Temperature regulates the distribution of species in a determined ecosystem.
Looking at the table you can see that the temperature of the water along the coast of Virginia has been increasing through the decades.
An increase in temperature may lead the species to migrate, where the temperatures are better for their survival.
It may also affect the local populations by increasing the rate of mortality of those individuals within the population that cannot adapt to the said change. Even if the poorly adapted individuals manage to survive, their reproduction chances will decrease as the adverse conditions might decrease the individual's fertility or make them seem like unsuitable mates.
On the other hand, those individuals of the population that are able to adapt to the changes are more likely to survive and parent the next generations, passing on the genes that allowed them to adapt to the environmental changes. Over the course of several generations, you'd expect the population to slowly change and the population of flounders living on the coast of Virginia will be eventually adapted to survive on higher than 17ºC temperatures.