Luis Cardona

• PhD Biological Sciences
• Professor (Associate) at University of Barcelona

Marine litter, including Floating Marine Macro-Litter (FMML) and microplastics (MP), poses a major threat to marine ecosystems. This study investigates the seasonal distribution of FMML and MP in the Ebro Delta, a key Mediterranean wetland, and evaluates the potential risk to three tern species (family Laridae, subfamily Sterninae) that rely on the...

Sandy coastal beaches are an important nesting habitat for marine turtles and a known sink for plastic pollution. Existing methodologies for monitoring the spatiotemporal patterns of abundance and composition of plastic are, however, disparate. We engaged a global network of marine turtle scientists to implement a large-scale sampling effort to ass...

Sandy coastal beaches are an important nesting habitat for marine turtles and a known sink for plastic pollution. Existing methodologies for monitoring the spatiotemporal patterns of abundance and composition of plastic are, however, disparate. We engaged a global network of marine turtle scientists to implement a large-scale sampling effort to ass...

We use data collected by onboard observers to assess the bycatch and immediate mortality of sea turtles in the Canary Current Large Marine Ecosystem (CCLME) and adjoining areas from 2016 to 2021. First, a dataset including 698 sets by drifting longlin-ers, 6300 tows by trawlers and 1029 sets by purse seiners was used to calculate the catch per unit...

Global change is rapidly reshaping species' habitat suitability ranges, hence leading to significant shifts in the distribution of marine life. Contrasting distributional responses among species can alter the spatial overlap between predators and prey, potentially disrupting trophic interactions and affecting food web dynamics. Here, we evaluate lo...

Reconstructing predator-prey interactions in a biological community provides a better understanding of species' ecological roles and helps predict how changes in one component will affect the others. Doris kerguelenensis is an Antarctic heterobranch mollusc that feeds on sponges, according to previous gut content analyses. Here, stable isotopes of...

Early juvenile loggerhead turtles (Caretta caretta) rely on gelatinous zooplankton, whereas individuals larger than 40 cm curved carapace length are adapted to crush hard-shelled invertebrates. Nevertheless, fish were reported to be the staple food of loggerhead turtles in the western Mediterranean 30 years ago. Here, the temporal consistency of su...

The response to climate change in highly dimorphic species can be hindered by differences between sexes in habitat preferences and movement patterns. The Antarctic fur seal, Arctocephalus gazella , is the most abundant pinniped in the Southern Hemisphere, and one of the main consumers of Antarctic krill, Euphausia superba , in the Southern Ocean. H...

The Mediterranean Sea is considered a biodiversity hotspot and hosts a broad diversity of shark species. Unfortunately , many shark populations have suffered a long story of overexploitation and their abundance has strongly declined over the last decades. A few studies have addressed the trophic role of sharks in the northwestern Mediterranean Sea,...

It is commonly assumed that the resolution of the isotopic niche of consumers can be improved with a larger number of chemical elements, but this is only true if steep environmental gradients exist at the appropriate spatial scale. Off Mauritania, the δ13C value is a useful proxy to understand the distribution of marine mammals along the inshore-of...

Understanding consumer trophic status and long‐term dietary changes can yield information about impacts of altered habitats on their ecology. In Hawai'i, coastal ecosystems have been significantly modified by the introduction of invasive seaweeds and mangroves, high nutrient load and overfishing, but so far, much is still to be understood about how...

The western Mediterranean Sea has traditionally served as a primary foraging ground for juvenile loggerhead turtles from three distinct regional management units: the North‐western Atlantic, the Mediterranean and Cape Verde. Nesting activities were sporadic. Recently, nesting activity on the beaches of eastern Spain has increased, due to warmer san...

Fisheries bycatch is a critical threat to sea turtle populations worldwide, particularly because turtles are vulnerable to multiple gear types. The Canary Current is an intensely fished region, yet there has been no demographic assessment integrating bycatch and population management information of the globally significant Cabo Verde loggerhead tur...

