Island Of Corsica Research Articles

Xylem formation patterns from Mediterranean to subalpine climate conditions reveal high growth plasticity of pine species on Corsica

Key messageBlack pine and Maritime pine exhibit considerable differences in growth phenology across elevation belts with a 1-month delay for xylogenesis and increasing growth rates from low, mid to high elevations.Investigating seasonal wood formation is crucial to understand tree growth responses to climate impact. The present study quantifies the variability of xylogenesis along an elevation gradient on the Mediterranean island of Corsica, where two native pine species (Pinus nigra Arnold ssp. laricio Maire and Pinus pinaster Aiton) grow from the upper tree line to sea level, partly in sympatry. We extracted microcores from 35 trees at 5 sites along an East–West transect from the coasts (10 m asl) to the island's central mountain ridge (1600 m asl) during bi-weekly sampling campaigns between 2017 and 2019. We applied generalised additive models to detect radial growth differences in elevation and species along with minimum temperatures for growth initiation. We found that trees in low elevations experienced over 2 months longer growth periods with higher maximum growth rates than in high elevations. The results show a 1-month delay for the beginning of tracheid formation between the low, mid and high-elevation belts but comparable timing for its termination. At the sites where both species co-occur, P. nigra accumulates more radial cells in a shorter time than P. pinaster. Trees at the two contrasting coastal sites have similar growth period lengths, but exhibit a time shift of over a month. Minimum temperatures around growth initiation vary between 3.1 °C for P. nigra and 9.9 °C for P. pinaster. These findings emphasise the high plasticity in the growth behaviour of one of the most widespread tree genera in Mediterranean and temperate zones.

An unusual carbon cycle budget of a small stream in a mountain silicate terrain: The case of the Gravona river (Corsica)

AbstractThe current research of carbon cycling in inland waters lacks a sound knowledge of carbon outgassing from small streams. As a consequence, these compartments of the terrestrial water cycle might still be seriously underrepresented in estimates of global carbon transfer budgets from land surfaces. This study investigated carbon sources and sinks of a mountain river in a silicate catchment. For this purpose, the high‐relief Gravona river, in the western part of the island of Corsica (France) in the Western Mediterranean, was investigated for field parameters, dissolved inorganic carbon (DIC) and its stable carbon isotopes (δ13CDIC). The source region was characterized by low DIC contents and high δ13CDIC values that decreased further downstream due to increasing soil respiration. Associated increasing DIC concentrations and elevated seasonality in the lower river section also indicated more respiration and subsequent DIC‐input by weathering. The aqueous partial pressure (pCO2(aq)) was lowest at the source of the Gravona river and samples from the cold season even showed undersaturation that led to uptake of atmospheric CO2. Further downstream, the seasonality of pCO2(aq) increased and was particularly pronounced near the river mouth where CO2 degassing took place. Average DIC flux along the river was 0.129 Gg C year−1 and was almost equal to CO2 degassing from the river surface with 0.128 Gg C year−1. Our study showed that on an annual basis the river is an overall weak to medium source of CO2 to the atmosphere even though headwater parts of the river seasonally act as CO2 sinks.

Sperm whale ship strikes in the Pelagos Sanctuary and adjacent waters: assessing and mapping collision risks in summer

Collisions with large vessels potentially present a major conservation issue for sperm whales in the Pelagos Sanctuary in the northwestern Mediterranean Sea. The exact numbers and locations of ship strikes remain largely unknown at present. In this study, sightings of sperm whales in summer (June–September) were gathered for the period between 1998 and 2008 from nine French and Italian organisations, together covering an area of more than 68,000km. Working on a regular grid of 0.1° × 0.1° latitude/longitude cells, approximate surface density of the whales was calculated using kriging methods. A database of shipping lanes of ferries and merchant vessels was assembled, and traffic density was mapped (kilometres travelled per cell). The data was overlayed and multiplied, using ArcGis, to create a relative density surface map of sperm whales correlated with the relative density of maritime traffic. Several maps of collision risk were drawn up according to the speed class of the vessels. Of living animals that had been photo-identified, 9% had scars attributed to ship strike. Results show that sperm whales are at high risk from merchant vessels along the French and Italian continental coasts and at risk from conventional ferries on the east side of the islands of Corsica and Sardinia. It was calculated that 74 animals could be in a ship strike risk situation during the summer period in the Pelagos Sanctuary. Based on these results, mitigation measures already in place were reviewed and new measures to reduce ship strike risk are suggested.

