Study discusses effect of pollutants on fertility
In a new study, researchers have found that shrimp-like creatures on the South Coast of England have 70 per cent less sperm than any other lesser polluted location in the world. They also discovered that individuals who lived in the survey area were 6 times less fertile, in comparison to those living in cleaner waters.
This discovery, published today in Aquatic Toxicology, mirrors similar findings in other creatures, including humans. The scientist leading research at the University of Portsmouth believes pollutants might be to blame, further highlighted by this latest research.
Professor Alex Ford, Professor of Biology, University of Portsmouth, says: "We normally study the effect of chemicals on species after the water has been treated. The shrimp that we have tested are often in untreated water. The study site suffers from stormwater surges, which are likely to become more common with climate change."
"This means that the creatures could be exposed to lots of different contaminants via sewage, historical landfills, and legacy chemicals such as those in antifoulting paints. There is a direct relationship between the incidence of high rainfall events and in the levels of untreated sewage."
Professor Ford describes the shrimp as "the canary in the mine" - concerned that the plight of the shrimp is only just the tip of the iceberg in terms of fertility problems in male creatures, both great and small.
"It is thought that some male fertility problems are related to pollution," said Professor Ford.
Most male fertility research has historically focused on vertebrate species. Very little is known about the effects of pollution on invertebrate fertility, especially those amphipods at the bottom of the food chain.
A decade ago University of Portsmouth scientists observed little shrimp with very low sperm counts in nearby Langstone Harbour. Surprised by such a result they decided to monitor the animals over the next 10 years.
When Marina Tenorio Botelho, a University of Portsmouth PHD student, could not continue with her lab-based research due to Covid restrictions she was given the task of data mining the decade's worth of statistics. Her routine study uncovered a worrying reality that these animals have consistently low sperm similar to those in areas that are industrially contaminated.
Professor Ford explains that other marine creatures are also suffering: "We know that pollutants are affecting male fertility levels of all species. Killer whales around our coasts are contaminated with so many pollutants that some can't reproduce. Recent studies have also suggested that harbour porpoises contaminated with highly toxic industrial compounds, known as polychlorinated biphenyls (PCBs), have smaller testes."
Researchers at the University of Portsmouth believe this new study feeds into wider studies on male fertility. Professor Ford says: "Researchers have been looking at worldwide declines in sperm counts of humans over the past 50 years. Research* has shown that in some countries, a boy born today will have half the sperm count of his grandfather and there are fears boys are getting critically close to being infertile."
Marina Tenorio Botelho's research also showed that female shrimp produce fewer numbers eggs and appear in low densities in the same waters. It suggests that because male shrimps' capacity to fertilize females is compromised, the females in turn have fewer eggs.