Mediterranean deep-sea ecosystems: Biodiversity, functioning and vulnerability = Ecosistemes profunds de la Mediterrània: Biodiversitat, funcionament i vulnerabilitat

[spa] En la presente tesis se han estudiado los patrones de biodiversidad, funcionamiento trófico y ecosistémico de los sistemas bentónicos de gran profundidad en el Mar Mediterráneo. El objetivo principal fue de describir y caracterizar los hábitats profundos, relacionando su biodiversidad y sus procesos de funcionamiento con los gradientes ambientales a lo largo de los ejes longitudinal, batimétrico y estacional. El estudio de la composición de comunidades y la respectiva recogida de muestras para los análisis tróficos se han realizado a través de arrastres profundos. Los resultados de análisis de composición de comunidades hallaron una correlación significativa entre las dinámicas de las capas oceánicas de superficie, la cantidad de alimento disponible en el fondo marino, y la composición de la megafauna estudiada. A escala reducida y considerando las variaciones estacionales, la biomasa bentónica mostró un patrón a U-invertida, con un pico a profundidades de 1000-1400 m. Una posible explicación de este fenómeno podría ser la combinación de forzajes ecológicos ligados a las diferentes distribuciones batimétricas de las especies. Para estudiar las relaciones tróficas en los ejes batimétricos y geográficos de gran escala, se utilizó el análisis de isotopos estables de las componentes bentónicas, de superficie, y de capas pelágicas intermedias. El amplitud de los nichos tróficos de las comunidades bentónicas se encontraron relacionados con indicadores de productividad de superficie, tanto primaria como secundaria. Asimismo, los procesos de utilización mesopelágica del carbono orgánico se hallaron en posición intermedia entre los de superficie y los del bentos profundo. Finalmente, un análisis ecosistémico a través de “Ecopath with Ecosim”, reveló que los ecosistemas de los taludes continentales del Mediterráneo son el resultado de un largo proceso de sucesión ecológica, han alcanzado un estado de estabilidad, y son particularmente vulnerables a factores de impacto humano, entre ellos, la explotación pesquera[eng] The Mediterranean Sea can be considered an excellent natural laboratory for benthic ecologists, due to its peculiar environmental conditions, its broad-scale gradients, and its deep-sea fauna. Primary production levels in the Mediterranean follow a longitudinal gradient, decreasing from west to east. The present thesis focused on the fine-mud benthos habitat of the Mediterranean Sea, on its bathyal and abyssal zones, and the compartment considered was demersal megafauna. The main objective of the present thesis was to describe and characterize the deep habitats of the Mediterranean Sea, relating their biodiversity and ecosystem functioning with the varying environmental conditions along the geographic, bathymetric, and temporal axes. The work was divided into four parts. In the first part, the patterns of distribution, biomass and abundance of bathyal and abyssal megafauna were studied, in relation with environmental variables, along longitudinal and bathymetric gradients. This was a large geographic scale study, across the three basins of the Mediterranean at depths of 1200-3000 m. Benthic biomass strongly decreased with depth and longitude (west-to-east). Results showed a significant correlation between the dynamics of surface layers, the amount of food available on the bottom, and the composition of benthos. In the second part, the seasonal fluctuations of benthic communities in the Catalan continental margin were observed. A highly replicated, multi-period study was conducted at depths of 900-1500 m. Total biomass followed an inverted U-shaped pattern, peaking at depths of 1050-1350 m. Range-related ecological forcings between shallower and deeper species may have caused this biomass accumulation at intermediate slope depths. The arrival of a new water mass from the deep basin to the slope in spring may have also driven an accumulation of biomass at 900-1050 m depth over the same period. An adjacent submarine canyon was also studied, comparing communities between the canyon and the open slope area. Analyses revealed higher diversity, but not biomass, inside the canyon than in the adjacent open slope, and a significantly different assemblage between the habitats. These results strengthen the concept of submarine canyons as hotspots of biodiversity and underline the importance of their conservation as diversity repositories. The third part is a study on trophic relations of deep-sea fauna, over the same large spatial transects considered in the first part, by means of natural-abundances stable isotopes analyses and the use of novel statistical methods to analyse heavy datasets all in once. Bulk-tissue d13C and d15N isotope ratios were analysed for benthic megafauna and associated surface and mesopelagic components from the 3 basins of the Mediterranean Sea. The trophic niche width and the amplitude of primary carbon sources were positively correlated with both primary and secondary surface production indicators. Moreover, mesopelagic organic matter utilization processes showed an intermediate position between surface and deep benthic components. Thus, both primary and secondary production processes taking place at surface layers are key drivers of deep-sea food web structuring. Finally, the fourth part integrates the whole collected dataset into the first ecotrophic model of a deep-water ecosystem in the Mediterranean Sea, evaluating the general ecosystem functioning as well as the degree of vulnerability of these ecosystems. The Ecopath with Ecosim approach was used to model the flows and biomasses of the Catalan Sea continental slope ecosystem at depths of 1000-1400 m. Network analysis identified low levels of consumer biomass cycling and low system omnivory index when compared with expected values of marine ecosystems, and higher cycling and omnivory when compared with available models of shallower areas of the Mediterranean. A simulation of the possible expansion of the red-shrimp benthic trawl fishery that currently operates at shallower depths, showed reductions in fish biomass and that the state of the deep continental slope ecosystem seems to be result of a long-term succession process, which has reached ecological stability, and is particularly vulnerable to human impact and, specifically, to fisheries exploitation

