Plant hectares of seagrass meadow

It's been a busy summer at Loch Craignish, and we're wrapping-up our seasonal marine habitat restoration activities, crunching the survey data, readying our native oyster nursery for a new intake, battening down the hatches for the winter and putting our minds to how the project will expand and evolve in 2025. This autumn update follows our summer newsletter; do contact us if you'd like to know more.

Seagrass, identifying optimum restoration sites:

As reported in our summer newsletter, our previous seagrass restoration efforts which saw seed and seagrass plants (rhizomes) being planted in the lagoonal area of Loch Craignish have experienced high failure rates. These poor results have been mirrored by other restoration projects around the UK.

Working with the Scottish Association for Marine Sciences (SAMS) we’ve been researching the causes of this by measuring the oxygen content of seabed sediments in the restoration areas. This invaluable science has revealed that the muddy lagoonal restoration sites in Loch Craignish are anoxic with high levels of sulfides which can be toxic to seagrass. The results of this science has determined a change in direction for our restoration efforts in 2024 in terms of:

• Site selection -prioritising the optimum locations for restoration based on oxygen and nitrogen levels
• Sediment improvement - investigating the possibilities for improving sediment in anoxic areas e.g. sand capping or probiotic concoctions
• Transplanting - informing where best to transplant plants e.g. don’t transplant aerobic sediment plants to anoxic sediment areas

 Seagrass harvest:

This year, between May – July, and with the help of over 40 volunteers we harvested, processed and replanted over 8,000 seagrass plants (rhizomes) in Loch Craignish over an area measuring approximately 0.12 of an acre. Informed by the above science, we focused on a single area, Dun Mhuilig Bay, adjacent to an existing seagrass meadow, where the seabed has positive oxygen levels. The seagrass was planted in bundles of 10 per m2.

In September, we surveyed the restoration area again, and excitingly, the translocated plants are healthy, growing and showing a steep increase in the number of seagrass shoots and rhizomes spreading along the seabed with interconnection happening already.

The rhizomes planted in May 2024, have shown the most growth, with up to a three-fold increase in the number of shoots per bundle and up to a five-fold increase in the area of seabed covered by each bundle.

It’s still too early to say whether this planting success represents a break-through – we need to get through the winter season and survey again in the spring – but nonetheless these are the most exciting results to be seen in the short history of the Loch Craignish seagrass project so far.

Seagrass seed harvest:

In August 2024, the team harvested 200,000 seeds from the donor meadow in Dun Mhuilig Bay over a three week period andSeawilding hosted two weekend volunteer sessions when we were assisted by 32 snorkel volunteers, some having come from as far away as the US and nine volunteers from the Dutch marine construction company Van Oord.

The seeds have gone into a chiller for winter storage and will be planted out next spring in a number of different trials. We are partnering with Van Oord to trial “sand-capping” by which 1000m2 of the lagoon will be covered in sand in 2024/25 to help mitigate the detrimental effects of anoxia and to try and improve seagrass seed germination rates. One hundred thousand seeds will be mixed into the sand and planted in the Spring.

In summary, over the last four years, we have learned much about the seagrass in Loch Craignish and, as a result of trial and error and the ongoing science, refined our methodologies accordingly. As we go forward, science will remain critical, and our engagement with the Scottish Association for Marine Sciences will continue on multiple fronts. It should be stressed that all these research outcomes are shared with our collaborative partners around the UK, notably Project Seagrass and Ocean Conservation Trust.

Other activities:

Oysters:

It’s been a frustrating year for our native oyster restoration efforts due to a lack of supply of new stock from the two UK hatcheries. Native oysters are notoriously difficult to breed and until supply issues can be resolved, all UK native oyster restoration projects hang in the balance.

However, we now have a significant stock of native oysters restored to the Loch Craignish seabed and our focus in 2024 has been to capture the wild spat to on-grow in our nursery cages where it’s afforded protection from predators. Guided by hydro-dynamic modelling, in June we suspended 150 cages filled with lime-covered mussel and scallop shell around the Loch. Adult oysters were added to release chemical cues to encourage larvae to settle.

These spat collectors are monitored regularly, and in November, newly-recruited oysters will be stripped off and placed in the nursery. However, oysters don’t spat every year, and because the sea temperature has been lower than normal – oysters need the water temperature above 16C to breed – we’re not overly hopeful this has been a good spatting year.

