Sensors determine love life of world-famous Essex oysters

Helping protect future stocks of the world-famous oysters from the Essex coast is the driving force behind an innovative new research project involving researchers at the University of Essex.

Marine biologists and computer scientists at Essex have teamed up with Colchester Oyster Fishery on Mersea Island to develop sensors that detect when oysters spawn – alerting the oystermen they need to prepare the estuary beds to encourage young oysters to settle.

This is the latest of several projects involving scientists at Essex and local fishing communities to support sustainable economic growth of rock oyster aquaculture in the East of England.

Dr Tom Cameron, from our School of Life Sciences (formerly the School of Biological Sciences), explained: “This project is about using an existing technology but deploying it to solve ecological problems that will support regional aquaculture. We have developed a sensor prototype using a magnetic field sensor and a small magnet placed on either side of an oyster shell which can detect when it opens to feed or when it opens to spawn.”

Oysters need a hard surface to grow, but this is not naturally found on the muddy estuary beds in Essex. The age-old solution is to lay “cultch” - crushed shells and stones - for oysters to settle onto.

But timing is crucial. High levels of sediment in Essex estuaries mean the habitats are changing all the time and good habitat areas can be buried in shifting muds. If the cultch is laid too early it could get buried before the oysters settle, too late and the oysters will grow elsewhere so the oystermen will not know where to harvest them.

Fishermen used to take cues from nature to tell them when the oysters were spawning. However, climate change has made this harder – the old cues are no longer being reliable enough. Since the 1960s there has been a rise in seawater temperatures, with excessive temperatures occurring more frequently and for longer periods of time. The lack of reliable cues and a need to understand how shellfish are responding to warmer waters has been a strong motivation to develop a remote sensor that can collect information from oysters from where they sit on the seabed.

Fellow Essex marine biologist involved in the project Dr Michael Steinke added: “Our project aims to develop an array of sensors that transmit data from multiple oysters at the same time out in the estuary. They will then be able to send data to the oystermen on land using 4G communication links, alerting them of the high probability of any oyster spawning activity, meaning they know when to prepare the oyster beds to increase their yield of free-swimming oyster larvae using the cultch.”

The £186,000 project, funded by the Biotechnology and Biological Sciences Research Council and the Natural Environment Research Council, is hoping to uncover other potential uses for the sensors in monitoring oysters, such as when they are experiencing stress and how they respond to environmental change. It was also a joint collaboration between our School of Biological Sciences and our School of Computer Science and Electronic Engineering.

The technology has many other potential uses with other shellfish. “There is also great potential to use our sensor to help with the restoration of native European oysters to the Essex Marine Conservation Zone (MCZ) – one of the largest inshore MCZs in the UK and the only one to be protected for the restoration of the world-famous Colchester flat oyster,” said Dr Steinke. “Just like in aquaculture of rock oysters, a lack of good habitat for settlement of juvenile oysters is a key limiting factor in the recovery of native European oysters.”

Dr Cameron added: “This is part of ongoing research where Essex marine biologists are supporting fisheries in the Eastern region – large areas of the rural coastal economy rely on aquaculture and fishing. We are interested in supporting this local economy through improving sustainable practice and management for activities that use the environment.”