Increasing sea surface temperatures should.
Lower the amount of dissolved oxygen in the ocean, depriving many
invertebrate animals of oxygen necessary to live.
Lower the amount of sea ice in polar areas. This will warm the water,
decreasing the abundance of primary producers and the number of
organisms that eat these producers.
Increase the temperature difference between the upper and lower parts of
the ocean, making upwelling less likely to occur. This will decrease ocean
nutrient levels, affecting the number of primary producers.
Raise water temperatures above the tolerance limits for many aquatic
organisms in tropical areas, increasing stress on these species.