In addition to the physical disturb

In addition to the physical disturbance associated with mechanical beach cleaning, this activity can also impact sandy beach fauna by removing a potential food supply.
Allocthonous wrack inputs are the dominant source of organic matter on sandy beaches and are highly variable in nature. We found that wrack volume did vary with cleaning regime, with the frequently cleaned beaches maintaining consistently low volumes of wrack, while infrequently cleaned and uncleaned beaches had higher, and more variable, volumes of wrack on our sampling dates.
We did not, however, detect any relationship between burrow densities and wrack volume, or sediment organic content (as a potentially less variable proxy for the delivery of organic matter to the beach).
This suggests that wrack accumulation may be too variable to accurately predict crab densities unless sampled extensively through time, and as such further temporal sampling would be required to better understand
the nature of wrack delivery to beaches in Sydney Harbour.
We suggest cleaning regime is a better proxy for levels of organic material on each beach than wrack volume at a single
sampling time.
Alternatively this lack of relationship could suggest that ghost crab populations in Sydney Harbour do not rely on marine sourced trophic subsidies, instead potentially seeking our terrestrial based food sources.
This, however, is unlikely given the highly modified nature of Sydney Harbour, where most of the native habitat surrounding beaches has been replaced with urban development.