How it started:
How does a project start? sometimes it is pure chance. Nine years ago I got invited to dive the caves in Sardinia by a local friend and just for a couple days. Conditions were amazing and I simply discovered a hidden cave diving paradise in Europe; it was so good that I immediately organised another week of cave diving with friends and started setting up classes in Cala Gonone.
Initially, most of the focus was fun diving and learning to shoot pictures as the environment was ideal: shallow decorated caves with good visibility, temperate water and navigation.
The whole coast of the gulf of Orosei is known for the colony of monk seals that inhabited the area in the past and we heard multiple rumours about fossilised bones in the Bel Torrente cave. Together with the expert underwater photographer Claudio Provenzani, we decided to go and shoot some pictures of the bones; we were expecting to find a couple bones, but we realised pretty fast it was a lot more than that.
At the same time, Dr Elena Romano asked to collect some sediment samples in the initial portions of the caves, to determine if there was some specific type of microscopic shell that she wanted to study. We took the samples and after (in my excited perspective) an incredibly long amount of time, we started to get positive feedback from the laboratory of the research institute doing the analysis.
The ball was rolling.
Science is fun:
Project Baseline Sardinia developed exponentially in the last four or five years, going from a friendly meet up in the beautiful location of Cala Gonone, to a lot more organised and structured campaign dedicated to conservation and scientific research.
Over time we focused more and more on science and one of the objectives became the study of benthic foraminifera (microscopic shells) that have been found in the anchialine coastal caves of the Orosei Gulf during the first campaign in 2013. By analysing these shells on site and in laboratory, researchers not only can understand and try to anticipate climate/environmental changes in the area, but especially they aim to demonstrate the foraminifera can be used as an environmental indicator in the different aquatic habitats, from marine to transitional waters.
They can be used, as a climate proxy, to reconstruct past climate by examining the stable isotope ratios and trace element content of the shells (called tests).
Because certain types of Foraminifera are found only in certain environments, they can be used to figure out the kind of environment under which ancient marine sediments were deposited.
For the same reasons, they make useful biostratigraphic markers, living foraminiferal assemblages have been used as bioindicators in coastal environments, including indicators of coral reef health. Because calcium carbonate is susceptible to dissolution in acidic conditions, Foraminifera may be particularly affected by changing climate and ocean acidification.
Collecting these samples requires a lot of work, as a start by having a precise survey of the cave, with marked stations. The distance between stations is 30 meters (100ft) and the collecting points are distributed on a transect going from the sea into the caves with brackish water and halocline till the the inner portions of the caves, where only fresh water is present. Water and sediment samples are collected in four different plastic probes and containers, following a precise protocol in order to get the relevant sediment. Over the years we developed simple but efficient procedures to carry a bag with materials for up to 15 stations, with numbered containers. Needless to say trial and error was involved in the learning curve and we went from loosing containers as they were too floaty (and all bottom time gone recovering them) to not enough water in the containers which resulted in them being cracked by pressure.
Divers also collected a number of sediment cores in specific areas of the caves, to be sent to laboratory for analysis together with the sediment samples, to specifically study the chronological evolution of the sedimentary records and of the foraminifera associations. Scootering back while holding vertical a sediment core can be quite fun.
Another objective of the project is to protect, by documenting and mapping, the fossilised bones of monk seal (today an endangered species on the IUCN red list) that have been found in Bel Torrente cave. Despite they have been partially discovered in 2004 by Prof. Sgualdini and dated 5/6000 years old by Dr Dewaele et al, there was no complete published survey or documentation. After initially mapping and geo-referencing all the bones in 2014, we realised they are more than 200 pieces spread in a passage between 750 and 1500 meters inside the cave (2000-4000ft). Of course seals could not have reach such a distance in an underwater cave and their presence there is explained only with different sea levels during ice ages. How they managed to get there and if there was another entrance still has to be discovered but we are nowadays documenting all major bones and jaws with photogrammetry and 3D models.
