British Cave Shrimp (Niphargus glenniei)
Key Details
| Taxonomic Groups: | Invertebrate > crustacean > Crustacean |
| Red List Status: | (Not Relevant) [(not listed)(nr)] |
| D5 Status: | |
| Section 41 Status: | (not listed) |
| Taxa Included Synonym: | (none) |
| UKSI Recommended Name: | Niphargus glenniei |
| UKSI Recommended Authority: | (Spooner, 1952) |
| UKSI Recommended Qualifier: | (none specified) |
| Red List Citation: | (not listed) |
| Notes on taxonomy/listing: | (none) |
Criteria
| Question 1: | Does species need conservation or recovery in England? |
| Response: | Yes |
| Justification: | Ancient endemic species (Devon & Cornwall only) and one of the oldest endemic fauna to England, probably surviving the last ice age in the far south west refuge. This has been noted for other Niphargus species higher up in the UK and how their distribution aligns with previous glacial fronts. Vulnerable to impacts of pollution of groundwater, increases in abstraction of local groundwater supplies with the potential to low water table and decrease recharge (from population increase/demands), plus potential for significant, prolonged changes to groundwater temperature regimes. Population trend not known as hard to access habitat directly. Possibly more widespread than currently known, although surveys to date have not recorded it east of Devon. |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | Listed in the British Odonata Red Data List (Daguet et al., 2008) as Regionally Extinct. Within Britain, it has only been recorded breeding in England and had a limited presence; its historic populations were small, localised and short-lived. A small number of transitory breeding colonies were recorded in the first half of the 19th Century in the Broads of North Norfolk. Habitat loss played a significant role in the species’ extinction; all known historic breeding sites are now unsuitable. It's English sites were situated at the western edge of its historic European range and its population was not significant to the species status on a global or European level. |
| Question 3: | At a landscape scale, would the species benefit from untargeted habitat management to increase habitat mosaics, structural diversity, or particular successional stages? |
| Response: | Yes |
| Justification: | At a landscape scale, land and water management activities which promote more naturalised conditions and limit anthropogenic impacts should help in the conservation of this species. Activities include: (1) Reducing sediment loads in rivers, as these can 'blind' the interstitial spaces within the hyporheic zone, reducing its functioning and habitat suitability for groundwater fauna. (2) Reducing pollution to groundwater, particularly pesticides and organophosphates which are extremely toxic to crustaceans. (3) Limiting nutrient enrichment to rivers and groundwaters, although some of the evidence here is contradictory as to the impacts on groundwater fauna. (4) Protecting cave and mine habitats from polluting materials and over exploitation. |
Species Assessment
| Current step on the Species Recovery Curve (SRC): | 3. National Monitoring Plan agreed and implemented |
| Recovery potential/expectation: | Low - Relict or natural rarity |
| National Monitoring Resource: | Structured - insufficient |
| Species Comments: | Since 1998, when recording of the species began in earnest and the Hypogean Crustacea Recording Scheme began (in 1999), N. glenniei was known from just 12 sites in the South Devon VC and 1 in the North Devon VC. Since then the number of sites has greatly increased and the known range of the species now also encompasses East and West Cornwall VCs. These records have mainly been the result of dedicated independent ad-hoc and structured surveys (e.g. Knight, L.R. 2001, Cave & Karst Science, Vol. 28, No. 1, p45 -46). In March 2024 the Environment Agency for England introduced a new national network for the routine monitoring of groundwater fauna. Currently there are 5 such monitoring sites in Devon and Cornwall which will be monitored annually, with additional sites likely to be added in future. This is a long-term monitoring programme, the aim of which is to help improve our understanding of groundwater ecology and knowledge of our natural capital - where the population of N. glenniei is an important element. |
Key Actions
Key Action 1
Proposed Action: Expand the number and spatial coverage of sites suitable for monitoring populations across its known range. Further monitoring eastwards of the species recorded extent would also be of value. Additionally the development and introduction of alternative sampling methods (e.g. eDNA) has huge potential value in adding our understanding of the distribution and population dynamics of this species. Such techniques will provide wider spatial coverage and allow great sample frequency from which more specific conservation actions and management plans can be developed.
Action targets: 3. National Monitoring Plan agreed and implemented
Action type: Status survey/review
Duration: >10 years
Scale of Implementation: ≤ 10 sites
High priority sites:
Comments: Action started 2024 and expected to complete 2034. In March 2024 the Environment Agency for England introduced a new national network for the routine monitoring of groundwater fauna. Currently there are 5 such monitoring sites in Devon and Cornwall which will be monitored annually, but it does not cover the breadth of habitats (geologies) that N.glenniei may occur, with additional sites likely to be added in future. This monitoring will help in providing long-term data on populations of groundwater fauna (that will likely include N. glenniei) at these specific sites. However, a wider monitoring network targeted at better understanding the population distribution of N. glenniei would be of value, however this is currently outside the scope of the Environment Agency's new groundwater ecology monitoring network. Currently this work is funded under Defra's Natural Capital Ecosystem Assessment programme. The intention will be to bring such monitoring networks into business as usual within the EA by 2028 I believe. Funding beyond this is unclear and could change at anytime should cuts to services occur. Additional funding would support surveys beyond the scope of the existing monitoring network and could usefully concentrate on confirming the known range of this important ancient endemic species.
Key Action 2
Proposed Action: Conduct targeted surveys of wells and boreholes located close to edge of the known range of species (e.g. Somerset) to confirm range limit.
Action targets: 2. Biological status assessment exists
Action type: Targeted monitoring
Duration: Unknown
Scale of Implementation: Not applicable
High priority sites:
Comments: This will provide information on whether the range limit is to do with historical glacial limits of ice sheet extent, or whether range is controlled by geology
Acknowledgment:
Data used on this website are adapted from Threatened species recovery actions 2025 baseline (JP065): Technical report and spreadsheet user guide (Natural England, 2025). Available here.