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PARAMETER POPULASI IKAN PICKHANDLE BARRACUDA, Sphyraena jello Cuvier, 1829 DI PERAIRAN PANTAI DHOFAR, SELATAN OMAN
No full textPROTECTIVE EFFECTS OF Pandanus tectorius LEAF EXTRACT AGAINST BIOTIC AND ABIOTIC STRESSORS INGNOTOBIOTIC Artemia TEST SYSTEM
Get PDFThis thesis work investigated a more sustainable and environmentally friendly approach to replacing chemical-based alternatives for improving abiotic stress tolerance and preventing shrimp diseases in aquaculture. The efficacy of methanolic Pandanus tectorius leaf extract (PLE) as a natural alternative for increasing shrimp tolerance to lethal abiotic stressors (i.e., temperature at 42?C for 15 min, pH 5.3 for 24 h, and salinity at 100 g/L for 48 h), and Vibrio campbellii (10? cells/mL), the latter of which causes Vibriosis, was examined. Artemia franciscana brine shrimp was used as the model organism in this study because it can be hatched axenically and grown in gnotobiotic systems. These systems provide conditions for precise evaluation of the prophylactic and metaphylactic effects of specific compounds or extracts, and the impact on host-environment or host-microbe interactions. The application of PLE increased Artemia's tolerance to abiotic stresses and Vibrio challenge at the series of doses (1 g/L - 6 g/L) during pretreatment. Tolerance can also be achieved by exposing the Artemia to methanolic PLE during the challenge in continuous exposure at 0.2 g/L. Methanolic PLE was found to be non-toxic to Artemia up to 6 g/L during pretreatment and 1 g/L during continuous exposure. It also increased the expression of genes necessary for maintaining the structural integrity of the exoskeleton against abiotic stresses, and innate immune genes (hsp70, hsp60, hsp90, hmgb1, proPO, and tgase) that protect against Vibrio. The upregulation of heat shock proteins and other immune genes following methanolic PLE exposure, as demonstrated by qPCR and transcriptomic analysis, as well as their potential roles and mechanistic actions in contributing to protection, were discussed. Moreover, it was revealed that methanolic PLE inhibited virulence factors such as enzyme activities (i.e., caseinase, lipase, phospholipase), swimming and swarming motilities, Vibrio colonisation in Artemia, and bacterial growth significantly. This study added to our understanding of the molecular basis of stress responses in shrimp, as well as the potential of methanolic PLE as a stress and bacterial disease control strategy. Further research should focus on optimizing methanolic PLE dosage, application methods, and its long-term effects on Artemia
Assessing the coherence in biological and environmental drivers of young sea bass abundance across important estuarine nursery areas of the northern European sea bass stock
No full textYear class strength is an important determinant of fish population size, but the
drivers are often unknown. The northern stock of European sea bass
(Dicentrarchus labrax) is an important target species for both commercial and
recreational fisheries. Scientific assessments showed a rapid decline in spawning
stock biomass from 2010-18 attributed to a combination of fishing mortality and
poor year class strength. Recruitment to the adult stock is linked to the
abundance and temporal dynamics of young bass in estuarine nursery areas,
but little is known about the relative importance of environmental and biological
drivers on the survival of these young life stages. In this study, we use Generalised
Linear Models to attempt to identify important local environmental (sea surface
temperature and river flow) and biological (chlorophyll-a concentration and
predator abundance) drivers of young sea bass abundance. We focus on seven
British and Irish estuarine areas that are important to the northern stock of
European sea bass. In four English estuarine areas there were good model fits to
the abundance of young sea bass, but predictors differed amongst these
suggesting that drivers of abundance may differ among individual nursery
areas. This was further demonstrated by poor fits of models generated for
English estuaries to interannual patterns of abundance in the Irish nursery
areas tested. The differences found in the most important abundance drivers
amongst areas highlight the complex and differing dynamics between estuaries. If the number of young bass that eventually join the adult stock is dependent
on survivors from a diverse set of unique nursery area conditions, then
endeavours to incorporate this knowledge into fisheries management
should be further explored
Dehydration, Rehydration and Thermal Treatment: Effect on Bioactive Compounds of Red Seaweeds Porphyra umbilicalis and Porphyra linearis
No full textThe nutritional and bioactive value of seaweeds is widely recognized, making them a
