Page 57 - BBC Wildlife Volume 36 #10

WILDNEWS

MEET THE SCIENTIST

StephenThackeray

Lake ecologist, Centre for Ecology & Hydrology

Ecologist Stephen Stephen studies
Thackeray reveals the freshwater plankton in his
laboratory. Below: Arctic
efects of ‘underwater charr are impacted by

heatwaves’ on freshwater increasing temperatures.
wildlife and the most
likely cause of the

high temperatures we
experienced throughout

June and July this year.

affodils flowering
in December, oak
trees coming into
leaf in March and
swallows arriving
Dbefore spring should
properly have sprung – we’ve all
noticed changes such as these.
Less well-known is that climate-
change-linked phenomena are also S Windermere’s Arctic oxygen levels. Over the summer,
happening beneath the surface of charr become stressed these had decreased to below 7mg
our lakes and rivers, unheralded. per litre, close to the charr’s limit of
As an example of spring’s now at anything above 15˚C. T 5mg per litre. When it breaks down,
untimely arrival below the water line, the algae also releases toxins that can
Stephen Thackeray, of the Centre for poison livestock, pets and people.
Ecology & Hydrology (CEH), cites Fieldwork for Thackeray and his
how perch in Lake Windermere of salmon and trout. “They become team involves taking water samples,
are spawning earlier. “It’s only a stressed at anything above 15˚C, recording temperatures and oxygen
few days each decade, but if this is so this is far above their thermal levels and analysing levels of
sustained over a long period it can range,” Thackeray explains. They nutrients such as phosphorus. He
be enough to disrupt relationships can dive (to 64m in Windermere) is also trying to devise new ways to
between species.” The appearance of to cool down but the habitat understand these ecosystems using
the perch larvae moves out of sync available to them is reduced. satellite imagery to spot freshwater
with the seasonal proliferation of the The problem is compounded as algal blooms – CEH recently launched
plankton they feed on, leading to warming temperatures also fuel an app, ‘Bloomin’ Algae’ so the public
poorer survival rates. the growth of blue-green algae can join in helping with this.
Thackeray is in little doubt that – cyanobacteria – which sinks to the Biodiversity decline has been more
this is being caused by long-term bottom and decomposes, depleting rapid in freshwater systems than in
changes in our climate, which also terrestrial or marine habitats. “The
probably contributed to the extremity Office for National Statistics (ONS)
of this summer’s prolonged values our freshwater systems at
Stephen: Liz Davidson; arctic charr: Ian Winfield temperatures in July were 2.2˚C anyone is going to find an answer, it’s
£39.5bn,” he says. “But what do the
heatwave. But while provisional
Met Office records suggest air
impacts on them mean for us?” If
most likely to be Thackeray himself.
above the 1981–2010 average, the
surface water in Windermere
James Fair
reached 22˚C, 4˚C higher than the
READ THE PAPER Read Stephen’s
long-term average. This, Thackeray
says, will impact species such as
blog: ceh.ac.uk/news-and-media/
Windermere’s Arctic charr, a relative

BBC Wildlife
October 2018 blogs/stephen-thackeray 57