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showing 10 items of 18693 documents
Effects of global warming on reproduction and potential dispersal of Mediterranean Cnidarians
2019
Water temperature directly affects life cycles, reproductive periods, and metabolism of organisms living the oceans, especially in the surface zones. Due to the ocean warming, changes in water stratification and primary productivity are affecting trophic chains in sensitive world areas, such as the Mediterranean Sea. Benthic and pelagic cnidarians exhibit complex responses to climatic conditions. For example, the structure and phenology of the Mediterranean hydrozoan community displayed marked changes in species composition, bathymetric distribution, and reproductive timing over the last decades. The regional species pool remained stable in terms of species numbers but not in terms of speci…
On several species of Oswaldella Stechow, 1919 (Cnidaria, Hydrozoa), including the description of a new species
2018
Oswaldella is the most speciose genus of Antarctic hydroids, being one of the most characteristic genera of hydrozoans of the Antarctic benthic marine ecosystem. A relatively high number of taxonomic characters allow species identification, but some key ones are difficult to study properly with a light microscope. In order to improve knowledge of species of the genus, a SEM survey of five of the 27 known nominal species of Oswaldella was carried out, including type material of O. grandis and O. terranovae. The study has revealed no significant differences between O. stepanjantsae and O. terranovae and, consequently, the former is considered a junior synonym of the latter. The type material …
Species ofAntarctoscyphusPeña Cantero, García Carrascosa and Vervoort, 1997 (Cnidaria: Hydrozoa: Symplectoscyphidae) collected by US Antarctic expedi…
2017
ABSTRACTAntarctoscyphus is one of the most characteristic genera of Antarctic benthic hydroids, with nine of the 10 known species considered to be endemic to the Antarctic; only Antarctoscyphus elongatus is also present in the sub-Antarctic region of Kerguelen. Accordingly, the genus was considered to have an Antarctic–Kerguelen distribution. Here we present the results of the study of the species of Antarctoscyphus collected from different Antarctic areas and from the Magellan region, during several expeditions under the United States Antarctic Research Program between 1958 and 1986. A scanning electron microscopy survey of all known species of the genus was carried out. Eight of the 10 kn…
No need to shout: Effect of signal loudness on sibling communication in barn owlsTyto alba
2017
In animal communication, signal loudness is often ignored and seldom measured. We used a playback experiment to examine the role of vocal loudness (i.e., sound pressure level) in sibling to sibling communication of nestling barn owls Tyto alba. In this species, siblings vocally negotiate among each other for priority access to parental food resources. Call rate and call duration play key roles in this vocal communication system, with the most vocal nestlings deterring their siblings from competing for access to the food item next delivered by parents. Here, we broadcast calls at different loudness levels and call rate to live nestlings. The loudness of playback calls did not affect owlets' …
Resource Partitioning in Food, Space and Time between Arctic Charr (Salvelinus alpinus), Brown Trout (Salmo trutta) and European Whitefish (Coregonus…
2017
Arctic charr and European whitefish are considered to be strong competitors in lakes, with the latter usually being the superior species. However, high niche plasticity and lake morphometry may suggestively facilitate resource partitioning and coexistence between charr and whitefish. Here, we explore the trophic niche utilization (diet and habitat use) of charr and whitefish co-occurring with brown trout in the deep and oligotrophic Lake Fyresvatnet, southern Norway (59˚05’N, 8˚10’E). Using CPUE, stomach contents and stable isotope analyses, a distinct resource partitioning was revealed between brown trout and the other two species. Brown trout typically occupied the littoral zone, feeding …
Surgical implantation of electronic tags does not induce medium-term effect: insights from growth and stress physiological profile in two marine fish…
2020
Abstract Background Telemetry applied to aquatic organisms has recently developed greatly. Physiological sensors have been increasingly used as tools for fish welfare monitoring. However, for the technology to be used as a reliable welfare indicator, it is important that the tagging procedure does not disrupt fish physiology, behaviour and performance. In this communication, we share our medium-term data on stress physiological profile and growth performance after surgical tag implantation in two important marine fish species for European aquaculture, the sea bream (Sparus aurata) and the European sea bass (Dicentrarchus labrax). Results Blood samples after surgical tag implantation (46 day…
Benchmark database for fine-grained image classification of benthic macroinvertebrates
2018
Managing the water quality of freshwaters is a crucial task worldwide. One of the most used methods to biomonitor water quality is to sample benthic macroinvertebrate communities, in particular to examine the presence and proportion of certain species. This paper presents a benchmark database for automatic visual classification methods to evaluate their ability for distinguishing visually similar categories of aquatic macroinvertebrate taxa. We make publicly available a new database, containing 64 types of freshwater macroinvertebrates, ranging in number of images per category from 7 to 577. The database is divided into three datasets, varying in number of categories (64, 29, and 9 categori…
Incidental catch of loggerhead sea turtles (Caretta caretta) along the Sicilian coasts by longline fishery
2018
It has been estimated that 44,000 Caretta caretta turtles die every year due to anthropomorphic activity in the Mediterranean Sea, and that longline fishing is one of the most significant causes of mortality. A total of 482 specimens of C. caretta were rescued from different parts of the Sicilian coast (Mediterranean Sea) from 2014 to 2016. The most numerous stranding was recorded during the spring and summer seasons, mainly along the north and eastern coasts of Sicily. The curved carapace length for all the specimens ranged from between 19 and 95 cm and most of these were young or sub adults. The highest number of strandings was recorded in 2014 and 2015, with 206 and 169 individuals, resp…
Effects of changing climate on European stream invertebrate communities : A long-term data analysis
2018
Long-term observations on riverine benthic invertebrate communities enable assessments of the potential impacts of global change on stream ecosystems. Besides increasing average temperatures, many studies predict greater temperature extremes and intense precipitation events as a consequence of climate change. In this study we examined long-term observation data (10-32years) of 26 streams and rivers from four ecoregions in the European Long-Term Ecological Research (LTER) network, to investigate invertebrate community responses to changing climatic conditions. We used functional trait and multi-taxonomic analyses and combined examinations of general long-term changes in communities with deta…
A multidisciplinary analytical framework to delineate spawning areas and quantify larval dispersal in coastal fish
2019
International audience; Assessing larval dispersal is essential to understand the structure and dynamics of marine populations. However, knowledge about early-life dispersal is sparse, and so is our understanding of the spawning process, perhaps the most obscure component of biphasic life cycles. Indeed, the poorly known species-specific spawning modality and early-life traits, along with the high spatio-temporal variability of the oceanic circulation experienced during larval drift, hamper our ability to properly appraise the realized connectivity of coastal fishes. Here, we propose an analytical framework which combines Lagrangian modeling, network theory, otolith analyses and biogeograph…