Research

Seven-year study of Essex otters

A seven-year study of otter distribution in Essex has shown that action is needed if the animals are to expand their populations in Essex rivers and coastal wetlands.

Chris and Sheila Mason in the Department of Biological Sciences have just completed the study of more than 230 sites for WWF-UK.

An otter photographed during the Essex study

Otters were once widespread in our rivers but disappeared from most of England and Western Europe in the late 1950s, due mainly to toxic chemical pollution, which caused reproductive failure. Otters began to re-establish in Essex in the mid-1990s, deriving almost entirely from captive-bred animals released in the eastern region.

From 1996 to 2002 all river catchments in Essex were surveyed annually for otters. In 1996, 27 per cent of 234 survey sites proved positive. By 2002, this had increased only slightly to 31 per cent, showing little overall population growth.

However, the researchers discovered that distribution had changed over time, and the Stour was the only major Essex catchment to have held otters throughout the study period.

Initially otters were recorded in the catchments of the Stour and Colne (including in Colchester), Cam, part of the Lea, and Hamford Water.

By 2002 otters were still found on the Stour, Lea and Cam, had re-appeared after several years absence on the Colne, had been lost from Hamford Water and were present, with limited distributions, on the Chelmer, Blackwater and Roding. The colonisation of London down the River Roding had faltered.

The study provided little indication that otters were beginning to consolidate and expand their populations, with long stretches of river and coastal wetlands still unoccupied.

The researchers concluded that high levels of traffic on the dense road network were the major threat to survival, and modification of river bridges to provide safe passage for otters was urgently required.

Although pollution is no longer considered a problem, much of the riverside habitat in Essex is of poor quality. To increase cover and resting sites for otters, scrub and reedbeds need to be encouraged, ideally as part of an extensive restoration of our degraded river floodplains, they concluded.

Work to boost coconut crops

Dr James Morison of the Department of Biological Sciences recently returned from a trip to Sri Lanka where he supervised the work of an Essex PhD student determined to tackle the problem of low drought tolerance of coconut crops.

Coconut is a very important crop throughout the humid tropics. As well as the main use as an oil crop, it also produces a host of other goods: roofing, timber, fibre for ropes and mats; alcohol, vinegar and sugar from the flower sap; clean drinking water and other food products. In Sri Lanka the plantations and industry are huge, with over 130 nuts alone produced per year for every man, woman and child in the country.

However, drought periods can last several months and while coconut palms usually survive such droughts, yields can be severely depressed. Therefore PhD student Athula Nainanayake's work at the Coconut Research Institute, Lunuwila (CRI), investigating how to select varieties with better drought tolerance is extremely important.

There is a large diversity of genotypes in cultivation all around the world, each suitable for different environments. Mr Nainanayake is looking at physiological and molecular aspects of drought tolerance using the extensive and very well established variety of collections the CRI has in 'gardens' and trial sites.

In collaboration with Dr Christine Raines, also from the Department of Biological Sciences, he will also be analysing palm samples at Essex at Essex to see if the molecular markers of drought tolerance can be used to help identification of tolerant coconut types.

Also in the printed October edition of Wyvern:

• Hope for migraine sufferers
• Diabetes research aims to reduce kidney problems
• Rainfall research could help flood control