Using funding from the Seafood Innovation Fund, Exo Environmental worked alongside Brightlingsea Harbour Commissioners, Essex, to develop and deploy novel oyster spatting discs. These discs were examined to determine whether their use could help to repopulate the native oyster population in the River Colne, which has a rich cultural and historical affiliation with oystermen and oyster fishery.

Using recycled aggregate materials and broken oyster shell with textured surfaces, Exo developed novel spatting discs, aimed at increasing bio-receptivity when compared to traditional plastic discs.

The discs were deployed at numerous locations in Brightlingsea Harbour alongside traditional plastic discs to determine their success against the industry standard. Different textured designs and combinations with lime and shell additions were also studied to determine the best configuration to attract oyster spat.

The results of the study were promising with a large amount of colonisation, however very few oysters were found on either the new Exo designs or the traditional plastic discs due to a poor yield that growing season.

As part of the EU Interreg Using Sediment as a Resource (USAR) project, Exo Environmental supported Brightlingsea Harbour Commissioners in their application for a marine licence to dredge the harbour and re-use the sediment to restore a series of borrow pits. These pits were originally dug out of the surrounding saltmarsh to build up the sea wall defence. Saltmarsh provides vital ecological services such as flood defence and boasting high biodiversity

Exo conducted numerous environmental studies to provide the MMO with relevant data to support the application. These included benthic ecological surveying, water flow and modelling, water quality monitoring before, during and after the dredging campaign to monitor any change, as well as vegetation and bird surveys.

Following the successful licence application, Exo acted as primary consultant and ecological clerk during monitoring of the project to ensure the appropriate environmental protection measures were put in place.

Several subsequent dredging campaigns were conducted which helped to fill the pits with dredged material. After time this material consolidated, and natural seral succession took place with pioneer salt marsh species beginning to colonise. Vegetation surveys conducted throughout the project lifetime categorised the change from bare mud to saltmarsh communities, helping to document and evidence the benefits of restoring saltmarsh habitats.

This project involved installation of brushwood fascines to help restore saltmarsh habitat in an intertidal estuarine environment. Exo was tasked by the Water Levels Management Alliance (WLMA) to design and install brushwood fencing along the river Deben in Suffolk, where an outfall was at risk of being undermined by erosion of the bare muds. The installation of brushwood helps to slow the flow and dampen the energy of the tide and waves, helping to facilitate the deposition of sediment. This sediment slowly accumulates and is colonised by saltmarsh species through the process of succession. These saltmarsh species further slow the flow and build up more sediment, forming a positive feedback cycle of habitat creation and erosion protection. The relevant MMO licence was also obtained for this work.

This project was funded through the EU Interreg H20:Source2Sea programme. The project involved collaborating with numerous partners including the Kent Wildlife Trust (KWT) and University of Essex (UoE). The aim of the project was to determine the feasibility of landscape-wide habitat restoration within Pegwell bay, Sandwich, Kent. Focussing on 3 main habitats: saltmarsh, seagrass and native oyster beds. Exo’s role was to develop a monitoring, sampling and surveying campaign to determine the existence, extent and health of these target habitats and then to determine the scope for their restoration.

To satisfy the objectives of the project at the 3 habitat types, the following surveying methods were used:

• Multibeam bathymetry of target site areas with integrated drone photogrammetry of shorelines areas: this was to determine elevations and underwater topographic features such as oyster beds. Following analysis of this data, it evident that no hard bed features were present and the area was dominated by mobile sands, indicating oyster beds were not present.

• This conclusion was supported by the next method of surveying used: Benthic sediment grab sampling. Using a Van Veen grab sampler, pre-determined sampling points were visited and samples of benthic sediment collected and analysed. No evidence of oysters were found in any of the 50 samples taken. Subsequent Particle Size Distribution analysis conducted by UoE showed that the coarse sediment needed for oysters was largely absent, with the bed dominated by fine graded sands to muds.

