What tool can help monitor light conditions in a land-based nursery?

Monitoring light conditions in a land-based nursery is essential for the successful growth of corals, as light is vital for photosynthesis, which affects coral health and development. A Photosynthetic Active Radiation (PAR) sensor is specifically designed to measure the quantity of light available for photosynthesis, focusing on the wavelengths of light that are most beneficial for plants and corals.

These sensors provide data on light intensity, enabling nursery managers to ensure that the light levels are optimal for the species being cultivated. This information is crucial for making adjustments to the nursery environment, such as modifying shading or adjusting the positioning of coral fragments to receive optimal light exposure.

In contrast, other tools like thermocouples measure temperature, salinity meters assess salt concentration in water, and refractometers are used to measure the refractive index of liquids, providing different types of information that are not specifically related to monitoring light conditions. Therefore, the PAR sensor is uniquely suited to the task, making it the correct choice for this question.