Water quality speaks volumes

This summer (2021) in all weathers our University of Portsmouth (UoP) Partners have been active in Langstone Harbour in the Solent with their smart water quality monitoring units. Thanks to the harbour master for access to some perfect choice of locations for all weather access to collect data from the units. The sediments and nutrients (such as nitrates and phosphates) arrive into the Solent from many sources and can influence eutrophication as well as the biodiversity. We had some biofouling and surprising residents in the water quality units, however this did not affect the data, and the units were cleaned and redeployed.

Recently the Solent Protection Society shared and interesting article about water quality concerns in the Solent. More of these concerns are being echoed around the UK and Europe where the Water Framework Directive (WFD) standards for dangerous substances in water and Good Ecological Status as well as conservation objectives are recognised.

RaNTrans water quality monitoring and data gathering is one important step towards informing conservation management options for improving coastal and marine transitional waters.

For those with a big appetite for water quality data it is a great idea to check out the Environment Agency’s water quality data archive.

Creatures great and small, as well as European Native Oysters (Ostrea edulis) thriving together

The buzz is that oysters are great nutrient and carbon bio-remediators. They remove nutrients by feeding on phytoplankton in the water and can filter up to 200 litres of water a day and whilst we know they can remediate nutrients, the ability to remediate carbon is still being explored and we don’t have much evidence for it yet so if we can remove carbon for now that would be great.

Already we are realising some benefits of restoring habitats and ecology with the oyster units that were deployed in spring this year. Various fish and naturally colonising species made their home in the oysters’ units. Excessive opportunistic colonisation could become a problem, especially if the species are invasive non-natives or levels of biofouling limits the water filtering ability of the oysters, however at this stage it is wonderful to see the abundance of species coexisting with our oysters.

Algal mat all around

Opportunistic algal mat was seen all around the southern coast this year. In some areas of the Solent and Poole harbour algal mat biomass appeared later than previous years by a few weeks however it quickly became established in the warmer months of July and August. This was another great opportunity for the hand-gathering team from UoP and BU to collect samples for the ongoing monitoring of species of algal mat and macro invertebrates that are common in these areas.

Summer evolution of algal mat biomass in France

During this summer period, the UCN continued to follow the evolution of algal deposits in Baie des Veys. To our astonishment, our stranded algae harvests for the months of July and August were relatively poor in terms of biomass. Nevertheless, in view of the evolution of the quality of the sediment characterized by a more consequent siltation at the end of summer, probably accentuated by the accumulation of decaying organic matter, the algae appeared again this year!

It was in September that we discovered a landscape completely changed on our study site resulting in a blackish aspect of the sandy-muddy substrate punctuated by the presence of water basins reflecting this same opaque colour and sometimes an irritating and annoying smell. However, it seems that in this atmosphere of advanced decomposition of algae, gulls and other shorebirds have found their abundance of food and seemed to benefit from this massive contribution of organic matter. We can’t wait to do our next sediment cores to discover what small invertebrates, insects, larvae, molluscs or crustaceans these birds were ravishing!

Algal deposits seen from space

With our access to satellite technology, automatic detection of seaweed mats on the foreshore using high-resolution satellite imagery was implemented this summer on the four study sites. The algorithms developed by ARGANS-FR using data from the Sentinel-2 A and B satellites (ESA/Copernicus) make it possible to estimate the algal cover on the foreshore with a spatial resolution of 10 metres. The results are provided to the partners in the form of maps showing the different types of vegetation detected with a colour code.

The detection of seagrass and salt meadow cover was carried out on winter images in the absence of green algae. The detection of green algal mats is performed daily on all new images received. The images presented here are examples of detections made at the four sites during the summer of 2021. The feedback from the measurements carried out during this summer in the field will allow the detection algorithms to be validated and improved if necessary. This mapping tool will be phenomenal for the creation of predictive maps and how we plan management of seasonal algal mat impacts.

Looking ahead

Look forward into October, we are preparing seaweed biosecurity and cultivation plans to deploy Laminara seedlings for the seaweed growth trial. This is another exciting phase for the project, with the anticipated nutrients in Langstone harbour providing vital nutrients for good seaweed growth. By next spring we should have an abundance of seaweed for the biochemical extraction phases of the project.