Fasciolosis in the Mediterranean island of Corsica (France): Insights from epidemiological and malacological investigations

Fasciolosis is a re-emergent parasitic disease of worldwide significance with a major global impact on livestock health and production. In the French Mediterranean island of Corsica, fasciolosis has been recognized for a long time but little is known about its dynamic as the main investigations are outdated. Three compartments - definitive domestic hosts, intermediate hosts and environment - involved in fasciolosis transmission were studied by applying an integrative and extensive approach: (1) farm and abattoir surveys, (2) snail sampling, identification and infection prospection, and (3) snail habitat analysis; and (4) a questionnaire-based survey to inquire about husbandry practices and environmental risks. Our results indicate a significant circulation of the liver flukes in Corsican livestock, with 90% (252/279) of the sampled farms testing positive for anti-F. hepatica antibodies. At the abattoir, 46% (67/149) of cattle were positive for F. hepatica antibodies and eggs were present in the bile of 19% (26/139) bovines. In addition, high prevalence of Dicrocoelium dendriticum (69%) was observed in slaughtered cattle. Malacological surveys registered the occurrence of several lymnaeid species in a variety of habitats throughout the island. In particular, we report for the first time the presence of the invasive lymnaeid snail Pseudosuccinea columella in Corsica, a potential intermediate host for F. hepatica. We also found that the presence of Galba truncatula and, to a lesser extent, that of Peregriana peregra, is associated with altitude. Fasciola hepatica DNA was detected in the latter species occurring at two different sites. Finally, a questionnaire-based study revealed risky management practices among Corsican farmers, low perception of transmission and a suboptimal use of flukicide treatments as main control strategy. Our results show that animal fasciolosis in Corsica is characterised by a significant circulation and a favourable epidemiological scenario for transmission to occur.

Notes on the use of genus Hyloicus Hübner, 1819, with the description of a new species of the “H. pinastri complex” from Corsica (Lepidoptera, Sphingidae)

The authors briefly discuss the merits of separating the genus Hyloicus Hübner, 1819, from the genus Sphinx Linnaeus, 1758, a treatment that has been debated for more than forty years. They provide a brief history of the development of the taxonomy of the members (all Palaearctic) of the “H. pinastri complex”. Then they report the unexpected finding that the representative of this complex on the island of Corsica represents a new species, described herein as Hyloicus corsica n. sp. It can be distinguished from its continental relatives, H. pinastri (Linnaeus, 1758) and H. maurorum Jordan, 1931, by its larger size, characters of the male genitalia and consistent genetic divergence of the standard DNA barcode marker (a fragment of COI gene). Only males have been observed so far, and the species is currently known as a Corsican endemic found in several localities in both southern and northern parts of the island.

Geochemical Analysis of Radar Backscatter (Sentinel-1) Over the Corsica Island Oil Spill

Geochemical Analysis of Radar Backscatter (Sentinel-1) Over the Corsica Island Oil Spill

Complex-valued time series based solar irradiance forecast

A new method for short-term probabilistic forecasting of global solar irradiance from complex-valued time series is explored. The measurement defines the real part of the time series while the estimate of the volatility is the imaginary part. A complex autoregressive model (capable to capture quick fluctuations) is then applied with data gathered on the Corsica island (France). Results show that even if this approach is easy to implement and requires very little resource and data, both deterministic and probabilistic forecasts generated by this model are in agreement with experimental data (root mean square error ranging from 0.196 to 0.325 considering all studied horizons). In addition, it exhibits sometimes a better accuracy than classical models such as the Gaussian process, bootstrap methodology, or even more sophisticated models such as quantile regression. Many studies and many fields of physics could benefit from this methodology and from the many models that could result from it.

