Alain Ponsero - Academia.edu (original) (raw)

Papers by Alain Ponsero

Marine Environmental Research, Dec 1, 2022

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Distributed under a Creative Commons Attribution-NonCommercial 4.0 International License Stomach content and stable isotope analyses provide complementary insights into the trophic ecology of coastal temperate bentho-demersal assemblages under environmental and anthropogenic pressures

Ecological Modelling, 2021

Abstract Ecological research focuses on the spatio-temporal patterns of ecosystems and communitie... more Abstract Ecological research focuses on the spatio-temporal patterns of ecosystems and communities. The recently proposed framework of Community Trajectory Analysis considers community dynamics as trajectories in a chosen space of community resemblance and utilizes geometrical properties of trajectories to compare and analyse temporal changes. Here, we extend the initial framework, which focused on consecutive trajectory segments, by considering additional metrics with respect to initial or baseline states. Addressing questions about community dynamics and more generally temporal and spatial ecological variability requires synthetic and efficient modes of representation. Hence, we propose a set of innovative maps, charts and trajectory roses to represent trajectory properties and complement the panel of traditional modes of representation used in community ecology. We use four case studies to highlight the complementarity and the ability of the new metrics and innovative figures to illustrate ecological trajectories and to facilitate their interpretation. Finally, we encourage ecologists skilled in multivariate analysis to integrate CTA into their toolbox in order to quantitatively evaluate spatio-temporal changes.

Genetics and biodiversity journal, Jan 25, 2021

Landfills have the advantage of meeting the energy needs of the birds quickly. They offer easy ac... more Landfills have the advantage of meeting the energy needs of the birds quickly. They offer easy access to food and widely available throughout the year. In this study, birds were counted using observation points on an open landfill in the restored of Souk-Ahras region (north-eastern Algeria) for one year from July 2013 to April 2014. Seventeen species (17) bird species belonging to eleven (11) families were found: Ciconidae, Corvidae, Accipitridae, Passeridae, Hirundinidae, Motacillidae, Columbidae, Ardeidae, Sturnidae, Laridae, and Pelecanidae, among them sedentary species, migratory, the visitors, and invasive species, which are exploiting the discharge for feeding or rest. Species richness and abundance in landfill site were found to be higher than that of naturel habitat around the site. Their abundance varied according to the seasons.landfill site support both common bird species as: Columba palumbus, Columba livia, Streptopelia decaoto, Ciconia ciconia, Corvus corax. In addition to that, rare bird species such as Pelecanus crispus. Ecology and dynamic of each species, during an annual cycle of bird's populations allow us observing all the interactions and reactions between the individuals and the different populations of birds. Souk Ahras landfill is a resting place and a source of food for birds, which means that it needs a censuses urgency update of migratory birds which frequent our region as well as monitor their state of health. It is also interesting to follow the process of colonization in urban Souk Ahras city.

Marine Environmental Research, Mar 1, 2022

Assessing fluxes of matter and energy in food webs within and across benthic habitats is importan... more Assessing fluxes of matter and energy in food webs within and across benthic habitats is important to understand the ecological functioning in bays and estuaries, where the productivity is favoured by a wide diversity of primary producers. The temporal variability (March vs September 2019) in the carbon and nitrogen stable isotope composition of primary food sources and benthic invertebrates consumers was investigated in a large intertidal area (Western English-Channel, France). The study area is influenced by megatidal conditions and characterised by salt marshes in the sheltered part, and seasonal Ulva spp. blooms. The spatio-temporal variability in the structure of the benthic food web was analysed at the scales of both the whole bay and the different assemblages, which constitute the mosaic of habitats. Inferences on potential sources fuelling the food web were supported by spatio-temporal patterns based on covariations and stable isotope trajectory analysis. Results highlighted that phytoplankton, microphytobenthos and SOM were, most likely, the main food sources. The trophic connectivity between salt marsh and benthic habitats within the bay was limited to some macrofauna species inhabiting muddy creeks within the salt marsh. Unexpectedly, the influence of Ulva blooms appeared also limited. Spatial patterns illustrates the constancy of the spatial variability in the benthic pelagic coupling, with a higher influence of microphytobenthos in the upper shore compared to low shore assemblages. This first attempt to characterize intertidal benthic food web constitutes a relevant baseline for the conservation of the bay of Saint-Brieuc where a National nature reserve has been created in 1998 for the conservation of overwintering birds. The spatial and temporal patterns of the benthic food web observed in this study (1) confirm the importance to consider food web variability at spatial and temporal scales from sampling Highlights ► The benthic invertebrates food web structure was studied in a large intertidal area using δ 13 C vs δ 15 N values. ► Stable isotope compositions were variable in space and time for some sources and consumers. ► Phytoplancton, microphytobenthos and SOM were the main sources supporting the benthic food web. ► Spatial variability in the benthic pelagic coupling was constant between March and September. ► The influence of salt marsh vegetation and Ulva blooms was limited.

