Use of stable isotope signatures (δ13C & δ15N) in the Black Sea Danubian area – new approach for understanding the influence of terrestrial discharge upon the marine ecosystem

Abstract. Coastal marine zones located in front of large rivers are of major biological interest. In these areas, the origin of the organic matter is complex and highly variable. The continental inputs, added to the nutrients already present in the marine environment, influence considerably the productivity and functioning of the ecosystems. Used for the first time in aquatic ecology on the Romanian coast, the proportion of stable isotopes of carbon (13C/12C) and nitrogen (15N/14N) allowed the identification of the organic material sources (terrestrial and marine) as well as the analysis of the food webs due to the predictable isotopic relation between consumers and their food. Preliminary analyses of stable isotopes of the particulate organic matter POM of the Danube water as well as marine POM, sediments and marine organisms were made on 186 samples collected at 10 stations in October 2004. The identification of the isotopic signatures of the main sources of organic material (terrestrial and marine) was achieved along with those of some groups of marine organisms present in this area (macrophytes, bivalves, polychaetes, amphipods, macrurans, brachyurans and fish). The results obtained in the Black Sea were compared with those of the Mediterranean Sea seawards the Rhone river and showed that the isotopic signatures of the two river POM were close to each other, whereas they largely differed in marine phytoplankton and macrophytes

Ecosystem-based assessment of a widespread Mediterranean marine habitat: The Coastal Detrital Bottoms, with a special focus on epibenthic assemblages

IntroductionCoastal detrital bottoms (CDB) are one of the most extensive habitats of the continental shelf worldwide, in the upper levels of the circalittoral zone. Hosting a diverse community structured by sediment grain size, trophic interactions and calcified organisms, CDB exhibit important ecological functions. In the Mediterranean Sea, CDB are constituted by recent elements partly provided by adjacent infralittoral and circalittoral ecosystems. Since the 2010s, the offshore extension of many Marine Protected Areas (MPAs) has resulted in the incorporation of vast areas of CDB, raising the issue of their management. The Marine Strategy Framework Directive (MSFD) has embraced the concept of an ecosystem-based approach involving taking into account the functioning of marine habitats and their related ecosystem services. The purpose of this paper is to propose an ecosystem-based quality index (EBQI) tested on CDB from the north-western Mediterranean Sea, focusing mainly on epibenthic assemblages.MethodsThe first step has been to define a conceptual model of the CDB functioning, including the main trophic compartments and their relative weighting, then to identify appropriate assessment methods and potential descriptors. Twenty-nine sites were sampled along the coast of Provence and French Riviera (Southern France). Study sites were chosen with a view to encompassing a wide range of hydrological conditions and human pressures.ResultsVery well-preserved sites were found in Provence in areas without trawling and terrigenous inputs, while impacted and low-ES sites were located in the vicinity of urbanized areas. The cover of rhodoliths characterizes the seascape and might be an indicator of the good ES of CDB and reduced human pressure. However, the absence of rhodoliths may also be induced by natural phenomena.DiscussionThe EBQI designed for CDB proved representative and useful for a functional assessment based on epibenthic assemblages. However, some descriptors have shown their limitations and should be further explored. We highlight here the priority of establishing an index corresponding to a societal demand (e.g., European Directives, Barcelona convention) as a basis for a broad and large-scale assessment, for practical reasons. We stress the need to better apprehend the role of the macro-infauna and to extend this index over a wider geographical scale

Feeding behaviour of Black Sea bottom fishes: Did it change over time?

2nd Joint European Stable Isotope User Meeting (JESIUM), Presquile de Giens, FRANCE, AUG 31-SEP 05, 2008International audienceThis Study was designed to improve knowledge in feeding behaviour of the round goby (Apollonia melanostomus (Pallas, 1814)), the red mullet (Mullus barbatus ponticus Essipov, 1927), the whiting (Merlangius merlangus (Linnaeus, 1758)), the flounder (Platichthys flesus (Linnaeus, 1758)), the sole (Solea solea (Linnaeus, 1758)), the turbot (Psetta maeotica (Pallas, 1814)) and the starry Sturgeon (Acipenser stellatus Pallas, 1771) from the north-western Black Sea. Gut content coupled with stable isotope analysis allowed describing food web variations according to species, in two seasons and at two areas located seawards the Danube River. Present results showed that most fishes have likely changed their feeding behaviour compared to past studies from the same area. Trophic niches were reduced and dietary overlap was common, as different fish species consumed the same dominant prey types. Fishes probably adapted their feeding behaviour to the increasingly low biodiversity of the Black Sea communities. (C) 2009 Elsevier Masson SAS. All rights reserved

