Browsing by Issue Date, starting with "2024-10-22"
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- Putative nociceptive responses in a decapod crustacean: The Shore Crab (Carcinus maenas)Publication . Kasiouras, Eleftherios; Hubbard, Peter; Gräns, Albin; Sneddon, Lynne U.Nociceptors are receptors that detect injurious stimuli and are necessary to convey such information from the periphery to the central nervous system. While nociception has been extensively studied in various taxa, there is relatively little electrophysiological evidence for the existence of nociceptors in decapod crustaceans. This study investigated putative nociceptive responses in the shore crabs, specifically their response to mechanical and noxious chemical stimuli. Extracellular multi-unit electrophysiological recordings were conducted from the anterior ganglion and the circumesophageal connective ganglia to assess nociceptive responses. Soft tissues at the joints of the chelae, antennae, and walking legs were stimulated using acetic acid (noxious stimulus) and von Frey hairs (mechanical stimulus), while nearby ganglion activity was recorded. The results indicate the existence of nociceptors in the tested areas, with mechanical stimuli eliciting shorter, more intense neural activity compared with acetic acid. Although acetic acid triggered responses in all areas, the antennae and antennules did not respond to mechanical stimuli. Though we acknowledge the challenges of conducting in vivo electrophysiological recordings, future research should focus on further characterizing nociceptor activity because the results suggest the presence of nociceptors.
- Effect of probiotic microorganisms on growth and health status of rearing species under biofloc technology (BFT)Publication . Rito, João Ribeiro; Sánchéz Peñaranda, David; Teodósio, RitaEnvironmental impacts associated with aquaculture productions are mainly related to the discharge of nutrient- rich wastewater, mainly N (Nitrogen) and P (Phosphorous). Biofloc technology (BFT), a microbial- based system, is seen as a promising sustainable production system. It operates as a zero-water exchange system, where nutrients and organic particles in the culture water are recycled by autotrophic and heterotrophic bacteria into protein- rich flocs, providing a complement food source to fish diets and ultimately improving circular economy. Biological control strategies, including bacterial probiotics or microalgae products, have proven to enhance the health of reared animals and improve water quality in aquaculture. This project aimed to deepen the knowledge of the ecology of microalgae for their cultivation in conditions that allow interaction with floccules, generating a food alternative that combines the benefits of both bacteria and microalgae. The effects of microalgae addition in the cultured species, Penaeus vannamei (Pacific white shrimp), were analyzed and compared with bacterial probiotic addition in a BFT production. Four different treatments were analyzed: biofloc (control), bacterial probiotic inclusion, microalgae inclusion, and a combination of both. This work was conducted in two phases, with the same experimental design but under distinct production conditions (density, tank volume, experimental period). Furthermore, shrimp resilience was assessed through three environmental challenges: 1) hypoxia, 2) density and 3) combined hypoxia and density, whereby shrimp survival was analyzed for each challenge. The results indicated that both bacterial and microalgae populations remained stable, providing both water quality and health benefits for the shrimps. Microalgae community evolution under biofloc conditions showed stability and capability to proliferate, even though nutrients overload on the culture water negatively impacted survival and growth performance of the reared shrimps. However, shrimp in microalgae-groups exhibited enhanced resilience when subjected to environmental stress challenges.