Marine Environmental Research

GABJ, 2021

cockle (Cerastoderma edule) has been collected by traditional fishing methods for many decades wi... more cockle (Cerastoderma edule) has been collected by traditional fishing methods for many decades without any evaluation or management of this resource taking place. Since 2001, the national Natural Reserve of the bay of Saint-Brieuc has carried out an evaluation of the stock and a mapping of the cockle fishing grounds each year. Analysis of the spatial structure of the population is approached by cartography through interpolation of the data using the Kriging method. The recruitment zones are geographically quite well defined and located in the areas limited to the mean-tide zone. The distribution of the population was affected by passive displacement of juvenile cockles. Evaluation using the matrix of individual numbers for each age group found the inter-annual mortality rates to be about 60%. Somatic production was estimated and expressed in ash-free dry weight (AFDW). The average annual production ranged from 7.4 g/m to 14.5 g/m. In the autumn of 2006, the minimum legal fishing siz...

Estuarine, Coastal and Shelf Science, 2021

Tracking and quantifying ecological changes at large and long-term scales is a central point for ... more Tracking and quantifying ecological changes at large and long-term scales is a central point for monitoring and conservation issues. The Community Trajectory Analysis Framework was used in complement with classical methods to analyse and represent long-term changes in marine habitats at 42 stations in the bay of Saint-Brieuc (western English Channel), sampled in 1987, 2001 and 2019. The taxonomic and functional trajectories of intertidal benthic assemblages were studied at local and assemblage scales. Whatever the perennial contribution of dominant prevalent species at the site scale, some species were highly variable over time and space, influencing the structuration of assemblages. Taxonomic changes were not systematically associated with significant changes in the functional properties at local and community scale. The consideration of local changes and variations at the species level explained the differences in composition observed at the scale of assemblages. Observed changes mainly reflected random population dynamics of structuring prevalent species in habitat under strong natural pressures, rather than specific changes of the community. Few species reveal the long-term effect of green tides in some assemblages. Overall, this study confirms the complexity to disentangle factors of changes in the absence of a monitoring strategy specifically devoted the measurement of environmental factors and anthropogenic pressures. The study also highlights the need for the development of benthic monitoring strategies at multiple spatial and temporal scales. Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.

Estuarine, Coastal and Shelf Science, 2016

All over the world, numerous bays and estuarine systems that are known to shelter essential fish ... more All over the world, numerous bays and estuarine systems that are known to shelter essential fish habitats are experiencing proliferations of green macroalgae known as green tides. Although the processes that enhance green tides in response to nutrient enrichment are well known, their consequences for ecological communities despecially for ichthyofaunad remain poorly studied. To estimate these consequences, this analysis focused on the two types of shallow systems that are experiencing green tides: sandy beaches and estuarine mudflats. In these two systems, macroalgae proliferation and fish community were surveyed along seasonal cycles at control and impacted sites that shared similar physicochemical parameters and sediment structure. To analyse the consequences of green tides on the fish community, a Before-After Control-Impact approach was used. This approach reveals no difference between fish communities at the control and impacted sites before the macroalgal bloom. Then, it underlines an influence of green tides on the fish community, and this influence varies according to the composition, density and duration of the macroalgal bloom. Indeed, when intertidal systems experienced short proliferation and/or weak density, green tides did not seem to impact the fish community. However, when green macroalgae proliferated in large quantities and/or when the proliferation lasted for long periods, the fish community was significantly affected. These modifications in the fish community led to a significant decrease in fish species diversity and density until fish disappeared from impacted sites at high proliferations. Furthermore, the response of fish species to green tides differed according to their functional guilds. Negative consequences for benthic and marine juvenile fish species were beginning at low proliferations, whereas for pelagic fish species they occurred only at high proliferations. Thus, green tides significantly affect fish habitat suitability because they lead to changes in the composition of the fish community and eventually to the local disappearance of fish at high proliferations.

