10.05.2019- Climate-(color)change

The guests on board our hot, sunny afternoon trip on the Ribeira Brava enjoyed sightings with two different groups of Short-beaked common dolphins (Delphinus delphis). With one of the groups we witnessed a frequently encountered anomaly on one individual: melanism. I’ve mentioned this on many blogs before but to recap: melanism describes an overproduction of the dark skin pigment melanin, causing a darker color in animals. This was the case for one large dolphin within the group and, as with previous cases, the animal was nonetheless perfectly integrated into the pod.

The reasons for such frequent sightings of this anomaly may be various but one possible factor is the animals adapting to a warming global climate. Currently the protective ozone layer in the Earths stratosphere is expanding, allowing more harmful UV rays to reach the Earths surface and potentially affect these highly surface-active dolphins. Thus an increase in the production of this protective skin pigment, melanin, that shields the animals skin from UV radiation makes perfect sense but that still remains a theory.

This change in an animals appearance as well as an increase in hybrids of different species are two phenomenon we can expect along with a variety of many others due to climate change. Changing climate and warming oceans expose animals to conditions that may bring about mutations, with a few being effective in the light of such changes, while others are largely damaging. As is the case with humans, the sun can also cause skin cancer in marine creatures and warmer waters also promote harmful algal blooms, poisoning all organisms in the food web. Changing climate also means changes in the physical properties of the ocean. Seasonal migrations of cetaceans such as the common dolphins or several baleen whales may shift and food shortages will occur in areas exposed to heat waves and other weather extremes.

But these are only a few of the minor, current challenges faced by cetaceans due to climate change, the IPCC (International panel for climate change) predicts even more severe outcomes for cetaceans and several other species, including humans. For many of us, climate change is still a hoax, a folklore about an armageddon that we won’t live to experience. We forget that it’s a reality, a disaster that is already happening and the dangerous truth is that we still cannot fathom the severity of it.

Melanistic dolphins are simply a beautiful representation of a changing world and prove how nature often finds a way in the face of such changes. But this shouldn’t reassure us: if global warming continues at its current pace, no living creature on the planet will have time to adapt to the inevitable catastrophic changes of the future.

By Paula Thake

Sightings of the day

Ribeira Brava

14:30 Short-beaked common dolphins