Global patterns and environmental drivers of suitable habitat for Dentex dentex and Sciaena umbra along the Corsican coast

Abstract Improving the effectiveness of marine spatial management is crucial to preserve marine ecosystems and also to support the fisheries economy. In this study, we aimed to determine the spatial distribution and suitable habitats (spawning and nursery sites) of Sciaena umbra and Dentex dentex using catches data in Corsica Island. Random forest models have been used as they are highly accurate and are suited to predict rare species distribution. Predictive maps of spatial distribution based on presence/absence data showed a high degree of spatial variability between species. Suitable habitats were close to shore in shallow waters for S. umbra and deeper and further offshore for D. dentex. We also observed that spawning sites were mainly located on the west coast, while nursery areas were distributed all around the island for D. dentex. In addition, we demonstrated the important contribution of environmental factors and local habitats (depth and Posidonia oceanica meadows) in the selection of their suitable habitats. Our results provide new knowledge for understanding ecological processes such as the selection of suitable habitats by fish species. Based on this information, spatial mapping can be implemented to improve the effectiveness of resource management over the long term.

Shallow-water waveguide acoustic analysis in a fluctuating environment.

The Acoustic Laboratory for Marine Applications (ALMA) is a deployable and autonomous acoustic system, designed by DGA Naval Systems, to address problems in underwater acoustics, such as sound propagation in fluctuating environments. In this article, data from the ALMA-2016 at-sea campaign are used to analyze the ocean fluctuation's influence on sound propagation in a shallow-water waveguide. The experiment took place on the continental shelf of the island of Corsica in November 2016. A source and a receiver array were 9.3 km apart in a nearly constant water depth of 100 m. The source emitted a variety of signals from which the chirp (1-13 kHz) is used to extract the waveguide eigenrays. To do so, a time-domain beamforming is performed on the match-filtered received signals with an automatic detection of local maxima in the time of arrival/direction of arrival (TOA/DOA) domain. A 2 min acquisition period of more than 13 h duration shows significant fluctuations in eigenray TOAs/DOAs. Qualitative comparisons with synthetic signals obtained from simulations in two and three dimensions permit reproduction of the observed eigenray fluctuations without including range dependence of the sound-speed profile.

Major regression of Posidonia oceanica meadows in relation with recreational boat anchoring: A case study from Sant'Amanza bay

The anchoring of large recreational craft constitutes one of the main threats in shallow marine habitats. In the Mediterranean, this activity has seen constant development during the last decades, causing major physical disturbances in Posidonia oceanica meadows and associated ecosystem services. In this context, the main aims of the present study are to estimate the impact of this anchoring on P. oceanica meadows surface areas and carbon fixation and sequestration capacities, in a particularly highly-frequented area (Sant'Amanza bay, Corsica Island). Accurate benthic marine habitats mapping was performed yearly (2019–2021) using a drone coupled with ground-truthing data. The evaluation of carbon fixation and sequestration by the plant was measured at 12 stations within the bay (−5 m to −30 m). The maps of the marine habitats reveal an extensive regression of P. oceanica meadows (7.5 ha) between 2019 and 2020. This destruction represents a 9% decline in the total carbon fixation and sequestration performed each year by P. oceanica meadows within the bay. The related ecosystem services loss is estimated at 4.72 million € yr−1. Although an overall decline of boat anchoring in the seagrass meadow has been observed (e.g. recent enforcement of anchoring regulations), other solutions should be experimented to manage this major carbon sink.

Evolution of personality and locomotory performance traits during a late Pleistocene island colonization in a tree frog.