Trophic links and riverine effects on food webs of pelagic fish of the north-western Black Sea

International audienceImproving the knowledge of trophodynamics in coastal marine ecosystems is important for fisheries management. The present study was designed to assess the influence of Danube River inputs on Romanian coastal marine food webs of the European sprat (Sprattus sprattus), the European anchovy (Engraulis encrasicholus) and the horse mackerel (Trachurus mediterraneus). Gut content analyses coupled with carbon and nitrogen stable isotope analyses described food web variations with fish size, season and distance from the Danube delta. Sprats fed on zooplankton, horse mackerel fed on polychaetes and small fish, and anchovies had an intermediate diet. The delta(13)C and delta(15)N ratios and mean trophic levels increased from sprats to anchovies and then to horse mackerel. Season strongly influenced the delta(15)N values of the three fishes, with lower values in spring than in autumn linked to higher Danube inputs into coastal waters in spring during the flooding period. Fish condition was related to diet and environmental factors, with higher conditions recorded in the north area in autumn and in the south area in spring. Danube River inputs influenced the diet, stable isotope ratios and condition of the main commercial pelagic migratory fishes of the north-western Black Sea

Spatial and temporal variations of stable isotope (delta C-13 and delta N-15) signatures of Danube waters and marine communities on the Black Sea Romanian coasts.

Encounters Ichthyology in France Conference, Paris, FRANCE, MAR 28-31, 2006International audienceCoastal marine zones located in front of large rivers are of major biological interest. The Danube is the second largest river in Europe after the Volga and represents 58% of the freshwater inputs to the Black Sea. Its delta, located between the North of Romania and the South of Ukraine, has a great impact on the sedimentation and marine ecosystems in the Black Sea. The objective of the present study was to estimate the impact of the seasonal fluctuations of the Danube particulate organic matter (POM) on the various marine trophic compartments (POM sea water, sediment, macro-invertebrates and fish) along the Romanian coasts. The ratios of the stable isotopes of carbon (C-13/C-12) and nitrogen ((15) N/N-14) allowed the identification of organic matter sources and the analysis of trophic webs. 670 analysis of stable isotopes of the particulate organic matter (POM) of the Danube water as well as marine POM, marine sediments and marine organisms (macrophytes, polychaetes, bivalves, gastropods, amphipods, macrurids, brachyurids and fishes) has been carried out on samples taken in 38 stations from the Northern, Central et Southern areas of the Romanian coasts in October 2004 and April-May 2005. The POM of the Danube presented average values of delta C-13 (-27.61 parts per thousand) and delta N-15 (4.39 parts per thousand), lower than those of the marine POM of the Black Sea (delta C-13 = -24.98 parts per thousand and delta N-15 = 7.08 parts per thousand). In the sea, the sediment presented average values decreasing from the North (delta C-13 = -20.02 parts per thousand and delta N-15 = 9.93 parts per thousand) to the South (delta C-13 = -23.59 parts per thousand, delta N-15 = 7.65 parts per thousand). Among invertebrates, stable isotope values depended on their trophic level and aptitude to consume the terrestrial POM brought by the river. The lowest values were found in polychaetes, copepods and amphipods, and the highest ones in macrurids, brachyurids and gastropods. Among the fish species studied, the lowest values of delta C-13 and delta N-15 were observed in starry sturgeon (Acipenser stellatus ponticus) and sprat (Sprattus sprattus), while the highest values was found in beluga sturgeon (Huso huso). These differences were explained mainly by differences in diet. Preliminary results showed a strong influence of the Danube particulate organic matter on the marine compartments of the Romanian coasts. The river influence decreased from the North to the South and was higher in spring when the river was flooding

Première capture de Fistularia commersonii Rüppell, 1838 dans la baie de Marseille (France, Méditerranée nord-occidentale).

