Yes, it is indeed true that for several species of sea turtles, the incubation temperature determines the sex of the resultant offspring. According to J.D. Miller, this is true for the turtles Chelonia mydas , Lepidochelys olivacea , Caretta caretta , Chelonia depressa , and Dermochelys coriacea . As far as why this is the case, it is open to speculation. Often, a female will lay several nests over a season, so some of her nests will consist of males, some females and some nests will have both sexes. It is possible that it is better for the survival of the animals if females hatch and make their way to the sea during warmer weather.
Sea turtles add to the biodiversity of life, and in that way they benefit humans.
They are beautiful and long lived organisms, but unfortunately they are under some stress, and are considered endangered. If anything, humans are a hindrance to sea turtles. There are several human activities that have an effect on the coral reefs, and some have different affects and severity of affects. Fisheries activities has the most severe affects and the most common. In terms of what actually happens to the reefs, it has been found that there is an increase in coral bleaching and mortality as the ocean temperatures increase.