In marine ecosystems, the temperature affects life stages such as breeding and migration. Additionally, temperature changes the ratio and abundance of prey, predators, and parasites. 

On a less biological level, temperature in our oceans we can track the rates of ocean warming from greenhouse gases and trace the mixing of different ocean currents and upwelling.  

California Office of Environmental Health Hazard Assessment, Coastal ocean temperature 

Most importantly, pH can be used to track Ocean Acidification, one of the largest indicators of climate change, being directly correlated to Carbon Dioxide Emissions. It affects the development of marine organisms like crabs and coral, which both are tied to massive economic markets.

National Oceanic and Atmospheric Association, Ocean Acidification 

Oxygen Reduction Potential, or ORP, is the ability for a body of water to break down waste products in the water. ORP is similar to Dissolved Oxygen in the sense that the higher ORP in the water, the easier it is for bacteria to decompose waste in the body of water. A low ORP value, less than 300 mV, is usually associated with water polluted with organic or synthetic waste. 

California Environmental and Natural Resources, Oxygen Reduction Potential (ORP)