Two Non-indigenous Dreissenids (Dreissena polymorpha and D. rostriformis bugensis) in a Southern Baltic Coastal Lagoon: Variability in Populations of the “Old” and a “New” Immigrant

Abstract

Dreissena polymorpha and D. rostriformis bugensis are freshwater Ponto-Caspian bivalve species, at present widely distributed in Europe and North America. In the Szczecin Lagoon (a southern Baltic coastal lagoon), the quagga was recorded for the first time in 2014 and found to co-occur with the zebra mussel, a long-time resident of the Lagoon. As the two species are suspected of being competitors where they co-occur, their population dynamics was followed at a site the new immigrant was discovered (station ZS6, northern part of the Lagoon) by collecting monthly samples in 2015-2017. The abundance and biomass of the two congeners showed wide fluctuations, significant differences being recorded between months within a year and between years. The abundance and biomass proportions between the two congeners changed from an initial domination of the newcomer quagga until mid-2015 to a persistent domination of the zebra mussel throughout the remainder of the study period. Both the abundance and biomass of the two dreissenids showed a number of significant associations with environmental variables, notably with salinity, chlorophyll a content, and temperature. The co-occurrence of the two dreissenids in the Lagoon is discussed in the context of their invasion stage; it is concluded that while the quagga seems to have achieved the "outbreak" stage, the zebra mussel, an "accommodated" invader present prior to the quagga immigration, reverted to that stage.

Understanding the complex dynamics of zebra mussel invasions over several decades in European rivers: drivers, impacts and predictions

“…declines in occurrences in Germany and relative abundances in Latvia) were sufficient to affect the overall European trend, giving the misguided impression that the overall European population was decreasing. While we are not aware of any adherent management‐related reason that could have led to the indicated decline in its relative abundance, ecological reasons, such as the competition with the congener D. rostriformis bugensis , might have played a role (Wawrzyniak‐Wydrowska et al 2019). This could have affected the decline of occurrences, while simultaneously indicating that D. polymorpha is still present in those sites.…”

Predicative Computing Structures and Hybrid Automates in Modeling Invasive Processes and Epidemic COVID Waves

“…Figure 1 shows interesting graphs as an example of qualitatively different scenarios of extreme threshold population dynamics, which was observed during the introduction of two invasive mollusks of the same family Dreissena rostriformis bugensis (quagga) and Dreissena polymorpha (zebra) in the coastal zone of the Baltic Sea [ 1 ]. The abundance of the mussel Dreissena polymorpha suddenly demonstrated eruptive dynamics: the effect of a rapid outbreak of abundance followed by a sharp decline.…”

“… Joint dynamics of invasion of competing mollusks Dreissena rostriformis bugensis and Dreissena polymorpha in the Baltic Sea with a threshold effect in the dynamics of biomass per unit area in Dreissena polymorpha [ 1 ]. …”