40-year long-term study of microbial parameters near Helgoland (German Bight, North Sea): historical view and future perspectives

Abstract

Since 1873, the waters at Helgoland Roads (sampling station "Kabeltonne") have been sampled daily to determine temperature and salinity. In 1962, microbiological parameters were determined for the first time to establish microbiological long-term studies on marine bacteria, starting with the colony-forming units (CFU). In the following years, several other microbiological parameters were integrated for different periods of time (e.g. activity parameters like ATP and ectoenzymatic activity, marine yeasts, oil-degrading bacteria, flagellates and molecular methods like PCR followed by denaturing gradient gel electrophoresis). To date, the total count of bacteria, flagellates and viruses have been acquired using fluorescent DNA dyes and epifluorescence microscopy. Here we present both a historical overview of the methods used and examples of results obtained over the past 40 years. Furthermore, we try to evaluate challenging new methods for marine microbial ecology, appropriate for long-term studies of marine bacteria.

The microbiome of North Sea copepods

“…In contrast, we were not able to detect any seasonality in the bacterial community of the studied copepods. Interestingly, the bacterial community of the water column of the sampling site Helgoland Roads displays clear seasonality, with well-differentiated successions of different bacterial groups (Gerdts et al 2004;Alonso-Sáez et al 2007;Eilers et al 2001;Teeling et al 2012;Sapp et al 2007). By combining these two findings, it can be hypothesised that the ''living surface'' copepod is selective, attracts specific bacterial populations and provides a niche, which is different from the pelagic environment.…”

Study on the effects of near-future ocean acidification on marine yeasts: a microcosm approach

“…At this site, yeast abundances (viable cell counts) have been recorded from 1964to 1966and from 1980to 1992(Meyers et al 1967Gerdts et al 2004) and additional information on yeast identities based on phenotypic identifications is available for certain periods (Meyers et al 1967;Ahearn and Crow 1980). For our study, a water sample was taken in mid-April 2011 and was incubated in laboratory microcosms at different pH levels (pH in situ [8.10], 7.81 and 7.67).…”

Ecological long-term research at Helgoland (German Bight, North Sea): retrospect and prospect?an introduction

“…It was only in the 1960s that the importance of microbial functions and loops in the marine pelagic food web were recognized, followed by the development of continually new methods and hypotheses. This is well reflected in the history of the Helgoland bacterial longterm series, with new methods constantly being introduced every few years, partly substituting the older ones (Gerdts et al 2004). In the 1970s, there was an increasing concern that oil pollution might become a chronic ecological problem in the North Sea.…”

“…In the 1970s, there was an increasing concern that oil pollution might become a chronic ecological problem in the North Sea. In order to monitor this development, regular measurements of the abundance of oil-degrading bacteria were initiated (Gunkel 1973;Gerdts et al 2004).…”

“…58,no. 4) presents a series of seven publications summarizing long-term studies at Helgoland on bacteria (Gerdts et al 2004), phytoplankton (Hoppenrath 2004;Wiltshire and Du¨rselen 2004;Wiltshire and Manley 2004), zooplankton (Greve et al 2004), macroalgae communities (Bartsch and Tittley 2004) and the macro-zoobenthos (Franke and Gutow 2004). Additional papers on related topics will appear in irregular succession.…”