Increases in sightings of marine fauna: covid19, nature or espionage?
Everyone has noticed that during the time we have been confined, videos and photographs of marine fauna have appeared colonizing a marine space where we are not generally used to seeing them and they are more like an anthropocentric property. Dolphins and whales inside nautical ports, sightings from our confined windows, images of dolphins made with drones from the balcony, peregrine sharks on the coast, groups of up to 6 whales together… some true, others not. In fact, we have seen the same video of a humpback whale (Megaptera novaeangliae) inside a port, which was supposedly Tarragona, Bilbao and Barcelona, and at some point even the whale itself became a small-fin whale (Balaenoptera acutorostrata). We have also seen videos of dolphins that, in the end, turned out not to be from a port in Sitges, nor from this year, but from a port in Turkey a few years ago.
On the other hand, through the collaboration that the Creus Canyon fishermen have with SUBMON, we have sightings of hundreds of dolphins, fin whales in large groups (something that has never happened in this area) or dozens of basking sharks, and questions are: are the animals taking advantage of the peace and tranquillity of the seas? Are we increasing the hours of observation at sea and therefore our success? Are there other factors that may be affecting it?
An ICM-CSIC report points to a very significant rebound in chlorophyll near the coast two weeks after the storm Gloria, which hit our coastline in late January. The injection of nutrients during the storm Gloria has caused a first increase in the abundance of phytoplankton. The same report argues that the mid-term effect of this storm can be expected to be mostly positive for certain components of marine ecosystems. The Fluviá, Tordera and Besós rivers do not have artificial systems for regulating their flow and, therefore, they carry their sediment and nutrient load directly to the platform near the coast. This supply of sediments and nutrients may be distributed, thanks to the action of marine currents and the usual storms in spring, towards other areas of the coast and the coastal platform. It is hoped that this increase will favour the growth of other components of the trophic network, such as large vertebrates.
On the other hand, it is also true that anthropogenic noise in the sea has been considerably reduced on the Catalan coast, according to the UPC bioacoustic applications laboratory, which has been reported to the media. This, of course, reduces the discomfort that cetaceans, purely acoustic animals, may have. It specially occurs more at the coast level and with the arrival of good weather and the departure of recreational boats.
But we also observe more, we have more time and we look more out the window, in general. Therefore, it may be that there is no specific cause but a sum of all of them. Despite marine animals usually respond better to fluctuations and food access, assuming acoustic discomfort, it is true that this silence is a new paradigm that will have to be studied in depth.
One last point or consideration is that scientists from the CSIC have pointed out that this colonization of wild fauna, not only marine but also terrestrial, can be a “trap” for many animals that find themselves taking advantage of spaces, reproduction or feeding areas that are ephemeral and to which the impact of our arrival will take them by surprise.