Eelgrass within the Ramsey Bay Marine Nature Reserve

Summary

The requester asked for the full scientific findings of a 2019 eelgrass survey in Ramsey Bay Marine Nature Reserve, and the Department of Environment, Food and Agriculture disclosed the complete report including methodology and results.

Key Facts

• Eelgrass (Zostera marina) is a protected species under Schedule 7 of the Isle of Man Wildlife Act 1990.
• The survey was conducted on July 10, 2019, using a drop-down camera from the vessel FPV. Barrule.
• Eelgrass presence is closely related to sandy substrates and water depths of less than 10 meters.
• The highest eelgrass densities were found north of Queen's Pier and in areas north and east of Gob ny Rona.
• The survey covered the southern part of Ramsey Bay MNR but was not extended further east due to time constraints.

Data Disclosed

• 2019
• July 10, 2019
• 1930s
• 33% to 90%
• 2011
• July 2018
• less than 10 m
• 1 and 3 metres
• Schedule 7

Original Request

In 2019, in light of a controversial proposal to destroy part of the Ramsey Bay Marine Nature Reserve (the Island's first such reserve and a 'core area' of our UNESCO Biosphere Reserve), DEFA undertook an extensive survey of eelgrass (Zostera marina) in Ramsey Bay. Eelgrass forms a vitally important habitat for wildlife (including commercially important seafood species) and is an extremely important carbon sink in the global fight against the climate emergency. For such reasons it is also a protected species under Schedule 7 of the Wildlife Act 1990. Please can the Department release the full and detailed scientific findings of this most recent eelgrass survey.

Data Tables (1)

Data Tables (reformatted)

Full Response Text

Ramsey Bay Marine Nature Reserve Eel Grass Survey (July 2019)

Background Eel grass (Zostera marina) is a marine flowering plant associated with shallow water sandy/gravel seabeds, and plays an important role in sediment binding, habitat provision, nutrient cycling and carbon capture.

Eel grass distribution was formerly much more extensive in the eastern Atlantic, but declined sharply in the 1930s due to a ‘wasting disease’, thought to be caused by a slime mould, possibly Labyrinthula zosterae. Additional destruction of eel grass beds, due various reasons, including pollution, nutrient inputs, sedimentation and direct seabed impacts, have further reduced its distribution and abundance, and estimates suggest specific area declines of between 33% and 90% compared to pre-1930s levels.

As such, the species is protected under Schedule 7 of the Isle of Man Wildlife Act 1990, and is listed as a Threatened and/or Declining Species & Habitat under OSPAR, to which the Isle of Man is a signatory.

Eelgrass still occurs in at least four sites around the Isle of Man, all of which are specifically protected inside Marine Nature Reserves1 within eelgrass conservation zones in Ramsey Bay MNR, Laxey Bay MNR, Langness MNR and Baie ny Carrickey MNR.

The largest expanse of eel grass was known to be in the south-west corner of Ramsey Bay MNR, which was designated in 2011, and which included an eelgrass conservation area in the original zoning. At that time the eel grass area was relatively conservatively estimated, and subsequent reports have indicated that the plant extends beyond the zone boundaries.

Following the re-desigation of Ramsey Bay MNR, along with the other 9 MNRs in July 2018, and recognition of the growing importance of eelgrass beds as a carbon sequestration and storage habitat, a more comprehensive survey of the Ramsey Bay eel grass population was undertaken.

Survey Method A boxed grid was mapped for the southern part of Ramsey Bay MNR (Figure 1), and within each grid square series of transects were surveyed using a drop-down camera from FPV. Barrule on 10th July 2019. The transects were roughly parallel to each other, and were conducted from west to east (broadly shallow water to deeper) (Figure 1).

The survey/drop-down camera drifted in a north-west to south-east direction, with the vessel moving to the start of the next transect upon completion of the transect line.

A continuous live video feed was observed onboard the survey vessel, and presence/density estimates, including positional data, were recorded. Density estimates were qualitative and recorded as sparse, medium and dense.

Subsequently, presence data points and associated densities were plotted on ArcGIS, and further analysed to provide an interpolated eel grass density gradient map (see results).

For this process the qualitative eelgrass density data from the survey (ie. dense; medium, sparse, not present) was used, filling in prolonged blank transect areas using points from

1 https://www.gov.im/marinenaturereserves/

vessel track data, and assuming no presence of eelgrass at those locations. Vessel track data was also used to verify the survey data and identify the order in which the transect lines were conducted. A linear kriging interpolation function was applied to the data in ArcGIS to produce a surface map of eelgrass density, restricted to a shapefile polygon drawn manually around the data.

Results

Figure 1 shows survey grids and associated transect lines where data were recorded. The survey was not extended further east than the survey grid squares, due to time constraints, but is expected to be completed in future.

Figure 1: FPV. Barrule plotter map showing Ramsey Bay MNR eel grass conservation zone (green boundary), survey grid squares (yellow), survey transect lines (red), vessel turning points (green symbols). Plant presence indicated by other coloured symbols.