In October, we’re receiving a supply of juvenile native oysters - 25,000 - from Morecambe Bay hatchery, and we expect possibly tens of thousands more in November. These will over-winter in our nursery cages and be released on the Craignish seabed next year.

In September, the team has been snorkelling over our five oyster release sites to try and gauge the quantities of oysters on the seabed. We know we have released approximately 300,000, but these went down at a small size (approx. 10 grammes), and are very vulnerable to predation by green crab and starfish, both of which exist in the Loch in large quantities. Science estimates that in the wild, only 1 in a million oyster spat reach a reproductive age. Our team estimate that there are now between 15,000 - 20,000 oysters, many of a reproductive size, on the seabed and among these we are seeing newly recruited juveniles. These recent surveys will help us optimise release sites next year, as well as research potentially non-destructive predator control to reduce the large numbers of starfish where necessary. We believe these large numbers are owing to the decade-long presence of a large sea-trout farm ¼ mile away from our release sites. Fin-fish aquaculture producing large quantities of sewage on the seabed are known to attract starfish.

Meanwhile, the team has visited a research hatchery at Bangor University where a research team has successfully raised native oysters in bulk, and we’re exploring options for establishing a low-tech hatchery in Argyll to replicate their methodologies. We hope to have more news on this initiative over the coming months.

Outreach:

It’s been another busy summer, and other highlights include hosting three work-interns for a month who assisted with our seagrass harvest and oyster spat-collector deployment; training community volunteers to become advanced snorkel divers so they can assist us with our underwater activities; hosting 19 members of Nature Scot’s marine division for a day to learn about marine habitat restoration; and engaging with scores of children through our busy Seawildlings activity days and our school’s engagement programme.

Our application, in association with the community voluntary association CROMACH (Craignish Restoration of Marine and Coastal Habitats) for Demonstration and Research Marine Protected Area status for Loch Craignish has been submitted to the Scottish Government. This will go to public consultation in 2025 (we hope).

In addition, Seawilding’s pioneering activities continue to get plenty of media coverage, most recently on BBC2 Scotland: The New Wild; BBC Radio 4’s Rare Earth and The Herald.

Looking ahead to 2025:

We hope we’ve turned a corner with our seagrass restoration in 2024 (we won’t know fully until early summer, 2025) and on the assumption that we have, we are planning to ramp up our planting activities to cover at least half a hectare, trialling various different methodologies including sand-capping. Research will continue into the microbiome of seagrass and how we can optimise selection of restoration sites and donor plant material.

Subject to the supply bottle-neck being resolved, we plan to raise 300,000 native oysters in our nursery and continue our research into optimum site selection for restored oyster reefs and predator control. We’ll continue our research into wild spat collection and explore the potential for establishing a low-tech hatchery in Argyll with the assistance of Bangor University. If this seems viable, preparatory work will start in the winter 2024/25.

In terms of outreach, we plan to expand our internship programme for undergraduates studying marine biology and the natural sciences to give training and work experience to 6 students over a ten week period. We’ll continue to train local community members in coastal biodiversity surveying, and advanced snorkel skills; we’ll build on the network of restoration projects across the UK we’ve helped establish and continue our knowledge-sharing with nationwide and international forums engaged in the practise and science of marine habitat restoration. 

We will continue our collaboration with Heart of Argyll Wildlife Association whereby approx. 200 primary school pupils a year visit Loch Craignish to learn about the sea and identify marine life. In addition, our youth group, Seawildlings, with 29 members of primary and secondary school aged children, will have yet another action-packed year of fun-filled, marine-related activity.

Seawilding now employs five people, four at Loch Craignish, and one at Loch Broom. It is funded by a variety of charitable foundations, for which we are continuously grateful.

• Autumn_Update_2024.pdf (PDF)
  

Seawilding Summer newsletter update: With air temperatures in Argyll hovering at 13C, the sea temperature much the same and our team still shivering in wetsuits, we’d love to welcome a proper summer, nonetheless our work to seawild Loch Craignish continues, always with good cheer, and there’s lots to report.

NATIVE OYSTER RESTORATION

Since we started in 2020, we’ve stuck to our ambition to restore the once plentiful population of native oysters that inhabited Loch Craignish, and which play such an important role in ecosystem health. We’ve been buying them in from a hatchery at finger-nail size, growing them to a bigger size in our floating nursery and releasing them on the seabed at a size that can withstand some predation.

