1 Ann Vanreusel The connectivity and distributionof free-living marine nematodes Ann Vanreusel Meioscool, Brest, 27 juni 2016

2 The connectivity and distribution of free-living marine nematodesIntroduction Their biology Their success Connectivity and distribution Cosmopolitan species Cryptic species Population genetics 3. Environmental management context Importance of cryptic diversity Connectivity between protected areas Recolonization of disturbed areas

3 Life Cycle of the nematode C. elegansIntroduction : Their biology – Life strategy Life Cycle of the nematode C. elegans

4 Introduction : Their biology – Life strategyHatched juvenile 150 µm Adult 40 µm 800 µm Singh et al, 2009

5 The connectivity and distribution of free-living marine nematodesIntroduction Their biology Life strategy Dioecious (copulation) Oviparous (eggs in environment) Occasionnaly Ovoviviparous ≠ juvenile stages (molting) (Dauer larva for some Rhabditids) )

6 Introduction Their success“Meios “ intermediate to micro- and macrofauna Retained on 38 (or 32) µm sieve Protists (forams) and metazoans Almost exclusively associated with seafloor (s.l.) - mainly as endofauna in soft sediments - also as epifauna on ‘hard’ substrates meiofauna macrofauna

7 Introduction Their success Metazoan meiofauna : Nematodes dominant

8 Introduction Their successMeiofauna increases in importance with increasing water depth Log Abundance (ind. m-²) Log Biomass (g C m-²) Water depth Rex et al. (2006)

9 Introduction Their success Often remaining taxon in anoxic conditions

10 Normoxia Anoxia Recovery23 days days Normoxia Anoxia Recovery 23 days days Densities Species richness

11 Håkon Mosby Mud volcano at Barents sea slope (1280m)Halomonhystera species more than ind/10 cm² in bacterial mats Van Gaever et al, 2006 nematode densities x per m² Depth (cm) H2S, O2 (mM) 0,1 0, ,5 0,7 0, ,1 1 2 3 4

12 Expected number of generaCold seeps Ifremer Coral rubble Expected number of genera for 51 individuals expected nr of genera (rarefraction) Ifremer NOC Ifremer & AWI Ifremer mbari Soft sediments : Shelf Slope Abyss Trench Manganese nodules Seamounts Cold water corals Vanreusel et al 2010 Canyons Hydrothermal vents NOC Ifremer Ifremer

13 Introduction Their success(Most) abundant and species rich metazoan phylum of (deep-sea) benthos Appears in (almost) all marine sea-floor associated environments Wide trophic range and flexibility (Moens and Vincx, 1997)

14 The connectivity and distribution of free-living marine nematodesIntroduction Connectivity and distribution Cosmopolitan species

15 2. Connectivity and distribution Cosmopolitan speciesLidia Lins et al in prep Acantholaimus Mid Atlantic ridge

16 2. Connectivity and distribution Cosmopolitan speciesThe connectivity and distribution of free-living marine nematodes 2. Connectivity and distribution Cosmopolitan species Species composition and diversity of Acantholaimus 60° South ° North

17 Known global distribution of Acantholaimus species

18 2. Connectivity and distribution Cosmopolitan speciesBathymeteric distribution of Acantholaimus species

19 2. Connectivity and distribution Cosmopolitan species (molecular defined)  comparison of 6 globally distributed locations Derycke, Guillini et al, in prep

20 The connectivity and distribution of free-living marine nematodesIntroduction Connectivity and distribution Cosmopolitan species Cryptic species

21 Sympatric cryptic species complex of Halomonhystera disjunctaDerycke et al. 2007

22 HMMV, Barents Sea, at 72°N 14°E, 1280 mSulphide rich sediments of bacterial mats colonized by high densities of H. disjuncta Ovoviviparous reproduction strategy

