Patrick Dauby

University of Liège | ulg · Unit of Systematics and Animal Diversity

In Antarctica, amphipods form a highly diverse group, occupy many different ecological niches and hold an important place in food webs. Here, we aimed to test whether differences in Antarctic amphipod feeding habits were reflected in their mandible morphology, and if mouthpart specialization could be used to describe amphipod trophic ecology. To do...

Mediterranean Posidonia oceanica meadows shelter an important biomass and biodiversity of amphipod crustaceans that graze on epiphytes. However, their actual significance for ecosystem functional processes is hard to estimate, due to the lack of adequate data. Here, a field microcosm-based inclusion experiment was used to test if three of the domin...

Nitrogen, carbon and sulfur stable isotopes are very powerful tools for trophic ecologists to delineate food webs of various ecosystems. More recently… the use of mixing models has exponentially increased to give a more specific vision of organism’s diets and trophic relationships. Two case studies will be presented to give a summary of what’s bee...

In Mediterranean exported seagrass macrophytodetritus accumulations, a diverse (more than 130 species) and abundant (up to 4900 id.m-2) macrofauna assemblage is found alongside meiofauna, microalgae, fungi and bacteria. Macrophytodetritus are mainly composed of poorly digestible yet highly colonized material: the dead leaves of the very productive...

Gut content examination and trophic markers (fatty acids, stables isotopes of C and N) were combined to delineate the diet of the dominant species of amphipods from Mediterranean Posidonia oceanica seagrass meadows and to highlight trophic diversity among this community. Our results indicate that, although all dominant species heavily relied on mac...

Posidonia oceanica is an endemic Mediterranean highly productive seagrass. Depending on the ability of the primary consumers to digest it alive, a generally important part of its foliar primary production falls in autumn, to decay inside the meadow or to be exported to sand patches to form “exported litter accumulations”. These accumulations are hi...

Seagrass ecosystems are extensive beds of marine flowering plants bordering tropical and temperate coastal regions. They play an important role in maintaining biological productivity and bio-geochemical cycles in the sea and support higher diversity and abundance of fauna in comparison to adjacent non-vegetated areas. The seagrass meadow primary pr...

Mediterranean Posidonia oceanica meadows shelter a high biomass and an important biodiversity of amphipod crustaceans. In other temperate meadows, the amphipods play an important part in the functioning of the ecosystem, notably in organic matter transfers from producers to higher level consumers. However, the situation in Posidonia oceanica meadow...

In the Mediterranean Sea, Posidonia oceanica meadows produce a huge amount of detritus, evaluated up to 300 to 2000 g dry wt m-2 yr-1. This litter is mainly composed of dead leaves but also of uprooted P.oceanica shoots and drift macro-algae from adjacent rocky bottoms. Although rich in refractory materials (lignin) and poor in P and N, these under...

Posidonia oceanica is a seagrass endemic to the Mediterranean Sea, and is able to form large monospecific areas, called meadows. These meadows shelter high biomasses and biodiversities of amphipod crustaceans. Moreover, It is now established that several species of these amphipods feed on the macro-epiphytes present on the leaves of the seagrass....

The purpose of this work was the evaluation of the trophic structure, diversity and small scale variation of macro organisms associated with Posidonia oceanica litter in the bay of Calvi (Corsica). Gammaridean Amphipods largely dominate our samples and G. fucicola accounts for 55% of the whole sample. Differences we observed between diversity and...

It is now established that several species of amphipods associated to Mediterranean Posidonia oceanica meadows consume the macro-epiphytes present on the leaves of the seagrass. Moreover, under controlled in vitro conditions, three amphipod taxa (Apherusa chiereghinii,Dexamine spiniventris and Gammarus spp.) are able to drastically deplete the biom...

Meiofaunal communities of the endemic Mediterranean seagrass, Posidonia oceanica , were sampled in five different habitats characterised by different degradation level of macrophytodetritus. In term of abundance, harpacticoid copepods represent half of the community followed by nematodes and polychaetes. Two meiofauna communities were distinguished...