Next steps in the future are quite challenging and exciting at the same time; we are planning to create physical models of the bones and, potentially, of some section of the cave where the fossils are located. Of course this will require close cooperation with local organisations and some serious effort in photogrammetry and digital modeling.
Hopefully the research on formainifera, despite being one of the very few projects of this type into caves, could be reproduced in different areas of the Mediterranean area, involving more scientific and research organizations.
Where and how:
The Sardinian coastline is one of the most beautiful geological scenarios in the Mediterranean area; high cliffs of white limestone dropping down into turquoise water and carved during geological eras by winds and the force of the sea. It is a very well known touristic area due to the beauty of the landscape.
In the north of the island there are many caves, both dry and underwater, which offer incredible opportunities not only to tourists and outdoors enthusiasts, but also to researchers and geologists.
North of the Orosei gulf, the village of Cala Gonone lies by the sea and just under a mountain made out of basaltic rock; south of the gulf, the town of Baunei is giving life again to civilisation. In the middle just wilderness and no sign of human infrastructures with the exception of sheperds sheds from nineteen century and trails for goats and mouflons. It’s the Gennargentu National Park, also known as Barbagia, an area that proved to be so wild and tough to conquer that only the antient Nuragic civilisation managed to create settlements here. Dated years ago, they were the ancestors of the sardinian inhabitants and left multiple remains of settlements, forts and stone curved glyphs, just in front of caves.
In the gulf, there are five major resurgences, underground fresh water rivers which are discharging their waters into the sea. These resurgences are characterised by being fresh water rivers with intrusion of salt water from the sea (similar genesis as the caves in Mexico) and the features inside the underwater passages are extremely beautiful as they formed partially as dry caves and you can find inside multiple decorations and speleothems that testify the different water levels during different ice ages.
The caves are mostly long sumps, with multiple connections with dry areas and this creates massive systems like the Bue Marino cave which is now a total of about 70 kilometres between dry and underwater passages.
The plateau above the cliffs, named Supramonte, is hiding a massive aquifer, reappearing only in the springs but the area is so vast that there is still huge portions to be explored; mainly we can distinguish between the western Supramonte, where caves are inland and water is fresh and eastern Supramonte, where the freshwater rivers end up in the above mentioned springs on the coastline. Activities in the area are carried out since many years by multiple groups, locals and from abroad or, how the Sardinians would say, people from the continent…
Community and rising environmental awareness:
During 2018 summer session, we had more than 40 volunteers working together for two weeks time; all GUE divers were having different levels of experience and qualification, from Cave1 to Rebreather (dives range from cave entrance to 100+ minutes DPV trigger time) but one common goal: assist researchers in their scientific studies.
We are running the project carrying out yearly campaigns dedicated to sediment sampling, media documentation, cave mapping and geo referencing of the paleontological remains; this has been possible through the support of multiple volunteers specialised in cave diving and surveying, dry caving and photo/video rendering.
All these efforts resulted in the spontaneous build up of a vibrant community of divers joining the project on regular basis; the involvement in the project gives all of the divers a much better and deeper appreciation of the connections between divers and science. In my mind we managed to achieve a great example of citizen science, involving all levels of divers and allowing them not just to work together, but to learn from each other.
There is also collateral tasks during the campaign weeks, like organising expositions of pictures and produce video documentaries to show local community and tourists the treasure they can find in these waters and increase community awareness of this extremely delicate habitat; also, we try to assist local decision makers in supporting the development of the long awaited marine protected area; more and more organisations are getting interested in these studies, both research institutes and local entities like the aquarium of Cala Gonone and private companies.
Mediterranean marine caves are renowned for their biodiversity and ecological value, yet are often poorly understood habitats due to the difficulties encountered in their exploration and monitoring.
Citizen science can be the missing link in sorting this issue and we as an organisation have the tools and capacity to provide researchers and local communities to understand the environment while developing in a sustainable way.