East Coast Marine Wildlife Records 2025
Exploring how citizen science, community rock pooling, and the Big Rock Pool Challenge are transforming marine biodiversity recording along the East coast of England.
Exploring how citizen science, community rock pooling, and the Big Rock Pool Challenge are transforming marine biodiversity recording along the East coast of England.
This report synthesises marine wildlife observations from the East coast of England, with particular focus on records submitted during 2025. All data analysed in this report were obtained from iNaturalist, an open, global biodiversity data platform that enables users to record, photograph, and identify species observations. Records are supported by photographic evidence and undergo community review, providing a transparent and verifiable data source.
iNaturalist data do not derive from systematic survey designs and therefore reflect patterns of observer effort as well as species occurrence. However, the scale, accessibility, and temporal resolution of the platform make it a powerful repository for examining changes in biodiversity recording, detecting novel or rare occurrences, and supporting regional ecological assessments.
To better focus the dataset on marine biodiversity, bird and plant records were excluded from the analysis. Remaining taxa were then cross-referenced against the World Register of Marine Species (WoRMS) to identify taxa recognised as marine species. Only taxa with confirmed marine affiliations were retained within the final dataset used for analysis.
There were 3,792 iNaturalist records from the East coast in 2025, compared with 8,198 records accumulated prior to 2025.
Marine wildlife recording along the East coast accelerated rapidly during 2025, with community-led recording initiatives, such as Big Rock Pool Challenge BioBlitz Battles, contributing thousands of new biodiversity records.
Marine iNaturalist recording activity along the East coast during 2025 represented a substantial proportion of all historic records from the region. The East Coast region showed the highest recording intensity, with 1,595 marine observations submitted during 2025 compared with 3,670 records submitted prior to 2025. Similar patterns were observed in the North East Coast and East Midlands Coast regions, with 2025 observations representing a considerable addition to the existing regional dataset.
The top 10 marine species with the highest number of iNaturalist observations along the East coast during 2025 are shown in the table below.
| Photo | Common Name | Latin Name | Total |
|---|---|---|---|
|
Grey Seal | Halichoerus grypus | 337 |
|
European Green Crab | Carcinus maenas | 254 |
|
Atlantic Beadlet Anemone | Actinia equina | 132 |
|
bladder wrack | Fucus vesiculosus | 104 |
|
Common Whelk | Buccinum undatum | 100 |
|
Common Periwinkle | Littorina littorea | 98 |
|
Common European Limpet | Patella vulgata | 78 |
|
Common Hermit Crab | Pagurus bernhardus | 76 |
|
Common Moon Jelly | Aurelia aurita | 75 |
|
Common Cockle | Cerastoderma edule | 60 |
Run by The Rock Pool Project, the Big Rock Pool Challenge returns to the same site once every month, and records are collected using iNaturalist in free public competitive BioBlitz Battle games.
Here, the number of observations added in 2025 are summarised, and compared with earlier project records, and species recorded by the project for the first time in 2025 are identified.
These results demonstrate how structured, repeat-visit citizen-science initiatives can substantially enhance the value of open biodiversity platforms such as iNaturalist, both by increasing record volume and by expanding documented species richness.
Full Big Rock Pool Challenge records for 2025 for our East coast hubs can be explored on iNaturalist:
The Big Rock Pool Challenge recorded 722 iNaturalist observations from East coast hubs during 2025. Both hubs began running their monthly BioBlitz Battle events in October 2025 and, despite starting late in the year, contributed a significant amount to the total iNaturalist records for the entire East coast!
There were 209 species recorded for the Big Rock Pool Challenge for the first time during 2025.
The 10 species with the highest number of records from Big Rock Pool Challenge surveys along the East coast during 2025 are listed below.
| Photo | Common Name | Latin Name | Count |
|---|---|---|---|
|
|
European Green Crab | Carcinus maenas | 47 |
|
|
Atlantic Beadlet Anemone | Actinia equina | 30 |
|
|
Common Periwinkle | Littorina littorea | 28 |
|
|
Common Hermit Crab | Pagurus bernhardus | 23 |
|
Grey Topshell | Steromphala cineraria | 19 |
|
Black Squat Lobster | Galathea squamifera | 16 |
|
Knotted Wrack | Ascophyllum nodosum | 14 |
|
Edible Crab | Cancer pagurus | 14 |
|
Dwarf Brittle Star | Amphipholis squamata | 13 |
|
Rockpool Prawn | Palaemon elegans | 13 |
147 species were recorded on iNaturalist on the East coast for the first time in 2025. Notable examples include Tima bairdii (12 records), Hydrophorus (5 records), Beroe (4 records), Dynamena pumila (4 records), Heteranomia squamula (4 records).
