The Szczecin Lagoon Ecosystem. The Biotic Community of the Great Lagoon and its Food Web Model

The Great Lagoon is a central part of the Szczecin Lagoon, a major component in the Odra River estuary system. It is also an important European natural heritage site and one of the largest resting places for migratory birds in the Baltic Sea area. The first part of Wolnomiejski's and Witek’s book gives a thorough overview of the most up-to-date knowledge of this region, including the assessment of its biological production. Based on these findings authors develop a food web model of the Polish part of the Szczecin Lagoon, identifying a total of 45 trophic-functional components. The model describes a variety of features ranging from the magnitude of consumption, to the amount of unassimilated food and export of individual system components, and serves as an invaluable source, helping researchers to estimate various ecological indicators of The Great Lagoon’s ecosystem

Comparison of primary production and pelagic community respiration rates in the coastal zone of the Gulf of Gdansk

The organic matter production/respiration balance in the coastal water column was examined, both the primary production and community respiration being measured with the oxygen light-and-dark bottle method. Community respiration (CR) was always lower than the gross primary production (GPP) measured at a standard light intensity of 390 µE m-2 s-1, which amounted, on average, to 30% of GPP. During most of the in situ sampling period, the coastal system (6-7 m depth) was found to be autotrophic, with depth-integrated GPP ranging from 6.7 mmoles O2 m-2 d-1 in December to 214.2 mmoles O2 m-2 d-1 in August, and CR ranging correspondingly from 6.0 to 177.7 mmoles O2 m-2 d-1. However, on some occasions heterotrophic conditions were recorded: depth-integrated GPP<CR. In summer (August) this was caused mainly by low water transparency, which repressed photosynthesis, while in winter (December) it was due to the short period of daylight

Silicon dynamics in the Oder estuary, Baltic Sea

Studies on dissolved silicate (DSi) and biogenic silica (BSi) dynamics were carried out in the Oder estuary, Baltic Sea in 2000-2005. The Oder estuary proved to be an important component of the Oder River-Baltic Sea continuum where very intensive seasonal DSi uptake during spring and autumn, but also BSi regeneration during summer take place. Owing to the regeneration process annual DSi patterns in the river and the estuary distinctly differed; the annual patterns of DSi in the estuary showed two maxima and two minima in contrast to one maximum- and one minimum-pattern in the Oder River. F)Si concentrations in the river and in the estuary were highest in winter (200-250 mu mol dm(-3)) and lowest (often less than 1 mu mol dm(-3)) in spring, concomitant with diatom growth; such low values are known to be limiting for new diatom growth. Secondary DSi summer peaks at the estuary exit exceeded 100 mu mol dm(-3), and these maxima were followed by autumn minima coinciding with the autumn diatom bloom. Seasonal peaks in BSi concentrations (ca. 100 mu mol dm(-3)) occurred during the spring diatom bloom in die Oder River. Mass balance calculations of DSi and BSi showed that DSi + BSi import to the estuary over a two year period was 103.2 kt and that can be compared with the DSi export of 98.5 kt. The difference between these numbers gives room for ca. 2.5 kt BSi to be annually exported to the Baltic Sea. Sediment cores studies point to BSi annual accumulation on the level of 2.5 kt BSi. BSi import to the estuary is on the level of ca. 10.5 kt, thus ca. 5 kt of BSi is annually converted into the DSi, increasing the pool of DSi that leaves the system. BSi concentrations being ca. 2 times higher at the estuary entrance than at its exit remain in a good agreement with the DSi and BSi budgeting presented in the paper. (C) 2008 Elsevier B.V. All rights reserved