Human Pressure on Sandy Beaches: Implications for Trophic Functioning

The effect of coastal development and tourism occupancy on the structure and trophic networks of sandy beaches was analysed for the first time, using mass-balanced trophic models. Ecopath models were applied to two beaches, representative of different anthropogenic pressures, a beach located inside a protected area and an urbanised beach with tourism infrastructure and high levels of visitors. Models comprised 28 compartment at the protected beach and 27 compartments at the urbanised beaches, including detritus, phytoplankton, zooplankton, invertebrates, fishes and birds. Results revealed that the protected area had higher values of total system throughput, biomass, ascendency and capacity, reflecting a more complex, organised, mature and active system, compared to the urbanised beach. Finally, different indicators of stress were analysed and we suggest the Finn cycling index as an indicator of anthropogenic impact on sandy beaches.