23 Phylogenetic analysis of H. disjuncta complexVan Campenhout et al 2014 ITS 18SrDNA Phylogenetische boom gebaseerd op de nucleaire merker ITS (internal transcribed spacer). Dit stukje sequentie is 900 base paren lang. Het belangrijkste zijn de nummers op een knooppunt (node). Het nummertje 97 (omcirkeld) geeft aan dat dit een juist classificatie is. Hoe dichter bij 100 hoe beter. Deze boom toont dus aan dat HD-HMMV clustert in de boom van GD1-5 en er niet buiten valt. Door de hoge node-scores van deze boom kan je ook zeggen dat HD-HMMV duidelijk meer verwant is aan GD1 en 4 dan met GD2,3,5. DM_900bp en Ddvit2_900bp is Diplolaimelloides een soort die gekozen werd omdat de sequentie afwkijkt van alle GD’s en HD-HMMV inclusief en ervoor zorgt dat onze boom een startpunt heeft (de outroup worden deze sequenties HD HMMV is one of several cryptic species from a species complex known to be associated with degrading macroalgae on temperate mud flats (GD1-GD5) De Rycke et al 2007 HD-HMMV is a seperate group but more closely related to GD1/4 than other sympatric species

24 HMMV, Barents Sea, at 72°N 14°E, 1280 mSulphide rich sediments of bacterial mats colonized by high densities of H. disjuncta H. hermesi (Tchesunov et al, 2015) Ovoviviparous reproduction strategy New species described as H. hermesi and closely related to coastal Halomonhystera disjuncta species

25 The connectivity and distribution of free-living marine nematodesIntroduction Connectivity and distribution Cosmopolitan species Cryptic species Population genetics

26 Two research hypotheses: 5 locations at m Box 1. Scotia Arc SG = South Georgia SO = South Orkneys Box 2. Antarctic Peninsula KG = King George Island Box 3. Eastern Weddell Sea AUS = off Auståsen ice rise BX = Bendex (no geographic ref) 1600 km 1900 km 2100 km 600 km ~2100 km ~2300 km ~15 km Two research hypotheses: 1. strong population genetic structure between distant locations (cryptic species?) 2. surface-dwelling nematodes are more easily resuspended and transported by bottom currents than deeper-dwelling nematodes, hence will have less strong population genetic structure Freija Hauquier et al. In prep

27 Diversity and population genetics of two abundant genera in Southern Ocean57mm 30 mm 20 mm ‘surface’ communities food oxygen more prone to resuspension ‘subsurface’ communities less food oxygen rapidly decreasing less likely to become resuspended Desmodora Sabatieria 0 – 3 cm 3 – 5 cm 2 sediment slices 0 – 3cm 3 – 5cm Stored on DESS 2 genera selected based on general occurrence at all 5 locations Desmodora = surface-dwelling epistratum feeder Sabatieria = deeper-dwelling deposit feeder (tolerant to low O2 levels)

28 Bayesian trees of COI haplotypes for Desmodora.2 species clades based on COI species I: widely spread, yet substantial genetic differentation between populations large intraspecific phenotypic variation (2 morphospecies) species II: only at location SO (but may be sampling bias) Bayesian trees of COI haplotypes for Desmodora. Colours = locations Haplotype network (numbers along branches = number of base differences No number = only 1 difference) Clade I Surface dwelling Desmodora

29 Sabatieria  4 species Subsurface species wide range narrow range

30 Species I haplotype network for ITS Strong population genetic structure in Sabatieria species with wide distribution range (higher Φst values in AMOVA)

31 Sabatieria species associated with reduced seep sediments in East Med.Annelies De Groote et al. MEDECO cruise (2007): Central Pockmark area (1700 m) Brine lake Cheops (3000 m) + Leopard skin pattern (3014 m) Madonna mud volcano (1650 m, Central Mediterranean area) Merian cruise (2009): Amon mud volcano (1150 m) Amsterdam mud volcano (2050 m) Amon MV Central pockmark area Amsterdam MV Brine lake Cheops MEDECO cruise (2007) Maria S. Merian cruise (2009)

