A range of water quality issues may be of concern in saline lagoons. The most obvious and critical water quality parameter in saline lagoons is salinity. This parameter helps to define the habitat and changes in salinity outside of normal variation for a site (tidally, seasonally) can have significant effects on the characteristics and biota of a site. Whilst it has not been comprehensively studied, sufficient is known about the importance of salinity and the factors which govern it in saline lagoons in the UK to enable management measures to be identified (see Bamber et al 1993, Bamber et al in prep.). The following section therefore considers other water quality issues of possible concern for lagoons.

In order to determine changes in water quality, and whether these lead to an impact, it is necessary to understand the natural condition of a site. For example, lagoons are naturally rich in organic material. It is evident that lagoons may also exhibit naturally elevated nutrient levels (see, for example, Taylor et al 1995) as a result of their low flushing characteristics and nutrient cycling within them, eg between biota and sediments.

However, due particularly to their restricted exchange with the sea and concomitant reduced flushing of dissolved or suspended materials, saline lagoons are potentially sensitive to changes in water quality or inputs of such material. The degree of sensitivity of a site to changes in water quality will be determined by:

• the type of lagoon (i.e. nature of exchange with the sea) and its size;
• communities and species present.

Sensitivity of different lagoons

Sensitivity of lagoonal communities and species

Summary of water quality issues

References