S. Olenin et E. Leppakoski, Non-native animals in the Baltic Sea: alteration of benthic habitats in coastal inlets and lagoons, HYDROBIOL, 393, 1999, pp. 233-243
Semi-enclosed coastal inlets are particularly interesting areas for studies
on non-native species since they show steep gradients in physical environm
ent, biological communities, pollution and intensity of human activities. D
ue to the ecotone effect their biota is constituted of a mixture of marine,
brackish and freshwater indigenous and non-indigenous species. In comparis
on with offshore areas the coastal inlets seem to be better invadible, and
the effects of introductions are more evident here. This paper presents res
ults of a comparative study on non-native benthic species in the semi-enclo
sed water bodies of the Southern (Curonian and Vistula lagoons) and Norther
n Baltic (inner Archipelago Sea and Northern Quark, Gulf of Bothnia), which
differ by their origin and present environment, scope of anthropogenic imp
act and level of euthrophication. These areas presently host at least 18 no
n-native benthic invertebrate species. The ecological role of these species
is evaluated in terms of: (a) their relative abundance and biomass in bott
om communities; (b) their `feeding/mobility' status and their ability to al
ter the physical/chemical environment of the ecosystems they invaded; (c) v
acancy/occupancy of the niches before these species introduced. The compara
tive analysis shows that the non-native species have significantly altered
ecosystems of the SE Baltic coastal lagoons, while their role in the northe
rn coastal waters still is much less important. The invadibility of differe
nt types of the Baltic coastal lagoons and inlets is discussed on the basis
of the present study.