This study conducted stable isotope analysis (δ¹³C, δ¹⁵N, and δ³⁴S) on the epidermis and two skeletal elements (rib and squamosal bones) of Hawaiian green turtles (Chelonia mydas) and putative diet items obtained from two neritic sites: the Kona/Kohala coast and Oahu. Turtle tissues were collected in 2018–2020 and diet samples in 2018, 2019, and 20...

As climate-related impacts threaten marine biodiversity globally, it is important to adjust conservation efforts to mitigate the effects of climate change. Translating scientific knowledge into practical management, however, is often complicated due to resource, economic and policy constraints, generating a knowledge-action gap. To develop potentia...

Detailed knowledge on habitat use by marine mammals is critical to understand their role in the ecosystem. The stable isotope ratios of carbon (δ 13 C) and nitrogen (δ 15 N) have been widely used to study the trophic ecology of marine mammals, but the stable isotope ratios of other elements such as sulfur (δ 34 S) and oxygen (δ 18 O) can better inf...

This paper aims to assess changes in the patterns of marine fish consumption by hunter-fisher-gatherer populations in the context of environmental change. To accomplish this objective, we used two methodological approaches: first, stable isotope analysis in ancient and modern shells of limpets and mussels to explore changes in the isotopic baseline...

Detailed knowledge of marine mammal diet is critical to understand their ecological roles and for the adequate management of marine resources. Antarctic fur seals (Arctocephalus gazella) in the Southern Atlantic Ocean rely largely on Antarctic krill (Euphausia superba) during the summer months, but their winter diet remains largely unknown. Here, s...

Viruses linked to animals inhabiting Antarctic latitudes remain poorly studied. Remote environments hosting large pinniped populations may be prone to exposure of immunologically naïve animals to new infectious agents due to increasing human presence or introduction of new animal species. Antarctic fur seals (Arctocephalus gazella) inhabiting the W...

We unveiled the isotopic niche of some medium-sized and large sharks in the NW Mediterranean Sea. These species would be functioning as high-level mesopredators, the diet of which was strongly dominated by cephalopods.

The ranges of many species are shifting poleward as global warming intensifies, but this process might be less intense in philopatric species, i.e. those with the tendency to reproduce at their natal sites. Marine turtles are highly philopatric and their vulnerability to global warming is exacerbated by a life history combining delayed sexual matur...

Environmental policies, including the European Marine Strategy Framework Directive (MSFD), generally rely on the measurement of indicators to assess the good environmental status (GES) and ensure the protection of marine ecosystems. However, depending on available scientific knowledge and monitoring programs in place, quantitative GES assessments a...

This study compares the δ15N values and the trophic position of two seabird species throughout the late Holocene in three regions in the southwestern Atlantic Ocean to assess the hypothesis that the decimation of megafauna led to changes in the trophic position of mesopredators. Modern and ancient mollusk shells were also analyzed to account for ch...

Up to date 264 Marine Protected Areas (MPAs) have been declared in the western Mediterranean Sea. The management plans of 25 of these MPAs include the loggerhead sea turtle (Caretta caretta) as a priority species to protect. However, the actual use of these MPAs by the species remains unknown. Therefore, it is important to assess their contribution...

We assessed the relationship between body size and several important life history parameters to understand the demographic significance of inter-population variability in the body size of loggerhead turtles Caretta caretta nesting in Boa Vista Island (Cabo Verde). The adult growth rate (0.34 ± 0.60 cm yr–1), annual mortality rate (0.13, 95% CI: 0.1...

El presente documento revisa la situación y aporta nuevos datos para las tortugas marinas en España durante el periodo 2013-2018. Se revisa el estado de conservación para el periodo 2013-2018 en cada una de las demarcaciones marítimas españolas: Levante –Baleares y Estrecho-Alborán para el Mediterráneo, y Noratlántica, Sudatlántica y Macaronesia en...

