No abstract

Bees may leave their nest in the event of an attack, but this is not their only response. Here, we examine the behavior of those individuals that remain inside the nest during a disturbance. Specifically, we test the hypothesis that bee workers usually exhibiting high levels of inactivity (i.e., 'lazy' bees) may function as defensive reserves that are more likely to respond when the colony is disturbed. We explore this hypothesis by simulating vertebrate attacks by vibrating or blowing carbon dioxide into two colonies on alternating days and measuring the movements and tasks performed by bees inside the nest. Our results show that regardless of the disturbance type, workers increase guarding behavior after a disturbance stops. Although previously inactive bees increased their movement speed inside the nest when the disturbance was vibration, they were not more likely to leave the nest (presumably to attack the simulated attacker) or switch to guarding behavior for any disturbance type. We therefore reject the hypothesis that inactive Bombus impatiens bumblebees act as defensive reserves, and propose alternative hypotheses regarding why many workers remain inactive inside the nest.

Groundwater in Scotland is, for the most part, weakly to moderately mineralised and dominated by the Ca and HCO 3 ions. The aquifer systems are almost entirely unconfined and most groundwater remains in contact with oxygen; some reducing groundwaters occur in deeper isolated cracks and joints within the many fractured bedrock aquifers such as Devonian sandstones. Groundwater depleted in oxygen is also common in the Coal Measures in the Midland Valley as a direct result of past coal and oil shale mining, when iron and other metals are taken into solution as the abandoned mine workings are allowed to flood. Low pH groundwaters are rare but do occur where calcite is absent in some basement rocks. Marine intrusion of coastal aquifers occurs locally in East Lothian and parts of Morayshire. Deeper circulating groundwaters are responsible for some of the more exotic spa waters, notably at Bridge of Earn near Perth. Nitrate contamination of groundwater is increasing in some areas, and is most prevalent in the south of Scotland. The Devonian aquifer in Fife and parts of the Permian sandstone aquifers of south-west Scotland are the worst affected.

Groundwater contributes only a small amount of raw water to public supply in Scotland and Northern Ireland, but it is nevertheless an important resource and is often the only reliable and potable source for rural communities. There is a striking similarity between the geology and structure of lowland Scotland and that of Northern Ireland due to the southwesterly continuation of the Midland Valley graben into Ireland. That similarity is not widely reflected in the hydrogeological conditions encountered in the bedrock aquifers on either side of the North Channel. Groundwater in both Scotland and Northern Ireland is under-utilized except in some isolated aquifer units where demand now warrants formal groundwater management. Knowledge of most of the major groundwater units, in particular of recharge and recharge processes, is not, as yet, sufficient to create operational models on which to base a system of abstraction licensing.