The aim of this work is to obtain expertise allowing to investigate the role of picophytoplankton in the pelagic trophodynamic processes (“Helgoland Foodweb Project”). Picophytoplankton are the smallest (< 3 µm), single celled plants and cyanobacteria, living in worldwide waters. They occur at all trophic states and form the dominating biomass. The autotrophs play an important role in the production of oxygen and are therefore a basis of life in, for example marine, water habitats. However, until now they are poorly identified and only small investigations on their physiology and interactions are carried out. This may occur from the lack of a suitable method to describe the range of picophytoplankton organisms in a whole.
This PhD project is based on an international cooperation and is part of the Marmic programme. In detail, the eukaryotic picophytoplankton organisms off Helgoland shall be identified, examined genetically, structurally and physiologically (with methods like HPLC, a fluorometer, FISH, DGGE, flow cytometry and EM), and their recognised basic role in trophodynamic processes shall be deliberated. All samples were taken from the surface at the Helgoland roads (54°11.18’ N, 07°54’ E) between March 2005 and March 2006. For picophytoplankton investigations, the water was pre-filtered over 10 and 3 µm with a maximum pressure of 200 mbar.
References
References chlorophyll-a of all Phytoplankton: Wiltshire & Manly, 2004; Franke H-D, Buchholz F, Wiltshire KH, 2004 http://www.pangaea.de Figure 7: EM pictures of the sample taken on 07.06.2005 Figure 4: FISH analysis, specific peaks during the year are highlighted
Figure 2: Chlorophyll-a concentration measured by HPLC Figure 3: Picophytoplankton contribution
Name:
Start of PhD Thesis:
Funding:
Britta Knefelkamp Jan. 2005 AWI / MarMic Figure 6: DGGE of Picophytoplankton
How to investigate Picophytoplankton composition best?
How to investigate Picophytoplankton composition best?
B Knefelkamp B Knefelkamp
My Thesis Committee:
My Thesis Committee: KH Wiltshire (AWI), GO Kirst (Uni HB, rtd), R Amann (MPI), J Throndsen (UIO, rtd), G Gerdts (AWI), W Eikrem (UIO), D Vaulot (SBR) Other participants:
Other participants: A Wichels (AWI), K Metfies (AWI), L Medlin (AWI), R Niestroj (AWI / FTH Berlin), C Gescher (AWI), N Simon (SBR), S Masquelier (SBR), E Foulon (SBR)
Picophytoplankton concentration increases when larger Phytoplankton decreases Percentage of Picophytoplankton high in winter, low in summer
Concentration Chlorophyll-a [µg/L]
0 0,2 0,4 0,6
March April
May May
June July
August September
October November
December January
February Month
Picophytoplankton
Picophytoplankton
0 2 4 6 8 10 12
All Phytoplankton
All Phytoplankton
Picophytoplankton contribution to Chlorophyll-a
0%
20%
40%
60%
March April
May May
June July
August September
October November
December January
February Month
Percent
Figure 1: Picophytoplankton organisms are “the little green dots” in the light microscope.
B u t W H O a r e t h e y ? B u t W H O a r e t h e y ?
Polyphasic analysis can give an answer ! Polyphasic analysis can give an answer !
Figure 5: Microarray analysis of the Picophytoplankton composition (carried out by R. Niestroj)
Not in January
BATHY01 BOLI02 Chlo01
Chlo02 CRYPT 053 CRYPT 053-25 CRYPT01 CRYPT01-25 CRYPT02 CRYPT02-25 CRYPT03 CRYPT03-26 CRYPT13 CRYPT46 CRYPTO A CRYPTO B DINO E-12 DINOB
Euk1209 EUK328 OSTREO01
PRAS01 PRAS03 PRAS04
PRAS05 PRAS06 PRAS07
PRAS08 PRAS09A1 PRAS09A2
PRAS09D PRAS10B PRAS10F
PRAS10H PRYM01 PRYM02
PRYM03 0
100 200 300 400 500 600
June January
Hits
Prym 02
Euk 328
Dino E12
Crypto B
Picophytoplankton variability
Higher Picophytoplankton variability in June than in January Differences in the occuring phylotypes in June and January
2 µm 2 µm
1 µm
1 µm 2 µm
2 µm
Bolidomonas sp.
Micromonas sp.
Chrysochromulina sp.
FISH: all Picophytoplankton
0 5 10 15 20 25 30
08.03.05 05.04.05
03.05.05 31.05.05
28.06.05 26.07.05
23.08.05 20.09.05
18.10.05 15.11.05
13.12.05 10.01.06
07.02.06 Date
Chlo 01 Chlo 02 Euk 1209R NChl 01 EukMix Bathy 01 Boli 02 Ostreo 01 Pela 01 Prym 02 Pras 01 Pras 03 Pras 04 Micro 01 Micro A Micro B Micro C
Concentration [cells * 103/ ml] Mamiellales, Bathycoccus pras. Prasinococcales Micromonas C Bolido-, Prymnesio-, Pavlovophyceae, Micromonas A Micromonas 1 Ostreococcus, Micromonas B
Picophytoplankton succession
Marker 31.05.05 07.06.05 14.06.05 Marker 17.01.06 24.01.06 31.01.06 Marker Picophytoplankton phylotypes
50 µm