32 Connectivity among isolated seeps of East MedA’ dam 331 ind. COI Cheops PM 21 haplotypes, 6 found in multiple seeps Haplotype A: widespread in all seeps Most haplotypes: exclusively found in one seep, in very low adundances Haplotypes E - N: more mutational differences AMOVA: ST-value:15 % variability explained by differences between seeps

33 The connectivity and distribution of free-living marine nematodesIntroduction Connectivity and distribution Cosmopolitan species Cryptic species Population genetics 3. Environmental context Importance of cryptic diversity

34 Phylogenetic analysis of H. disjuncta complexImportance of cryptic diversity Van Campenhout et al 2014 ITS 18SrDNA Phylogenetische boom gebaseerd op de nucleaire merker ITS (internal transcribed spacer). Dit stukje sequentie is 900 base paren lang. Het belangrijkste zijn de nummers op een knooppunt (node). Het nummertje 97 (omcirkeld) geeft aan dat dit een juist classificatie is. Hoe dichter bij 100 hoe beter. Deze boom toont dus aan dat HD-HMMV clustert in de boom van GD1-5 en er niet buiten valt. Door de hoge node-scores van deze boom kan je ook zeggen dat HD-HMMV duidelijk meer verwant is aan GD1 en 4 dan met GD2,3,5. DM_900bp en Ddvit2_900bp is Diplolaimelloides een soort die gekozen werd omdat de sequentie afwkijkt van alle GD’s en HD-HMMV inclusief en ervoor zorgt dat onze boom een startpunt heeft (de outroup worden deze sequenties HD HMMV is one of several cryptic species from a species complex known to be associated with degrading macroalgae on temperate mud flats (GD1-GD5) De Rycke et al 2007 HD-HMMV is a seperate group but more closely related to GD1/4 than other sympatric species

35 Life-history response of coastal GD1-3 species to bathyal cold seep conditions Life history response of GD1-3 at a salinity of 34, a temperature of 4°C and in the presence of 1mM sulphides (Na2S). Start (6 females, 4 males) First egg(s) First adult(s) First dead inoculated nematode 17-18 days 7-10 days 12-17 days End of experiment: F1 adults are sexually active First Juvenile(s) Minimum generation time Egg deposition time Embryonic development Juvenile development Minimum adult life span Van Campenhout, et al 2015

36 3. Environmental context Importance of cryptic diversityDifferent tolerance of cryptic species of Halomonhystera disjuncta (GD1,2 and 3) to changes in environment (sulphides, temperature and pH). Offspring minimum adult life span p = 0,006 p = 0,0001 GD GD2 GD GD2 GD3 did not survive in the presence of sulphides. Van Campenhout, et al 2015

37 3. Environmental contextImportance of cryptic diversity

38 3. Environmental context Importance of cryptic diversityDe Meester et al, 2011 Different species interactions between species in changing environmental conditions

39 The connectivity and distribution of free-living marine nematodesIntroduction Connectivity and distribution Environmental context Importance of cryptic diversity Connectivity between different areas

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41 Are APEIs effective and representative?Environmental Management Plan for the Clarion Clipperton Zone 9 areas of particular environmental interest (APEI), on a provisional basis, to protect the biodiversity and ecosystem structure and functioning of the zone APEI = “large areas with self-sustaining populations and a broad range of habitat variability”

42 Turnover East West ≠ ≠ 30 % species loss = = No species loss

43 The connectivity and distribution of free-living marine nematodesIntroduction Connectivity and distribution Environmental context Importance of cryptic diversity Connectivity between different areas Recolonization of disturbed areas

44 26 year old disturbance in nodule areaMevenkamp et al 26 year old disturbance in nodule area 1 White spot 2 Crest 3 Valley 4 Outside track 1 2 3 5

45 Thank You !!! The connectivity and distributionof free-living marine nematodes Is the sky the limit? ‘Everything is everywhere ‘ ? Distribution through water column (?) Thank You !!!