Martínez, M.L.; Silva, R.; López-Portillo, J.; Feagin, R.A., and Martínez, E. 2020. Coastal ecosystems as an ecological membrane. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 97-101. Coconut Creek (Florida), ISSN 0749-0208.
A membrane is a continuous layer that separates the interior of a cell from its surrounding cells or environment. It is selectively permeable because it regulates the transport of water, ions, and organic compounds. Its primary function is protection. Relatively analogous to a cell membrane, coastal ecosystems can be considered as an ecological membrane because they regulate the bidirectional transport of materials between the terrestrial and marine ecosystems and provide protection. The components of the ecological membrane include coral reefs, seagrass beds, beaches, coastal dunes, mangroves, marshes, and coastal lagoons. The selective permeability depends on the ecosystem. Pollutants and heavy metals, carbon, and nutrients are captured by the biota and sediments of mangroves, seagrasses, and marshes, and thus decrease the impact of pollution from the watershed to the ocean. Seagrasses, mangroves, beaches, and coastal dunes mitigate the inland effects of storms and hurricanes by reducing wave energy during storm surges. We examine how coastal ecosystems act as ecological membranes by looking at the evidence available. We focus on the flow of two features: heavy metals towards the ocean and waves towards the continent. We use field data to show how heavy metals are trapped by mangroves and coastal lagoons, which are porous ports of entry and exit. Also, wave flume experiments demonstrate how wave erosion is mitigated by vegetated coastal dunes, which act as protective barriers. Management schemes can be improved if coastal ecosystems are considered as components of a dynamic ecological membrane.