Delineating priority areas for highly mobile marine megafauna represents a major challenge for conservation biology. To manage such areas, one must understand both their spatial properties (i.e., location, number, extent), and the level of exposure to a number of given pressures. Here, we used a combination of ensemble distribution models, field-ba...

Detailed knowledge of habitat use by marine megafauna is critical to understand their ecological roles and for the adequate management of marine resources. Antarctic fur seals (Arctocephalus gazella) inhabiting the Atlantic sector of the Southern Ocean prey largely on Antarctic krill (Euphausia superba) and play a central role in managing the krill...

Antarctica is considered one of the most pristine regions on Earth, but evidences of global and local anthropogenic pollution exist. Chromium (Cr), lead (Pb) and mercury (Hg) are bioaccumulated and sometimes biomagnified through the trophic web. We aim to determine whether a latitudinal gradient of these trace elements exists in benthic organisms a...

Understanding the trophic niches of marine apex predators is necessary to understand interactions between species and to achieve sustainable, ecosystem-based fisheries management. Here, we review the stable carbon and nitrogen isotope ratios for biting marine mammals inhabiting the Atlantic Ocean to test the hypothesis that the relative position of...

• Historically, the Mediterranean Sea supported a rich shark fauna. Presently, however, populations of most shark species have significantly declined, largely due to intense fishing pressure. • Interviews with crew members of bottom trawlers, drifting longliners and bottom longliners operating off the Costa Brava (Catalonia, NE Spain) were conducte...

Changes in the duration and frequency of foraging trips by female otariids may result in changes in the duration and frequency of lactation bouts and hence influence pup growth rate, unless females modify milk energy density and/or the total amount of milk delivered depending on the trip duration. To test this hypothesis on South American sea lions...

Loggerhead turtles (Caretta caretta) voluntarily ingest floating plastic debris and hence are chronically exposed to plastic additives, but very little is known about the levels of these compounds in their tissues. This work studied the presence of organophosphate esters (OPEs) on sea turtles collected from two different areas in the western Medite...

• Marine aquaculture, and its fast‐growing development, has the potential for wider environmental, ecosystem, and biodiversity impacts. This study assesses the impact of fish farming on a bottlenose dolphin (Tursiops truncatus) population within the Gulf of Ambracia (western Greece) between 2007 and 2018. Two different study areas were defined in o...

The threats posed by floating marine macro-litter (FMML) of anthropogenic origin to the marine fauna, and marine ecosystems in general, are universally recognized. Dedicated monitoring programmes and mitigation measures are in place to address this issue worldwide, with the increasing support of new technologies and the automation of analytical pro...

Stable isotopes of C and N have been used to assess the effect of the duration of the sea ice season on the structure of benthic, Antarctic coastal food webs. Samples of suspended particulate organic matter, macroalgae and macroinvertebrates were collected at five subtidal rocky sites across a latitudinal gradient along the western Antarctic Penins...

Con el año actual finaliza el “Segundo Convenio de Colaboración entre la Consejería de Innovación, Investigación y Turismo del Gobierno de las Illes Balears y el Instituto Español de Oceanografía para la consolidación y el desarrollo científico de la Estación de Investigación Jaume Ferrer (La Mola, Menorca)” firmado el 30 de diciembre de 2015. Los...

The document updates the knowledge on observations and incidences, including fishing bycatch, as well as other relevant information on projects and conservation of marine turtles carried out in the Spanish Mediterranean area, as part of the global Mediterranean region marine turtles assessment.

Most of the knowledge about the biology, ecology, and conservation needs of sea turtles has been obtained from studies of adult females on nesting beaches and, to a lesser extent, from observations of juveniles and subadults in their foraging and development habitats. Those studies have principally sought to understand natal homing and nest site fi...

