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Ecosystem of the Polish part of the Vistula Lagoon from the perspective of alternative stable states concept, with implications for management issues

Kornijów R.

Oceanologia

2018

No. 60 (3)

390--404

The alternative stable states concept finds broad application in reference to both terrestrial and aquatic ecosystems. For some reason, attempts to implement the concept to explain processes observed in estuaries and Baltic lagoons are very rare. Based on information included in publications issued over the last 60 years, three co-existing states were designated within the strongly elongated basin the Vistula Lagoon, namely: phytoplankton-dominated (Middle Basin), macrophyte-dominated (Elbląg Bay), and transition state balancing between the two former ones (West Basin). Regions of the lagoon representing such states are similar in terms of nutrient concentrations, but they considerably differ in terms of: exposure to wind and wave action, salinity, anthropogenic impact, and multi-level top-down regulations. The paper discusses the role of such drivers, responsible for both the maintenance of a given state, and the past transition into the present alternative state. Moreover, it presents chances for the improvement of the situation, as well as threats which can undermine them.

Ecosystem maturation follows the warming of the Arctic fjords

Węsławski J. M., Buchholz F., Głuchowska M., Weydmann A.

Oceanologia

2017

No. 59 (4)

592--602

Two fjords in West Spitsbergen (Hornsund 77°N and Kongsfjorden 79°N) differ with regard to their exposure towards increasingly warm Atlantic water inflow. Hornsund remains in many respects cooler than Kongsfjorden (on average 2°C SST in summer) and is less influenced by warmer and more saline Atlantic waters. Reported changes in the physical environment (temperature rise, freshwater inflow, salinity drop, turbidity, fast-ice reduction, coastal change) are discussed in the context of biological observations in the pelagic and benthic realms with special reference to krill (Euphausiacea). We conclude that well-documented changes in the physical environment have had little effect on the fjord biota and that both organisms and their ecological functions in the fjords are well adapted to the scale of ongoing change. The observed changes fit the definition of ecosystem maturation, with greater diversity, a more complex food web and dispersed energy flow at the warmer site.