Meiofaunal community structure of the Deep Hypersaline Anoxic Basins in relation to their

extreme environmental characteristics

E. Hatziyanni, N. Lampadariou, P.N. Polymenakou & A. Tselepides

Institute of Marine Biology of Crete, Heraklion Crete, Greece

Methodology/work description

• Meiofaunal and macrofaunal community structure (abundance, biomass, species composition and diversity) within the DHABs and along an oxic-anoxic gradient• Comparison of benthic communities among the various DHABs and with those from adjacent sediments outside the influence of DHABs, as well as with those from other reduced environments• Identify specific morphpological and physiological adaptations of different meiofaunal and macrofaunal groups

IMBC involvementIMBC involvement

WP 3: Analysis of the species diversity, community structure and phylogeny of micro-organisms and meiofauna in Mediterranean Deep Hypersaline Anoxic Brines (DHAB)

0

20

40

60

80

100

Discovery L’ Atalante Urania Bannock

indi

v 10

cm

-2

Meiofaunal abundance (0-6cm) out of DHABs

12-43 indiv 10cm-2

copepods (adults+nauplii, 4-13%)foraminifera (25-50%)nematodes (41-64%)

miscellaneous (2-7%)

Chloroplastic pigments (0-0.3cm)Out of DHABs

Chl a

Phaeopigments

CPE

Discovery L' Atalante L' Atalante Urania Bannock0

0.4

0.8

1.2

1.6

(MCAT01) (MCAT03)

μg g

-1d

sed

Chl a

CPE

Phaeopigments

100

0

20

40

60

80

0 0.5 1 1.5

Discovery

0 0.5 1 1.5

L' Atalante(MCAT01)

0 0.5 1 1.5

L' Atalante(MCAT03)

Chloroplastic pigments (vertical distribution)Out of DHABs

dept

h in

sed

(cm

)

Urania

0

20

40

60

80

100

Bannock

μg g-1 d sed

Organic Carbon (0-0.3cm, wet oxidation)Out of DHABs

0

0,02

0,04

0,06

μmol CO2 day-1 ml-1

Discovery basinMCAT01 MCATO3L’ Atalante basin Urania basin Bannock basin

0

0.4

0.8

1.2

%1.6

Typical deep sea meiobenthos Plankton

Discovery

L’ Atalante ATAL01 ATAL02

Urania

Bannock BANN02 BANN01

Meiofauna within the DHABs

Other taxa (bivalves,gastropods)

102030405060708090

DiscoveryMCAT02 MCATO4

L’ Atalante Urania BannockMCBANN2 MCBANN1

indi

v 10

cm

-2

benthic foraminifera (allogromiidae)nematodes

bivalvia (lucinidae/vesicomyidae)gastropods

crustaceamiscellaneous

plankton

Meiofauna within the DHABscommunity structrure

5. 15. 25. 35. 45. 55.Time-->

Uraniax104

0

30

60

90

120

Cholest-5-en-3β-ol

Discoveryx104

0

30

60

90

120

Cholest-5-en-3β-ol

L’ Atalante

Cholest-5-en-3β-ol

Bannock

5. 15. 25. 35. 45. 55.

Cholest-5-en-3β-ol

Cholest-5-en-3β-ol within the DHABs (Mass Spectrometry)

0 5 10 15 20

2

4

6

8

10

0 1 2 3

dept

h in

sed

(cm

)

0 1 2 3 0 1 2 3

% OC (wet oxidation)

Discovery L' Atalante Urania Bannock

Organic carbon within the DHABs

Disc Atal Uran Bann

Out of brine

Brine area

0 5 10 15 20

μmol day-1 ml-1

Discovery basin L' Atalante basin Urania basin Bannock basin

0 0.5 1 0 0.5 1 0 0.05 0.10 0.150 0.05 0.1 0.15

2

4

6

8

10

Out of brine (CO2 production)

Brine area (CO2+CH4 production)

Carbon mineralization within the DHABs

Disc Atal Uran Bann

dept

h in

sed

(cm

)

0 0.5 1

Outside the influence of brinesOutside the influence of brines

Typical oligotrophic environment of the E.Mediterranean

Food availabilitylow levels of sedimentary chloroplastic pigmentslow quality of sedimentary OM

Meiobenthoslow standing stocks

response to food supply

typical abyssal assemblages dominated by nematodes and foraminifera

In the brinesIn the brines

Presence of benthic speciesadapted (?) to the extreme characteristics of the basins

Elevated values of sedimentary parametersHigh abundances of plankton organisms

Extreme but not azoic conditions

Natural sediment traps accumulating OM and decaying organisms

NematodesAllogromiidae foraminifera Lucinidae / Vesicomyidae bivalves, gastropods