Ocean Sandy Beaches

Sandy beaches are important dynamic coastal systems that border most of the shores worldwide (Goncalves et al., 2008). On first glance, you would think that sandy beaches are barren, empty stretches of land. However, there is a large amount of marine life found on top of and within the sand. Sandy beaches are one of the most extensive intertidal systems worldwide, and the macrofauna of these habitats make up the greatest proportion of most open shores (Lercari et al., 2002). Ocean sandy beaches are environments in which physical structure can be defined in terms of three variables: sand grain size, wave climate, and tidal regime (McLachlan and Dorvlo, 2005). The following essay looks at the impact that wave action has on the sandy beach communities

A study conducted on sandy beaches by Bally (1981) found that the mean number of macrofaunal species found in areas of high, medium and low wave action were 11, 17 and 30 respectively. This further provides evidence that wave action has an impact on species abundance. In relation to wave height, McLachlan and Dorvlo (2005) found that the variability in marine species richness was greatest at low wave heights and decreased in areas of greater wave heights. Hence, it can be said that areas of high wave height and high wave action have a low abundance of marine species and species richness.

Meiofauna and macrofauna inhabiting the finer grain size beaches are confined to the oxygenated top few centimetres (Rodriguez et al., 2003), in order to avoid unoxygenated, stagnant black sand. On the other hand, the meiofauna found on beaches with large grain sizes can reach deep into the sediment (Rodriguez et al., 2003), in order to avoid the effects of wave action at the surface. Macrofauna can be negatively affected by wave action on beaches with high wave action and, therefore, tend to reside in more favourable beaches that have less wave action (McLachlan et al., 1996; Rodriguez et al.,

Wave action has an impact on the communities of sandy beach ecosystems. However, the impacts vary between meiofauna and macrofauna. Macrofaunal communities tend to be found in areas of low wave action and, mostly, on the surface of the sand. Due to macrofauna being found in low wave action areas, they are often found towards the low tide mark. Meiofaunal communities tend to be found in areas of high wave action, but can be found in both areas. They occur below the sand surface and are generally found further up the shore, towards the high tide mark. Wave action is very important to sandy beaches and along with other processes, help give structure to the sandy beach