So far, we’ve put down around 350,000 native oysters on the seabed, and owing to the unwanted attention of crabs and star-fish we reckon around 90,000 have survived. Still, that’s a lot of oysters and given the science indicates that only 1 in a million oyster larvae survives to become an adult, it’s pretty good. Excitingly, we’ve been finding small, juvenile oysters attached to boat hulls and nursery cages which indicate this newly restored population is now reproducing.

In 2024, we planned to grow another 300,000 oysters in our nursery to release on the seabed but, frustratingly, both UK hatcheries that supply native oysters have been struggling to get their brood stock to breed. A bit like Giant Pandas, you can give them all the love in the world, but they won’t necessarily oblige. It means that both our Craignish and Wester Ross projects, and every other UK oyster restoration project, has been without supply for over 12 months. We hope this will be rectified by the late autumn.

So we’ve had to be inventive, and this year, as our “restored” stock breeds, we’re trying to catch the wild oyster larvae floating in the water column to on-grow in our nursery. It’s a technique used by commercial oyster farmers in France. We’re suspending 150 lime-covered cages of mussel and scallop shell around the Loch and each of these “spat-collectors” includes adult oysters which release chemical cues to encourage the free-floating larvae to settle. 

If successful, come October, we can transfer this “spat-on-shell” to either our nursery cages or directly onto the seabed restoration sites.

In the meantime, we’ve commissioned hydro-dynamic modelling of Loch Craignish from MTS-CFD Ltd to help us better understand the movement of oyster larvae and where to focus our restoration efforts. The larvae float in the water column for 14 days before they settle, yet our modelling shows that despite the ebb and flow of tides, most of the larvae stays in the Loch, apart from big Spring tides when some gets flushed out to re-populate other areas. This has been reassuring to see, and once again shows how this project is producing cutting-edge research which is of use to the wider science of native oyster restoration in Europe.

SEAGRASS RESTORATION

This spring and summer we have welcomed 42 volunteers – some from as far away as New Zealand and France – to our Craignish boathouse HQ to help process seagrass for transplanting onto restoration sites.

The Seawilding team of snorkellers harvest the plants from donor meadows at low spring tide; the volunteers separate and bundle them up with steel washers to give purchase on the seabed, and the bundles are transplanted onto the restoration sites in about 1 metre of water.

These hands-on sessions in our busy boathouse are always fun and rewarding, and we’re forever grateful to our enthusiastic volunteers. This year we aim to harvest at least 10,000 plants to enhance an existing meadow at Dunvhullaig bay.

However, seagrass restoration is proving challenging. Last year we planted approx. ½ acre of seagrass plants in a muddy, lagoonal area of the Loch. We had high hopes that the plants would do better than seed. Our recent summer survey reveals that on average about 6% of the plants have survived. It’s success of a sort – we’ve proven plant transplanting works better - but there’s now growing evidence, backed by a recent scientific paper, that we’ve got a problem with the site. We’re learning that seagrass likes well-aerated substrates, and our Craignish lagoon is muddy and “anoxic” or lacking in oxygen, which impedes the growth of both seagrass seed and plants.

To counteract this, in 2024, we’ve been sampling the oxygen levels of seabed sediments and choosing better sites, while the Scottish Association for Marine Science is conducting laboratory analysis to understand our sediments better. We’re partnering also with the Dutch marine construction company Van Oord to trial “sand-capping” at Loch Craignish, whereby a thin skin of sand is deposited on the lagoonal mud to counteract anoxia. This technique has been successful in Sweden. In the autumn, Seawilding and Van Oord will harvest over 100,000 seagrass seeds with the aim of planting these in the sand-capped area next spring.

We long to say that we’ve cracked seagrass restoration, and we’re planting this wonder species at scale, but the truth is all UK seagrass projects face challenges. Certainly, there are pockets of success, we’re producing invaluable research, and because we’re networked together, the science is progressing fast. One day we hope this newsletter will trumpet that we’ve found the answer… Stay with us!

GREAT SEAGRASS SURVEY

In May, in conjunction with BSAC (British Sub-Aqua Club), we held the second year of the Great Seagrass Survey whereby snorkellers and divers around the UK survey seagrass meadows around the coastline.

The data is entered into the national databases, the hope being that by recording the whereabouts of these endangered species we can afford them better protection. So far, around the UK, 1118 hectares of different types of seagrass has been mapped by the project – an incredible result!

