Final answer:
Marine species, including pteropods, mollusks, and corals, are being impacted by ocean acidification owing to increased CO2 levels. Extremophiles and alkaliphiles are examples of organisms that can adapt to shifting pH levels in the ocean. These adaptations allow them to thrive in environments that would be inhospitable to most other organisms.
Step-by-step explanation:
The student's question is related to the biological concepts of ocean acidification and the adaptation of marine organisms to changes in the ocean's pH levels. Organisms like mollusks, vertebrates, and tiny plankton known as pteropods are already being affected by more acidic oceans. These organisms depend on calcium carbonate to build their shells, which is becoming less available due to increased ocean acidity.
Some marine species are able to adapt to these changing conditions, such as extremophiles which thrive in very acidic or alkaline environments, and alkaliphiles, microorganisms that grow best at pH levels between 8.0 and 10.5. Examples of such organisms include Vibrio cholerae, which prefers slightly basic pH levels, and Natronobacterium, which can withstand a pH of 10.5. Additionally, certain species like Halobacterium are considered extremophiles because of their ability to survive in conditions such as high salinity, which surpasses the tolerance levels of many organisms. These adaptations are crucial as they may lead to reduced competition and permit the organisms to survive in their harsh habitats.