Dissolved silicon (DSi) is biologically processed to produce siliceous skeletons by a variety of organisms including radiolarians, silicoflagellates, choanoflagellates, plants, diatoms and some animals. In the photic ocean, diatoms are dominant consumers over competing other silicifiers. In Antarctica, where DSi is not particularly limiting, diatom...

Microplastics are present in almost all seas and oceans, including the Southern Ocean. To the south of the Antarctic Polar Front, microplastics are present mainly west to the Antarctic Peninsula, but information is scarce about their impact on the pelagic food web. Here, we analysed 42 scats of male Antarctic fur seals (Arctocephalus gazella) colle...

The aim of the present study was twofold: (i) to validate the drone methodology for floating marine macro-litter (FMML) monitoring, by comparing the results obtained through concurrent drone surveys and visual observations from vessels, and (ii) to assess FMML densities along the North Western Mediterranean Sea using the validated drone surveys. Th...

Dissolved silicon (DSi) is biologically processed to produce siliceous skeletons by a variety of organisms including radiolarians, silicoflagellates, choanoflagellates, plants, diatoms and some animals. In the photic ocean, diatoms are dominant consumers over competing other silicifiers. In Antarctica, where DSi is not particularly limiting, diatom...

Resource partitioning in polymorphic fish species is expected to be altered by human exploitation, as individual specialization is density dependent in many vertebrates. We tested this hypothesis using the ballan wrasse Labrus bergylta as a model species. We compared the isotope niches of the plain and spotted morphs of the species in a marine prot...

Fish skeletal remains recovered from two archaeological sites dated in the Middle Holocene of Tierra del Fuego (Argentina) were analysed to describe habitat use patterns by hake in the past and predict changes in a warmer world. Mitochondrial DNA was successfully extracted and amplified from 42 out of 45 first vertebra from ancient hake and phyloge...

Herbivores consume foods that are often low in many essential nutrients and high in structural constituents difficult to digest. In this situation, nutritional quality is of paramount relevance for food selection. Neritic juvenile green turtles (Chelonia mydas Linnaeus 1758) in the western South Atlantic are plant-based omnivores relying primarily...

Fish skeletal remains recovered from two archaeological sites dated in the Middle Holocene of Tierra del Fuego (Argentina) were analysed to describe habitat use patterns by hake in the past and predict changes in a warmer world. Mitochondrial DNA was successfully extracted and amplified from 42 out of 45 first vertebra from ancient hake and phyloge...

Using rainbow wrasse as a model species, we evaluate the impact of protection on the relationship between body size and: i) trophic position (TP), based on δ¹⁵N; and ii) body condition (BC), based on weight-at-length. We found that the biomass of the rainbow wrasse, their predators and their competitors was higher inside the no-take marine protecte...

Detailed knowledge on habitat use by marine mammals is critical for understanding their ecological role and for adequate management. Here, we assess the habitat use patterns of thirteen species of marine mammals along the salinity gradient of the Río de la Plata estuary and the adjoining western South Atlantic Ocean, for which we use the ratios of...

Natural or human-induced environmental changes can modify the structure of ecological communities and thus alter food web interactions. After the collapse of hake stocks (Merluccius hubbsi) provoked by fisheries over the Patagonian shelf in 1997 profound changes have taken place in the community, including long-term dietary shifts in some marine ve...

Green turtles are megaherbivores with a key role in the dynamics of tropical seagrass meadows, but little is known about their relevance as herbivores in tropical reef habitats. We conducted underwater censuses of green turtles, herbivorous fishes and sea urchins in two distinct tropical regions: Fernando de Noronha (Western Atlantic Ocean) and the...

Explaining the mechanisms driving niche partitioning among species is of great importance in ecology. Unlike the fundamental niche, a species’ realised niche can only be measured in situ, as a result of biotic and abiotic interactions defining its size. Following current methodology, the realised niche of a species is often influenced by the rare a...

The sublittoral forests formed by the fucoid algae Cystoseira spp. are important juvenile habitats for many Mediterranean fish species. However, the spatial variability of juvenile fish assemblages within the forests and the potential environmental drivers, such as depth and habitat complexity, remain poorly understood. We estimated densities, size...