Submarine canyons in the Catalan Sea (NW Mediterranean): Megafaunal biodiversity patterns and anthropogenic threats

12 pages, 13 figuresThe continental margin of the Catalonia is crossed by several submarine canyons of different evolutionary history (Fig. 1) (Canals et al., 2004a). The main characteristic of the circulation pattern on the Catalan coast is a slope current referred to as the Northern current, which is associated with a shelf–slope density front that in this area flows mainly towards the southwest (Font et al., 1988). This baroclinic current separates the low-salinity shelf waters from the denser open-sea saline watersPeer reviewe

Relating nutritional condition and food of Anchovy Larvae (Engraulis encrasicolus, Linnaeus 1758) in the Gulf of Lions (North-Western Mediterranean)

Lavoro di internato condotto presso l’Institut de Ciències del Mar di Barcelona, analizzando il contesto del Golfo del Leone e considerando la specie E. encrasicolus (Linnaeus 1758), che rappresenta la specie pelagica economicamente più importante della regione Una prima analisi ha riguardato la valutazione della condizione nutrizionale delle larve e la loro comparazione per definire se vi fossero differenze rispetto a due periodi diversi di cattura (e quindi ad una diversa condizione trofica e oceanografica)

Ecosistemes profunds de la Mediterrània: Biodiversitat, funcionament i vulnerabilitat

Memoria de tesis doctoral presentada por Samuele Tecchio para optar al grado de Doctor en Biodiversidad por la Universitat de Barcelona (UB), realizada bajo la dirección del Dr. Francisco Sardà Amills y de la Dra. Eva Zoe Ramírez Llodra del Institut de Ciències del Mar (ICM-CSIC).-- 138 pagesThe deep sea is the portion of the ocean that stands below 200 m depth, both in the water column and in the benthos (Gage & Tyler 1991). It is the largest biome of planet Earth, with about 90% of the ocean area being deep sea (Ramírez-Llodra et al. 2010a). In the past decades, researchers have loved to refrain that “we know more about the surface of the Moon than about our deep oceans”. To date, this still holds true. The deep sea is considered impenetrable, difficult and expensive to reach and observe. [...]The author has been financed by a JAE pre-doctoral grant from the Spanish Research Council (CSIC), from December 2008 to November 2012. This work has been carried out in the framework of the following research projects: - BIOFUN (CTM2007-28739-E), from the European Science Foundation (ESF); - PROMETEO (CTM2007-66316-C02/MAR), from the CYCIT, Spain; - HERMIONE (G.A. 226354), from the European UnionPeer reviewe

Patrones de biodiversidad de la megafauna demersal del mar profundo en las cuencas occidental y central del Mediterráneo

