1. Introduction to Raphidophyceae
IOC Certificate of Proficiency in Identification
of Harmful Marine Microalgae
University of Copenhagen
6-19 August 2017
Introduction to
Raphidophyceae
Jacob Larsen
IOC Science and Communication Centre on Harmful Algae, Copenhagen, Denmark –

2. Principal charateristics of Raphidophyceae
from Hara & Chihara 1987
heterokont flagellates with 2 flagella, often difficult to observe in LM
without cell wall, very fragile
most species have nume-rous chloroplasts with chl a+c
fucoxanthin in the marine representatives
trichocysts or mucocysts present in most species

3. Raphidophyceae Golden Brown Raphidophytes Green Raphidophytes
Vaucheriaxanthin derivatives
freshwater species
Gonyostomum
Merotrichia
Vacuolaria
Chattonella marina. var. antiqua
C. marina var. marina
C. minima
C. globosa
C. marina var. ovata
C. subsalsa
C. verruculosa
Chlorinimonas sublosa
Fibrocapsa japonica
Haramonas dimorpha
H. pauciplastida
H. viridis
Heterosigma akashiwo
Olisthodiscus luteus ?
Psammamonas australis
Dictyochophyceae
Viciciius globosus
Pseudochattonella verruculosa
Golden Brown Raphidophytes
Fucoxanthin dominated carotenoids
marine/brackish water species

4. Chattonella marina var. antiqua

5. Chattonella subsalsa Principal characteristics 2 apical flagella
30-70 µm long
oblong (drop-shaped)
may cause fish kills
widely distributed
C. antiqua
C. subsalsa
20 µm

6. Heterosigma akashiwo Principal characteristics 2 sub-apical flagella
8-25 µm long
sack-of-potato-shaped
may cause fish mortality
widely distributed
Lugol preserved

7. Fibrocapsa japonica

8. Fibrocapsa japonica Principal characteristics 2 apical flagella
20-30 µm long
oval, slightly flattened
mucocysts in the posterior end of the cell (arrow)
may cause fish mortality
widely distributed

9. Fish kills

10. Fish kills
Occurrence of Ch. antiqua, marina, subsalsa, globosa, fish icons indicate blooms associated with mass mortality
Occurrence of Ch. antiqua, marina, subsalsa, globosa, fish icons indicate blooms associated with mass mortality
From Imai & Yamaguchi 2012

11. Fish kills
Khan, S., O. Arawaka & Y. Onoue. 1996a. Neurotoxin production by a chloromonad Fibrocapsa japonica (Raphidophyceae). - Journal of the World Aquaculture Society. 27:
Khan, S., O. Arawaka & Y. Onoue. 1996b. A toxicological study of the marine phyto-flagellate, Chattonella antiqua (Raphido-phyceae). - Phycologia 35:
Khan, S., O. Arawaka & Y. Onoue Neurotoxins in a toxic red tide of Hetero-sigma akashiwo (Raphidophyceae) in Kagoshima Bay, Japan. - Aquaculture Research 28: 9-14.
from Khan et al. 1996a

12. Fish kills
from Khan et al. 1996a

13. Fish kills Raphidophytes may produce Brevetoxins
Reactive Oxygen Species
Free Fatty Acids
From Dorantes-Aranda et al. 2013

14. Genera of marine raphidophytes
Chlorinimonas
cell without tubular
invagination
cell yellow-green
cell with tubular
invagination
cell golden-brown
Few, 5-8-(13) chloroplasts
Many chloroplasts, >10; cell not or only slightly compressed
flagella inserted in an apical gullet, with posterior, rod-shaped mucocysts
flagella inserted in an apical gullet; chloroplasts arranged radially
flaqella inserted in a sub-apical or lateral oblique groove;
cell ‘sack-of potato’-shaped
+ pyrenoids; cell regularly oval, strongly compressed; benthic
Haramonas
2 forms; benthic stage irregularly discoid
Chattonella
Heterosigma
Fibrocapsa
Olisthodiscus
Psammamonas

15. Identification of Raphidophyceae
Species of raphidophytes are very fragile and usually cannot be identified to species in preserved samples – they may not even be recognized as raphidophytes
Lugol preserved