Yorkshire’s Crystal Moss Animal
A few weeks ago, we received an exciting email regarding a record of a very interesting species on the River Foss. In over 20 years of collating and disseminating species records from across the entirety of North and East Yorkshire, with its varied habitats and sites, it’s unusual for us to receive a record of an animal that we can say quite confidently we had never heard of before!
As part of the Natural England Species Recovery Programme, the Lincolnshire Chalk Streams Project (LCSP) were awarded funding to help locate, translocate, and ultimately protect a tiny, rare, aquatic invertebrate: the Crystal Moss Animal Lophopus crystallinus.
Lophopus crystallinus - image by Dr Hanna Hartikaine, Nottingham University
Sarah Teasel, Chalk Stream Trainee Officer Apprentice, explains more about this unusual species: ‘Lophopus crystallinus, also known as the Crystal Moss Animal, is a freshwater invertebrate species of bryozoan and is one of eleven freshwater Bryozoa found in Britain, and the only member of the family Lophopodidae found in the UK. It is now regarded as threatened with a formal classification as ‘RARE’ in the British Red Data Book of Invertebrates Other than Insects and is currently listed as a priority species in Section 41 of The Natural Environment and Rural Communities Act 2006.
L.crystallinus populations appear to have suffered severe declines since the late 20th century due to changes to their environment, with few populations persisting in only a select number of locations throughout the UK. Having once been a common sight in places such as the Norfolk Broads, this beautiful filter feeder is an important part of freshwater ecosystems, helping to cycle nutrients between aquatic and terrestrial biomes, as well as contributing important ecosystem services through the purification of freshwater.’
There are only three sites where this species has been recorded in over 20 years: Burton Mill Pond in West Sussex (50 individuals, 2004), Chill Brook in Oxford (10 colonies, 2001/02) and Barton Blow Well in Lincolnshire, boasting over 2584 conies in 2002, indicating favourable conditions during that period supported a surge in population density. This level of abundance has not been observed elsewhere possibly since the late 1900’s.
Blow wells are a geological feature that creates a unique spring habitat, where water outflows in the coastal plain as opposed to at the bottom of a hill or slope. In fact, this specific formation occurs only between Louth, Lincolnshire, and Barton-Upon Humber, where the chalk that forms the Lincolnshire Wolds occurs, resulting in 37 blow wells.
The Crystal Moss Animal species recovery project led by LCSP aims to identify the ecological requirements of this bryozoan species in order to support the successful translocation of colonies of statoblasts; tiny, dormant reproductive propagules that withstand environmental extremes, and can form a new bryozoan colony when conditions are right. The translocated statoblasts will come from a blow well donor site and be used to establish new populations at other suitable blow well sites.
When it comes to monitoring, translocation, and reintroduction, the Crystal Moss Animal provides some unique obstacles. Sarah explains ‘Monitoring efforts for the species can be challenging due to its size, with colonies growing between 3mm- 50mm in diameter and are often found attached to submerged substrates, making detection difficult. Additionally, the species is thought to undergo local extinction and recolonisation events and colonies may regress into a gelatinous form during winter conditions, regenerating again in the springtime.
Statoblasts under the microscope - image by Aimee McClelland, Nottingham University
L.crystallinus colonies are made up of individual organisms known as zooids which then form a colony. They reproduce both sexually and asexually, though sexual reproduction is rarely observed and remains poorly documented. Their two main modes of reproduction are through asexual budding, where each zooid forms two sister zooids giving rise to the colony, and when a colony reaches its size limit (typically up to 40 zooids for L.crystallinus) it may fragment, forming new colonies. As well as producing statoblasts, the colony also have what are called Lophophores, an extensible crown of tentacles used to feed on micro-organisms by creating their own current in which to draw food from the surrounding water, forcing organisms through to the mouth of the zooid, feeding upon algae, bacteria, nematodes, rotifers and other organisms.’
Initially, the project looked to conduct a translocation to bolster what was presumed to be a strong population in Barton Blow Well. However, as the project had to change trajectory in light of a new discovery.
‘As the project developed it became clear that, unfortunately, the species does appear to have suffered a further decline at Barton Blow Well, as numerous visual surveys over the past year have revealed an absence of colonies and only one positive eDNA sample. In response to this the LCSP started to look further afield at other historical sites including Burton Mill Pond, where they were thrilled to discover one single statoblast from debris samples taken in June 2024. Since then, there have been a further 27 statoblasts found at a site in York. The results from eDNA sampling have shown 17 positive samples from 12 separate sites spanning across 8 counties, marking exciting new records for species presence!’
It was after this discovery that Sarah contacted NEYEDC to make us aware of this incredible new record at the River Foss, which we were delighted to receive! It is incredibly encouraging to know that new sites have been identified for the species and that our area hosts the environmental conditions needed to support them, especially in light of their decline in areas where they have traditionally been recorded.
These findings will help the LCSP to understand the current population dynamics of L.crystallinus and aid the next steps of their project, which will look to attempt hatching and rearing of statoblasts in captive conditions, which would then be suitable to translocate. This has already been attempted by the University of Nottingham, who also partnered with the project to develop its eDNA testing. In addition, The Deep aquarium in Hull have also partnered with LCSP, and are planning to attempt rearing of the statoblasts this year.
It was fantastic to be contacted by the LCSP regarding the news of statoblasts found in our area, bringing to our attention this special species recovery project and new records for our area.
You can find out more about the Lincolnshire Chalk Streams Project here: Home - Lincolnshire Chalk Streams Project and read about their many projects and initiatives within Lincolnshire and beyond.
Acknowledgements
Thank you to Sarah Teasel, Chalk Stream Trainee Officer Apprentice for the information provided on the project and the Crystal Moss Animal, and Aimee McClelland and Dr Hanna Hartikainen of Nottingham University for their images.