10 pages, 5 figures, 3 tables[EN] Abundance, biomass and diversity patterns of bathyal and abyssal Mediterranean megafauna (fishes and invertebrates) were analyzed in the western Balearic Sea, the western Ionian Sea and the eastern Ionian Sea. Sampling was conducted with a Otter-trawl Maireta System (OTMS) at depths ranging from 600 to 4000 m. A series of ecological indicators were computed: total abundance and biomass, Margalef species richness, Shannon-Wiener diversity and Pielou’s index of evenness. A multidimensional scaling was applied, indicating that the megafauna communities were grouped by depth, while geographic area had a less defined influence. Margalef richness declined with depth in all three areas, but more steeply in the western Ionian Sea. Pielou’s evenness behaved differently in the three zones, showing a V-shaped curve in the eastern Ionian while showing a decreasing pattern in the other two areas. At lower slope depths, massive presence of the fishes Alepocephalus rostratus in the western basin and Bathypterois mediterraneus in the central basin caused a sharp reduction in evenness[ES] Se analizaron los patrones de abundancia, biomasa y diversidad de la megafauna (peces y invertebrados) batial y abisal del Mediterráneo. El muestreo se llevó a cabo con el Sistema de Arrastre Maireta a profundidades entre 600 y 4000 m, en el mar Balear occidental, el mar Jónico occidental y el mar Jónico oriental. Por cada pesca, se calculó una serie de indicadores ecológicos, después de estandardizar por el área de barrido: abundancia y biomasa totales, riqueza específica de Margalef, diversidad de Shannon-Wiener y el índice de equitatividad de Pielou. Se aplicó un multidimensional scaling (MDS) que indicó un agrupamiento de las comunidades de megafauna por profundidad, mientras que el área geográfica tiene una influencia menos definida. El índice de riqueza específica de Margalef disminuye con la profundidad en las tres áreas, pero de manera más pronunciada en el Mar Jónico occidental. La equitatividad de Pielou se comporta de manera diferente en las tres zonas, presentando una curva en forma de V en el Jónico oriental, y un patrón decreciente en las otras dos áreas. En el talud continental inferior, la presencia masiva de los peces Alepocephalus rostratus en la cuenca occidental y Bathypterois mediterraneus en la zona central causan una reducción drástica de la equitatividadThe authors wish to kindly thank the participants of the DESEAS project and the officers and crew of the R/V García del Cid. The DESEAS project was funded by EEC DG Fisheries Study Contract N. 2000/0039. ST is funded by a JAE-PRE-2008 grant from the CSlC, SpainPeer reviewe

Structure, functioning, and cumulative stressors of Mediterranean deep-sea ecosystems

International audienceEnvironmental stressors, such as climate fluctuations, and anthropogenic stressors, such as fishing, are of major concern for the management of deep-sea ecosystems. Deep-water habitats are limited by primary productivity and are mainly dependent on the vertical input of organic matter from the surface. Global change over the latest decades is imparting variations in primary productivity levels across oceans, and thus it has an impact on the amount of organic matter landing on the deep seafloor. In addition, anthropogenic impacts are now reaching the deep ocean. The Mediterranean Sea, the largest enclosed basin on the planet, is not an exception. However, ecosystem-level studies of response to varying food input and anthropogenic stressors on deep-sea ecosystems are still scant. We present here a comparative ecological network analysis of three food webs of the deep Mediterranean Sea, with contrasting trophic structure. After modelling the flows of these food webs with the Ecopath with Ecosim approach, we compared indicators of network structure and functioning. We then developed temporal dynamic simulations varying the organic matter input to evaluate its potential effect. Results show that, following the west-to-east gradient in the Mediterranean Sea of marine snow input, organic matter recycling increases, net production decreases to negative values and trophic organisation is overall reduced. The levels of food-web activity followed the gradient of organic matter availability at the seafloor, confirming that deep-water ecosystems directly depend on marine snow and are therefore influenced by variations of energy input, such as climate-driven changes. In addition, simulations of varying marine snow arrival at the seafloor, combined with the hypothesis of a possible fishery expansion on the lower continental slope in the western basin, evidence that the trawling fishery may pose an impact which could be an order of magnitude stronger than a climate-driven reduction of marine snow

Comparative ecological analysis of Mediterranean deep-sea ecosystems and simulations of global change

Conference and workshops Ecopath 30 years – Modelling ecosystem dynamics: beyond boundaries with EwE, 4-14 November 2014, Barcelona, Spain.-- 2 pages, 1 figureDeep-sea ecosystems need allochthonous energy for their functioning. Continuous sinking streams of particles and occasional, still unpredictable, point-like pulses of organic matter are the processes performing the required energy input. Productivity of the benthos is related with food availability or, more specifically, to marine snow input. Thus, as ocean waters have undergone a constant warming over the past century, the levels of primary productivity (and, by consequence, the marine snow input) have been observed to fluctuate with different patterns across the oceansWe thank the funding agencies and colleagues of the BIOFUN (CTM2007-28739-E) and PROMETEO (CTM2007-66316-C02) research projects, and the officers and crew of the R/V García del Cid and Sarmiento de Gamboa. ST was funded by a JAE-PRE-2008 pre-doctoral grant from CSIC, Spain, and co-financed by the European UnionPeer Reviewe

