Are digestive enzymes activities affected by starvation and low oxygen conditions in bivalves?5 answersDigestive enzyme activities in bivalves can be significantly affected by both starvation and low oxygen conditions. Starvation has been shown to decrease various digestive enzyme activities in mussels, while low dissolved oxygen levels can lead to changes in stable isotope ratios in oysters, indicating a starvation response where tissues are catabolized. Additionally, hypoxia can trigger molecular responses related to autophagy, apoptosis, and inflammation in bivalves like mussels and oysters. Furthermore, infaunal clams like Arctica islandica regulate internal oxygen levels to enhance nitric oxide (NO) accumulation, which can depress metabolic rates by inhibiting cytochrome-c-oxidase activity. Therefore, both starvation and low oxygen conditions play crucial roles in altering digestive enzyme activities and metabolic responses in bivalves.
What are the specific temperature ranges that trigger coral cell death?4 answersThe specific temperature ranges that trigger coral cell death vary depending on the species. In the case of Porites lobata, exposure to 34°C for 24 and 48 hours resulted in up-regulation of genes involved in programmed cell death (PCD) and apoptosis, indicating that coral cells are headed towards bleaching and death with increased temperature. Similarly, in the study of coral reefs in the Florida Keys, sustained temperatures below 12°C caused physiological impairment and nearly 100% mortality of Montastraea faveolata and Porites astreoides corals. On the other hand, Siderastrea siderea showed minimal effects and readily recovered from the cold-water anomaly. These findings suggest that different coral species have different temperature thresholds for cell death, with some being more tolerant to high temperatures than others.
How does climate change affect marine life?5 answersClimate change has significant impacts on marine life and ecosystems. Rising sea surface temperatures, ocean acidification, and changing physical and chemical parameters are altering biological processes, food web structure, and ecosystem dynamics. These changes affect marine populations and ecosystems at all levels of organization, leading to potential disruptions in fish stocks, migration patterns, and the health of marine species. Additionally, climate change can result in the degradation of coral reefs and shellfish due to ocean acidification, impacting both tropical coral reef ecosystems and the shellfish aquaculture industry. The warming of the oceans can also lead to more intense seasonal rainfall, causing immense sedimentary systems and muddy waters in the depths of oceans, making them uninhabitable for most marine species. Overall, climate change poses a significant threat to marine life and requires adaptations in marine management, conservation, and governance to mitigate its effects.
What substrate affinitie scan bivalves have?4 answersBivalves have affinities for soft substrates, such as those found in the Swan Estuary. They are suitable as biological indicators because they respond to changing environmental conditions. The bivalve community and populations in the Swan Estuary have shown significant changes over time. Relationships have been found between bivalve distribution, abundance, and biomass, and major environmental conditions in the estuary, such as nutrient enrichment and changes in hydrology. Bivalves also demonstrate a causal relationship to the toxicity of chromium. The ease of sampling, abundance, and widespread distribution of bivalves make them potential biological indicators within the Swan Estuary.
How does parasite load impact the biomineralisation of bivalves?3 answersParasite load can impact the biomineralisation of bivalves. Shell alterations, such as dome or igloo-shaped calcifications, have been observed in bivalves infected with digenean trematode parasites. These shell reactions are believed to be a response to the presence of the parasites and are likely influenced by the characteristics of the host shell structure. In addition, parasite load can lead to changes in the abundance, growth rate, mortality, body mass, and somatic production of bivalves. Larger clams with high parasite loads may experience increased mortality, which can have a significant impact on their fecundity and ability to recover their population. Therefore, parasite load can affect the biomineralisation of bivalves by inducing shell reactions and influencing various physiological processes.
How does temperature affect fish respiration?5 answersTemperature has a significant impact on fish respiration. Fish exposed to cold water experience a decrease in metabolic rates due to the effects of temperature on biochemical reactions. The respiratory metabolism of fish, such as the snakehead (Channa argus), is positively correlated with temperature, with resting metabolic rate (RMR) increasing as temperature rises. The thermal metabolic sensitivity of fish can vary depending on the temperature range, as indicated by the V-shaped Q10 values change in RMR. Acclimation to chronic temperature changes can reduce the metabolic thermal sensitivity of fish. Additionally, the regulation of ventilation frequency (VF) alone may not be sufficient to meet the oxygen demand of fish as temperature increases. Cold acclimation can lead to compensation in VF to maintain oxygen supply. Overall, temperature plays a crucial role in fish respiration, affecting metabolic rates and oxygen demand.