• From these grab samples and walkover vegetation surveys undertaken at low tide, it was also concluded that eelgrass was not present.

• Finally, saltmarsh vegetation surveys were conducted to determine species richness and overall health of saltmarsh. From the drone imagery we found the most dominant habitat type in good ecological condition.

Following the study, it was concluded that there was potential for intervention to improve the salt marsh at Pegwell Bay, particularly with a focus on the northern part of the site. The most promising interventions would increase the height and depth of the marsh from its front onto the mudflats.

In March 2023, Exo Environmental completed a report funded by the Broads Authority as part of the Nature for Climate Peatland Grant Scheme (NCPGS). The project aims to increase adaptability to climate change and respond to the biodiversity crisis by overcoming the barriers to peatland restoration. The report discusses the importance of peatlands, the influence of human activities on peatlands and the extent of peat within the Broads study site.

Firstly, we completed a review of the historic findings and current literature regarding the formation of the Broads peat and its history to modern times. This allowed us to identify and provide a clear breakdown of what has led to the state of the Broads peatland as it is today.

In the field, Exo conducted extensive surveying of 14 sites within the Broads with 4 major sample areas surveyed at; Beccles Farm, Buckenham, Heckingham and Horsey, discussed at length within the report. The process of surveying firstly began with establishing the sample area and planning out a 100m grid of coring locations. Exo then sent out a fully equipped team to begin coring the grid in order to establish the presence, extent and grade of peat in the area.

Peat coring was completed with hand augers, extracting 20cm samples at a time until 1m below ground or to the bottom of the peat if peat was present. A deep core of up to 3m is taken at each site to gain a better understanding of the underlying geology in the area.

Extracted peat is then classified on the Von Post Scale which grades peat on its humification (oxidisation) level (H1 -> H10). This evaluation is done by examining the general characteristics of the peat cores such as fibre content, water content/colour and extrudability when handled.

With the data collected, Exo was able to provide a detailed analysis of the health and extent of the peat in these areas. The findings added to the existing peat data set and providing information which will prove vital in the plans for restoration of the historic peatland found throughout Broads.

The East Hills area is located on the North Norfolk coast by Wells-next-the-Sea, a mile out from shore, it borders the Stiffkey Saltmarsh.

Once dominated by Eelgrass beds, the borders of the Saltmarsh encroach on the Eelgrass beds as the mudflat becomes more stabilised overtime. The area has now also seen the increased presence of opportunistic macroalgae taking hold within the extents of the Eelgrass beds.

The Eelgrass survey was carried out to discharge a licence condition as part of Wells Harbour’s dredging campaign. Arising dredged material is deposited on the eastern bank of the channel from where the material naturally deposits over the intertidal area.

The results of the surveying informed the decisions on carrying out work to encourage growth on the receding habitat.

In September 2021 Exo were involved in an exciting project on Mersea Island, Essex. Exo worked to install over 140m of brushwood sea defences along Cobmarsh and Packing shed island in the Mersea harbour approaches.

The work formed part of a wider scheme of nature-based solutions and utilising natural processes for low-cost sea defence. The Mersea Harbour Protection Trust employed Exo based on our explicit experience of brushwood work and working with nature projects, such as USAR and SARCC https://www.sarcc.eu.

The purpose of these brushwood installations is to trap and control the movement of dredged sand and gravel. This function is crucial, as without the brushwood the prevailing wind and tide would entrain the sand and cover vulnerable and special saltmarsh habitats.

This dredged material has now been placed within retaining brushwood structures, as part of beneficial use of dredged material, to recharge areas lost to erosion.

The placement of the material, which has come from capital dredging at Harwich, occurred over a few days in November 2021 when the spring tides allowed the large Hopper dredger Sospan Dau to fill the compartments with the material, using a rainbow discharge/placement method.

It is now over to the brushwood to keep this sediment in place and stabilise it enough to prevent it covering valuable saltmarsh habitat and provide suitable substrate for beach nesting birds, which has been lost over the years due to coastal erosion.