DIVE TRAINING

Two generous donors – True Travel Foundation and Weatherbys Bank – have provided the means for four of our team to train and qualify as scientific divers. This upskilling of our operational team and investment in kit is a game-changer as being able to spend significant time underwater, instead of duck-diving with a snorkel, should make our work so much easier.

In July, our divers will trial harvesting and planting seagrass for the first time. We look forward to seeing how much it increases efficiency while exploring the benefits of being unrestricted by tides, operating at greater depths and keeping warm in dry-suits. Now our dive team will be available to assist other restoration projects where diving is an advantage.

In the meantime we’ve been training community volunteers to advanced snorkel level and some of these will be helping us harvest seed in August.

INTERNS

We’ve had three delightful interns – marine and environmental science undergraduates, Holly, Damson and Liam, join us for the month of June. They’ve been helping with seagrass rhizome transplanting, native oyster surveying, and nursery cleaning while earning their “advanced snorkeller” qualifications. This is the second year we’ve provided internships – 6 interns so far - and it’s such a valuable offering. We gain from their enthusiasm, knowledge, insights and muscle-power and they get work-experience which is hard to come by for young people wanting a career in marine conservation. The interns were funded by Charities Aid Foundation America and Rewilding Britain.

WESTER ROSS

Our Wester Ross project, which aims to restore 300,000 oysters to Loch Broom, has also been hit by the lack of oyster supply. So, unable to do much in the water we’ve been doing a lot of outreach, working with 6 primary schools, the Ullapool Sea Savers and the Ullapool High School, doing classroom sessions on the importance of the sea, surveying the beaches of the Wester Ross Marine Protected Area and monitoring our oysters in Ullapool harbour.   The children and the teachers love these hands-on sessions and fortunately the bivalves are robust. The project continues to raise 5,000 oysters in a floating nursery, and to survey and monitor the release sites in Loch Broom. Surveying has also started for a new native oyster restoration project at Loch Ewe in partnership with the National Trust for Scotland and Scottish and Southern Energy.

SEAWILDLINGS

Funded by The Monkeypuzzle Charitable Trust, our Seawildlings youth group has grown and now includes not only primary-aged school children but also high schoolers from the Craignish area. Marine-themed activities over the last few months have included coastal bushcraft, learning about ‘Victorian Female Collectors and the Sea’, sea-art installations, coasteering, rock climbing, abseiling, kayaking, snorkelling and an overnight camping trip with a bio fluorescent night-walk to observe all sorts of colourful seaweeds and marine creatures not visible in ordinary light.

CITIZEN SCIENCE

Our schools programme, run by our partner organisation Heart of Argyll, continues to see pupils from 7 local primary schools conduct “citizen science” on our oyster cages hanging off the yacht centre pontoons at Loch Craignish. The school children monitor bio-metrics such as growth and survival, and identify the multiple marine species that inhabit the cages. It’s a great success and since the programme started in 2020, 386 children have been involved and teachers from 11 different organisations.

ECO-MOORING

This summer, following a grant from the Crown Estate, we will be installing Loch Craignish’s first eco-mooring! Conventional moorings use chains that scour the seabed and are particularly damaging to seagrass and other sensitive habitats, whereas an eco-mooring has tackle lifted off the seabed and has minimal impact. We’ll be watching how it performs and maybe one day we’ll see many more installed in the Loch.

SEAWILDING BOAT

Seawilding has taken delivery of a new work-boat – Seawilder – funded by the Scottish Marine Environmental Enhancement Fund (SMEEF). Our boat will carry up to 6 staff/passengers around the Loch and will comply with rigorous health and safety requirements. The boat is in the process of being “coded” for commercial operations and should be launched later this summer. We hope the next newsletter will see bubbly spewing over her bow.

DEMONSTRATION & RESEARCH MARINE PROTECTED AREA

Finally, our community’s application for Loch Craignish to become a Demonstration and Research MPA has been submitted to the Scottish Government. The purpose of the D&R MPA is for the community and all the key stakeholders of Loch Craignish to work together to improve the health and biodiversity of the loch.

This will be the first time such a model of local community management will be operational in Scotland, and if successful it can be replicated in other areas around the country. We’re told it may be several years before we hear if we’ve got the designation - fingers crossed – it will be a triumph if we do.

• SW_Newsletter_Summer_2024_Final_1.pdf (PDF)