Trophic Dynamics of Deep-Sea Megabenthos Are Mediated by Surface Productivity

8 pages, 3 figures, 1 tableMost deep-sea benthic ecosystems are food limited and, in the majority of cases, are driven by the organic matter falling from the surface or advected downslope. Species may adapt to this scarceness by applying a wide variety of responses, such as feeding specialisation, niche width variation, and reduction in metabolic rates. The Mediterranean Sea hosts a gradient of food availability at the deep seafloor over its wide longitudinal transect. In the Mediterranean, broad regional studies on trophic habits are almost absent, and the response of deep-sea benthos to different trophic conditions is still speculative. Here, we show that both primary and secondary production processes taking place at surface layers are key drivers of deepsea food web structuring. By employing an innovative statistical tool, we interpreted bulk-tissue d13C and d15N isotope ratios in benthic megafauna, and associated surface and mesopelagic components from the 3 basins of the Mediterranean Sea at 3 different depths (1200, 2000, and 3000 m). The trophic niche width and the amplitude of primary carbon sources were positively correlated with both primary and secondary surface production indicators. Moreover, mesopelagic organic matter utilization processes showed an intermediate position between surface and deep benthic components. These results shed light on the understanding of deep-sea ecosystems functioning and, at the same time, they demand further investigationThis study was supported by the European Science Foundation BIOFUN project (CTM2007-28739-E), and the Spanish Ministry of Science and Innovation PROMETEO project (CTM2007-66316-C02/MAR). ST was funded by a JAE-PRE CSIC grant, and ERL was supported by a JAE-DOC CSIC postdoctoral grant, both with co-funding from the European Social Fund. JN was supported by a post-doc contract of the ‘‘Juan de la Cierva’’ program (Spanish Ministry of Economy and Competitiveness). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscriptPeer reviewe

Biodiversity patterns of deep-sea benthic megafauna on western and central Mediterranean basins

39th CIESM Congress, Venise, Italie.-- 1 page, 2 figuresAbundance, biomass and diversity patterns of bathyal and abyssal Mediterranean megafauna were analysed. Sampling was conducted with a bottom otter-trawl at depths ranging from 600 to 4000 m in the western Balearic Sea, the western Ionian Sea, and the eastern Ionian Sea. A general decline in diversity with depth along the three zones was found, while influence of geographic area was less markedPeer Reviewe

Rhythmic behaviour of marine benthopelagic species and the synchronous dynamics of benthic communities

11 pages, 7 figures, supplementary data associated with this article can be foundin the online version at https://doi.org/10.1016/j.dsr.2014.10.003Light-intensity cycles drive the relentless motion of species in the oceans, and water column migrants may cyclically make contact with the seabed, hence influencing the temporal dynamism of benthic ecosystems. The influence of light on this process remains largely unknown to date. In this study, we focus on the occurrence of day-night changes in benthic communities on the western Mediterranean continental shelf (100. m depth) and slope (400. m depth) as a potential result of a behaviourally sustained benthopelagic coupling. We analysed fluctuations in species abundance based on trawling at hourly intervals over a 4-day period as a proxy of activity rhythms at the seabed. We also measured light in situ to assess how the depth-related decrease of its intensity influences species rhythms and the occurrence of the putative benthopelagic synchronisation. Temporal similarities in the catch patterns for different species were screened by dendrogram analysis. On the continental shelf, species performing diel migrations (i.e., over a 24. h period) that were either vertical (i.e., benthopelagic) or horizontal across depths (i.e., nektobenthic) clustered together separately from the more sedentary endobenthic and epibenthic species. At the same depth, waveform analysis showed a significant diurnal increase in the catch of water column species and benthic species at night. Such coupling was absent on the continental slope, where light intensity was several orders of magnitude lower than that on the shelf. Our data indicate that diel activity rhythms, which are well known for vertical pelagic migrators, are also evident in the benthos. We discuss the role of light as a major evolutionary driver shaping the composition and biodiversity of benthic communities via visual predation. © 2014 Elsevier Ltd.This research was funded by the RITFIM project funded by the Spanish CICYT (CTM2010-16274). JA is a post-doctoral fellow of the Ramón y Cajal programme of the Spanish GovernmentPeer Reviewe