Species – area
relationships for sandy
beach macrobenthos in
the context of intertidal
Anton McLachlan and Atsu Dorvlo
College of Agricultural & Marine Sciences
and College of Science,
Sultan Qaboos University,
Sultanate of Oman.
OCEANOLOGIA, 49 (1), 2007.
The marine species richness (MSR) recorded in 159 sandy beach surveys was
analysed in relation to beach width (W). MSR is the number of macrobenthic
species collected in a standard intertidal transect survey, excluding insects. Beach
width (W) was estimated by dividing the spring tide range [m] by the beach face
slope, to give a value in [m]. The relationship between MSR and W was best
described by a semilog (exponential) model, which was highly significant:
MSR = .5.2+ 10.8 logW.
The fit of a power model (MSR = cWz) was also significant. The steep slope of
the curve for a power model (z = 0.49) suggests that beaches function as isolated
rather than contiguous habitats and that the nature of the habitat becomes more
benign as beaches widen. There are some latitudinal effects, with tropical beaches
displaying a higher species-area relationship for any beach width than other regions.