The settlement of demersal animals is influenced both by physical processes ruling the distribution of pelagic juveniles in the open ocean and by the active selection of suitable benthic habitats by those same pelagic juveniles. Green turtles inhabiting the coastal areas of the western South Atlantic Ocean derive primarily from the rookery at Ascen...

Determining both the nutrient requirements of a species and its digestive strategy is critical to gain a full understanding of its nutrition. Herbivores consume foods that are often low in many essential nutrients and high in structural constituents, which may result in reduced digestibility. The assessment of the digestibility coefficient is thus...

Understanding the structure and functioning of marine ecosystems requires information about the trophic relationships between species. Herbivory is the major determinant of ecosystem dynamics, but little is known about resource partitioning between herbivores in the eastern Mediterranean. Extensive meadows of the seagrass Posidonia oceanica develop...

Los juveniles de la tortuga verde (Chelonia mydas) abundan en toda la costa de Brasil (Santos et al. 2015), en Uruguay (Vélez-Rubio et al. 2013) y el norte de Argentina (González Carman et al. 2012). La gran mayoría proceden de las playas de nidificación de la isla Ascensión ( 7°56′33″S 14°22′05″O; Reino Unido), la principal zona de nidificación de...

SWOT Report XIV features an up-to-date, comprehensive map of sea turtle distribution in the Mediterranean, a picture of loggerhead movements in the Atlantic, and expert answers to the most frequently asked questions about sea turtles. Other articles explore the effects of red tides on turtles, best practices for transporting stranded turtles, and...

The Marine Turtle Specialist Groups Regional Reporting initiative aims to gather information from all all Regional Management Units (RMUs) updating on the current status and knowledge for all sea turtle populations (RMUs) in such a manner that it is presented in a standardized form and made available to the public. In the case of the Mediterranean...

Stable carbon and nitrogen isotope ratios in the skeletal elements of both ancient and modern marine species from the Beagle Channel were used to compare the structure of Late Holocene and modern food webs, and predict potential changes as a result of a Sea Surface Temperature (SST) increase in the region. Complementary, ancient and modern shells o...

Here, we analyse changes throughout time in the isotopic niche of the Franciscana dolphin (Pontoporia blainvillei), the South American fur seal (Arctocephalus australis) and the South American sea lion (Otaria flavescens) from the Río de la Plata estuary and adjacent Atlantic Ocean to test the hypothesis that fishing may modify the diet of small-ga...

In order to gather information on the current state of the still existing shark populations and the impact fisheries have had on them, a survey of over 30% of the fishing fleet operating in the Costa Brava (NE Catalonia) was conducted between October 2016 and November 2017. A total of 42 interviews were carried out on trawlers (72,1%), surface long...

The available information regarding the 2 sea turtle species breeding in the Mediter-ranean (loggerhead turtle Caretta caretta and green turtle Chelonia mydas) is reviewed, including biometrics and morphology, identification of breeding and foraging areas, ecology and behaviour, abundance and trends, population structure and dynamics, anthropogenic...

The available information regarding the 2 sea turtle species breeding in the Mediterranean (loggerhead turtle Caretta caretta and green turtle Chelonia mydas) is reviewed, including biometrics and morphology, identification of breeding and foraging areas, ecology and behaviour, abundance and trends, population structure and dynamics, anthropogenic...

ABSTRACT: The available information regarding the 2 sea turtle species breeding in the Mediterranean (loggerhead turtle Caretta caretta and green turtle Chelonia mydas) is reviewed, including biometrics and morphology, identification of breeding and foraging areas, ecology and behaviour, abundance and trends, population structure and dynamics, anth...

Background Tetrapods do not express hydrolases for cellulose and hemicellulose assimilation, and hence, the independent acquisition of herbivory required the establishment of new endosymbiotic relationships between tetrapods and microbes. Green turtles (Chelonia mydas) are one of the three groups of marine tetrapods with an herbivorous diet and whi...

