The CASE of increasing salinity in the Broads

By Lucy Roberts

– Working with external organisations

Lucy undertakes fieldwork across the Norfolk Broads. Image by Lucy Roberts.

Lucy undertakes fieldwork in the Norfolk Broads.
Image by Lucy Roberts.

What’s the one thing that I wasn’t prepared for when finishing my DTP training and embarking on my PhD? That working 9-5, despite being a classic song, really isn’t feasible? Or that fieldtrips to California don’t happen every year? Well, yes both of these, but mainly that planning and undertaking fieldwork in the UK, whilst collaborating with external organisations and local landowners, would be one of the most challenging experiences of my PhD.

I’m lucky that my studentship includes a CASE collaboration with the Broads Authority, who are responsible for the conservation, navigation and planning permission of the Norfolk and Suffolk Broads National Park. When my supervisor first proposed a CASE partnership to me, I thought “Great! More money!”, but working with the Broads Authority has become much more than that.

As well as building collaborations and gaining an insight into the inner workings of a conservation organisation, the CASE partnership has given me access to data, contacts at the Environment Agency, the National Trust, and with local landowners, and the opportunity to join the catchment stakeholder group. On land, river systems fall into catchments – areas where all surface water drains to a specific river or lake. This group brings together a range of people (conservationists, researchers, farmers, fishing groups and sailing clubs) to discuss environmental threats to the catchment. In return, the Broads Authority will use my findings to inform future management decisions for coastal lakes and wetlands, which are being increasingly influenced by saltwater intrusion inland. So, what exciting, groundbreaking research could be used to inform these decisions?

An SEM image of an ostracod valve

An SEM image of an ostracod valve
(Cyprideis Torosa)
Image copyright of David Horne, used with permission

The main focus of my research is to extend the record of salinity for 5 specific Broads in the Upper Thurne area beyond data collected by the Environment Agency and Broads Authority. Tiny aquatic crustaceans called ostracods build their calcium carbonate shells from elements taken solely from the surrounding water, so their shells provide a unique record of water temperature and / or salinity at the time the shell was formed. The amount of trace metals, such as strontium and magnesium, in fossilised ostracod shells taken from lake sediments can therefore used to reconstruct past salinity of a particular catchment.

Previously, shell geochemistry like this has only been used to infer relative changes in salinity, but when combined with modern measurements it may be possible to convert these ratios of metals into numeric salinity values. Understanding the impacts of past salinity on biodiversity will enable effective conservation policies to be established for priority species in areas that are currently uninfluenced by seawater intrusion.

Despite the obvious advantages of my CASE partner to the project, in a catchment that has been riddled with environmental and stakeholder conflicts, being associated with any particular organisation can also have its downfalls. The Broads, being home to 11,000 recorded species and over 1,500 priority species for conservation, is an area that many people feel strongly about, whether it be from a fishing, navigation, birding, or conservation point of view. Managing these expectations is a difficult task for the Broads Authority, and pleasing all stakeholders isn’t always possible. Learning to adapt and manage the way I discuss my research with different stakeholders has been an important part of planning my research, especially when organising the seven field visits I will be undertaking between July 2015 and December 2016.

Building links with my Broads Authority supervisor, contacts at the Norfolk Wildlife Trust, and local landowners, to inform them of my research plans and aims, was an important aspect of my PhD before any fieldwork could begin. These contacts are incredibly important links for me, not only to allow physical access to the sites, but also as an incredible source of local knowledge and expertise on the sites, both past and present. Despite the Broads Authority being responsible for the overall management of the Broads, in many cases they are not the landowners. Being associated with them therefore does not guarantee access to any of my intended field sites.

Lucy's project involves taking sediment cores from lakes.

Lucy’s project involves taking sediment cores from lakes.
Image by Lucy Roberts.

There’s a misconception that turning up at a lake with a boat and taking away some samples is an easy process – who’s going to notice some missing mud from the bottom of a murky lake? In reality, obtaining the correct permissions is essential, especially when it comes to later publishing the data.

Many phone calls later, with the incredibly helpful John Blackburn at the Norfolk Wildlife Trust, I realised that it was going to take more than just him agreeing to me taking some samples. In fact, he could only give me permission for one of my field sites, which I unfortunately only realised on the day before I was planning to visit another of the sites – not ideal when the phone signal in Norfolk is basically none existent!

Visiting my field sites, based in the Upper Thurne catchment in the north east of the Broads, involves liaising with and obtaining permissions from six different landowners, ranging from local farmers to national organisations. Planning fieldwork at the largest of my field sites, Hickling Broad, involved permission from the Broads Authority (management), the Norfolk Wildlife Trust (landowner) and, given the presence of several rare species, and its status as a Site of Special Scientific Interest (SSSI); Natural England. Another site requires additional permission from a private landowner and the National Trust!

Communication with each stakeholder can be very different. Sometimes I need to discuss the conservation and policy implications of my research with other scientists and conservation organisations, on other occasions I am trying to create awareness and engage with the public.

Most recently I embarked on my first four-day seasonal sampling trip to the Thurne Broads with my two eager field helpers. A broken core tube, a lost bung and 30 numb fingers later, we’ve returned with 62 water samples, 19 surface sediment samples and 19 ostracod samples taken from aquatic plants. These samples will be used to map seasonal variations in the salinity of the system, which is influenced by a complex combination of storm surges, hydrogeology and human activity in the catchment.

Lucy undertakes fieldwork across the Norfolk Broads.

Understanding how biodiversity responds to changes in salinity will be important to inform conservation management
Image by Lucy Roberts.

With the salinity of the current system monitored and understood, collecting and performing geochemical analysis of trace-metal ratios from modern ostracod shells will allow the ratios of fossilised shells from sediment cores taken last September to be calibrated into numeric salinity values.

Counting and identifying plant and animal remains in the core samples will also allow me to reconstruct how the biodiversity of the system is influenced by changes in salinity. By providing information on the impacts of changing salinity before regular monitoring began, this data will help inform important regional management decisions.

Having a CASE partner isn’t the easy ‘free’ money I may have initially been expecting. Working with the Broads Authority and planning and undertaking my fieldwork in collaboration with external organisations has been a challenging but invaluable experience, all whilst ticking off those transferrable PhD skills for project management and communication! Why go to California every year when you can have permission to collect mud from the Norfolk Broads whenever you like?!

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