Shore environment: problems for organisms and their investigators
In July 1980, a survey of rocky shore in the rance estuary, in northern France, found that the more marine area were well populated width a variety of marine snails-limpets, topshells and winkles. At the one site, the topshell Monodonta lineata was common at all tidal levels. Then, after a sudden change from dull wet weather to hot sunshine, most individuals from high on the shore became moribund and accumulated near the bottom of the shore. The population was devastated. Fifteen months later, in october 1981. monitoring work in the Severn estuary, in south west britain, showed the fauna of a rocky promontory to be dominated by the limpet Patella vulgata....
These casual observation make the point that while most organisms on the rocky shores are fundamentally "marine", they have to cope with being out of water at regular intervals, and so have to deal with the rigours of life in air. Temperature changes and desiccation cause major problems for both plants and animals. At high temperature, enzyme systems can be damaged, and desiccation may the water external membranes as well disrupting circulation and the water content of tissues. At low temp the most serious problems are caused by the physical effects of ice formation. Marine organisms thus endure periods of low tide while they wait for the water to return.
Extract to: Little & Kitching.1996. The Biology of Rocky Shores. Oxford University Press. |
