First Results of Zooplankton and Fish Studies. B. Christiansen, Anneke Denda, Henrik Christiansen

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1 Cruise Maria S. Merian 14/1: Structure and Function of Pelagic and Benthic Communities of the Eastern Mediterranean in Relation to Physical Drivers and Bottom Topography First Results of Zooplankton and Fish Studies B. Christiansen, Anneke Denda, Henrik Christiansen

2 Some topics of the cruise Long-term study of the pelagic communities of the Levantine Basin: Effects of the EMT Influence of Eratosthenes Seamount on the surrounding water masses and the role of its interaction with the quasi-stationary eddies Influence of eddies on the productivity of the seamount Possible influence of local seamount effects (Taylor caps, upwelling, permanent fronts) on pelagic fauna (food supply, retention) Role of vertically migrating zooplankton for the food supply of seamount communities Can Eratosthenes Seamount be regarded as biodiversity hotspot?

3 Participating institutions DZMB Senckenberg am Meer, Abteilung DZMB, Wilhelmshaven/Hamburg, Germany HCMR Hellenic Centre for Marine Research, Dept. of Deep-Sea Ecology, Heraklion, Greece OC-UCY Oceanography Centre, University of Cyprus, Nicosia, Cyprus SAMS Scottish Association for Marine Science, Oban/Scotland, UK UHH-IHF Universität Hamburg, Institut für Hydrobiologie und Fischereiwissenschaft, Hamburg, Germany URO Universität Rostock, Institut für Aquatische Ökologie - Meeresbiologie, Rostock, Germany vti Johann Heinrich von Thünen-Institut, Institut für Fischereiökologie, Hamburg, Germany

4 Study areas: Levantine Basin, Eratosthenes Seamount Sampling box 1: Ierapetra Deep 33 Sampling box 2: Eratosthenes Seamount

5 Eratosthenes Seamount: Sampling stations

6 Preliminary results: Zooplankton Relative composition of zooplankton at Eratosthenes Seamount based on abundance data. Top: water column ( m); bottom: depth stratified Copepoda are the by far dominating zooplankton group, making up more than 80% of all zooplankton Among the Copepoda, Calanoida are predominating Apart from Copepoda, only Ostracoda and Chaetognatha reach significant shares with 4-6% Gelatinous organisms (Cnidaria, Thaliacea, Appendicularia) play a minor role Vertical differences in zooplankton composition are small. Cyclopoida have highest shares above 200 m; Ostracoda and Chaetognatha below 200 m Depth interval /m Relative share /%

7 Preliminary results: Zooplankton Horizontal distribution of zooplankton standing stocks (biomass) in the upper 1000 m along a north-south transect N=2 differences between locations are generally small trend for lower standing stocks above seamount as compared to base region indication for enhanced biomass at the northern rim station (arrow), probably affected by the core of the Cyprus eddy

8 Vertical distribution of zooplankton biomass concentration in the upper 1000 m. Top: mean of all stations; bottom: Station 1101 (northern rim) biomass concentrations are highest in the upper 100 m and generally decrease with depth Station 1101 (northern rim) in the vicinity of the Cyprus eddy core differs from all other stations and shows high biomass concentrations also in the mesopelagic layer The high biomass at depth at station 1101 leads to a higher standing stock in the water column ( m) as compared to the other stations Preliminary results: Zooplankton

9 Preliminary results: fish A total of 11 fish species in 8 families were caught with longlines and trawls Most fish were caught in very low numbers The catshark Galeus melastomus was predominant in longline catches on the summit of Eratosthenes Seamount The tripod fish Bathypterois spp. were predominant in trawl catches on the upper slope The most abundant fish in trawl catches on the bathyal plain north of Eratosthenes was the rattail Chalinura mediterranea Bathypterois sp. Galeus melastomus Cataetyx laticeps

10 Conclusions The standing stocks of zooplankton and fish at Eratosthenes Seamount are very low There are no indications for an enhanced zooplankton biomass above Eratosthenes Seamount as compared to the surrounding ocean The Cyprus eddy probably affects the vertical distribution and standing stock of zooplankton The diversity of zooplankton and fish was low, as is typical for the eastern Mediterranean. An effect of Eratosthenes Seamount on the biodiversity of zooplankton and fish could not be observed, but this has to be confirmed by detailed taxonomic analyses The relatively high catch numbers of ripe demersal sharks Galeus melastomus above the top of Eratosthenes Seamount indicate that this may a reproductive area for this species and possibly also for the deep-water shark Etmopterus spinax