The dependence between bacterial production and environmental conditions in the Gulf of GdañskAuthor(s): Anetta Ameryk | Beata Podgórska | Zbigniew Witek
Journal: Oceanologia ISSN 0078-3234
Volume: 47; Issue: 1; Start page: 27; Date: 2005;
Keywords: Bacterial production | Bacterial to primary production ratio | Gulf of Gdań | sk | Baltic Sea
Bacterial production, primary production and a number of other environmentalfactors were measured during six cruises in the Gulf of Gdańsk conducted invarious seasons from 1995 to 2001. Bacterial production (BP) in theepipelagic layer ranged from 1.5% (April) to 80% (July) of the gross primaryproduction (PP). Significant differences were observed between the BP/PPratios in estuarine and open-water areas. The highest values were recorded inthe coastal area and near the mouth of the river Vistula. It suggests thatallochthonous organic matter has a great influence on BP. The correlationsbetween particular parameters and regression analyses indicated that BP inthe Gulf of Gdańsk depended on temperature, organic nitrogen concentration,PP, chlorophyll a concentration, organic phosphorus concentration, salinityand biochemical oxygen demand. Of all the independent variables, thetemperature had the greatest impact on BP (R2 = 0.62). There was aninverse parabolic relationship between bacterial production and temperature.It appears that above a temperature of 12°C bacterial productiondepended on substrates to a higher degree than on temperature. The negativecorrelation between BP and concentrations of mineral nitrogen and phosphorusin the annual cycle were probably due to an indirect dependence. A multipleregression equation, which included temperature and organic phosphorusconcentrations, explained 78% of the variation in BP.Increasing BP resulted in an increasing biomass of bacterivorousnanoflagellates and of bacterivorous ciliates, which is indicativeof bottom-up control in this segment of the trophic chain.