valuable food source. To use seaweeds as food, drying and thermal treatments are required, but these treatments may have a negative impact on valuable bioactive compounds. In this study, the effects of dehydration, rehydration, and thermal treatment on the bioactive compounds (carotenoids, phycobiliproteins, total phenolic content (TPC), total flavonoids content (TFC)), antioxidant (ABTS and DPPH radical scavenging activities) and anti-Alzheimer?s (Acetylcholinesterase (AchE) inhibitory
activities, and color properties of Porphyra umbilicalis and Porphyra linearis seaweeds were evaluated. The results revealed significant reductions in carotenoids, TPC, TFC, and antioxidant activities after the seaweeds? processing, with differences observed between species. Thermal treatment led to the most pronounced reductions in bioactive compound contents and antioxidant activity. AchE inhibitory activity remained relatively high in all samples, with P. umbilicalis showing higher activity
than P. linearis. Changes in color (?E) were significant after seaweeds? dehydration, rehydration and thermal treatment, especially in P. umbilicalis. Overall, optimizing processing methods is crucial for preserving the bioactive compounds and biological activities of seaweeds, thus maximizing their potential as sustainable and nutritious food sources or as nutraceutical ingredients
Chaetomorpha linum Extract as a Source of Antimicrobial Compounds: A Circular Bioeconomy Approach
No full textThe circular bioeconomy is currently a promising model for repurposing natural sources;
these sources include plants due to their abundance of bioactive compounds. This study evaluated the
antimicrobial properties of a Chaetomorpha linum extract. Chaetomorpha linum is an invasive macroalga
from the Orbetello Lagoon (Tuscany, Italy), which grows in nutrient-rich environments and has been
forming extended mats since 2005. The biomass is mechanically harvested and treated as waste,
consuming considerable manpower and financial resources. As a potential way to increase the value
of such waste, this study found that C. linum extract (CLE) is a source of antimicrobial compounds.
The phytochemical characterization of the extract revealed the predominant presence of palmitic acid,
a fatty acid with known antimicrobial activity. Based on such findings, four bacterial species of high
clinical relevance (Enterococcus faecalis, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia
coli) were tested, revealing a notable antibacterial activity of the extract on Enterococcus faecalis (MIC,
32 ?g/mL). Computational analyses identified a potential Enterococcus faecalis molecular target for
palmitic acid, offering molecular insights on the interaction. This study presents a comprehensive
in vitro and in silico approach for drug and target discovery studies by repurposing C. linum as a
source of antimicrobial bioactive compounds
Assessing the coherence in biological and environmental drivers of young sea bass abundance across important estuarine nursery areas of the northern European sea bass stock
No full textYear class strength is an important determinant of fish population size, but the
drivers are often unknown. The northern stock of European sea bass
(Dicentrarchus labrax) is an important target species for both commercial and
recreational fisheries. Scientific assessments showed a rapid decline in spawning
stock biomass from 2010-18 attributed to a combination of fishing mortality and
poor year class strength. Recruitment to the adult stock is linked to the
abundance and temporal dynamics of young bass in estuarine nursery areas,
but little is known about the relative importance of environmental and biological
drivers on the survival of these young life stages. In this study, we use Generalised
Linear Models to attempt to identify important local environmental (sea surface
temperature and river flow) and biological (chlorophyll-a concentration and
predator abundance) drivers of young sea bass abundance. We focus on seven
British and Irish estuarine areas that are important to the northern stock of
European sea bass. In four English estuarine areas there were good model fits to
the abundance of young sea bass, but predictors differed amongst these
suggesting that drivers of abundance may differ among individual nursery
areas. This was further demonstrated by poor fits of models generated for
English estuaries to interannual patterns of abundance in the Irish nursery
areas tested. The differences found in the most important abundance drivers
amongst areas highlight the complex and differing dynamics between estuaries. If the number of young bass that eventually join the adult stock is dependent
on survivors from a diverse set of unique nursery area conditions, then
endeavours to incorporate this knowledge into fisheries management
should be further explored
