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48
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Introduction
Sea turtle ecology, behaviour, & conservation. In prep. are papers on plastic ingestion, bycatch in fisheries,an population survey using citizen science.
We are also working on local lizard (Teira dugesii) ecology, behaviour and evolution,and its interaction with humans.
Current institution
Additional affiliations
September 1992 - present
Publications
Publications (48)
Biologging and biotelemetry are essential tools to better understand marine species and consequently contribute to increasing our knowledge of marine ecosystems as a whole. Assessing marine megafauna trajectories is traditionally performed with significantly high cost and labor, without guaranteeing the equipment recapture, where quick georeferenci...
Animal coloration is often shaped by a myriad of factors that lead to differences in colour through changes in the chromatophores. Depending on how this variation is partitioned, coloration is often categorized as continuous or polymorphic. However, the boundaries between these two categories are not always clear. Here, we investigated whether the...
The Madeira and Porto Santo Islands have both witnessed substantial habitat loss since their initial colonization. Despite their small size and the degradation of their natural habitats, they harbor a rich diversity of terrestrial invertebrates, including a significant number of endemic species. While research on Orthoptera fauna has predominantly...
Wildfires increase globally in frequency and extent as a consequence of climate change. These wildfires may have negative effects on insect populations.
Macaronesia is a global biodiversity hotspot with wildfires occurring annually, but the consequences of these wildfires on endemic insects are poorly understood.
Using bioacoustics monitoring, we s...
Living on islands entails numerous challenges for animals, among which population density approaching carrying capacity of trophic resources stands out. To overcome this limitation, many insular lizards can supplement their insectivorous diet with increasing portions of plant material. The Madeira wall lizard, Teira dugesii, is a medium-sized lacer...
Sea turtles are considered as bio-indicators for monitoring the efficiency of restoration measures to reduce marine litter impacts on health. However, the lack of extended and standardised empirical data has prevented the accurate analysis of the factors influencing litter ingestion and the relationships with individual health. Historic data collec...
Sea turtles have various life-stages, typically being oceanic foragers as juveniles while shifting to more coastal habitats as they mature. The present study focuses on the least studied and well known of these, the juvenile oceanic life stage for the loggerhead sea turtle, Caretta caretta. Loggerhead sea turtles remain threatened by fisheries and...
The endangered loggerhead sea turtles (Caretta caretta) are a relatively abundant sea turtle species in Madeiran waters, where they encounter various environmental stressors: from natural to anthropogenic. The physiological stress response is increased corticosterone (CS) level in the blood, achieving 2 ng/mL. Although there are various analytical...
The loggerhead sea turtle Caretta caretta is a vulnerable migratory species that spends its first years of life in the open sea. During this developmental phase, loggerheads can be found foraging in the epipelagic zone of the waters surrounding the Madeira Archipelago, providing a rare opportunity to gather information on the ecology of its oceanic...
This document, the MRR, includes the description of the criteria and species assessed, along with compilation of the results obtained during the implementation of the pilot monitoring programmes under the MSFD for marine birds, mammals and turtles in the three Macaronesian archipelagos (Azores, Madeira and Canary Islands) but also from other additi...
Most sea turtle species spend part of, or their entire juvenile stage in pelagic habitats. A key question is how pelagic turtles exploit their environment to optimize prey intake and maximize fitness. This study combined animal telemetry with remote-sensed environmental data to quantify the drivers and patterns of foraging behavior of juvenile logg...
Analysis of abundance and population structure of Plesionika narval was performed on data concerning 5,255 specimens obtained from 62 fishing sets carried out off the Madeira archipelago (Northeastern Atlantic) between 2004 and 2008 in a depth range from 101 to 350 m. Abundance ranged from 0.01 to 19.74 specimens-per-trap and significant difference...
locomotion flatfish
ms Wirtz and Davenport
film of flatfish locomotion.
ms Wirtz and Davenport
Several experimental surveys were carried out in the Northeastern Atlantic, Madeira archipelago from 1991 to 2008 to explore new fisheries resources. This study examined the selectivity of bottom and floating traps and the analysis of yield-per-recruit (YPR) and biomass-per-recruit (BPR) providing helpful insight to the management of the shrimp Ple...
Parasites of deep-water fishes are less known in comparison to the parasites of fishes living in the demersal and epipelagic ocean zones. In the present research note we report the occurrence of larval trypanorhynch cestodes in a rare deep-water fish, the deep-water brotula, Cataetyx laticeps. Based on the 28S rDNA (region D1-D3) sequence homology...
Life history traits of Plesionika narval were studied in the Northeastern Atlantic, Madeira archipelago including growth, age, sexual maturity, recruitment pattern and mortality. A total of 28262 specimens were sampled over a period of 8 years comprising two time series from 1991 to 1995 and 2004 to 2008. The relative growth pattern showed a negati...
Standard biochemical parameters were determined in wild juvenile loggerhead sea turtles Caretta caretta living offshore Madeira Island, northeast Atlantic. We analyzed the influence of age, sex, sea surface temperature, and body condition index on biochemical parameters including uric acid, total bilirubin, total cholesterol, creatinine kinase (CK)...
