Significance of pelagic and benthic primary production in two shallow coastal lagoons of different degrees of eutrophication in the southern Baltic Sea

Abstract

Primary production by pelagic and benthic rnicroalgae was measured in 2 shallow coastal lagoons in the southern Baltlc Sea by in situ and laboratory incubations to quantify the significance of these 2 malor groups of primary producers in absolute and relative terms. Pelagc primary production rates per volume at saturating hght conditions were 7 to 12 times higher at the polytrophic location KirrBucht (Darss-Zingst Bodden) than at the meso-/eutrophic location Rassower Strom (Nordriigensche Bodden). Chlorophyll a specific primary production rates, however, were in the same range at both locations, except for 1 situation in spnng which is exphcitly discussed. The pelagic chlorophyll a specific maxin~unl light utilization coefficient ( a ' ) tended towards higher values in Kirr-Bucht samples, which can be interpreted as an adaptation to a lower supply of irradiance. Pelagic and benthic primary production varied seasonally, with highest rates occurring in June/July. A calculation of short-term variability due to cloud-modulated avadabllitv of irradiance revealed reductions of pelaqic and benthic gross production (GP) rates on overcast days, compared to bright days, in the range of 26 to 69% and 62 to 82 "C,, respectively. Net community production (NP) rates were more severely reduced than GP rates on overcast days. Benthic NP was generally reduced to below zero on overcast days, whereas it was nlostly positive on bright days at both locations. To evaluate the significance of the different optical properties of both types of water (diffuse vertical attenuation coefficient, k = 3.3 to 3.7 and 0.5 to 0.7 m-' at Kirr-Bucht and Rassower Strom, respectively) for pnrnary production, the benthic and pelagic contributions at both sites were calculated regarding a water depth of 2 m, which is about the mean depth of the Bodden systems This standardization revealed obvious differences in basic conditions for primary production which remained undetected when the comparison of the 2 sites was based on the water depths in which the in situ incubations had been carried out (0.6 and 3.4 m at Kirr-Bucht and Rassower Strom, respectively) In meso-/eutrophic Rassower Strom at a depth of 2 m, benthic GP would contribute about 30 to 45% to the total GP of microalgae, depending on weather conditions and seasons. At the same depth in polytrophic Kirr-Bucht, the microalgae on the sediment surface would account for only 0 3 % or less of total GP. This demonstrates that optical properties of the water, which are closely related to the trophic state of the system, exert strong control on varying proportions of productivity, attributable to planktonic versus benthic nlicroalgal communities. It can be concluded from the modeled data that the difference between both locations will be most prominent dunng periods of low supply of radlant energy, Like on overcast days.

Factors governing phytoplankton biomass and production in tropical estuaries of western Taiwan

“…We used SigmaPlot (v. 8.02, SPSS) for nonlinear regression fitting and considered the results acceptable when the fit was significant (p o0.05) and the power of the performed test was 4 0.80. We used a photosynthetic quotient of 1.2 to convert O 2 fluxes into CO 2 fluxes for daily integration and literature comparisons (Meyercordt et al, 1999).…”

Viability of bacteria from different aquatic habitats. I. Environmental conditions and productivity

“…2) is at the lower end of reported values for polluted or eu-to hypertrophic waters (Table 4). The origin of the high POC levels in the Darß-Zingst bodden, which lowers the DOC:POC ratios so drastically, is assumed to be mainly autochthonous (Schumann et al 2001) and is produced mainly by phytoplankton (Meyercordt et al 1999). …”

Physical and biogeochemical controls on light attenuation in a eutrophic, back-barrier estuary

“…Back-barrier estuaries, especially along the Atlantic coast of the United States, are typically shallow systems colonized by benthic primary producers (Ziegler and Benner, 1998;Meyercordt et al, 1999;McGlathery et al, 2001). Prior to urbanization and agricultural influence in the watersheds, many systems were characterized by high densities of seagrass and relatively low light attenuation.…”