It is now established that several species of amphipods associated to Mediterranean Posidonia oceanica meadows consume the epiphytes present on the leaves of the seagrass. However, little or no work has been undertaken to quantify this interaction. Here, we present the results of an in vitro experiment that used seagrass mimics to estimate the impa...

Efficient sampling of amphipod crustaceans associated with Posidonia oceanica (L.) Delile meadows is difficult, due to their complex community structure and to the heterogeneity of the meadows. Here we compare three sampling techniques: the hand-towed net, the air-lift, and light traps. Each of the methods shows specific advantages and disadvantag...

Posidonia oceanica is a seagrass endemic to the Mediterranean Sea, and is able to form large monospecific areas, called meadows. These meadows are critical features of the Mediterranean coastal zones, and are of great ecologic and economic importance. Posidonia oceanica meadows shelter high biomasses and biodiversities of amphipod crustaceans. In...

Amphipods are one of the most diverse and abundant taxa of vagile invertebrates associated to Mediterranean Posidonia oceanica meadows. Therefore, they likely play an essential part in those ecosystems’ functioning, notably in organic matter transfers from producers to higher level consumers. Nevertheless, their trophic ecology remains poorly known...

Vagile invertebrates are regarded as key-components of Posidonia oceanica meadow ecosystems, particularly in organic matter transfers from primary producers to higher level consumers. Among these invertebrates, amphipod crustaceans are one of the most abundant and diverse groups, and probably play an important role in meadow ecosystem functioning....

In seagrass meadows, several groups of vagile invertebrates are well known to perform a nocturnal rise from the lower layers of the meadow to the foliar stratum. This vertical migration is generally regarded as a defense mechanism against predation by diurnal fishes, as well as a mean to maximize the exploitation of trophic resources offered by the...

At least 17,000 km separate the endemic Mediterranean Posidonia oceanica (L.) Delile from the eight other species of the same genus (P. angustifolia Cambridge and Kuo, P. australis Hooker, P. coriacea Kuo and Cambridge, P. denhartogii Kuo and Cambridge, P. kirkmanii Kuo and Cambridge, P. ostenfeldii Den Hartog, P. robertsoniae Kuo and Cambridge, an...

This study focused on the ingestion and assimilation of Posidonia oceanica (L.) Delile litter by Gammarella fucicola Leach and Gammarus aequicauda Martynov, two dominant detritivore amphipods of the P. oceanica leaf litter. Scanning electron microscope observations indicated that leaf litter is highly colonized by diverse diatoms, bacteria and fung...

The discrepancy between the ecological significance of amphipods in the Antarctic and our poor knowledge of their ecofunctional role calls for a more detailed investigation of their trophic status in this ecosystem. A total of 12 amphipod species from suspension feeder to scavenger have been considered in this study. Our objective was to investigat...

Stable isotopes of carbon and nitrogen are increasingly used in marine ecosystems, for ecological and environmental studies. Here, we examine some applications of stable isotopes as ecological integrators or tracers in seagrass ecosystem studies. We focus on both the use of natural isotope abundance as food web integrators or environmental tracers...

Peracarid crustaceans form a significant part of the macrobenthic community that is responsible for scavenging on large food falls onto the sea floor. Although several studies are available about scavengers from tropical and temperate seas, very little information has been published about such species living in Antarctic waters, particularly at gre...

By using the stable isotope 15N, we have measured in situ the uptake of nitrate and ammonium by the seagrass Posidonia oceanica, its leaf epiphyte community, the brown macroalgae Halopteris scoparia and the suspended particulate organic matter (SPOM). In Revellata Bay (Gulf of Calvi, Western Corsica), which is a very nutrient-poor region, the speci...

Nitrogen (δ15N) and carbon (δ13C) isotopic compositions of Posidonia oceanica were determined during three seasons along a bathymetric gradient (4-38 m depth). The δ15N values are low (2.2±0.9‰) and variable. They do not show any relation to depth or sampling dates. There is a significant difference between the δ15N values of the youngest and the o...

The accurate assessment of Antarctic biodiversity, the understanding of its ecofunctional role and the requirements for its conservation are recognized current priorities in the context of global environmental change and accelerating loss of biodiversity. Fauna and flora inventories, taxonomy and classification, processes driving the origin, mainte...

