Brown algal biodiversity and ecology in the eastern

Mediterranean Sea

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

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!

Brown algal biodiversity and ecology in the eastern

Mediterranean SeaThe 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

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.

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

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

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)

• 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

Re-oligotrophication of the Saronikos Gulf

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)

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)

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.

Peristeria station in 1998

Peristeria station in 2008

Decline of benthic vegetation coverage

Re-oligotrophication!!

Decline of benthic vegetation coverage

• Re-oligotrophication

Two underlying trends:

• Increased sea urchin grazing due to overfishing (fewer predators)

Kastelorizo

Kastelorizo

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 refuge and substrate for numerous other marine organisms.

Korinthiakos Gulf

Korinthiakos Gulf

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)

Koudounes, Saronikos Gulf

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.

Alien macroalgae

Stypopodium schimperi and Asparagopsis taxiformis expanding in Greek coasts

Sounio, Saronikos Gulf Koudounes, Saronikos Gulf

Salamina, Saronikos Gulf

However, no significant impact to marine vegetation compared with other pressures, except in cases of invasive behavior!

corresponding paper in preparation

Impact of aliens?

aliens 13%

indigenous87%

Marine flora in Rhodes Isl.(Species no.) aliens

31%

indigenous69%

Marine Vegetation in Rhodes Isl.(Vegetation coverage)

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

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).

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)

An unexpected diversity of pathogens affecting brown

algae in Greek waters!

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.

Eurychasma dicksonii Anisolpidium ectocarpii

Anisolpidium sphacellarum from Lesvos, 2009

a b

c d

Microphotographs of Anisolpidium sphacellarum infecting Sphacelaria sp.: Intracellular infection structures were observed in the host’s apical cells (a, detail in 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

Microtubule organization of the oomycete pathogen Eurychasma in the brown alga

Pylaiella

A new species from Greek waters: Padina ditristromatica

A new species from

Greek waters: Padina

ditristromatica

Win et al., 2011: EJP

10 countries14 institutions…

Thank you!

Brown algal biodiversity and ecology in the eastern Mediterranean Sea:

ParticipantsSteering 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