These records highlight the value of iNaturalist as a dynamic biodiversity data platform, capable of capturing emerging records of both conspicuous and previously under-recorded marine wildlife through sustained public participation.
When considering the 2025 results we asked:
To help answer this question, the observed dataset was compared against 1,000 randomised versions of the data. These randomised datasets kept the same overall number of observations in each time period, but redistributed observations among species at random.
The histogram shows the range of overall community change expected under these randomised conditions. The blue vertical line shows the actual level of change observed during 2025.
The observed 2025 value falls well outside the range produced by the randomised datasets, suggesting that the changes in recording patterns during 2025 were substantially greater than would be expected by chance alone. Some species showed particularly strong trends, these included species whose records had increased, as well as species whose records had decreased.
Below are the 10 marine species showing the largest positive standardised change in records during 2025 compared with East coast records from previous years.
Figure 1: Marine taxa showing the greatest positive change in East coast iNaturalist recording patterns during 2025 compared with pre-2025 records.
Several interesting marine species showed unusually large increases in East coast records during 2025. These included the hydrozoan Tima bairdii, the scale worm Harmothoe imbricata, common cuttlefish Sepia officinalis, common goby Pomatoschistus microps, the brown seaweed Halidrys siliquosa, the squat lobster Galathea squamifera, the velvet swimming crab Necora puber, bottlenose dolphin Tursiops truncatus, the sea slug Okenia nodosa, and the sea slug Berthella plumula.
These results do not necessarily mean that these species became more common, but they do show that they were recorded much more often than expected during 2025. This may reflect a mixture of real ecological patterns, better recording effort, new survey locations, and more people looking closely at rock pool and coastal wildlife.
Figure 2: Marine taxa showing the greatest negative change in
East coast iNaturalist recording patterns during 2025 compared with
pre-2025 records.
Several marine species showed noticeably lower recording levels during 2025 compared with previous East coast recording patterns. The strongest relative decreases were seen in large jellyfish species such as Cyanea capillata and Cyanea lamarckii, alongside familiar shoreline species including common starfish Asterias rubens, shore crab Carcinus maenas, common periwinkle Littorina littorea, and Baltic tellin Macoma balthica.
Interestingly, some of the species showing declines are normally among the most familiar and frequently encountered coastal animals. Large gelatinous species such as lion’s mane jellyfish Cyanea capillata and sea gooseberry comb jellies Pleurobrachia pileus showed particularly strong decreases relative to previous years. Because these species can appear in large seasonal blooms, even small changes in timing or coastal conditions can strongly affect how often they are recorded.
Full records of standardised change values for East coast marine
wildlife may be found here:
East
coast standardised change dataset
The Big Rock Pool Challenge is part of the UK's growing movement of community-powered marine citizen science.
Every month, volunteers and participants across the UK explore their local coastline, photograph marine wildlife, and contribute observations through iNaturalist.
Whether you're an experienced marine naturalist or completely new to rock pooling, you can get involved for free.
The 2025 East coast iNaturalist dataset highlights the growing value of public participation in marine wildlife recording. Thousands of observations were submitted across the region, including many species rarely recorded previously on iNaturalist. The results also show that the species being recorded during 2025 differed substantially from previous years, demonstrating how rapidly citizen-science datasets can grow and evolve when more people become involved.
Particularly encouraging were the contributions from the Big Rock Pool Challenge hubs at Beadnell Haven and Shoeburyness. Despite launching only in late 2025, these hubs contributed a significant amount of the East coast marine iNaturalist records submitted during the year, while also adding many species to the project for the first time.
These findings demonstrate that anyone can contribute meaningful scientific data simply by exploring the coast, photographing wildlife, and sharing observations through iNaturalist. Every observation helps improve understanding of marine biodiversity, track changing species patterns, and build long-term datasets that may become increasingly important as marine environments continue to change.
If you would like to get involved, join one of our free monthly Big Rock Pool Challenge BioBlitz Battle events or start recording your own marine observations on iNaturalist. Whether you spot a common limpet or a rarely recorded jellyfish, your observations can help build one of the UK’s largest community-driven marine biodiversity datasets.
Find out more about the Big Rock Pool Challenge here:
Explore marine wildlife observations on iNaturalist here: