While declines in horseshoe crab populations have been attributed to over-harvesting, population genetic analysis has indicated that they are, as a species, vulnerable to climate change. Whether or not they have been impacted by the current changes in climate, there is little doubt that this already stressed species will be put under further pressure as the ocean warms. Horseshoe crabs are, of course, an important source of food for a number of species, and as with any species, their decline effects the ecosystems they live in, but humans also rely on them. Their blood provides us with the ability to detect harmful contaminants on medical equipment. "No IV drug reaches your hospital pharmacy without its horseshoe crab test."