International audienceLe poisson flûte est considéré comme le champion des invasions lessepsiennes. Dans les années 2000, après une croissance exponentielle de ses populations en Méditerranée orientale, il est devenu très abondant dans les débarquements des pêcheries de cette région. Dans cette étude est signalée la première capture de deux individus de poisson flûte dans la baie de Marseille (France, Bouches du Rhône) en octobre 2016, constituant la capture avérée la plus nord-ouest de la Méditerranée. Cette espèce est un prédateur piscivore très actif. L'individu échantillonné, une femelle de 99 cm LT, avait consommé 6 poissons appartenant à 3 genres : Spicara, Symphodus et Atherina

Spatial and temporal variations of stable isotope (delta C-13 and delta N-15) signatures of Danube waters and marine communities on the Black Sea Romanian coasts.

Encounters Ichthyology in France Conference, Paris, FRANCE, MAR 28-31, 2006International audienceCoastal marine zones located in front of large rivers are of major biological interest. The Danube is the second largest river in Europe after the Volga and represents 58% of the freshwater inputs to the Black Sea. Its delta, located between the North of Romania and the South of Ukraine, has a great impact on the sedimentation and marine ecosystems in the Black Sea. The objective of the present study was to estimate the impact of the seasonal fluctuations of the Danube particulate organic matter (POM) on the various marine trophic compartments (POM sea water, sediment, macro-invertebrates and fish) along the Romanian coasts. The ratios of the stable isotopes of carbon (C-13/C-12) and nitrogen ((15) N/N-14) allowed the identification of organic matter sources and the analysis of trophic webs. 670 analysis of stable isotopes of the particulate organic matter (POM) of the Danube water as well as marine POM, marine sediments and marine organisms (macrophytes, polychaetes, bivalves, gastropods, amphipods, macrurids, brachyurids and fishes) has been carried out on samples taken in 38 stations from the Northern, Central et Southern areas of the Romanian coasts in October 2004 and April-May 2005. The POM of the Danube presented average values of delta C-13 (-27.61 parts per thousand) and delta N-15 (4.39 parts per thousand), lower than those of the marine POM of the Black Sea (delta C-13 = -24.98 parts per thousand and delta N-15 = 7.08 parts per thousand). In the sea, the sediment presented average values decreasing from the North (delta C-13 = -20.02 parts per thousand and delta N-15 = 9.93 parts per thousand) to the South (delta C-13 = -23.59 parts per thousand, delta N-15 = 7.65 parts per thousand). Among invertebrates, stable isotope values depended on their trophic level and aptitude to consume the terrestrial POM brought by the river. The lowest values were found in polychaetes, copepods and amphipods, and the highest ones in macrurids, brachyurids and gastropods. Among the fish species studied, the lowest values of delta C-13 and delta N-15 were observed in starry sturgeon (Acipenser stellatus ponticus) and sprat (Sprattus sprattus), while the highest values was found in beluga sturgeon (Huso huso). These differences were explained mainly by differences in diet. Preliminary results showed a strong influence of the Danube particulate organic matter on the marine compartments of the Romanian coasts. The river influence decreased from the North to the South and was higher in spring when the river was flooding

Otolith shape analysis of three gobiid species of the Northwestern Black Sea and characterization of local populations of Neogobius melanostomus

International audienceThe present study describes the otolith shape and age of three species of Gobiidae: Neogobius melanostomus (Pallas, 1814), Ponticola eurycephalus (Kessler, 1974) and Mesogobius batrachocephalus (Pallas, 1814) from the Western part of the Black Sea. These phylogenetically close species showed otolith shape differences. The round goby, Neogobius melanostomus, showed differences in otolith shape between local populations, probably related to differences in diet and environmental variability influenced by the Danube River inputs in the North of the study area. The age of these commercially exploited species was estimated by otolith microstructural analysis and the results were linked to sex, size and weight. This information is valuable for fishery management purposes

Le choix alimentaire des sardines

International audienc