{"id":"river-aquatic-insects","slug":"river-aquatic-insects","name":"River Aquatic Insect Richness Dataset","description":"How many families of mayfly, stonefly and caddisfly each standardised kick sample contained, at 2,611 long-record English river sites from 1965: 117,713 observations. These are the orders whose larvae live in the riverbed and cannot leave it, and they are the first thing a river loses when it warms, silts or is polluted. 9,611 of the samples held none of the three at all, and those zeros are the most informative values in the set.","methodology":"Derived by Hydrionis from the Environment Agency’s published taxon lists for each three-minute kick sample. Every record is rolled up to its family through the Agency’s own taxon dictionary before distinct families are counted, because analysts identify to mixed ranks — 1.1 million records to family, 734,000 to species, 261,000 to genus — and counting raw taxa would measure the depth of identification rather than the river. 484 of the 487 EPT taxa in the dictionary resolve to a family; the three that do not are the order-level entries, recorded when an analyst identified no further than \"a caddisfly\", and they contribute nothing. Every sample that was taken and analysed carries a value, so a sample containing no EPT is held as zero rather than omitted. The taxon lists themselves are read and discarded; none is stored.","domains":["ecosystem"],"metricIds":["ept-family-richness"],"subjectScope":"Environment Agency river macroinvertebrate monitoring sites in England with a long record","cadence":"irregular","version":"1.0.0","released":"2026-08-28","changelog":[{"version":"1.0.0","date":"2026-08-28","summary":"First release.","additions":["EPT family richness at 2,611 long-record English river sites, from 1965."]}],"limitations":["A count of families, not of insects. One mayfly and four hundred both count once, so richness and abundance can move in opposite directions in the same sample.","Counted at family rank throughout. Species-level richness would be a different and larger number, and the two must not be compared. Total abundance is published by the Agency and is not held: a three-minute kick is designed to find what is present rather than to count it, and the published values reach 333,372 individuals in one sample against a median of 79.","A low ceiling. Britain holds only about thirty EPT families and the observed maximum is 23, so a change of one or two families is within the variation between visits and only a sustained shift means anything.","Strongly seasonal, like the indices from the same samples: spring and autumn communities differ, and a comparison mixing them will find the calendar rather than the river.","Describes the sampled reach, not the river, and conditions can differ sharply above and below a discharge or a weir.","Sites with short records are excluded, so any national picture describes long-monitored sites, which the Agency chose for reasons and which are not a random sample of English rivers.","No dragonfly series is held. The taxon lists contain Odonata and a richness series was computed and refused: a three-minute kick sample is not a dragonfly survey, and the median sample containing any Odonata holds exactly one taxon against a maximum of nine across six decades."],"context":{"hydrionisClass":"water-dependent-system","biologicalBasis":"taxon-richness","whyHeld":"The community indices held beside this say what the riverbed community indicates about pollution, flow and sediment. This says how much of the sensitive part of it is left. Mayfly, stonefly and caddisfly larvae need cool, well-oxygenated water and clean gravel, they spend months or years in the bed, and they cannot move when conditions turn — which makes their family count one of the plainest statements available about whether a reach is habitable. It measures insects, not water.","waterRelevance":["Biological condition of riverbeds, as a count rather than a score","Loss of the most oxygen- and sediment-sensitive insect orders","A biodiversity measure that can sit beside the water quality and flow records for the same reach","Reaches degraded enough to hold none of the three orders at all"],"suitableUses":["Tracking EPT family richness at one river site over decades","Comparing sites sampled under the same Environment Agency protocol and season","Reading richness beside the WHPT, LIFE and PSI indices from the identical samples","Identifying reaches that consistently return zero, which the held zeros make visible"],"unsuitableUses":["Reading richness as a count, density or abundance of insects","Comparing family richness with species richness from any other source","Comparing with EPT richness from another country or another sampling protocol","Treating a difference of one or two families between visits as a change in the river","Attributing a change in richness to water quality, flow or sediment because the two moved together; season, analyst, substrate and recent spates all move it","Summing richness across sites, which counts shared families repeatedly"],"joinDimensions":[{"kind":"shared-identifier","on":"The Environment Agency site identifier, shared exactly with the macroinvertebrate index series computed from the identical samples","limitation":"The strongest join available here, because it is the same sample and not merely the same place: richness and the indices describe one kick net on one day. It reaches no further than that site, and says nothing about the reach above or below it."},{"kind":"publisher-stated","on":"The Agency’s WFD water body identifier, carried on every held site","limitation":"An assignment by the publisher, not a geometry Hydrionis has checked. It does not establish that two sites in one water body are connected, or which is upstream."}],"relationshipConfidence":"contextual","eligibility":{"api":true,"download":true,"overlay":true,"publicPage":false}},"observationCount":117713,"seriesCount":2611,"subjectCount":2611,"from":1965,"to":2026,"sourceIds":["uk-ea-ecology"],"units":["count"],"redistributable":true,"commerciallyReusable":true,"citation":"Hydrionis (2026), River Aquatic Insect Richness Dataset, version 1.0.0. Retrieved from https://hydrionis.com/data/datasets/river-aquatic-insects/","downloads":[{"file":"/downloads/observations-ecosystem-uk-ea-ecology.csv","format":"CSV","label":"ecosystem observations from EA ecology (637,594 rows)"}],"apiPath":"/api/v1/datasets/river-aquatic-insects.json","lastFetched":"2026-08-28","fields":[{"id":"ept-family-richness","name":"EPT family richness","definition":"Number of distinct mayfly, stonefly and caddisfly families recorded in a standardised three-minute kick sample.","unit":"count","nativeGeography":["monitoring-station"],"comparabilityNotes":"A count of families, not of insects: one mayfly and four hundred both count once, so richness and abundance can move in opposite directions in the same sample. Counted at family rank throughout, by rolling every species and genus record up through the publisher’s own taxonomy, because the analysts work to mixed ranks and counting raw taxa would measure the depth of identification rather than the river. Records identified no further than the order contribute nothing and are excluded. Comparable only between samples taken under the same protocol — the Environment Agency’s standardised three-minute kick sample. Not comparable with indices from other countries, which use different taxon tables and different sampling, even where the numeric range looks similar. Strongly seasonal. Spring and autumn samples from one site are not two readings of the same quantity, and a comparison that mixes them will find differences that are the calendar rather than the river. Describes the sampled reach, not the river. Conditions can differ sharply above and below a discharge, a weir or a tributary confluence. Richness is bounded by what exists: Britain holds only about thirty EPT families, so the ceiling is low and a change of one or two families is within the variation between visits."}]}