A one-year in situ experiment using 15N as a tracer was designed to assess the N recycling in the leaves of the seagrass Posidonia oceanica (L.) Delile. P. oceanica was shown to partly recycle the internal nitrogen pool of its leaves in order to contribute to new leaf growth. The leaves sampled in June 1999 contained 20% of the quantity of 15N foun...

The uptake of nitrate and ammonium by the roots and leaves of Posidonia oceanica were determined between February 1993 and June 1999 by in situ experiments using the isotope 15 of nitrogen (N-15) as a tracer in a nutrient-poor coastal zone of the NW Mediterranean Sea (Revellata Bay, Corsica). Nitrate and ammonium leaf uptakes are recorded at 0.05 a...

In order to assess the relative trophic importance of mangrove litterfall and aquatic primary production in the mangrove creeks of the Coringa Wildlife Sanctuary (Andhra Pradesh, India) and the adjacent semi-enclosed Kakinada Bay, carbon and nitrogen stable isotope ratios were determined in a variety of benthic invertebrate species collected at 22...

The new opportunity given by the underground gasifier developed at Alcorisa in Spain (Province of Teruel) in the framework of an European experiment has promoted a better understanding of gasification in a natural reactor. The thermodynamical equilibria of gasification reactions and the repartition of the stable isotopes of carbon (13C/12C) in the...

Stable isotope (13C/12C and 15N/14N) analyses were performed on 90 species belonging to different benthic communities sampled in the eastern Weddell Sea. The study focused on eight amphipod species whose isotopic composition was compared to their previously described respective gut contents. Amphipod stable isotope ratios correspond fairly accurate...

Antarctic amphipods from the Weddell Sea and Bransfield Strait were collected to investigate the impact of various species and feeding types on lipid and fatty acid compositions. In combination with digestive tract content analyses, such information can help clarify the type of feeding mode of the various amphipod species. Micro- and macropredatory...

As they represent one of the most diversified taxonomic groups on Antarctic bottoms, amphipods are likely to play a complex role in biogeochemical fluxes that occur within benthic ecosystems. The aim of this paper is to present, using both digestive tract analyses and relative species abundance data, the impact of amphipod feeding on different pote...

Increasing our limited knowledge of the marine biodiversity and distributing efficiently the biodiversity information are presently high priorities in the cont€xt of global change and ..biodiversity crisis". In the fiamework of the scAR EASIZ programme, ANT'PHIPODA' a ..Reference Centre for Antarctic Marine Biodiversity" devoted to amphipod crustac...

Amphipod crustaceans form one of the most diversified animal groups within the Antarctic macrozoobenthos, both from the taxonomic point of view (more than 800 species have been recorded in the Southern Ocean) as by niche occupation and at the community level. Thus, amphipods are likely to play an important role in the organic matter fluxes that occ...

Quantitative samples of benthos were taken on a stony beach (cobbles and pebbles) in the maritime Antarctic (Admiralty Bay, King George Island. South Shetland Islands) at low tide just below the water line, during a complete annual cycle. Macrobenthos consisted mainly of amphipods (ca. 860/o of total number), gastropods (10.5%) and nemerteans (2.7%...

Within the Southern Ocean, amphipods have achieved a conspicuous ecological radiation which gave rise to the development of numerous feeding strategies. The aim of this study is to apply the carbon and nitrogen stable isotope ratio methodology to delineate the trophic relationships involving benthic amphipods in the eastern Weddell Sea food webs. T...

The aim of this work was to identify and compare, using nitrogen and carbon stable isotope data, the food sources supporting consumer communities in a Mediterranean seagrass bed (Gulf of Calvi, Corsica) with those in an adjacent epilithic alga-dominated community. Isotopic data for consumers are not significantly different in the two communities. P...

Associations of tunas and dolphins in the wild are quite frequent events and the question arises how predators requiring similar diet in the same habitat share their environmental resources. As isotopic composition of an animal is related to that of its preys, stable isotope (C-13/C-12 and (15)/N-14) analyses were performed in three predator specie...

