Ecological consequences of biological invasions: three invertebrate case studies in the north-eastern Baltic Sea

Abstract

Population dynamics and ecological impacts of the cirriped Balanus improvisus, the polychaete Marenzelleria neglecta and the cladoceran Cercopagis pengoi were investigated in the north-eastern Baltic Sea. After an increase during the first decade of invasion, the density of M. neglecta and C. pengoi declined afterwards. The studied abiotic environmental variables did not explain the interannual variability in the seasonal cycles of M. neglecta and C. pengoi indicating that the species are at their initial phase of invasion. The population dynamics of B. improvisus was best described by water temperature. B. improvisus promoted the growth of the green alga Enteromorpha intestinalis. M. neglecta enhanced the content of sediment chlorophyll a and reduced growth and survival of the polychaete Hediste diversicolor and growth of the amphipod Monoporeia affinis. Concurrent with the invasion of C. pengoi the abundance of small-sized cladocerans declined, especially above the thermocline. C. pengoi had become an important food for nine-spined stickleback, bleak, herring and smelt.

Effects of nonindigenous species on diversity and community functioning in the eastern Gulf of Finland (Baltic Sea)

“…The aquatic ecosystem now differs widely from its ''pristine'' state. Similar patterns have been observed in other Baltic coastal waters (Kotta et al 2006) and in the Caspian Sea. The latter water body was dramatically changed after intentionally introduced fishes and invertebrates (Karpevich 1975) and more than 20 other newcomers invaded from the Black Sea since the Volgo-Don channel opened in 1952 (MordukhaiBoltovskoi 1960).…”

Disturbance-related patterns in unstable rocky benthic habitats of the north-eastern Baltic coast

“…The second hypothesis concerned persistent calcareous structures produced by sessile invertebrates. A widespread and conspicuous species in the north-eastern Baltic Sea that produces such structures is Balanus (Amphibalanus) improvisus (Durr and Wahl, 2004;Kotta et al, 2006). It can be expected that similar dynamics occur for B. improvisus tests as for those of other barnacle species (Reimer, 1976;Silva et al, 2014), and the remnant empty tests of B. improvisus can be left on the substratum after death, especially in sheltered habitats such as underneath boulders (Liversage, 2012).…”

Are aliens threatening European aquatic coastal ecosystems?

“…Non-native species may be also complementary to natives in their responses to environmental change. The alien barnacles Balanus improvisus and Elminius modestus supplement and extend the native barnacle range into brackish water where none occurred before (Lawson et al 2004;Kotta et al 2006).…”