Recent empirical and theoretical studies suggest that personality and locomotory performance traits linked to dispersal abilities are crucial components of the dispersal syndromes, and that they can evolve during range expansions and colonization processes. Island colonization is one of the best characterized processes in dispersal biogeography, and its implication in the evolution of phenotypic traits has been investigated over a wide range of temporal scales. However, the effect of island colonization on personality and performance traits of natural populations, and how these traits could drive island colonization, has been little explored. Noteworthy, no studies have addressed these processes in the context of late Pleistocene range expansions. Here, we investigated the contribution of island colonization triggered by postglacial range expansions to intraspecific variation in personality and locomotory performance traits. We compared boldness, exploration, jumping performance, and stickiness abilities in populations from 3 equidistant areas of the Tyrrhenian tree frog Hyla sarda, 2 from the main island (Corsica Island), and 1 from the recently colonized island of Elba. Individuals from Elba were significantly bolder than individuals from Corsica, as they emerged sooner from a shelter (P = 0.028), while individuals from Corsica showed markedly higher jumping and stickiness performance (both P < 0.001), resulting as more performing than those of Elba. We discuss these results in the context of the major microevolutionary processes at play during range expansion, including selection, spatial sorting, founder effects, and their possible interaction with local adaptation processes.

On ten high-mountain lakes of Corsica island (France) – A delayed report of an investigation in summer 1970

In August 1970, ten mountain lakes on the island of Corsica (France) were studied. Temperatures and oxygen concentrations were measured as depth profiles, the shading effects of surrounding topographic elevations as skyline values compared to corresponding daily solar elevations. Turbidity and approximate underwater light spectra were evaluated using six color Secchi discs. Alkalinity and electrical conductivity values showed extremely soft water in the lakes. The influence of altitude on lake surface temperatures was analysed, compared to lakes in the Caucasus region and could be separated from the influence of topographical sun shading. Six copepod species were found in zooplankton samples and compared to meta-communities in lakes in other mountain regions.

Smart IM-MS and NMR study of natural diastereomers: the study case of the essential oil from Senecio transiens.

Unambiguous identification of the components of a natural mixture remains a challenging and meticulous issue. Usually, different analytical techniques and laborious separation protocols are employed; nevertheless, in some cases, delicate and equivocal problems are hardly addressed by traditional methods. In this context, an original methodology for the analysis of natural samples consisting of recent mass spectrometry methods based on ion mobility (MS-IM) is proposed. As an example, a polar fraction obtained by the essential oil prepared from Senecio transiens, an endemic plant harvested on the Corsica Island, was selected for this study to show how IM-MS-based methods easily provide very useful insights suggesting the presence of two diastereomers. To unambiguously confirm this hypothesis and verify reliability of the IM-MS results, the purified compounds were further analysed by means of nuclear magnetic resonance (NMR) methodologies, allowing the structural elucidation and the identification of two new natural compounds, diastereomers of 4-acetoxy-5,9-dimethyl-3-(2-methylpropenyl)-2-oxabicyclo[4.4.0] dec-9-ene, reported here for the first time.

Changes in lipid and fatty acid contents of gonad during the reproductive cycle of the Mediterranean swordfish Xiphias gladius

Swordfish Xiphias gladius is a large pelagic fish distributed worldwide and exploited for human consumption, however there is limited knowledge about its reproductive biology, especially regarding lipid dynamic in gonads. In teleost fish, reproductive success and offspring survival are associated to lipid availability for gamete synthesis. This study investigated the lipid composition, including lipid classes and fatty acids (FA) of cell membrane and reserve lipids (i.e., polar and neutral lipids, respectively; PL and NL), along female and male gonad development of a swordfish population from waters surrounding Corsica Island in the Mediterranean Sea. Overall, swordfish gonads contained <2% wet weight of total lipids, with testes and ovaries having similar fat content. Lipid classes and FA concentrations remained unchanged during testes maturation. However, concentrations of phosphatidyl choline (PL), triacylglycerol (NL), and some FA (16:0, 18:1n-9, and 22:6n-3) followed an “inverted U-shaped” relationship with the ovarian maturation. In both PL and NL, 22:6n-3 was the main polyunsaturated FA (>20% of total FA), while 20:5n-3 and 20:4n-6 were minor (3–6% of total FA) and varied little with maturation. 22:6n-3 and 18:1n-9 were selectively allocated to the ovarian maturation (increased in concentration and in proportion with maturation) until spawning. Finally, swordfish gonads might represent a good food source for humans given that 150 g of swordfish ovaries can cover the daily requirements in omega-3 for humans, but research on pollutants should also be conducted to evaluate their implications on the reproduction output of this species, and on the safety of swordfish gonads for human consumption.

