PERMANOVA analyses for differences in meiofaunal community structure. Spatial variation of meiofaunal abundance in the Blanes submarine Canyon along a bathymetric gradient Sara Román 1* , Chiara Romano 1 , Marta Segura 1 , Ann Vanreusel 2 , Daniel Martin 1 1 Centre d’Estudis Avançats de Blanes (CEAB – CSIC9, c/ Accés a la Cala St. Francesc, 14, E-17300 Blanes, Spain 2 Ghent University, Department Biology, Marine Biology research group, Krijgslaan 281 S8, B-9000, Ghent, Belgium Email: sara.roman@ceab.csic.es 3. RESULTS Acknowledgements: We gratefully thank the other teams of the project and the crew of the R/V Garcia del Cid for helping during the cruises. The present work was developed within the framework of the DOS MARES Project (CTM2010-21810-C03-03). 1. INTRODUCTION Submarine canyons are hotspot of benthic biomass and productivity in the deep-sea (e.g. Gilli et al., 2000; Granata et al., 2004, De Leo et al. 2010) and play a significant role on the exchanges of energy and matter between shelf and open sea. The Blanes submarine Canyon (NW Mediterranean sea) deeply incise the continental slope and shelf (Amblas et al., 2006) and acts as a preferential conduit for the transport of particulate material towards open sea (Zuniga et al 2009). Meiofaunal communities are responsible for a significant amount of sediment remineralisation and support significant trophic pathways (Leguerrier et al., 2003) and have been scarcely studied in Blanes Canyon (Romano et al., 2013; Ingels et al., 2013). The aim of this study was to investigate changes in the meiofauna in a depth gradient along the canyon and its relationships with the sediment biogeochemistry to understand the main driving factors controlling their assemblages . 4. CONCLUSIONS -A total of 19 meiofaunal taxa were found. Nematoda was always the dominant group (87-95%) followed by Copepoda (2-5%) and Nauplius larvae (1-4%). -Meiofaunal communities were affected by both sediment layers and depth. - Overall, the first sediment layers are much more similar than the deeper layers and contained a significantly more number of specimens. - The abundance was higher at 500 m and tended to decrease with depth. -The sediment was mainly fine-grained hemipelagic mud with a high silt content. - This preliminary study showed a noticeably high heterogeneity in meiofaunal abundance among replicates at each depth in Blanes Canyon, which may prevent to distinct clear bathymetrical patterns. -Along the canyon axis the contents of clay, TN and Chl-a were the main contributors in explaining meiofaunal assemblage distribution. Sediment descriptors 2. MATERIAL AND METHODS Samples for meiofaunal and biogeochemical analyses were collected with a multi-corer in Autumn 2012 during the DosMares-II cruise aboard of the R/V García del Cid. We analyzed data at six different depths along the canyon axis: 500, 900, 1200, 1500, 1750 and 2000 m deep. Two-three replicate corers were taken at each depth, being each corer divided in three sediment layers (0-1, 1-2 and 2-5 cm depth). Meiofaunal organisms were extracted by the LUDOX flotation method (Vincx, 1996) and counted and classified at higher taxon level under stereomicroscope. Sediment descriptors were grain size distribution, measured