Water under pressure

Climate change

Climate change is placing increased pressure on rivers, streams and other watercourses. The predominant issues involved with climate change are rising temperatures, more sporadic rainfall events and the alteration of nutrient cycles and water chemistry.

Warmer temperatures bring hotter, drier conditions to watercourses and the increased evaporation of water. This leads to many pressures including:

Extended dry periods, reducing water availability for human use
Shrinking of habitats, threatening native species
Reduction of flow rates
Increased vulnerability to pollution and degradation, declining water quality

These increased temperatures bring sporadic periods of increases rainfall, which itself has detrimental effects on watercourses. Examples of these include:

Increased flood risk due to the overwhelming of both natural waterways and drainage systems
Enhanced sedimentation that can clog rivers and smother habitats
Degradation of water quality due to influx of nutrients, pathogens and sediments

The changing climate also brings with it changes in nutrient cycles and water chemistry. This can have the following consequences:

Seasonal shifts in nutrient levels, for example, dissolved organic nitrogen, which can endanger the species that rely on the nutrients involved
Potential lower dissolved oxygen levels, since warmer warmers are less capable of holding gases, threatening all aerobic life in the threatened watercourse

Flooding

Flooding has an impact not just on human communities, but also on ecosystems and the natural functions of the watercourse itself. Although, while flooding events can be destructive, they can also bring some unseen environmental benefits.

The main concern involved with flooding events is damage to local communities, the risks of which consist of:

Damage to infrastructure, homes and agriculture
Threat to life
Economic losses
Environmental damage

Damage to ecosystems and wildlife may also take place during flooding events. This occurs due to the following factors:

General habitat destruction
Drowning and displacement of wildlife
Disease proliferation
Genetic isolation due to fragmented habitats
Deposited sediment can smother organisms and habitats
Transportation of pollutants

Changes to river morphology may occur during flooding events, potentially altering future flood risk and flow:

Erosion of riverbanks
Change in course and shape of the river
Channels deepen and widen

While the general consensus on flooding is understandably negative, it can bring some potential benefits to wildlife:

Floodwater can transport nutrients to ecosystems where there is a deficit
Groundwater supplies may be recharged, an important factor for water industries facing potentially exhausted groundwater supplies

Pollution

Pollution has a significant impact on watercourses as it can cause major degradation and loss of ecosystem functions. However, while some pollution sources are well-recognized, such as agriculture and sewage, others such as road runoff, microplastics and flea-treatment pollution are easily overlooked.

Agriculture

Agricultural pollution impacts 40% of water bodies in England and is widely regarded as being the largest polluter in the UK.

Nutrient pollution is a major form of agricultural pollution, when excess nutrients are leached from farmland into water environments. The surplus of nutrients such as nitrates and phosphates encourages algal blooms that lead to decreasing dissolved oxygen content through the process of eutrophication. Sources of nutrient pollution from agriculture include:

Runoff from fertilizers
Livestock manure
Soil erosion

Additionally, pesticides applied to crops can also be washed into watercourses. This is incredibly harmful for wildlife, especially invertebrate species, and may result in a large drop in biodiversity

Sewage

Sewage is one of the leading polluters of watercourses, affecting 36% of water bodies in England. The issue is especially prominent in our local area, with the River Wye and Severn Catchment badly degraded by sewage inputs.

Sewage inputs can introduce the following damaging pollutants:

Excess nutrients that result in oxygen depletion, similarly to agricultural pollution
Harmful pathogens that can be damaging to both wildlife and humans

Road runoff

Road runoff pollution is responsible for 18% of waterbody failures in England, and occurs when pollutants gather on road surfaces during dry weather and are transported to water environments by later rainfall.

Road runoff can contain many pollutants with neurotoxic, immunotoxic and carcinogenic properties, including:

heavy metals
hydrocarbons
microplastics

Microplastics

Microplastic pollution is an increasing concern, with concentrations found in watercourses increasing.

Microplastics are defined as plastic particles less than 5mm in size. They originate from primary microplastics, such as intentionally manufactured small plastic particles such as microbeads, and secondary microplastics, resulting from the breakdown of larger plastic items due to UV exposure, mechanical abrasion or biodegradation. Examples of secondary microplastic sources include:

fish nets
plastic bags
plastic bottles
packaging materials
synthetic fabrics

Microplastics have raised concerns since they can persist in environments for hundreds to thousands of years, with some types potentially lasting even longer.

Once they’ve entered a watercourse, microplastics can clog the organs or roots of plants and animals which have consumed them. They also may cause malnutrition and exposure to toxic substances associated with the plastics. The ability of microplastics to absorb other contaminants can facilitate the impact of pathogens, invasive species and persistent organic pollutants.

The leading concern associated with microplastics are their entry into the human food chain through fish consumption and even both bottled and tap water. Exposure can lead to the following risks :

increased cardiovascular risk, including heart attack and stroke
reproductive and development issues
immune and inflammatory responses
increased cancer risk
pathogen transport

Flea treatment

An unexpected pollutant to many, but currently widespread in rivers across Wales. Pollutionoccurs when spot-on flea treatment that is applied to the back of the pet’s neck is washed off into water environments via:

direct swimming in the watercourse
washing off in home showers that eventually reaches streams
rinsing the pipette in the sink

The chemicals involved in this type of pollution are fipronil and imidacloprid, both of which are found in many spot-on flea treatments. As insecticides, these chemicals carry many risks:

both chemicals are detrimental to aquatic insects which play vital roles in water ecosystems
fipronil is not specific and can be toxic to humans and animals if accidentally consumed in high enough concentrations. It excites the nervous system, potentially leading to vomiting, seizures, and in extreme cases, paralysis and even death

The following precautions can be taken when using spot-on flea treatment to reduce the risk of watercourse pollution:

pets should be kept out of water environments for a minimum of 4 days after application
bathing and grooming should be limited in the days following treatment
used pipettes should be binned rather than rinsed

Biodiversity Loss

The loss of biodiversity in watercourses is detrimental to not just the ecosystem, but also to our communities. Biodiversity has become vulnerable because of the following factors:

climate change
pollution
habitat degradation and loss
overexploitation
invasive species
river fragmentation and flow alteration

The result of these issues lowering biodiversity brings many negative effects:

ecosystems weaken as interspecies relationships and services decline
reduced food security as fishery yields and pollination decline
water degradation due to the loss species with natural water cleansing activities
less genetic diversity makes species more vulnerable to the named climate issues as they are increasingly unable to recover

Recreation

While recreational activities in and around watercourse environments can be sustainable if done correctly, improper recreation can cause habitat disturbance and degradation:

boating can reduce vegetation cover
bathing/wading can increase sediment concentration and introduce pollutants, disturbing habitats and degrading water
recreational fishing can reduce biodiversity and may threaten extinction if vulnerable species are overexploited

Disturbance to ecological assemblage can alter food webs and productivity due to increased turbidity and nutrients.