Contatti linguistici lungo le coste tirreniche: storia della parola marruffo

Abstract The article intends to reconstruct the linguistic history of a particular fishing gear called marruffo, which is still used in the Gulf of Naples and in a few places of the North Tyrrhenian coasts. The marruffo is a fishing trap used by fishermen to preserve the catch while awaiting sale. Conical in shape, it looks like a large basket with a lid, in which fish or crustaceans of various types are placed. Starting from the 1871 work by the naturalist Achille Costa, entitled La pesca nel golfo di Napoli, the attestations of marruffo in Campania, Sardinia and Corsica are outlined. I put forward the hypothesis that the object arrived on the Tyrrhenian coasts as a consequence of migrations of fishermen from the Neapolitan area to the islands of Tuscany, Sardinia and Corsica between the 18th and 19th century. Since in southern Italy the name marruffo also indicates a jug for wine or water, I hypothesize that the word was extended from the lexicon of everyday life to the fishing lexicon throughout a process of resemantization, as it was demonstrated for other similar cases.

Insight into the morphology and genetic diversity of the Chaetoceros tenuissimus (Bacillariophyta) species complex

ABSTRACT Among the marine planktonic diatoms, Chaetoceros is among the most species-rich genera, and many Chaetoceros species are considered important primary producers. However, little is known about the ecology and distribution of the few small solitary species within this genus, including Chaetoceros tenuissimus. This article describes a minute Chaetoceros strain, identified as C. tenuissimus (named CT16ED) that was isolated at a coastal lagoon in Corsica Island, Western Mediterranean. The strain was characterized by light microscopy and scanning and transmission electron microscopy, with a specific focus on the fine structure and construction of setae and its behaviour in culture. The CT16ED strain was compared with other strains we isolated from the species type locality (Ostend Harbour, North Sea) by sequencing a fragment of the nuclear ribosomal DNA (rDNA) spanning from the 18S rDNA to the D3 region of the 28S rDNA, and the plastid rbcL gene that codes the large RuBisCO subunit. Based on the literature and the available sequence data, the analysed strains were similar to C. tenuissimus but the phylogenetic analysis indicated a C. tenuissimus species complex that contained several clades, therefore the current taxonomic status of C. tenuissimus is discussed. The comparison with the available rDNA and rbcL sequencing data of strains assigned to species considered as synonyms of C. tenuissimus, including Chaetoceros simplex var. calcitrans, Chaetoceros calcitrans and Chaetoceros calcitrans f. pumilus, suggested that these taxa are paraphyletic within the genus Chaetoceros.

Anaplasma capra in sheep and goats on Corsica Island, France: A European lineage within A. capra clade II?

Anaplasmosis is a tick-transmitted disease due to several species of the genus Anaplasma. In 2019, we demonstrated the presence of Anaplasma capra in two deer species at a zoological park in mainland France. As we suspected its presence in Corsica, we surveyed 11 geographically distant sheep or goat farms. Using molecular tools such as nested PCR targeting 16S ribosomal RNA (rRNA), citrate synthase (gltA) and heat-shock protein (groEL) genes, we detected the presence of A. capra on 5/11 farms, in 26/108 blood samples (24%), in sheep as well as in goats. Genotyping and phylogenetic analysis of A. capra revealed that isolates from Corsica island grouped closely with A. capra isolates reported in red deer and swamp deer from a zoological reserve in mainland France, as well as in roe deer from Spain, in a separate and well supported clade within A. capra clade II. This third report of the tick-borne bacterium A. capra in Europe suggests a potentially larger presence of this pathogen on the European continent, on domestic, native as well as wild ruminants, a broad host range already described in Asian countries for this species.

