Direkt zum Inhalt springen

Water01 - IMOTOX

About

Identifying and monitoring of harmful cyanobacteria

Blooms of harmful cyanobacteria have been shown to increase in both frequency and severity due to global warming, particularly through increased nutrient loads at extreme weather events with elevated winter/spring rainfall and flushing events followed by extended periods of summer drought. These blooms threaten our shrinking freshwater resources in several ways: By increasing turbidity and consequently depriving submerged plants of light they suppress invertebrate and fish habitats and can thus affect biodiversity. On the other hand, release of cyanotoxins during blooms can cause problems for fisheries, drinking water reservoirs as well as recreational water activities. As part of the International Graduate School of Science and Engineering (IGSSE), the IMOTOX project team aims to develop a monitoring and early warning system for cyanobacterial blooms, and research factors influencing bloom formation, toxicity and collapse. This will be achieved through a close interaction of molecular microbiology, and remote sensing technology. The early detection of the rise of potentially harmful cyanobacteria in freshwater lakes shall be achieved by remote sensing, followed by a targeted molecular and microbial verification, which in turn will allow time for taking appropriate counter measures.


 

 

Research focus of the remote sensing part:

To monitor blooms, empirical algorithms based on band ratios or statistical approaches like genetic algorithms can be applied, since blooms are usually dominated by a single species. However, such algorithms are inherently not universally applicable and need to be tuned to the current situation. A challenge lies in the identification of different groups of phytoplankton under non-bloom conditions, as needed to establish an early warning system. If more than a single species affects the water colour, data analysis must be based on bio-optical models which are able to simulate the measured sensor signal of all bands for all possible concentrations of the optically active components in the water. These models have to be fed with inherent optical properties (IOPs) that characterise the actual water constituents. This is particularly difficult for cyanobacteria, because the IOPs of cyanobacteria are highly variable due to their capability to adapt the concentration and composition of light-harvesting pigments to the light conditions during growth. Therefore, one focus of this project lies on investigating the variability of the absorption and fluorescence properties of cyanobacteria, their parameterisation and implementation into bio-optical models.

Contact: anna.goeritz(at)tum.de (IGSSE - PhD student); Peter.Gege(at)dlr.de (Supervisor at The Institute of Remote Sensing Technologies  (DLR))


Research focus of the microbiology part:

Harmful algal blooms (HABs) are caused by a number of phytoplankton species. In freshwater systems blooms of potentially toxin-producing cyanobacteria are frequently found, particularly of the genera Microcystis, Anabaena and Planktothrix. The most common cyanobacterial toxin present during HABs is the hepatotoxic cyclic peptide microcystin. The genes required for microcystin synthesis are known in several species of microcystin-producing cyanobacteria. However, toxin-producing and non-toxic strains generally co-occur in an aquatic system. Environmental factors that trigger a shift in the population structure and an exponential growth of toxin-producers have been studied intensively over the years. It is generally acknowledged that high temperatures and high nutrient concentrations as well as a change in pH contribute to HAB formation. Biotic factors such as protozoan grazing and viral lysis by cyanophages are influencing the formation of such blooms as well, but their role is far less understood. Of particular interest is the question whether protozoa and cyanophages lead to an increase of toxin concentration by inducing a defence mechanism of the cyanobacteria and releasing toxins by lysing cyanobacterial cells, or whether they could contribute to the collapse of the HAB by decimating the population of toxic cyanobacteria.

Identification and quantification of cyanobacterial species was until recently exclusively based on morphological microscopic analysis. However, morphological differentiation between toxin-producing and non-toxic cyanobacteria strains of the same species is not possible. In this project a molecular approach employing polymerase chain reaction (PCR) and quantitative polymerase chain reaction (qPCR) techniques will be used to target the toxin genes in order to distinguish the strains on the basis of the presence or absence of those genes. Furthermore, qPCR analysis will determine the level of gene transcription and how it is influenced by biotic and abiotic factors. Laboratory experiments will lead to a better understanding of these interactions and field studies in selected lakes will characterize the cyanobacterial population and its toxicity during algal blooms.

Contact: pia.sharma(at)tum.de

 


Image credits:  

(1) Cyanobacteria bloom in the Baltic Sea – DLR, IMF Status Report 2013

(2) Octocopter – DLR Oberpfaffenhofen

(3+4) Cyanobacteria bloom in the Bergknappweiher near Weilheim, Bavaria – F. Bauer, LSI

01-01-1970
14.02.17

Registration now open: IGSSE Forum 2017

29-31 May 2017, TUM Science and Study Center Raitenhaslach, Burghausen

25.04.17

EuroTech postdoc workshop: Success in academia?

20-22 September 2017, Technical University of Denmark, Lynby Campus

18.04.17

Project team ROLITOS in a German documentary

10 May 2017, 11.30 pm Suedwestrundfunk (TV)

30 May 2017, 10.30 pm Bayerischer Rundfunk (TV)

11.04.17

Apply now: McKinsey 'Forschergeist' symposium

9-11 June 2017, Berlin

For doctoral researchers and postdocs!

10.04.17

Register now: ICMSB 2017

26-28 July 2017, TUM Study and Science Center, Raitenhaslach

14.02.17

Registration now open: IGSSE Forum 2017

29-31 May 2017, TUM Science and Study Center Raitenhaslach, Burghausen

05.06.16

10th IGSSE Forum

Smart cooperation - science and technology in, with and for society

15.12.15

The Science of Cooking

Doctoral Candidates explore the Secrets of a great Dinner

26.11.15

ATUMS@IGSSE

Having heard of a great Canadian Kick-Off Meeting, everyone at IGSSE was thrilled to welcome the...

20.11.15

Breakfast at IGSSE´s

Meet the IGSSE team every other month! All the things IGSSE members wanted to asked but never dared...

13.10.15

Save the Date: Canadian ATUMS Speaker on "Global Science- Global Career"

26. November 2015, 6-8 pm, IAS Faculty Club, Garching Campus

20 < lib.tabbedcontent
May - 2017
Sun Mon Tue Wed Thu Fri Sat
  02 03 04 05 06
07 08 09
10
11 12 13
14 15 16
17
18
19
20
21 22
23
24 25 26 27
28
29
30 31  
Wednesday, 10. May 2017
Project team ROLITOS in a German documentary
10 May 2017, 11.30 pm Suedwestrundfunk (TV) 30 May 2017, 10.30 pm Bayerischer Rundfunk (TV)
Wednesday, 17. May 2017
Podiumsdiskussion: Frauenförderung - Quo vadis?
17. Mai 2017, 14- 16 Uhr, Hochschule Weihenstephan-Triesdorf, Weidenbach
Friday, 19. May 2017
Tuesday, 23. May 2017
Monday, 29. May 2017
Registration now open: IGSSE Forum 2017
29-31 May 2017, TUM Science and Study Center Raitenhaslach, Burghausen