This document provides background and rationale for a project studying brown algal biodiversity and ecology in the eastern Mediterranean Sea. Key points include: - The Mediterranean is a biodiversity hotspot for brown algae, with over 50 species of the genus Cystoseira recognized. - The project will establish the first institutional herbarium and taxonomic image database of eastern Mediterranean seaweeds. Over 100 taxa have already been identified. - Long-term monitoring shows re-oligotrophication of the Saronikos Gulf but a decline in Cystoseira populations, likely due to overgrazing from sea urchin populations increased

1. Brown algal biodiversity and
ecology in the eastern
Mediterranean Sea

2. Brown algal biodiversity and
ecology in the eastern
Mediterranean Sea:
Rationale for Project
• The Mediterranean is the cradle of phycology and
marine biodiversity research!
• Theophrastos, Aristotle, Plinius (Pliny), Dioskoridis –
and others!
• φύκος (alga) is derived from φκιασίδι (φυκιασίδι),
meaning a material used for cosmetology

3. Brown algal biodiversity and
ecology in the eastern
Mediterranean Sea:
Rationale for Project
• Brown algae are major benthic primary producers in
coastal ecosystems worldwide – especially in
temperate and polar seas
• The Mediterranean is a hotspot of brown algal
biodiversity!

4. Brown algal biodiversity and
ecology in the eastern
Mediterranean Sea
The case of Cystoseira
• The genus Cystoseira: 52 species currently recognized
worldwide, 47 of which occur in the Mediterranean –
and 19 of which are endemics!
• Cystoseira communities are considered the climax stage of
algal community development => coastal water biological
quality element according to the Water Framework Directive.
• Important canopy algae structuring associated communities
• In serious decline in much of the NW Mediterranean
• Mostly known from shallow waters, but also recent
discoveries from deep waters

5. Herbarium
• The first institutional East Mediterranean
Seaweed Herbarium.
• Includes species collected from around the
Eastern Mediterranean Sea.
• To be housed and curated at the Faculty of
Biology, University of Athens
• Among the most significant long-term
outputs of this project.

6. Taxonomic Image Database
• The first image base of Eastern
Mediterranean brown algae.
• Possible base for future guide or
educational books.
• Selected images will be transferred to
www.algaebase.org, the world’s largest
knowledge resource for algae

7. Contribution to the knowledge
of macroalgal biodiversity
• More than 100 distinct taxa of
macroalgae identified / recorded
so far from Greek waters.
• New brown algal records within the
framework of this project:
 Feldmannia simplex
 Hincksia granulosa
 Taonia atomaria f. ciliata

8. Re-oligotrophication of the Saronikos Gulf
• Large dataset documenting the re-oligotrophication of the Saronikos
Gulf (Athens coasts).
• Massive seasonal blooms of nitrophilous green algae have been reduced
over the last 15 years, reflecting a lower nutrient input.
“Long-term environmental change impacting marine vegetation in an Eastern
Mediterranean embayment: The case of the Saronikos Gulf” (under revision)

9. Re-oligotrophication of the Saronikos Gulf
• Increase in seaweed biodiversity: total species number
per sample has increased!
• This reveals an improvement of coastal water quality
• Consistent with decline of nitrophilous green algae

10. Re-oligotrophication of the Saronikos Gulf:
Cystoseira Populations
Standing stock of Cystoseira species has been gradually decreasing,
despite the improvement of coastal water quality (and despite reduced
competition by nitrophilous green algae)

11. Cystoseira species
• Indicator species of high water
quality / low nutrient levels
• Keystone species of benthic
communities.
• Still many open questions regarding
the taxonomy of this genus
• A better understanding of East
Mediterranean Cystoseira taxonomy
and biogeography is an important
objective of this project
• Collection of numerous herbarium
specimens, matched by silicagel
samples for DNA barcoding
(collaboration with Canadian Barcode
of Life Network)

12. Decline of benthic vegetation coverage
• Cystoseira populations and
seaweed vegetation generally
have been gradually decreasing
over at least 10 years
• Increased grazing, related to
human-induced pressures.
• Sea-urchin over-population,
attributed to intense overfishing,
has recently created “barrens” in
areas previously rich in
macroalgae.
• Saronikos Gulf highly impacted.

13. Decline of benthic vegetation coverage
Peristeria station in Peristeria station in
1998 2008
Re-oligotrophication!!

14. Decline of benthic vegetation coverage
Two underlying trends:
• Re-oligotrophication
• Increased sea urchin grazing due to
overfishing (fewer predators)

15. Kastelorizo

16. Kastelorizo

17. Deep-water Sargassum
• These large seaweeds are rare
and poorly studied in the
Eastern Mediterranean due to
their deep habitat.
• Found on small stones and
pebbles at about 40-50
meters depth.
• Their thalli were covered by
many other marine life forms:
smaller algal epiphytes and
plenty of zoobenthic species,
juveniles and eggs, revealing
their importance as keystone
species structuring deep-
water habitats, thus providing
Korinthiakos Gulf
refuge and substrate for
numerous other marine
organisms.