with a Malvern Mastersizer 2000 (0.02-2000 µm); organic carbon (OC) and nitrogen (TN) concentrations, measured using an elemental analyzer EA Flash series 1112 and NA2100; and chloroplastic pigments (Chlorophyll a,Chl-a, and phaeopigments), extracted in 90% acetone and separated using UPLC (Ultra Performance Liquid Chromatography). Relation between Meiofauna and Sediment Descriptors References: - Amblas D, Canals M, Urgeles R, Lastras G, Liquete C, et al. (2006). Marine Geology, 234: 3–20. - De Leo FC,Smith CR, Rowden AA, Bowden DA, Clark MR (2010) Proccedings of the Royal Society B: Biological ciences. - Gili J.M, Pagès F, Bouillon J, Palanques A, et al. (2000) Deep-Sea Research I, 47: 1513–1533. - Granata TC, Estrada M, Zika U, Merry C (2004) Scientia Marina, 68 (Suppl. 1): 113–119. - Zuñiga D , Flexas MM, Sanchez-Vidal A, et al.(2009). Progress in Oceanography, 82: 239–251. - Leguerrier D, Niquil N, Boileau N, Rzeznik J, et al. (2003) Marine Ecology Progress Series, 246:17‑37. - Vincx M (1996) In: Hall GS, ed. CAB International, University Press, Cambrigde, pp 214-248. - Ingels J, Vanreusel A, Romano C, et al. (2013). Progress in Oceanography 118: 159-174. - Romano C, Coenjaerts J, Flexas MM, Zuñiga D, et al. (2013) Progress in Oceanography 118: 144-158. 2-5 1-2 0-1 -- 2-5 1-2 0-1 -- 2-5 1-2 0-1 -- 2-5 1-2 0-1 -- 2-5 1-2 0-1 -- 2-5 1-2 0-1 0 20 40 60 80 100 2000 1750 1500 1200 900 500 Sand (%) Silt (%) Clay (%) Source df SS MS Pseudo-F P(perm) Unique perms Depth 5 5506,2 1101,2 19,119 0,0349 9921 Layer 2 17085 8542,5 14,831 0,0001 9954 DepthXLayer 10 7674,5 767,45 13,324 0,1381 9889 Res 33 19008 576 Total 50 50753 Source df SS MS Pseudo-F P(perm) Unique perms Depth 5 5506,2 1101,2 19,119 0,001 9917 Layer 2 17085 8542,5 14,831 0,0316 9928 Depth x Layer 10 7674,5 767,45 13,324 0,9378 9875 Res 33 19008 576 Total 50 50753 Variable SS (trace) Pseudo-F P Prop. Clay 13930 18,536 0,0001 0,27446 Silt 2010,1 2,0228 0,1207 3,9645E-2 Sand 2233,1 2,2552 0,0938 4,3999E-2 TN 5218,3 5,6154 0,0063 0,10282 OC 2620,9 2,6681 0,0613 5,164E-2 Chl-a 5212,8 5,6088 0,0059 0,102271 500 m 900 m 1200 m 1500 m 1750 m 2000 m Abundance (ind.10cm -2 ) 0 500 1000 1500 2000 Chl a ( m g/g) 0.00 0.01 0.02 0.03 0.04 0.05 0.06 TN (%) 0.08 0.10 0.12 0.14 0.16 Meiofauna abundance (ind. 10cm -2 ) Nematoda abundance (ind. 10cm -2 ) Chl a (m g/g) TN (%) DISTLM results based on the meiofauna abundance data and sediment descriptors. PERMANOVA analyses for differences in sediment descriptors. Metazoan meiofauna y = 17072 x -0.397 R² = 0.337 0 500 1000 1500 2000 0 500 1000 1500 2000 2500 92% 2% 3% 1% 2% Nematoda Nauplii Copepoda Polychaeta Other taxa Abundance (ind.10cm -2 ) Non-metric MDS plots based on meiofaunal abundances. Principal component analysis (PCA) ordination based on sediment decriptors. PC1=39.9% and PC2=68.2%. -4 -2 0 2 4 PC1 -4 -2 0 2 4 PC2 Depth 500 900 1200 1500 1750 2000 Clay Silt Sand TN OC Chla CPE Transform: Square root Resemblance: S17 Bray Curtis similarity Layer 0-1 1-2 2-5 2D Stress: 0.07 a Transform: Square root Resemblance: S17 Bray Curtis similarity Depth 500 900 1200 1500 1750 2000 500 500 900 900 900 1200 1200 1500 1500 1500 1750 1750 1750 2000 2000 2000 2D Stress: 0.09 b View publication stats View publication stats