Publications by authors named "Michaelidis B"

The severity, frequency, and duration of extreme events, in the context of global warming, have placed many marine ecosystems at high risk. Therefore, the application of methods that can mediate the impacts of global warming on marine organisms seems to be an emerging necessity in the near term. In this context, enhancing the thermal resilience of marine organisms may be crucial for their sustainability.

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The present research focuses on the seasonal changes in the energy content and metabolic patterns of red porgy (Pagrus pagrus) sampled in a fish farm in North Evoikos Gulf (Greece). The study was designed in an effort to evaluate the influence of seasonality in several physiological feauteres of high commercial importance that may affect feed intake and growth. We determined glycogen, lipids and proteins levels, and cellular energy allocation (CEA) as a valuable marker of exposure to stress, which integrates available energy (Ea) and energy consumption (Ec).

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Article Synopsis
  • - The study examines the genetic diversity of five populations of the narrow-clawed crayfish (Pontastacus leptodactylus) in Greece, focusing on three translocated populations and their origins, particularly linking them to Turkish lake Eğirdir.
  • - Using nine microsatellite loci, the research found that while the populations show low genetic diversity in terms of alleles, they still exhibit overall genetic diversity, which indicates potential local adaptation despite overfishing and habitat degradation challenges.
  • - The findings highlight the Evros river population as having high genetic diversity, making it a valuable candidate for conservation efforts and future restocking initiatives, marking a significant first step in developing management practices for crayfish populations in Greece.
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The copepod Lernathropus kroyeri constitutes one of the major parasites for the Mediterranean aquaculture, infesting the sea bass Dicentrarchus labrax causing thus disruptions of growth performance and occasionally mortalities. Despite the large spread and the high frequency of this parasite in mariculture farms of Eastern Mediterranean, L. kroyeri genetic profile from aquaculture as well as the pathophysiological response of D.

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Hypometabolism is a common strategy employed by resilient species to withstand environmental stressors that would be life-threatening for other organisms. Under conditions such as hypoxia/anoxia, temperature and salinity stress, or seasonal changes (e.g.

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Article Synopsis
  • Bivalves, especially the economically valuable flat oyster (Ostrea edulis), are heavily affected by climate change, particularly due to their vulnerability to changing temperatures in the Mediterranean.
  • This study focused on the physiological responses of juvenile O. edulis to different seawater temperatures (21 °C, 25 °C, and 28 °C), highlighting the potential for stress-related damage as temperatures rise.
  • Findings revealed that temperatures above 25 °C activate stress-related genes and can lead to a switch from aerobic to anaerobic metabolism, increasing the risk of cell damage and impacting the oysters' survival.
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Temperature affects organisms' metabolism and ecological performance. Owing to climate change, sea warming constituting a severe source of environmental stress for marine organisms, since it increases at alarming rates. Rapid warming can exceed resilience of marine organisms leading to fitness loss and mortality.

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Land snails occupy a variety of habitats, with differing temperature and humidity regimes and exhibit a wide span of adaptations, to withstand abiotic condition changes. The present work's aim was to examine the correlation of habitat's thermal adversity in different Mediterranean type habitats with the land snail's antioxidant and heat shock responses. For this purpose, snails of different species from populations along a north-south axis from the islands and mainland of Greece were exposed to elevated temperature and antioxidant enzyme activities, and Hsp70 and Hsp90 levels were determined in their tissues.

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The fan mussel is currently on the brink of extinction due to a multifactorial disease mainly caused to the highly pathogenic parasite , meaning that the selection pressure outweighs the adaptive potential of the species. Hopefully, rare individuals have been observed somehow resistant to the parasite, stretching the need to identify the traits underlying this better fitness. Among the candidate to explore at first intention are fast-evolving immune genes, of which toll-like receptor (TLR).

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Disease outbreaks in several ecologically or commercially important invertebrate marine species have been reported in recent years all over the world. Mass mortality events (MMEs) have affected the noble pen shell (), causing its near extinction. Our knowledge of the dynamics of diseases affecting this species is still unclear.

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Aquaculture is affected by numerous factors that may cause various health threats that have to be controlled by the most environmentally friendly approaches. In this context, prebiotics, probiotics, and synbiotics are frequently incorporated into organisms' feeding rations to ameliorate the health status of the host's intestine, enhancing its functionality and physiological performance, and to confront increasing antimicrobial resistance. The first step in this direction is the understanding of the complex microbiome system of the organism in order to administer the optimal supplement, in the best concentration, and in the correct way.

