Distribution patterns of bacterioplankton and chlorophyll-a in the German Wadden Sea

Abstract

In a first synoptic evaluation, the temporal and spatial distribution of bacterioplankton and chlorophyll-a were determined in the German Wadden Sea. Three surveys were undertaken in winter, spring, and summer of 1994 using up to eight ships simultaneously between the river Ems and Sylt island. Despite intensive hydrodynamic mixing of the Wadden Sea water, spatial gradients were obvious. The abundance of bacterioplankton ranged from 0.4 to 26×10 5 ml -1 and chlorophyll-a varied between <0.1 and 79 µg l -1 . In winter, relatively homogeneous distribution patterns of both parameters with small gradients were found. Highest chlorophyll-a values connected with a highly patchy structure were observed in spring, while in summer both total chlorophyll-a values and the complexity of the distribution pattern had decreased. In contrast, bacterial numbers increased steadily from January to July with the highest bacterial densities and greatest patchiness observed in summer. Moreover, in some regions of the Wadden Sea, a trophic succession of algae as carbon producers and bacteria as consumers was evident. Correlation analysis verified the relationship between bacteria and chlorophyll a, indicating bottom-up control of bacterial abundance in the northern part of the German Wadden Sea. Since the observed regression slope is remarkably low (0.12-0.46) compared to literature values (0.5-0.8), we suggest that the link between phytoplankton and bacteria found here is a special characteristic of the Wadden Sea as a transition zone between the coastal region and the outer North Sea.

Composition of free-living, aggregate-associated and sediment surface-associated bacterial communities in the German Wadden Sea

“…Our bacterial numbers are well in the range of other studies on the Wadden Sea (Admiraal et al 1985, Van Duyl & Kop 1988, Grossart et al 2004. Poremba et al (1999b) reported lower numbers from the North Frisian Wadden Sea. Please note that we only assessed total bacterial numbers in the water column and did not differentiate between the free-living and aggregate-associated fractions.…”

Oxygen Profiles Across the Sea-Surface Microlayer—Effects of Diffusion and Biological Activity

“…These enrichments have been previously observed in the field (Hardy and Apts, 1984). Nevertheless, in our study, autotrophic biomass and bacterial abundances were about one order of magnitude larger compared to the natural environment (Poremba et al, 1999;Sperling et al, 2012). Despite this very high biomass accumulation, we identified typical members of natural marine bacterial and eukaryotic communities with strong differences between the SML and ULW (Supplementary Figures 6, 7).…”

Illustrating the importance of particulate organic matter to pelagic microbial abundance and community structure—an Arctic case study

“…Values for BACT, VLP, and VB were strongly correlated with the PCA 1 axis (POM/chl a; Table 2). Bacterial abundance often correlates with chl a (Cole et al 1988, Poremba et al 1999) and POM (Kimura et al 2001). In contrast to other studies, we observed no significant correlation between bacterial abundance and VLP with inorganic nutrients or DOM (Carlson & Ducklow 1996).…”