Working with water and ecology

Monitoring the health of our sampling points

The Watercress Company are a stakeholder in the wider river network. Managing Director, Tom Amery states “we are a substantial part of the water source.  If we cherish our water and it's clean when it leaves us we are proud to pass it on and encourage others to be respectful throughout the river network! There are many challenges downstream, including removing trees increasing river temperature, septic tank discharge, road wash and runoff from less sustainable farming operations”.

In 2016, we asked an independent freshwater ecologist (Aquilina Environmental) to carry out an invertebrate survey at one of our sampling points.

Following the standard EA sampling protocol, aquatic macroinvertebrates were collected using a standard size FBA D-frame pond net from the major habitats along the stream (stands of different wetland plants, distinctive substrates, tree roots etc.). All the different habitats present were allocated a proportion of the overall sampling time (3 minutes) and different areas of the same mesohabitat were subsampled to ensure that as great a range as possible was sampled.

Each location was also searched for an additional minute looking for surface dwelling animals such as water skaters and whirligig beetles and inspecting submerged habitats such as logs and larger stones for attached animals.

We imagined that the results from our sampling points would be broadly similar, as the water quality is the same at each farm, however each of the surveys gave quite different results.  This was because each of the sampling points had different habitats with varying levels of shading and water flow.  The substrate also influenced the findings as in some locations there were gravel bases and others had a silty substrate.  It was evident that these environmental characteristics have a very significant effect on biodiversity when water quality is the same. There may also be an effect of the sunlight axis, direction of flow and any shading on water temperature and biodiversity.
 

We repeated that survey again in 2018 with an addition of a further two testing locations.  We have seen an improvement in biodiversity over the two years and the report presenting this information in detail can be found at the foot of the page. 

This type of survey work will be carried out on a regular basis now that we have established some baseline levels, and any improvements can be recorded.

We have also carried out a survey on one of our farms upstream of any settlement facilities where the only water was that which has come from watercress beds. The aim of this study was to see which species were living in watercress bed water without any outside influences, and to investigate what could be done to improve this biodiversity which will be monitored by further survey work in the future.  A video of this survey work, with explanations from Robert Aquilina can be found below.

Further survey work was carried out in May and September 2019 and these have shown some things of interest. in the May sampling, we found two species that had not been seen in previous surveys on these sites. The first was Melampophylax mucoreus (a caddis) which is locally distributed throughout England but rather unevenly and is associated with alkaline streams and rivers. The caddis is similar to the Drusus annulatus that we regularly find but the case is made from slightly larger and perhaps more irregular sand grains than Drusus's. Both are Limnephilid caddis. It is a late flier and so may be under-recorded as most caddis flies are recorded from the adult stage. We also found Niphargus aquilex (a crustacean related to Gammarus) which is found in headwaters and springs where it has been washed out of its normal subterranean habitat by heavy rain. It is blind unlike the usual Gammarus in the streams. The results from September generally show some improvements across all 4 sites surveyed.

The surveys carried out in May 2020 showed an improvement in scores for each index reported. This included increased numbers of gammarus at each site over the same time last year which was welcome news, as was the presence of Heptageneid mayflies and Perlodid stoneflies which have been reported in this survey. It is pleasing to see that the water quality is good enough to maintain high biodiversity as the water leaves our farms.

The latest surveys were carried out in September 2020 and showed increases in the number of gammarus present at each site compared to the same period last year. As can be expected, there is some year on year variation in the results and these are explained in the full survey report below, but the work continues to demonstrate that the water quality leaving our farms is good, As we gather more data year on year it will be interesting to see if we are able to identify any meaningful trends in the biodoversity present.

2021 surveys are currently under way and the results will be published here as soon as they are available.

All the survey results can be found below the maps. And here is how South East Farmer (p8) reported on the findings:

Kick tests at the river with Tom Amery and Robert Aquilina. Robert explains how the water quality is tested then gets into the river to collect a sample of invertebrates to examine them.

Results of macroinvertebrate sampling

Reports prepared by Robert Aquilina MSc MCIEEM.

Farm locations and kick sampling points

Maps showing the locations of our kick tests are below, together with some photos showing the different types of channel morphology and habitat at each of these locations which helps when looking at the results. Whilst the water quality is the same at each location, the results are quite different and one of the main differences is the local environment.

We have also taken some underwater footage of these kick sampling locations which clearly demonstrates the different types of channel structure and environment given that the water quality on each site is the same, which will clearly have a large effect on the biodiversity present.