18. Korinthiakos Gulf

19. Together with the large Sargassum species, the alien green alga Caulerpa
cylindracea was also observed, forming a dense carpet on the sea bed,
apparently competing with the Sargassum population
(Korinthiakos Gulf)

20. Koudounes, Saronikos Gulf

21. Massive abundance of Nematochrysopsis
• An algal species not previously
encountered in the Eastern
Mediterranean was observed forming
large-scale mucilaginous, carpet-like
accumulations, dominating the seabed.
• Samples were identified as
Nematochrysopsis marina (Feldmann)
Billard, a peculiar chrysophyte.
• The phylogenetic affinity of
Nematochrysopsis is unclear.
• We are collaborating with Robert A.
Andersen (Michigan, USA), a world
expert for chrysophyte algae, for
further elucidating the biology and
taxonomic affiliation of this ecologically
clearly very relevant organism.

22. Alien macroalgae
Stypopodium schimperi and Asparagopsis taxiformis
expanding in Greek coasts
Sounio, Saronikos Gulf Koudounes, Saronikos Gulf

23. Salamina, Saronikos Gulf

24. Impact of aliens?
Marine flora in Rhodes Isl. Marine Vegetation in Rhodes Isl.
(Species no.) (Vegetation coverage)
aliens aliens
13% 31%
indigenous
69%
indigenous
87%
However, no significant impact to marine vegetation compared with other
pressures, except in cases of invasive behavior!
corresponding paper in preparation

25. New Alien Introductions
• First records of 3 alien
macroalgae within the
framework of this
project:
1. Botryocladia
madagascariensis
2. Hypnea anastomosans
3. Hypnea valentiae
“A new contribution to the alien red macroalgal flora of Greece (Eastern
Mediterranean) with emphasis on Hypnea species”
submitted to Cryptogamie Algologie

26. Laboratory Cultures
• Laboratory cultures have been established from
macroscopic field thalli as well as from thalli grown in
culture from collected substratum, the latter representing
a method rarely employed so far in floristic studies.
• We have so far established 109 brown algal isolates from
13 Greek localities. They have been purified to the end that
these unialgal, contamination-free clonal cultures are now
available for sequencing.
• Nuclear and cytoplasmic markers will be selected for which
data from other brown algae do already exist. This work
will contribute to the revision of the phylogeny of the
Ectocarpales. It will complement studies on the diversity of
the same families undertaken at the British and French
coasts of the Channel (project MARINEXUS and barcoding
project by Myriam Valero simultaneously submitted to the
Bibliothèque du Vivant).

27. An unexpected diversity of
pathogens affecting brown algae
in Greek waters!
First records of for the eastern Mediterranean
(Lesvos 2009 and Kavala 2012):
• Eurychasma dicksonii (basal oomycete)
• Anisolpidium ectocarpii (Hyphochytriomycota)
• Anisolpidium sphacellarum (Hyphochytriomycota)

28. An unexpected diversity of
pathogens affecting brown algae
in Greek waters!
Eurychasma dicksonii Anisolpidium ectocarpii
a b
Micrographs of two intracellular pathogens in an Ectocarpalean host (Lesvos 2009): The algal
host showed numerous pathogenic sporangia of the oomycete pathogen Eurychasma dicksonii
with the characteristic net sporangium (a, arrow). Anisolpidium ectocarpii (b) in this instance
was found co-infecting the same sample. Infection structures were always found in apical
cells and showed narrow evacuation tubes (arrow). Scale bars: 50 μm.

29. Anisolpidium sphacellarum from
Lesvos, 2009
Microphotographs of
Anisolpidium
sphacellarum infecting
Sphacelaria sp.:
Intracellular infection
structures were
observed in the host’s
apical cells (a, detail in
a b b). The number of
pathogenic thalli in a
single apical cell varied
(b and c). Each
sporangium shows a
single narrow
evacuation tube
(d, arrows). Scale
bars: 50 μm
c d

30. Microtubule organization of the oomycete
pathogen Eurychasma in the brown alga Pylaiella

31. A new species from Greek waters:
Padina ditristromatica

32. A new species
from Greek
waters:
Padina
ditristromatica
Win et al., 2011: EJP

33. 10 countries
14 institutions
…

34. Thank you!

35. Brown algal biodiversity and ecology in the
eastern Mediterranean Sea:
Participants
Steering Group
Christos Katsaros, University of Athens, Greece - Project
Leader
Panayiotis Panayiotidis, Hellenic Centre for Marine
Research, Greece - Lead Scientist
Konstantinos Tsiamis, Hellenic Centre for Marine
Research, Greece - Assistant Project Manager & Co-
Investigator
Frithjof C. Küpper, University of Aberdeen, Scotland -
Advisor