynes. In particular, groynes supported filter-feeding organisms which play an important role by
linking benthic and pelagic food webs. The dominance of the suspension feeders affects crucial estuarine
ecosystem services and may have important implications for the estuarine management by altering the
estuarine ecological quality status. Hence, artificial substrates should be considered in future conservation
planning and in ecological quality monitoring of the benthic fauna according to the European
Water Framework Directive.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
Format:
application/pdf
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