Physalia physalis is one species that has taken advantage and will likely continue to take advantage of human involvement. In fact, many species that have r-selected traits enjoy the worldwide disturbance patterns common within the Anthropocene. Physalia features a number of these traits. It produces many offspring, disperses over the entire ocean following reproduction, can tolerate many different oceanic conditions as it travels across nearly every ocean, and is able to obtain nutrients from a variety of prey sources.
However, Physalia does not have the typical features of short generation times and association with humans. Although its reproduction has not been extensively studied, based upon the presence of smaller individuals in the spring, its sexual reproduction is said to occur during the fall. Physalia makes up for the relatively long annual reproduction time by producing many, many gametes when it does reproduce. Physalia has an entirely negative direct economic effect on human society. It is responsible for causing epidemics of envenomations each year, which are painful, costly, and can result in death, however rare. Humans cannot consume it and it does produce any usable value for us. Despite this, I believe that a case can be made that Physalia has positive indirect effects.
The stinger marks left by a Portuguese Man o' War... ouch!
Although I am not personally aware nor could I find any examples, it is possible that the Portuguese Man o’ War has cultural or social importance for some group. I think that the main positive effects involve themselves within environmental service and ethical categories. Physalia diet is comprised of 70-90% fish, with small shrimp, other crustaceans, and small planktons. Of the fish that an individual consumes, most of those fish are in the larval stage. In the absence of the siphonophores and jellyfish, we can expect to see a rise in the number of other predators of larval fish, such as copepods, amphipods, arrow worms, etc. or an increase in the number of fish. In that regard, Physalia helps regulate the amount of fish within the open ocean, which is an enormously important service to the fishing industry to ensure that marine ecosystems do not get out of sorts, perhaps causing a fishery collapse. Individuals are also eaten by larger animals, like the ocean sunfish or loggerhead sea turtle, which are two other important members of open ocean ecosystems. Beyond environmental service values, there is an intrinsic value to having bright blue bobs in the ocean. We should preserve the biodiversity of the ocean due to the intrinsic value of every species.
As climatic conditions change, our benefits from Physalia might outweigh the problems we receive from it. This is because Physalia is part of a very delicate ecosystem and provides valuable services to it. Although this may be the case, there are clear problems that they cause too. Surges of Physalia have occurred globally and have picked up in frequency. In 2010, the Portuguese Man o’ War swarmed the Mediterranean basin and caused thousands of injuries. Although the populations in the Mediterranean decreased in number in the following years, North Atlantic Oscillation projections show that these sorts of invasions by Physalia will likely increase within the Mediterranean area, perhaps causing a sort of source-sink relationship, with the North Atlantic being the source and the Mediterranean becoming a sink.
These invasions are not the only negative event that will occur, regrettably. Siphonophores tend to thrive in low-oxygen conditions. Because the oceans are warming, the water “holds” less O2 and thus Physalia proliferation is expected. It is not just global warming that will cause the oceans to warm. Pollution, like fertilizers, cause reductions of dissolved O2. Two other major incidences of Physalia landings in India and Australia give further clues to what is in store for us. Unusual numbers of Physalia were observed on beaches in conjunction with unusually strong winds. Although correlation is not causation, it is reasonable to suggest that global incidences of changing weather patterns will result in increased swarms at beaches.
A map showing the O2 concentration trends from 1958-2015
Currently, Physalia is not listed on the IUCN’s Red List; it is data deficient. Although its difficult to ascertain just where its populations are present and how many colonies exist, the species is of little concern to conservation biologists. It is entirely possible that it will be assigned a conservation status in the future, which is dependent upon how climate change impacts oceanic conditions. I think it is more likely that Physalia will be the target of strategies aimed at preserving other species, though. As previously mentioned, Physalia is likely to thrive and expand its range under new climatic conditions wrought by humanity. To combat Physalia effects on larval fish population, it might need to be culled to protect some ecosystems similar to how rats are selectively culled. Even if it were to become endangered, conservation would be a very steep uphill battle. Physalia is not a keystone species and is unlikely to be a flagship species. It does not fulfill any vital role that some other organism could not fulfill, nor would anyone be donating to a “Save the Portuguese Man o’ War” campaign. It has caused too many problems for people (e.g., envenomation) to gain much traction. It would be difficult to establish Physalia as an indicator species. We do not know enough about the species to understand how it relates to others as an indicator of open ocean ecological health. For better or worse, Physalia is probably going to stick with us for millennia to come.
Works Consulted