ABSTRACT
de Almeida, L.R.; Ávila-Mosqueda, S.V.; Mendoza, E.; Silva, R., and van Tussenbroek, B.I., 0000. Relationships between spatiotemporal variation of nearshore seagrass cover and shoreline position in a Mexican Caribbean reef lagoon.
The ecological importance and ecosystem services of seagrass meadows are widely recognized, including dissipation of wave and current energy and trapping and stabilization of sediments, thereby protecting the coast from erosion processes. Changes in meadow coverage area and composition can influence the shoreline position, particularly near the coast. Since 2015, periodic Sargassum spp. inundation events in the Mexican Caribbean have been identified as the main factor for seagrass meadow loss in the nearshore zone. This natural experiment permits examination of the way in which the spatiotemporal variation of the bottom vegetation cover is related to dry beach width, in addition to other potential factors that could have influenced the shoreline position. An investigation was conducted on different sections along a 5.3-km-long stretch of coast in the Mexican Caribbean between 2011 and 2024 The section with the least human influence, but also without removal of beached algal masses (section 1), experienced the most significant loss of nearshore vegetation following the first sargassum event in 2015. In the southern sections (2 and 3), there was a marked loss of nearshore vegetation between 2018 and 2021, possibly due to the chronic effects of successive sargassum events (such as turbid water or increased organic matter on the seafloor), burial caused by the migration of underwater dunes or sediment transported from north to south, either from beach replenishment or from the previously impacted section 1, or negative effects of the anti-sargassum barrier installed in 2019. Except for stretches with beach replenishment and migration of underwater dunes, significant relationships were found between nearshore bottom cover and dry beach width parameters. The dry beach width was smaller in areas where the percentage of dense vegetation was lower or the distance of the vegetation from the shoreline was greater, indicating the importance of nearshore vegetation in coastal stability.