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Article Synopsis
  • The study focuses on mass mortalities of populations along Mediterranean coastlines, highlighting the risks to species survival due to both pathogens involved.
  • It compares two Greek populations from Kalloni Gulf and Maliakos Gulf, one hosting only one pathogen and the other hosting both, using physiological and immunological markers.
  • Results show that individuals with both pathogens have reduced physiological performance, indicating a synergistic effect in mortality linked to seasonal variations.
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In biofouling communities, ascidians are among the most damaging species, presenting severe threats, such as depressed growth rates and decreased chances of lower survival, to shellfish aquaculture. However, little is known concerning the fouled shellfish physiology. In an effort to obtain information for the magnitude of stress caused by ascidians to farmed five seasonal samplings took place in a mussel aquaculture farm suffering from ascidian biofoulants, in Vistonicos Bay, Greece.

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Physiological stress patterns of marine organisms in their natural habitats are considerably complex in space and time. These patterns can eventually contribute in the shaping of fish' thermal limits under natural conditions. In the view of the knowledge gap regarding red porgy's thermal physiology, in combination with the characterization of the Mediterranean Sea as a climate change ''hotspot'', the aim of the present study was to investigate this species biochemical responses to constantly changing field conditions.

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Freshwater crayfish are considered as aquatic products of high quality and high nutritional value. The increasing demand has led to populations reduction in several locations throughout their range. Thus, the development of appropriate rearing conditions is considered necessary, among which, optimization of their diet is a basic part.

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Recently, P. nobilis populations have suffered a tremendous reduction, with pathogens potentially playing a crucial role. Considering its highly endangered status, mechanisms leading to mass mortalities were examined in one or multiple pathogens infected populations.

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(Eschscholtz, 1823) (Decapoda:Astacidea:Astacidae) constitutes an ecologically and economically highly important species. In the present study, the mitochondrial genome of the freshwater crayfish from Greece is analyzed for the first time, using 15 newly designed primer pairs based on available sequences of closely related species. The analyzed coding part of the mitochondrial genome of consists of 15,050 base pairs including 13 protein-coding genes (PCGs), 2 ribosomal RNA gene (rRNAs), and 22 transfer RNA genes (tRNAs).

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Organisms can modify and increase their thermal tolerance faster and more efficiently after a brief exposure to sublethal thermal stress. This response is called 'heat hardening' as it leads to the generation of phenotypes with increased heat tolerance. The aim of this study was to investigate the impact of heat hardening on the metabolomic profile of Mytilus galloprovincialis in order to identify the associated adjustments of biochemical pathways that might benefit the mussels' thermal tolerance.

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Marine heatwaves (excessive seawater temperature increases) pose high risk to bivalves' health and farming. The seawater temperature increase is responsible for various pathogen population expansions causing intense stress to marine organisms. Since the majority of knowledge so far derives from laboratory experiments, it is crucial to investigate stress responses in field conditions in order to understand the mechanisms leading to bivalves' mortality events after exposure to temperature extremes.

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Due to the rapid decrease of populations during the previous decades, this bivalve species, endemic in the Mediterranean Sea, is characterized as 'critically endangered'. In addition to human pressures, various pathogen infections have resulted in extended reduction, even population extinction. While is characterized as one of the major causative agents, mass mortalities have also been attributed to sp.

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Raw-bivalves consumption is a wide trend in Mediterranean countries. Despite the unambiguous nutritional value of seafood, raw consumption of bivalves may involve risks that could pose a significant threat to consumers' health. Their filter-feeding behavior is responsible for the potential hosting of a wide variety of microorganisms, either pathogenic for the bivalves or public health threats.

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Temperature, a major abiotic environmental factor, regulates various physiological functions in land snails and therefore determines their biogeographical distribution. Thus, species with different distributions may present different thermal tolerance limits. Additionally, the intense reactivation of snail metabolic rate upon arousal from hibernation or estivation may provoke stress.

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Global warming affects the aquatic ecosystems, accelerating pathogenic microorganisms' and toxic microalgae's growth and spread in marine habitats, and in bivalve molluscs. New parasite invasions are directly linked to oceanic warming. Consumption of pathogen-infected molluscs impacts human health at different rates, depending, inter alia, on the bacteria taxa.

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Ectotherms are exposed to a range of environmental temperatures and may face extremes beyond their upper thermal limits. Such temperature extremes can stimulate aerobic metabolism toward its maximum, a decline in aerobic substrate oxidation, and a parallel increase of anaerobic metabolism, combined with ROS generation and oxidative stress. Under these stressful conditions, marine organisms recruit several defensive strategies for their maintenance and survival.

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Considering temperature's upcoming increase due to climate change, combined with the fact that Mediterranean mussels Mytilus galloprovincialis (Lamarck, 1819) live at their upper limits [critical temperatures (Tc) beyond 25 °C], we cannot be sure of this species' sustainable future in the Mediterranean Sea. Deviation from optimum temperatures leads to cellular damage due to oxidative stress. Although ascorbic acid (AA) is a major scavenger of reactive oxygen species (ROS), its capacity to minimize oxidative stress effects is scarcely studied in aquatic organisms.

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