Manor Farm - Old Alresford

Bishop’s Sutton Watercress Farm

Drayton Farm - New Alresford

Gammarus on watercress farms

Although not directly relating to the kick sampling, we have seen many gammarus in watercress bed and feed carriers on our farms, sometimes in very large numbers. These can be found both at the tops and bottoms of the beds and in the feed carriers. The video below shows large numbers of gammarus in the feed carrier at Springvale Farm. This carrier takes only secondary water, that is water that has flowed through one section of watercress beds already, and shows that the water quality is good enough to support a thriving community of gammarus.

Engagement with conservation groups

 There has been significant pressure from the fishing community and local environmental groups, both on the watercress industry to reduce the levels of phosphate in the discharge water, and on the EA to regulate effectively.

We have met with Salmon and Trout Conservation UK and with local landowners to tell them what we have been doing to reduce our discharge levels. 

We also have representatives who attend meetings of the Upper Itchen Initiative, a group that has been meeting for over 10 years, concerned with the protection of the Upper Itchen river catchment and its tributaries. The group comprises of statutory bodies, riparian landowners, business interests and local stakeholders. This group is kept informed of our progress at each meeting. 

We also attend meetings of the Test and Itchen Catchment Partnership which brings together local people and organisations to plan and deliver positive actions that will improve our water environment and are a supporter of their lottery funded Watercress and Winterbournes project as a member of the NFU Watercress Association.

Over the past few years we have been working closely with the EA to formulate an action plan and to report to them on our progress. This successful working relationship has contributed to the success we have had with permit compliance in the first year of monitoring.

Salmon tagging with the Game and Wildlife Conservation Trust

We have not just been working on our Hampshire farms. We have also been assisting the Game and Wildlife Conservation Trust with access to our sites to allow electrofishing to measure and tag salmon and trout in the River Frome in Dorset. This is interesting and important work and has shown that salmonid numbers in the Frome have been good in recent years. It also helps with monitoring the migration of salmon and trout from the river to the sea, and enabled the researchers to track survival from year to year for fish returning to the river to spawn.

Ecological Research

We have also been working with Asa White from Brighton University, who has been researching for a PhD. His subject area is the effects that watercress farming and salad crop washing has on macroinvertebrate and fish populations in chalk streams. His intention is to tease out any effects from watercress farm discharges from the myriad of other environmental parameters which have a bearing on the biota that is being found.

The rationale of the research is not to condemn watercress production, but to objectively seek out any effects discharges might have on the aquatic communities. It was inspired by comments that a few fishery owners had made at a chalk stream forum that they believed that watercress farming was having an impact on fish populations. There was no data to back up these claims, and indeed at many sites fish populations seemed to be thriving, so it was decided undertake some research to see if there was any truth in what they posited.

The results of this research are nearly complete and will be published early in 2020.

In 2020 we also assisted a Southampton University Masters student by providing a location to carry out some research into the drift of Gammarus and parasitism. He is hoping to discover that drift of Gammarus pulex can be affected by flow, temperature, light and parasitism. The main hypothesis of the study is that parasitised G.pulex do not avoid high flows, only healthy individuals do that. The objective is to prove/disprove this by collecting data on G.pulex drift. Also, to see whether light and temperature of the water have any effect. To address the question a couple of sites with different flows, temperature and light are needed. One of the sites used was our discharge point at Manor Farm. He found no parasitised Gammarus and also found that there were around 5 times as many Gammarus in the shaded areas to the areas in direct sunlight. The report has not yet been published but once it has we will update our website.

Reptile Monitoring

In addition to looking at the aquatic environment we have deployed reptile tins around our sites in Dorset and are monitoring these on a regular basis to see what we can find. So far we have found several grass snakes, but no sign of smooth snakes or slow worms yet. We will keep looking!

A further survey was carried out in April 2021 and we found another 11 grass snakes and one slow worm.

We are now drawing this type of wildlife monitoring to a close and will focus our resources on continued monitoring of the aquatic environment.

Public engagement

The Watercress Company are also keen to engage with the wider public and people who have an interest in chalk stream ecology. Part of this engagement is to write articles for publication, an example of which can be found below, when we were asked to write an article for the Test and Itchen Association Rivers Report 2018. The Watercress Company also sponsors the Alresford Watercress Festival and has a stand there each year.