Intensive food production in salmon farms and Almería’s greenhouses generates substantial pollution, from nutrient-rich waste and chemicals in fish pens to plastic, fertilisers, and pesticides in the soil. These pollutants alter ecosystems, degrade land and water quality, and create hidden environmental costs that extend far beyond the visible farms and fields.
A plastic waste processing facility in Almería's Sea of Plastic in Spain
Both salmon farms and Almería’s intensive greenhouses generate pollution as a core part of their production processes. In salmon aquaculture, uneaten feed, faeces, and chemical treatments accumulate in the water, altering nutrient cycles and harming local biodiversity. In greenhouses, plastic waste, fertilisers, and pesticides infiltrate soils and waterways, degrading ecosystems and leaving persistent chemical residues. These parallel forms of pollution reveal how industrial food production transforms the environments where it takes place, creating significant ecological pressures.
The consequences of this pollution are closely tied to social and labour conditions. Workers and nearby communities contend with chemical exposure, contaminated soils, and water pollution, which affect health and livelihoods. In both salmon farming and intensive greenhouse agriculture, the systems generate economic gains while imposing environmental and human costs on those living and working within them, making the impacts stark yet often overlooked.
Waste from salmon farms seeps into surrounding waters, carrying uneaten feed, faeces, and chemicals that alter nutrient levels and harm marine life. These pollutants accumulate over time, turning once-healthy ecosystems into nutrient-rich, oxygen-poor zones.
Water quality inside sea pens is often poor
Excess feed and fish faeces pollute the water
Almería’s greenhouses generate vast amounts of plastic waste, from covers to irrigation tubing, much of which is dumped or left to degrade in the environment. This pollution fragments soils, clogs waterways, and persists forever as it breaks down into smaller particles, creating a tangible and long-lasting ecological burden.
Around 34,000 tonnes of greenhouse plastic is thrown away annually
Plastic twine is often discarded in the environment
Groundwater has been polluted by greenhouse chemicals and fertilisers leaching into the soil, causing toxic algal blooms
Nutrient runoff from greenhouses and nearby farms feeds lakes and coastal lagoons, triggering eutrophication and rampant algal growth. These blooms deplete oxygen levels, harm aquatic life, and disrupt local ecosystems, turning productive waters into zones of ecological stress.
The same water is used for greenhouse irrigation - with storage tanks often clogged by algae. Farmers regularly bleach their tanks to kill algae, with toxic colours visible from above.
Polluted groundwater affects greenhouse irrigation, with many farmers bleaching their tanks
Salmon pens often accumulate rotting feed and faeces (and sometimes dead wildlife trapped by the netting), creating dense organic detritus on the seafloor and water surface. This buildup depletes oxygen in the water column, making artificial aeration essential to keep the fish alive.
Dead seabirds are not uncommon, trapped in netting
Water quality is often so poor that constant aeration is needed
Large volumes of plastic are sent along with plant materials for composting
Much of Almería’s greenhouse plastic is sent to composting facilities in an effort to close the circular economy loop. In practice, however, the sheer volume and contamination of the material mean most fails to biodegrade effectively, revealing the limits of circularity and leaving persistent waste in soils and processing sites.
Over time, greenhouse plastics degrade within compost into smaller fragments, releasing microplastics and chemical residues into soils and waterways. These particles persist in the environment, entering food chains and accumulating plastics in the food production system, where they can affect both ecosystems and human health.
After composting, plastic is still clearly visible as white and blue patches