Well with the ph above 7 that means the water is more of a base due to the salt within the water. the decrease in the ph is due to gloabal warming and the melting of ice which is somewhat diluting the water more. the wildlife within the ocean has been there since you or i so some creatures have developed a very specific habbitat and less salt withing the water could have effects on them. one such instace is if the organism needs a lot of salt. a decrease in salt would mean that their cells would bloat with water until they explode. this would obviously hurt the species as a whole and in turn effect the whole food chain.
There are some living things that are so sensible of changing of temperature or pH, in this way some plants, animals or protozoa can die, in this way the food chain that they belong would be different, affecting another living things. so at the end can be the result of lost of biodiversity.
The reason why there are more hares than foxes in the ecosystem is because if only 10% of the energy gets passed on to the next trophic level, then you need to have more lower level animals available to supports the animals higher up the food chain. The fox must eat several hares to gain enough energy for growth and development.
