CNIDARIAN ZOOPLANKTON DISTRIBUTION ACROSS GEOGRAPHICAL, VERTICAL, BIOTIC

AND ABIOTIC GRADIENTS IN THE MEDITERRANEAN SEA

Golo, R; Damian, A; Fuentes, V; Tilves, U; Acevedo, M; Canepa, A; Ziveri, P

Introduction Aims M&M Results Discussion Conclusion

MedSea cruise map

Station (17, neutonic net and Bongo)

Hyperstation (6, + MOCNESS)

Introduction Aims M&M Results Discussion Conclusion

• Few studies on this scale and with this sampling effort “Gelatinous predators eat herbivorous zooplankton and fish larvae (Purcell, 1981; Alvariño, 1985; Arai, 1988; Mfewatsakis and Conover, 1991).”

• “They (siphonophores) can represent up to about 20% of the total zooplankton biomass (Longhurst, 1985). ”

• “Siphonophores (cnidarians) are widely distributed vertically and horizontally in all seas the world over (Vinogradov, 1970; Alvariño, 1971; Margulis, 1972; Pugh, 1975; Longhurst, 1985).”

• “In the western Mediterranean, siphonophores represent 45–67% of the

total macroplankton in the upper 200 m (Boucher and Thiriot, 1972).”

1. Determine the distribution and abundance of jellyfish in Mediterranean sea during May 2013

2. Determine the vertical distribution of jellyfish in the water column during May 2013

Introduction Aims M&M Results Discussion Conclusion

Introduction Aims M&M Results Discussion Conclusion

– environmental parameters

• CTD (temperature, salinity & fluorescence)

• Water samples: – Depth: Niskins (chlorophyll, MPS, C/N, pH)

– Surface: Continuous water system

– Field: Zooplancton samples

• Neuston net (surface, 800µm)

• Bongo net(0-200m, 300µm)

• Mocness net (5 depths, 300µm)

– Laboratory analysis:

• Sorting and identification

• Biovolume

Introduction Aims M&M Results Discussion Conclusion

Neustonic net stations map (abundance)

Introduction Aims M&M Results Discussion Conclusion

Total abundance (%)

Siphonophora

Salps

Leptomedusae Trachymedusae

Scyphomedusae

Anthomedusae

Narcomedusae

Species

Total 29

Siphonophora 18

Scyphomedusae 2

Trachymedusae 2

Anthomedusae 2

Leptomedusae 1

Narcomedusae 1

Salps 3

Richnness

Neustonic net results

• Correlation between presence of Solmaris sp. and

Pelagia noctiluca ephyras (.997), “Narcomedusae usually have a diet of gelatinous animals, including other hydromedusae” (Mills and Goy, 1988; Purcell and Mills,1988; Larson et al. 1989)

• Pelagia noctiluca: Found four sampling points with more than 10 ind/m3 (ephyras and adults) and one station with more than 500 ind/m3

Introduction Aims M&M Results Discussion Conclusion

Neustonic net results

Introduction Aims M&M Results Discussion Conclusion

Bongo stations map (abundance and biovolume)

> Biovolume

Introduction Aims M&M Results Discussion Conclusion

Chlorophyll Map (May 2013)

Introduction Aims M&M Results Discussion Conclusion

Species

Total 47

Siphonophora 25

Sciphomedusae 1

Trachymedusae 4

Anthomedusae 11

Leptomedusae 4

Narcomedusae 2

Salps 3

Siphonophora

Salps

Leptomedusae

Trachymedusae

Sciphomedusae

Anthomedusae

Narcomedusae

Total abundance (%) Richnness

Bongo net results

Introduction Aims M&M Results Discussion Conclusion

Total frequency

Presence

Siphonophora 100%

Sciphomedusae 33%

Trachymedusae 86%

Anthomedusae 76%

Leptomedusae 19%

Narcomedusae 19%

Salps 86%

Bongo net results

Introduction Aims M&M Results Discussion Conclusion

Siphonophora Abundance (All cnidarians) Ab (Sipho) Presence

Muggiaea atlantica 15% 38% 38%

Eudoxoides spiralis 6% 8% 67%

Bongo net results

Introduction Aims M&M Results Discussion Conclusion

Temperature

Horizontal Distribution models (GLM)

Muggiea atlantica (Temp+Ox+Chl) Eudoxoides spiralis (Temp+Chl)

Temperature

Chlorophyll

Oxygen

Chlorophyll

Bongo

Oxygen (N.S.)

Introduction Aims M&M Results Discussion Conclusion

MOCNESS net stations map (abundance)

Introduction Aims M&M Results Discussion Conclusion

Siphonophora

Leptomedusae

Salps

Trachymedusae

Scyphomedusae

Anthomedusae

Narcomedusae

Species

Total 28

Siphonophora 18

Scyphomedusae 1

Trachymedusae 1

Anthomedusae 3

Leptomedusae 1

Narcomedusae 1

Salps 3

Mocness net results

Total abundance (%) Richnness

Introduction Aims M&M Results Discussion Conclusion

Vertical distribution

Muggiea atlantica

Salinity

De

pth

Tem

pe

ratu

re º

C

Presence and abundance of Muggiea atlantica >

Introduction Aims M&M Results Discussion Conclusion

Vertical distribution

Eudoxides spiralis

Salinity

De

pth

Tem

pe

ratu

re º

C

Presence and abundance of Eudoxides spiralis >

Introduction Aims M&M Results Discussion Conclusion

Vogtia spinosa

Vertical distribution

Salinity

De

pth

Tem

pe

ratu

re º

C

Presence and abundance of Vogtia spinosa >

Introduction Aims M&M Results Discussion Conclusion

• In the three types of sampling (different nets) siphonophores dominate, but dominance is shared (salps) when we use neustonic net. Represent over 60% of cnidarians in samples taken by Bongo and MOCNESS

• Vertically dominance of siphonophores is even more exaggerated, many environments dominated by different sp. The first meters salps dominate, especially in western Med.

• Pelagia noctiluca appears in big aggregations (“Blooms”) in western, possible effects on fisheries and tourism if it comes at the cost.

• Difference between eastern and western Mediterranean, both in composition sp. and biovolum. (Muggiea atlantica vs. Eudoxoides spiralis)

Thanks!

“Siphonophores are recognised as voracious predators which could have a major impact on

the structure and dynamics of the zooplankton” (Alldredge, 1984; Mackie et al.,

1987; Matsakis and Conover, 1991).