VU

Northern Summer Mayfly

Siphlonurus alternatus

Unknown

Overview

A detailed profile for this species is sourced from the IUCN Red List of Threatened Species as assessments become available.

Siphlonurus alternatus faces significant pressure from water pollution and eutrophication in its Nordic freshwater habitats, which degrades water quality and reduces oxygen levels essential for larval development. Climate change poses an additional threat by altering water temperatures and flow patterns in the cold-water streams this species requires. Habitat fragmentation from hydroelectric development and urban expansion further isolates populations and reduces available breeding sites.

Threat summary

Habitat

This mayfly species inhabits cold, well-oxygenated streams and rivers in northern Europe, particularly in mountainous and boreal regions. The larvae develop in clean, fast-flowing waters with rocky or gravelly substrates, while adults emerge for brief mating flights near these aquatic habitats.

FRESHWATER· major

Threatened in Canada

VU

Lepiota echinella

Unknown
EN

Nymphaea loriana

Declining
EN

Lake Lamprey

Entosphenus macrostoma

Unknown
VU

Paddlefish

Polyodon spathula

Unknown

Frequently asked questions

Why is Northern Summer Mayfly classified as Vulnerable?
Northern Summer Mayfly is classified as Vulnerable because the population is declining and the species faces a high risk of extinction in the medium-term future if current pressures continue. Siphlonurus alternatus faces significant pressure from water pollution and eutrophication in its Nordic freshwater habitats, which degrades water quality and reduces oxygen levels essential for larval development. Climate change poses an additional threat by altering water temperatures and flow patterns in the cold-water streams this species requires. Habitat fragmentation from hydroelectric development and urban expansion further isolates populations and reduces available breeding sites.
Where does Northern Summer Mayfly live?
Northern Summer Mayfly occurs in Canada, Czechia, Denmark, Estonia, Finland, and France (plus 9 other countries). Country-level distribution data is sourced from the IUCN Red List and cross-referenced with GBIF occurrences.
What are the main threats to Northern Summer Mayfly?
The main threats to Northern Summer Mayfly are ai-1, ai-2, ai-3, and ai-4. The full IUCN-classified threat record for this species is detailed on the species page.

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