Seasonal variation of bioluminescence in the Mediterranean Sea Jessica Craig, Alan Jamieson, Phil Bagley & Monty Priede Oceanlab, University of Aberdeen, Scotland, UK

 Bioluminescent sources (BL) Talk outline  Measurement technique  BL Distribution in the Mediterranean Sea  Seasonal variation at NEMO & NESTOR  Differences between NEMO & NESTOR

Bioluminescent sources  BACTERIA - Steady baseline source of light Mesoplankton – mm (e.g. copepods) Macroplankton – mm (e.g. euphausiids) Megaplankton – mm (e.g. medusae & large colonial organisms (e.g. pyrosomes))  ANIMALS - Non steady-state flashes Two types: (Dussart et al. 1965, Sieburth et al. 1978) (Dussart et al. 1965, Sieburth et al. 1978)

Bioluminescent sources Quantum emission (photons.flash-1) BL wavelength centred on 480nm (Heger, 2007) (Heger, 2007) BL requires a stimulus

Measurement method ICDeep profiler Camera Mesh ICDeep - ICCD camera - Gain control - To 5 x lux (min faceplate sens.) Mesh x 400 mm

ICDeep deployment sites in the MS

BL in the Mediterranean Sea Algerian Basin W Ionian Sea (NEMO) Mid Ionian Sea E Ionian Sea (NESTOR) Depth Mean BL± SDMean BL± SDMean BL± SDMean BL± SD ± ± ± ± ± ± ± ± ± end 0.30± ± 0.15 June 09 May 09 Sept 08 May09 Oct 08 May 09 NEMONESTOR

BL analysis 1. Is there seasonal variation in BL at NEMO and NESTOR? 2. Is there a difference in BL between NEMO and NESTOR? Generalised Additive Modelling (GAM) - models non-linear relationships

Seasonal variation Table 2. GAM analysis results - difference between spring and autumn BL density in the E and W Ionian Sea. W Ionian Sea (NEMO)E Ionian Sea (NESTOR) p-value< NEMO NESTOR

Seasonal variation NEMO NE Atlantic Ocean - Observation of autumnal deep maxima (Gillibrand et al. 2007) Autumnal deep maxima attributed to enhanced biomass fed by export of spring surface primary productivity to deeper water

Difference in BL between sites Table 2. GAM analysis results - difference between BL density in the E and W Ionian Sea in the spring and autumn SpringAutumn p-value<0.001

Seasonal difference between sites NEMONESTOR (Mean BL sources. m -3 ) Autumn Spring m m NEMONESTOR (Mean BL sources.m -3 ) Autumn Spring NEMONESTOR Mean Flashes.hour -1 Autumn 42 Spring 62 Impacts with OM (Priede et al. 2008)

Summary Significant seasonal variation at the NEMO site - BL density 3x higher in autumn m cf. spring - What is the fate of this deep peak? BL decreases towards the East MS - consistent with previous studies where ANTARES and NESTOR sites were compared (Priede et al. 2008, Craig et al. 2009) Significant difference in BL between NEMO & NESTOR - 2-3x higher at the NEMO site at depth m

Thanks to: Harilaos Kontoyiannis (HCMR) and crew of the RV Aegaeo Gian Pietro Gasparini (CNR-ISMAR) and crew of RV Urania Francesc Sarda (ICM-CSIC) and crew of RV Sarmiento de Gamboa KM3NeT Project UK Natural Environment Research Council Thank you! Acknowledgements

References Craig J, Jamieson A, Heger A, Priede I G (2009) Distribution of bioluminescent organisms in the Mediterranean Sea and predicted effects on a deep-sea neutrino telescope, Nuclear Instruments and Methods in Physics Research Section A, 602(1): doi: /j.nima doi: /j.nima Dussart B.H., Les différentes catégories de plancton, Hydrobiologia 26 (1965), pp. 72–74. Gillibrand E.J.V., Jamieson A.J., Bagley P.M., Zuur A.F., Priede I.G. (2007) Seasonal development of a deep pelagic bioluminescent layer in the temperate Northeast Atlantic Ocean. Marine Ecology Progress Series. 341: Heger, A In situ observations of bioluminescence in the deep sea: benthic and pelagic measurements in the Atlantic Ocean and Mediterranean Sea. PhD, University of Aberdeen Priede I G, Jamieson A, Heger A, Craig J, Zuur A F (2008) The potential influence of bioluminescence from marine animals on a deep sea underwater neutrino telescope array in the Mediterranean Sea, Deep Sea Research Part I, 55: doi: /j.dsr doi: /j.dsr Sieburth J.McN., V. Smetacek and J. Lenz, Pelagic ecosystem structure: heterotrophic compartments of the plankton and their relationship to plankton size fractions, Limnology and Oceanography 23 (1978), pp. 1256–1263.

NEMO TS