Current affairs make life hard for stickleback dads

Unlike many nesting animals, it is the three-spined stickleback fathers, rather than mothers, who are responsible for parental care and nest building.

The fish, which live in the sea as well as in lakes and rivers, build their nests during the spring – and the severe rainfall experienced across Europe this spring is likely to have made this task much more strenuous.

Heavy downpours raise river flow rates, meaning that the dads have to work harder to ensure the nests are strong enough to withstand the heavier currents.

The males build nests from algae, sand and debris, which they glue together using a protein called “spiggin”, formed in their kidneys.

They then gather together clutches of eggs from a number of different females, and fertilise them – keeping the eggs safe in the nest. The male fish then guards the eggs and young fry until they are strong enough to swim away.

The heavier flow rates this year mean the fish will have had to produce more of the spiggin in order to keep the nest strong enough to withstand the stronger currents.

Producing spiggin requires energy – meaning fathers have less energy for everything else they need to do.

This could limit the number of babies the father is able to look after each year.

The good news is - the fish appear to be adapting very well.

Three-spined stickleback are regarded as something of an evolutionary “supermodel” due to their remarkable ability to adapt to environmental change.

The fish originally resided solely in the sea, but many found themselves landlocked after the last ice age roughly 10,000 years ago.

Since then, they have made themselves at home in freshwaters across the Northern hemisphere – though there are also plenty still living in the oceans.

University of Leicester researchers have found that the fish may be capable of adapting well to heavier flow rates.

Dr Iain Barber, Head of the University of Leicester’s Department of Biology, is leading a study of three-spined sticklebacks’ nesting habits.

He and his team are observing the fish in their laboratory to see how their behaviour changes for different water flow rates.

The team are careful to ensure the water flow rates are within the spectrum of what the fish would experience in their natural environments.

Dr Barber said: “You don’t really think about fish building nests – but it is actually quite common. With three-spined sticklebacks, it is the males who build the nests and invest considerably in making sure those babies have a good start in life.

“Sticklebacks are subject to all of the changes aquatic habitats are undergoing. If there is a lot of rain in the springtime, as there has been in recent years, it means there is higher water flow in rivers at the time when male sticklebacks are building nests. The results of our studies suggest that this means they need to put more glue into their nests to make them stronger.

“Being a stickleback parent is very demanding. Parental males need to chase off rivals and build nests, and must put all their spare energy into parental care. Producing more of the glue protein is energetically expensive. It is likely to have a knock-on effect on their ability to raise multiple broods.

“Our research has shown that stickleback fish do respond to changes in the environment. One of the predictions about climate change is that rainfall will increase, and become less predictable – with high volumes of rain at unseasonable times of year.

“Sticklebacks appear to be very well adapted to cope with changes in their environment – and can change their nests and nesting habits depending on the water flow levels.”

Dr Barber recently reviewed findings from the ongoing study - along with other research on fish nest building - in the journal Avian Biology Research, which normally only publishes papers about the nesting habits of birds. The paper, entitled The evolutionary ecology of nest construction: insight from recent fish studies, can be viewed at: http://tinyurl.com/md7j45q.

The research was funded by the Natural Environment Research Council (NERC).