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Individual specialization in vertebrates is often related to morphological variability, but can also reflect a diversity of trajectories during the learning sensitive period in early life. In both cases the capacity of adults to adapt to new environments can be limited if further morphological or behavioral change is not possible. Adult loggerhead...

Tetrapods do not express hydrolases for cellulose and hemicellulose assimilation and, hence, they require the establishment of endosymbiotic relationships between with microbes. Green turtles (Chelonia mydas) are one of the three groups of marine tetrapods and shift to an herbivorous diet after several years consuming pelagic animals. We characteri...

The colonisation of new suitable habitats is crucial for species survival at evolutionary scale under changing environmental conditions. However, colonisation potential may be limited by philopatry that facilitates exploiting successful habitats across generations. We examine the mechanisms of long distance dispersal of the philopatric loggerhead s...

Survival during the settlement window is a limiting variable for recruitment. The survival is believed to be strongly determined by biological interactions and sea conditions, however it has been poorly investigated. We examined the settlement patterns related to relevant biotic and abiotic factors (i.e. Density-dependence, wind stress, wave height...

White seabream settler densities time-evolution (left) and rate of settler arrivals (right). Left panels: measured settler (10–20 mm) density variation (dots and squares) and adjusted double sigmoid functions (lines). Right panels: values are indicated as daily % of total settlers arriving to each cove. (TIF)

Parameters of the curve fitting settlers (10–20 mm) variations at each cove. Lmax is the maximum juvenile density, C is the slope parameters, w is the peak width and r2 the correlation coefficient. (DOCX)

Results of repeated measures ANOVA comparing juvenile total density and partial densities of individuals at total length (TL) of 10–20 mm (D10-20), 20–30 mm (D20-30) and ≥30 mm (D>30) over time (Sampling days, SD) at different orientations (Northeast and Southwest) and the coves (three in each orientation) off Menorca Island. SS: Sum of Squares; DF...

General additive model of settling dynamics of the whole white seabream juvenile population. Blue represents the northeast coves, and yellow the southwest coves. Fitted lines (solid line), 95% confidence intervals (color shaded areas) and residuals (dots) are shown. (TIF)

White seabream mortality rate. Density-dependent mortality relationship for juveniles smaller than 20 mm including all the individuals counted in the six coves. The vertical axis represents the daily mortality rate in percentage. (TIF)

Detailed knowledge on migratory routes connecting distant breeding, developmental and foraging areas is a key prerequisite for the successful management of marine vertebrates. The present study combines stable isotopes analysis of carapace scutes and satellite tracking of juvenile green turtles as an experimental approach to understand the pre and...

Individual specialization can be an advantageous strategy that increases the predation success and diminishes the intra-population competition. However, trophic specialisation can be a handicap in changing environments if the individuals are unable to use different prey or feeding grounds in response to change. Southern elephant seals (Mirounga leo...

Stable isotope ratios of C and N in the bone tissue of three different skeletal elements (angular, cleithrum and vertebra) of three fish species from different evolutionary lineages (Clupeiformes, Atheriniformes and Notothenioidei) were determined before (δ¹³Cbulk and δ¹⁵Nbulk) and after demineralization and delipidation (δ¹³Cdml and δ¹⁵Ndml). One...

Ocean currents profoundly impact all life in the oceans and over a broad size spectra species may show both horizontal and vertical movements to stay on preferred locations. As a corollary it might be expected that individuals in preferred oceanic habitats may simply drift with flows. We explored these scenarios by both satellite tracking young pel...

Green turtles are found in the waters of the Canary Islands but little is known about the ecology and anthropogenic pressures that threaten them. Our results have revealed that juvenile green turtles, ranging in curve carapace length from 26.9-81.0cm, are regularly found in the archipelago and originate from rookeries in both the eastern and wester...