The cockle Cerastoderma edule has been collected by traditional fishing methods for many decades ... more The cockle Cerastoderma edule has been collected by traditional fishing methods for many decades in the Bay of Saint-Brieuc, a 2 900 ha tidal bay, without any evaluation or management of this resource. Since 2001, the National Natural Reserve of the bay of Saint-Brieuc has carried out an annual assessment of the stock and a mapping of the cockle fishing grounds. The assessment takes place between the end of July and mid-August on a regular sampling network of 131 stations 500m apart and covering the whole of the 2900 ha inter-tidal foreshore. Cockles are harvested for each station within a square of 0,25m² and measured in laboratory. This led to the development of a predictive model on the fishing grounds production using the growth stages of each individual and the biomass. The model provides benefits for managers, in particular: • A mid-term prediction (1 to 2 years) of the fishable part of the cockle fishing ground. This allows requests from institutional organizations to be answ...

Aquatic Conservation: Marine and Freshwater Ecosystems

Revue D Ecologie La Terre Et La Vie, Dec 1, 2011

Estimation dE la consommation dE la macrofaunE invErtébréE bEnthiquE par lEs oisEaux d'Eau En bai... more Estimation dE la consommation dE la macrofaunE invErtébréE bEnthiquE par lEs oisEaux d'Eau En baiE dE saint-briEuc (francE) alain Ponsero 1 & patrick Le Mao 2 summary.-Estimation of benthic macrofauna consumption by water birds in the bay of Saint-Brieuc (France).-the biomass and productivity of benthic invertebrates were studied in the bay of saint-brieuc in connection with the consumption by the nine most numerous wader and duck species present on the site. this consumption is about 1.9 g ash free dry weight/m 2 /year, it is similar to that obtained in the bay of mont-saint-michel but very lower to results from Wadden sea. Eutrophication generally induces an increase in overall productivity of the intertidal coastal ecosystem, as it has been observed in the German part of the Wadden Sea since the 1950s. Consequently, the bird populations grow very significantly in eutrophic systems. but this is not the case in the bay of saint-brieuc where macrozoobentic biomass produced and consumed by birds is comparable to what was observed in the bay of mont-saint-michel, an oligotrophic marine site characterized by relatively low biomass and productivity. in the bay of saint-brieuc excessive inputs of nutrients induce an important development of Ulva armocicana, responsible for the spectacular green tides which greatly impact this bay each summer. the proliferation of Ulva brings the nutrient flows to a standstill and by the way regulates the production of microphytoplankton and so, indirectly, the abundance of higher trophic levels.

La distribution spatiale des limicoles et des ressources benthiques comme outil de gestion The na... more La distribution spatiale des limicoles et des ressources benthiques comme outil de gestion The national nature reserve of Saint-Brieuc Bay, located in the north of Brittany, is a site of international importance for wintering birds. The nature reserve (1,140ha) borders a sandy foreshore of 2,900ha. The diversity and abundance of birds present in intertidal coastal ecosystems are closely related to the type, density and the accessibility of prey, and the sediment characteristics. The macrofauna and sediment characteristics were studied in Oct 2010 and Mar 2011, using a regular sampling network of 131 stations 500m apart and covering the whole of the 2,900 ha intertidal area. A study of the distribution and activity of six wader species took place during the winters of 2010/11 and 2011/12. For each flock of birds, we determined the proportion of roosting and feeding birds. The position of the flocks was determined with laser range-finder binoculars which measures distance and viewing angle. The position of the observer was obtained with a GPS unit, and the position of the birds was calculated using trigonometry. It was then possible to map the usage of the foreshore by birds in time and space. In order to further understand the predator-prey system, we mapped both the main feeding areas of the birds and their benthic food resources. For example, we showed a very close relationship between the distribution of Eurasian Oystercatchers Haematopus ostralegus at low tide and Cockles Cerastoderma edule whose size exceeds 20 mm, and between Red Knots Calidris canutus and Thin Tellin Tellina tenuis. This study allows managers to determine areas that are important to major bird conservation issues. By comparing the potential foraging habitats with habitats that are currently exploited by birds, it also evaluates the impact of disturbances and development projects on the use of the area by birds. These information are used to improve our understanding about the compatibility of the complex benthic resources/birds/human activities system.