Analysis of teleost sagittal otoliths contained in scats has been widely used to determine the diet of seals. This method is based on the assumption that relative frequencies of otoliths in scats faithfully reflect those offish in the diet. This assumption has rarely been tested experimentally. We compared the ratios of herring (Clupea harengus) to...
Changes in the behavior of individual animals in response to environmental characteristics can provide important information about habitat preference, as well as the relative risk that animals may face based on the amount of time spent in hazardous areas. We analyzed movement and habitat affinities of ten loggerhead turtles (Caretta caretta) tagged...
Sex ratios are a fundamental trait for species reproduction. In species with temperature-dependent sex determination (TSD),
sex ratios are not necessarily even, which has important demographic consequences. We examined the sex ratio of juvenile pelagic
stage loggerhead turtles Caretta caretta offshore Madeira Island, North Eastern Atlantic, using l...
The Mediterranean fruit fly (medfly), Ceratitis capitata (Wied.), like many other polyphagous tephritids (Diptera: Tephritidae), preforms a lek as mating system. The sterile insect technique (SIT) requires released males to survive in the field, and to compete with wild males in attracting, courting and mating with wild females. The effects of the...
The helminth fauna of pelagic-stage loggerhead sea turtles, Caretta caretta, is still poorly known. Here, we describe the helminth-component community of healthy, free-ranging juvenile loggerhead sea turtles captured in the waters around Madeira Island, Portugal. Fifty-seven were used in this study. The esophagus, stomach, intestine, liver, gallbla...
Five species of monogeneans were recovered from the gill filaments of 181 chub mackerel, Scomber japonicus, from the Madeiran waters of the Atlantic Ocean, Portugal, during 2004/2005. The monogenean Pseudokuhnia minor showed the highest prevalence (98.68%) and a mean intensity of 28.23, followed by Kuhnia scombri (prevalence of 43.71% and mean inte...
Compensatory growth (CG, accelerated growth that may occur when an organism that has grown at a reduced rate as a result of suboptimal environmental conditions is exposed to better conditions) is considered an adaptation to variable en- vironments. Although documented thoroughly under captive conditions, CG has rarely been studied in wild populatio...
Intracytoplasmic inclusion bodies were detected in the mature red blood cells of twenty juvenile loggerhead sea turtles, Caretta
caretta, captured in Madeira. The bodies were mostly single, round to oval, frequently irregular in outline, and their diameter varied from 0.5 to 2.0 μm. Most bodies were associated with small granular areas, often in th...
Analysis of fish otoliths in scats and vomits of Galapagos fur seals (Arctocephalus galapagoensis) and Galapagos sea lions (Zalophus californianus wollebaeki) was used to determine the numerical composition of the diets for the post-El Nino year 1983, the cold seasons in 1984 and 1985, and the warm season in 1986. Between 84 and 99% of all otoliths...
Analysis of fish otoliths in scats and vomits of Galápagos fur seals (Arctocephalus galapagoensis) and Galápagos sea lions (Zalophus californianus wollebaeki) was used to determine the numerical composition of the diets for the post-El Niño year 1983, the cold seasons in 1984 and 1985, and the warm season in 1986. Between 84 and 99% of all otoliths...
Molecular markers based on mitochondrial (mt) DNA control region sequences were used to test the hypothesis that juvenile loggerhead sea turtles (Caretta caretta) in pelagic habitats of the eastern Atlantic are derived from nesting populations in the western Atlantic. We compared mtDNA haplotypes from 131 pelagic juvenile turtles (79 from the Azore...
Molecular markers based on mitochondrial (mt) DNA control region sequences were used to test the hypothesis that juvenile loggerhead sea turtles (Caretta caretta) in pelagic habitats of the eastern Atlantic are derived from nesting populations in the western Atlantic. We compared mtDNA haplotypes from 131 pelagic juvenile turtles (79 from the Azore...
Columbus crabs, Planes minutus (Crustacea: Brachyura) live in the open ocean attached to floating substrata including Sargassum, flotsam, and sea turtles. Eighty-two percent of 128 loggerhead turtles (Caretta caretta) checked, harboured a total of 172 crabs. Crabs inhabiting flotsam occurred in mixed sex groups of adults and juveniles, with a mean...
The effects of the 1982–83 El Niño (EN) were most severe in the eastern tropical Pacific (see Fahrbach et al. and Arntz et al., this Vol.) and the seal populations in the area of Galapagos and Peru suffered most from the impact of this event. The ocean around the Galapagos warmed rapidly in September 1982 and remained warm until July 1983 with a sh...
Questions
Question (1)
Can anyone advise on animal radio tags (VHF) that are compatible with a Telonics TR-5 receiver? The tags should be relatively inexpensive, should have a battery life of a few weeks, and should be easily embeddable in epoxy for water tightness. Most importantly, they should be available in Europe to avoid customs.