More than 100 species belonging to plant and animal taxa that are commonly observed in the intertidal zone were collected on both rocky and soft bottom shores of Brittany, France, to be analysed for their 13C/12C ratio. Plant material displayed a wide range of δ13C values (from -12 to -34‰), with relatively distinct values among producer groups (Ch...

In Revellata Bay Gulf of Calvi, Corsica, France, the sparid fish Sarpa salpa L. is the main macro-consumer of Posidonia oceanica L. Delile leaf. Stomach contents were analysed and 13C/12C isotopic ratios were measured in fish muscle and potential food sources algae, P. oceanica leaf and its epiphytes to determine their relative contribution to the...

A new, completely automated gas chromatography technique has been developed to separate the different gaseous compounds produced during underground coal gasification for their (13)C/(12)C and D/H isotope ratio measurements. The technique was designed for separation and collection of H(2), CO, CO(2), H(2)O, H(2)S, CH(4), and heavier hydrocarbons. Th...

The complete CO2 system, dissolved oxygen, nutrients and chlorophyll concentrations, fluorescence, salinity and temperature of surface seawater have been determined in the English Channel and the Southern Bight of the North Sea during Spring 1994. As already mentioned in a previous study, this area is characterized by important spatial and temporal...

Several techniques commonly used to remove epiphytes from seagrasses were tested on the same Posidonia oceanica (L.) Delile material: shaking, scraping, sonicating and soaking in acid. The effects of each treatment on the epiphyte removal rate and on the seagrass itself were assessed by scanning electron microscopy. The advantages and disadvantages...

A sediment trap experiment was carried out in the Bay of Calvi (Corsica, France) over a Posidonia oceanica seagrass bed, at a depth of 36 m. The traps collected 44 samples over a complete annual cycle and allowed a rough partition between 'sinking' and 'resuspended' matter. The measured annual flux of particulate matter amounted to 1.3 kg m(-2), of...

Mediterranean Leptomysis species are bentho-nectonic shrimps living close to seagrass bed bottoms, forming swarms during the day and feeding on detritus and sedimentary organic matter during the night. As this matter is derived from different plant sources (phytoplankton, seagrasses, macro- and microalgae), assimilated carbon entering mysid tissues...

The study was performed in the English Channel, the Celtic Sea, and the Southern Bight of the North Sea in June and October 1991. SW to NE gradients of suspended matter mass and of lithogenic components (Ti and Al) linked to riverine inputs and to depth shallowing, are observed; organic carbon and nitrogen display an opposite distribution pattern a...

The Gulf of Calvi, Corsica, presents a wide diversity of biocoenoses, amongst which the seagrass Posidonia meadow is prevalent. More than 100 plant, animal and sediment samples from various biotopes were analysed for their stable carbon isotope ratios, to assess carbon flows within the food chains. Marine plants display a wide range of δ13C values,...

Chitin was estimated in samples of planktonic crustaceans living in Calvi Bay (Corsica). The percentages of chitin, with respect to dry weight, are comprised between 3.10% in Clausocalanus spp. and 12.22% in Cladocera (mainly Evadne ). The percentage of chitin remained approximatively constant during larval development in Calanus helgolandicus (3.2...

Thèse (Docteur en Océanologie)--Universite de Liege, 1985. Includes bibliographical references (p. 263-277).

The different theories about the taxonomic position of European marine Cladocera have been confronted with the results of comparative investigations performed with scanning electron microscope and mathematical clustering analysis. It appears that both genera, Evadne and Podon, including the six species of Podonidae, have to be considered as valid.

From 1989 to 1992, five cruises were conducted in an area covering the English Channel, the Celtic Sea and the Gulf of Biscay. During these campaigns, suspended matter was collected by different techniques in order to analyze the spatial and vertical distribution of several particulate trace elements in relation to the global biogeochemical cycle o...

Since the role of continental shelves and coastal areas in the global biochemical carbon are nowadays a leading concern in oceanographic research programmes, this study aims to define the specific effect of nutrients on the onset and development of the phytoplankton bloom at the ocean margins. Comparison experiments of the carbon, nitrogen and phos...