{"id":26294,"date":"2020-01-28T00:01:58","date_gmt":"2020-01-28T04:01:58","guid":{"rendered":"http:\/\/beyondpesticides.org\/dailynewsblog\/?p=26294"},"modified":"2020-01-28T16:35:04","modified_gmt":"2020-01-28T20:35:04","slug":"documented-decline-of-mayflies-a-keystone-species-destabilizes-ecosystems","status":"publish","type":"post","link":"https:\/\/beyondpesticides.org\/dailynewsblog\/2020\/01\/documented-decline-of-mayflies-a-keystone-species-destabilizes-ecosystems\/","title":{"rendered":"Documented Decline of Mayflies, a Keystone Species, Destabilizes Ecosystems"},"content":{"rendered":"

\"\"(Beyond Pesticides,<\/em> January 28, 2020) In more bad news from the insect world, recent research reveals a precipitous decline in numbers of mayflies<\/a> in territories where they have been historically abundant. Reported by National Geographic<\/em><\/a> and published in the Proceedings of the National Academy of Sciences<\/em>,<\/a> the research finds that in the Northern Mississippi River Basin, seasonal emergence of burrowing mayfly (genus Hexagenia<\/em>) adults declined by 52% from 2012 to 2019; in the Western Lake Erie Basin, from 2015 to 2019, the reduction was a shocking 84%. Neonicotinoid insecticides are a significant factor<\/a> in this decline because mayflies are exquisitely vulnerable to their impacts, even at very low exposure levels.<\/p>\n

Ephemeroptera<\/em> to entomologists \u2014 and \u201cmayflies\u201d to the rest of us \u2014 are a keystone species, one on which other species in an ecosystem are very dependent, and without which, the ecosystem would undergo drastic change. The Latinate name is apt: mayflies are among the most short-lived organisms, with lifespans across the 2,000+ known species lasting from five minutes to one day to a few weeks. Like damselflies and dragonflies, members of an ancient group of insects, the 600 North American species, as do their global kin, make optimal reproductive use of their brief adult lifespans: each female can lay from as few as 50 to as many as 10,000 eggs on the surfaces of water bodies. Those eggs then sink to the lake or river floor, after which they emerge as nymphs and spend up to two years<\/em> foraging on bottom sediments before appearing as adult mayflies. Read more about the unusual lifecycle of the mayfly here<\/a>.<\/p>\n

The plummeting mayfly \u201ccount\u201d is especially alarming<\/a> because mayflies are a critical, primary food source in aquatic and terrestrial ecosystems, and provide an important ecological service. As the research study notes,<\/a> \u201cSeasonal animal movement among disparate habitats is a fundamental mechanism by which energy, nutrients, and biomass are transported across ecotones. A dramatic example of such exchange is the annual emergence of mayfly swarms from freshwater benthic [lake or river bottom] habitats. . . . Annual . . . emergences represent the exchange of hundreds of tons of elemental nutrients, thousands of tons of biomass, billions of organisms, and trillions of calories worth of energy to the surrounding terrestrial habitat. . . . A single emergence event can produce 87.9 billion mayflies, releasing 3,078.6 tons of biomass into the airspace over several hours.\u201d<\/p>\n

Jason Hoverman, an ecologist at Purdue University, commented,<\/a> \u201cMayflies serve critical functions in both aquatic and terrestrial ecosystems. Because of their important role as prey, reductions in their abundance can have cascading effects on consumers throughout the food web.\u201d In a Beyond Pesticides Pesticides and You<\/em> article, \u201cPoisoned Waterways,\u201d<\/a> the authors put it squarely: \u201cWithout this critical keystone species, an important food source and nutrient recycler would be lost.\u201d<\/p>\n

In addition, because they thrive only in clean, high-quality water, mayfly populations serve as barometers of water quality, according to Kenneth Krieger<\/a>, emeritus director of the National Center for Water Quality Research at Heidelberg University,<\/a> and an expert on Lake Erie mayflies. The study co-authors conclude,<\/a> \u201cAs ecological indicators, these losses may signal deterioration in water quality and, if current population trends continue, could cascade to widespread disappearance from some of North America\u2019s largest waterways.\u201d<\/p>\n

Three phenomena account<\/a> for most of this dive in mayfly populations: (1) dramatically increased use of neonicotinoid pesticides<\/a> in recent years in these regions; (2) algal blooms<\/a>, especially in Lake Erie, caused primarily by runoff of agricultural fertilizers and other nutrient-dense pollutants; and (3) the warming impacts of the climate crisis, which include higher water temperatures that can cause havoc with the development of these tiny creatures. Taken together, these factors are complexes of nasty synergies:
\u2022 nutrients in fertilizer runoff feed algal blooms that starve water of oxygen and generate toxic byproducts to which mayflies are susceptible<\/p>\n