Figure 2 shows GIS-plotted, qualitative eel grass density points along survey transects based on video observations. See figure legend for further details.

The presence of eel grass was observed to be closely related to habitat type (predominantly on sandy substrate) and water depth (less than 10 m). The highest eel grass densities were found to the north of Queen’s Pier, inside the ‘dolphin’, and in areas north and east of Gob ny Rona, where densities included complete plant coverage for several metres. Medium densities were typically clumps of several plants together, or single plants with a spacing of less than a metre apart. Most eel grass areas observed were considered ‘sparse’, consisting of single plants with spacing of between 1 and 3 metres.

Figure 2 GIS map showing existing eelgrass conservation zone and density-related eel grass points from survey observations.

Figure 3 GIS-extrapolated eel grass density map for southern Ramsey Bay, based on July 2019 survey data and linear kriging interpolation function (see methods section for details).

Estimated eelgrass area from the interpolated map was 98 hectares (0.98 km2), with densities estimated at; sparse: 67 ha (0.67 km2), medium: 24 ha (0.24 km2), dense: 7 ha (0.07 km2), noting the potential errors inherent in interpolating from point data, and the likelihood of over-estimation, given the transect approach. The existing eel grass conservation zone of Ramsey Bay MNR is approximately 28 hectares (0.28 km2)

Discussion The survey revealed that the extent of eel grass in south-eastern Ramsey Bay is much more extensive than previously quantified, although it was known that eel grass did extend outside the current conservation zone.

The relative extension, assuming that the existing conservation zone was fully covered to some degree, means that total coverage is now approximately 125 hectares (1.25 km2) compared with the previous conservation zone of 28 ha (0.28 km2).

There are several important implications of this survey result.

Firstly, as a protected and rare species on the island, and an OSPAR-listed species/habitat, specific conservation measures need to be considered in relation to the Ramsey Bay MNR zoning plan, for example, extension of the existing eelgrass conservation zone. This would require a public consultation process, including with the fishing industry.

Eel grass beds constitute an important marine habitat for carbon capture and storage (blue carbon), with some estimates indicating their potential to be up to 35 times more effective than tropical rainforest. Isle of Man Governments commitments under the ‘Climate Change Action Plan’2 includes Actions 5 ‘to increasing natural carbon capture opportunities whilst protecting and enhancing ecosystems, to help reach net zero by 2050’. Existing eel grass meadows, their continued protection, appears consistent with achieving this objective, and so their habitat expansion, and inclusion in the Action Plan over coming years will provide a valuable mechanisms for reaching net zero carbon.

The recent development of an Isle of Man 0-3 nm3 management plan for inshore waters, includes fisheries and Marine Nature Reserves plans, and carbon audits and management for both sectors. Ramsey Bay MNR would be included in both considerations, due to the increasingly important scallop fishery in the fisheries management zone, although scallop dredging does not occur in eel grass areas. Balancing the economic and blue carbon value of such areas will be an important consideration in the development of these inshore management plans, but should provide beneficial opportunities for all sectors.

Overall, the observed expansion of eel grass habitat in Ramsey Bay MNR is a positive development for the reasons outlined above. Their status as biodiversity nursery areas, for both commercial and non-commercial species, as carbon fixation and storage habitats, and as a protected species means that significant efforts should be made to protect this area from the well-established damage impacts associated with this habitat4; eg. inadequately controlled marine and shore-side developments and works, runoff of sediment and chemical pollutants, towed and other fishing gear, boat anchors, climate change, algal blooms and marine invasive species5.

Future work is expected to include completion of the survey towards Maughold Head, and comparison with observed densities and previously assessed habitat types for the area.

2 https://www.gov.im/media/1368096/gd20190101-iomg-action-plan.pdf 3 GD 2019/0098 4 https://www.ospar.org/work-areas/bdc/species-habitats/list-of-threatened-declining-species- habitats 5 https://www.sciencedirect.com/science/article/abs/pii/S0304377097000077

Freedom of Information Co-ordinator Corporate Services Directorate Thie Slieau Whallian, Foxdale Road, St John’s, Isle of Man, IM4 3AS Tel no (01624) 685854 Fax no (01624 685851 Email: defa@gov.im www.gov.im

Our ref: 1205049 27th March 2020

Dear ###

We write further to your request which was received on 2nd March 2020 and which states:

"In 2019, in light of a controversial proposal to destroy part of the Ramsey Bay Marine Nature Reserve (the Island's first such reserve and a 'core area' of our UNESCO Biosphere Reserve), DEFA undertook an extensive survey of eelgrass (Zostera marina) in Ramsey Bay. Eelgrass forms a vitally important habitat for wildlife (including commercially important seafood species) and is an extremely important carbon sink in the global fight against the climate emergency. For such reasons it is also a protected species under Schedule 7 of the Wildlife Act 1990. Please can the Department release the full and detailed scientific findings of this most recent eelgrass survey."

The information that is being released to you is attached. Please quote the reference number 1205049 in any future communications.

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Yours sincerely