Splashing in the Esk

Sam Jones – River Esk Project Student

I’m new here, both to the blog and the National Park. I started working at the North York Moors National Park at the start of this month and am already having a great time getting involved in everything and anything I can.

I am working here for a year as part of my Undergraduate University degree with a focus on the Freshwater Pearl Mussel project on the River Esk in the north of the Park.

The Freshwater Pearl Mussel is a very large and long lived endangered species of mollusc. It is already very rare in England with a handful of healthy populations scattered throughout the northern waterways of the country. The River Esk is the only remaining refuge of the mussel in North Yorkshire and the population here is stressed and struggling to reproduce. This is thought to be caused by the deposition of excess silt and sand over the mussel’s habitat and may be influenced by organic pollutants as well. To find out more about the mussels’ plight see our website.

I’ve been brought in to help assess the overall water quality up and down the river. This will be done by sampling selected sites for invertebrates (insects, worms, crustaceans, molluscs, etc.) and then identifying the different families and species that I find. The types of invertebrates that you find can tell you how clean and healthy that stretch of the river is as they vary in their ability to survive in harsher conditions. For example a freshwater worm will tell you little as they can survive anywhere in nearly any conditions but a mayfly nymph can tell you a great deal as they tend to be much less resilient and need higher quality streams.

I’ve spent the last few weeks planning and scouting the best sampling sites to try to get as good a feel for the conditions of the river as possible within my year long timescale. This has entailed running up and down the river (both figuratively and literally) trying to find suitable sites that aren’t so deep that my waders will not cope but aren’t so shallow that they will not yield the proper samples. Add to this accessibility issues, the need for sites long enough to sample, and not wanting to get swept away by the current, and it is no simple task.