New field methodological approaches for the study of benthic boundary layer (BBL) biodiversity

P. Koulouri, C. Arvanitidis, D. Koutsoubas,C. Dounas & A. Eleftheriou

Institute of Marine Biology & Genetics (IMBG, www.marbigen.org)Hellenic Centre for Marine Research (HCMR, www.hcmr.gr)E-mail: yol72@her.hcmr.gr

Over the last decade... many facets of benthic research have been accompanied by significant technological research in acoustic techniques, deep-sea technology, diving techniques..Yet in contrast, a slowdown in technological progress on macrofauna techniques and a scarcity of ideas in technical and methodological issues, with research relying on established methods. One can hardly come to the conclusion that the existing methodology concerning sampling of an extremely complex environment has reached any degree of perfection.

A. Eleftheriou & A. D. McIntyre (eds), 2005. Methods for the study of Marine Benthos. 3rd Edition.

epi-benthosSediment-water interfaceBenthic Boundary LayerinfaunaWater columnBIODIVERSITY OF BENTHIC BOUNDARY LAYER (BBL) MACROFAUNA Hyperbenthic sledges have been used over the last 30 years, but there are still practical difficulties to sample efficiently at the sediment-water interface, thus underestimating BBL biodiversity.hyper-benthos zooplankton BBL species constitute an important link in marine food webs as consumers of detritus particles and associate microbes, meiobenthos and plankton and as prey for demersal fish, epibenthic crustaceans and cephalopods.

Benthic sledge of Shand & Priestley (1999)Development of innovative methodologies in order to investigate the effects of bottom trawling on benthic nutrient fluxes , sediment biogeochemistry and BBL macrofauna (DG. XIV, Studies for the support of CFP)TOWED TRAWL SIMULATOR SLEDGE (TTSS1)Dounas et al., 2007. Continental Shelf Research, 27: 2198-2210.Dounas C., 2006. Journal of Experimental Marine Biology & Ecology, 339: 251-259.Dounas et al., 2004. American Fisheries Society Symposium, 41: 539-544.

TOWED TRAWL SIMULATOR SLEDGE (TTSS2)Koulouri et al., 2009. Journal of Plankton Research, 31 (7): 753-762.Koulouri et al., 2004. American Fisheries Society Symposium, 41: 529-537.Koulouri et al., 2003. Journal of Marine Biological Association U.K., 83: 1363-1368.TTSS2 is designed to artificially resuspend the surface sediment and sample at the same time, in addition to the BBL species collected by the typical hyperbenthic sledges, the macrofaunal organisms residing on or just above the sediment-water interface.

HYPERBENTHIC SLEDGE (HS)

Some more . . .technical details . . .

Application of the TTSS2 and traditional benthic, hyperbenthic & planktonic samplers in the continental shelf of the Cretan SeaWP2 plankton net (16, S=13 m3)Smith-McIntyre grab (10, S=0.1 m2)Hyperbentic Sledge (17, S=290 m2)TTSS2 (28, S=29 m2)1st experimentUSNL box corer (16, S=0.1 m2)Tselepides et al., 2000

species exclusively present in the samplerSpecies richness (S)ES (100)Stress: 0.02 ANOSIM test: R=0.99, p

Smith-McIntyre grabTTSS2Dominant species collected by the TTSS2 and the benthic samplers* species exclusively present in the samplerUSNL box corer% = relative density

2nd experimentBathymetric distribution of BBL macrofauna in the continental shelf and upper slope of the Cretan SeaHSTTSS2Almost ALL of the macrofaunal species living in the BBL were found to reside at the sediment-water interface.

Species richness (S)HS, S=290 m2TTSS2, S=29-116 m2ES (100)Macrofaunal groups

Dominant species residing at the sediment-water interface50 m100 m200 m300 m% = relative density

Diet of demersal and bentho-pelagic fish and BBL macrofaunal diversity in the continental shelf of the Cretan Sea zooplanktonhyperbenthos infauna epibenthos3rd experiment

Conclusions . . . The application of special hyperbenthic sledges modified to resuspend the surface sediment, such as TTSS2, seems to be more suitable than typical hyperbenthic sledges for studying BBL macrofaunal diversity at least in oligotrophic shelf and upper slope areas. Further development and application of TTSS2 in other continental shelf and slope areas could be an effective tool in order to describe trophic interactions within the BBL habitat. BBL biodiversity comprises a mixture of taxa with different ecological habits and distribution patterns near the bottom and therefore complementary information derived from both traditional and novel sampling techniques is essential.

***************