Unusual Sting by a Nonindigenous Caterpillar in Europe

On the French island of Corsica, a 57-y-old woman without significant medical history was stung on the left thumb while she was taking care of an ornamental Ficus benjamina plant. Immediately, she felt intense pain in her hand. She saw a strange caterpillar, later identified by the local poison center as Acharia stimulea. The pain in her hand was evaluated as 8 of 10 using the numerical pain rating scale; only a slight erythema was visible on her skin. Symptoms disappeared within 2 h with use of local anti-inflammatory ointment and oral painkillers. Three other caterpillars emerged out of the soil of the potted plant during the following week. This sting by a saddleback caterpillar is exceptional in Corsica. French garden store owners and healthcare professionals should be informed that caterpillars can be imported across the oceans to Europe on different plants.

Chemosensory Receptors in the Larval Maxilla of Papilio hospiton

Among the butterflies of the genus Papilio (Lepidoptera: Papilionidae), Papilio hospiton (Géné) has a geographical distribution limited to the Mediterranean islands of Sardinia (Italy) and Corsica (France). This is mainly due to the host range that includes only a few plant species of Apiaceae and Rutaceae growing on these islands. In a previous electrophysiological investigation conducted on the maxillary gustatory system of larvae of P. hospiton and its closely phylogenetically related species Papilio machaon, a significantly higher spike activity was shown for the gustatory neurons of lateral and medial styloconic sensilla in P. hospiton when bitter compounds were tested. This effect was possibly correlated to the limited host choice range for P. hospiton. To shed light on the molecular aspects of this phenomenon, we investigated the expression pattern of sensory-related sequences by conducting a transcriptomic analysis from total RNA isolates of P. hospiton larval maxillae. We identified several transcripts that may be involved in taste (one gustatory receptor, one divergent ionotropic receptor, and several transient receptor potential channels, TRPs) as well as transcripts supporting an olfactory function for this appendage, including odorant receptors (ORs), antennal ionotropic receptors (A-IRs), sensory neuron membrane proteins (SNMPs), and odorant-binding proteins (OBPs). We used Human Embryonic Kidney (HEK293A) cells to heterologously express two of the identified receptors, PhospOR1 and PhospPain, together with their orthologs from P. machaon, for functional characterization. While our data suggest no activation of these two receptors by the ligands known so far to activate the electrophysiological response in larval maxillary neurons of Papilio species, nor temperature activation of both Papilio TRPA-channel Painless, they represent the first attempt in connecting neuronal activity with their molecular bases to unravel diet specialization between closely related Papilio species.

Anatomy of a deformed upper crust fragment from western Alpine Corsica (France): insights into continental subduction processes

ABSTRACT In Corsica Island (France), a belt of metamorphic continental units derived from the European margin is exposed at the western rim of the Alpine Corsica. This study provides a complete anatomy of one of these units (Tour de Valletto Unit) consisting of a Palaeozoic basement covered by an Early Jurassic – late Eocene sedimentary succession. This unit records a polyphase tectono-metamorphic history acquired during the late Eocene – lower early Miocene convergence processes involving the Adria and Europe continental plates. Using a multidisciplinary approach, we reconstructed in detail the P-T path of the Tour de Valletto Unit. The path shows a metamorphic climax at blueschist facies conditions suggesting that the unit was accreted at c. 40 km of depth. After its accretion, the Tour de Valletto Unit was exhumed up to the Earth surface following a path characterized by an increase of temperature and a decrease of pressure. The reconstructed tectono-metamorphic history of the Tour de Valletto Unit is compared with those of the other continental units located in western Alpine Corsica to discuss the exhumation processes active during continental subduction.