Biodiversity and ecological processes of mega and macrofauna along a trans-Mediterranean transect and comparisons with the Atlantic.

ICM-CSIC, UB, UPC, CEAB, IMEDEA-CSIC

Summary

The Mediterranean Sea is a unique system characterised by homeothermia and a steep gradient of increasing oligotrophy from West to East. The aim of BIOFUN is to characterise, under an ecosystem approach, two deep-sea habitats – the mid-slope and abyssal plain – including for the first time the analysis from viruses to megafauna, to understand the linkages between biodiversity patterns and ecosystem functioning in relation to environmental conditions along a gradient of increased oligotrophy from West to East.  

IP1 will undertake a multidisciplinary study in collaboration with other partners in BIOFUN to characterise the mid-slope and abyssal plains in the Mediterranean Sea along a longitudinal trophic gradient with increasing oligotrophic conditions from West to East and compared to the more productive Atlantic site. In particular, the overall aim of IP1 is to investigate the biodiversity of the megafauna (fish and invertebrates) and macrofauna and to understand the trophic structure and life cycle of key species in relation with the physical and geochemical environmental conditions as well as with the other faunal size-classes. This will allow describing patterns of distribution and ecosystem functioning, providing essential data to evaluate the vulnerability of the populations to fluctuations in food input as well as to anthropogenic impact such as fisheries or pollution.

 Work plan

Cruise: ICM-CSIC will lead a trans-Mediterranean cruise along a longitudinal gradient in order to sample habitats of differing environmental characteristics and food availability. The cruise will take place in summer 2009 and will sample the two main BIOFUN areas: the Algerian-Balearic Basin and the Ionian Sea at 1200 and 3000 m depth, as well as the Levantine Basin and the Messina Abyssal Plain (4100 m). This multidisciplinary cruise will characterise the water column (CTD) and the sediment (coring) and will sample for microbes, meio and macrofauna (multicorer) and megafauna (Agassiz trawl, OTSB and Epibenthic sled). The cruise will be coordinated in time and space with the other BIOFUN cruises and it will include the participation of other BIOFUN partners, to ensure integration of sampling in time and space, which will be essential for the trophic structure analyses. In addition, we will coordinate efforts with CEFREM for the characterisation of the hydrodynamic and physico-geochemical patterns of the NW Mediterranean slope. In particular, several 3 arrays of automated sediment traps and current meters will be deployed for two 6-month periods within the NW Mediterranean experimental sites.

BIOFUN main study sites: ABB, Algerian-Balearic Basin; MAP, Messina Abyssal Plain; IS, Ionian Sea; LB, Levantin Basin 

Anaylses:

1. Physical and geochemical studies: Total mass and major constituents (organic and inorganic carbon, opal, lithogenic material) will be determined for all sediment trap samples to provide a quantification of the basic features of settling material. Physical and sedimentological characteristics (grain size, dry bulk density, water content), major constituents and sedimentation rates will be analysed in the sediment samples to provide a balance between sinking material and deposited material.

2. Biodiversity, biomass and abundance of mega and macrofauna will be quantified from trawl, sledge and corer samples and statistical comparisons will be made between sites.

3. Trophic studies will be conducted by analysing stomach contents and using biomarkers and stable isotope analyses in key megafauna species.

4. Life histories will be studied with histology, microscopy and image analyses will be used to determine gametogenetic cycles, while fecundity will be quantified.

5. Ecological models will be developed using data generated from field work.

6. Determination of contaminants will be conducted using gas chromatography coupled with mass spectrometry and ion selection mode.