Beaching and Natural Removal Dynamics of Pelagic Sargassum in a Fringing‐Reef Lagoon

Abstract

Extraordinarily large quantities of the pelagic brown macroalgae Sargassum spp., consisting of species S. fluitans and S. natans and hereafter referred to as sargassum, invaded the shores of the Caribbean and tropical West Africa in 2011 (Franks et al., 2012;Gower et al., 2013) and have been reoccurring since then (Johns et al., 2020;Wang et al., 2019). Drifting on the ocean surface, sargassum provides shelter and habitat for marine species (e.g., fish, shrimp, crab, and turtles). Once arriving in nearshore waters and washing ashore,

Multiscale distribution patterns of pelagic rafts of sargasso (Sargassum spp.) in the Mexican Caribbean (2014–2020)

“…The numerical modelling of the Puerto Morelos lagoon showed that sargasso cast is more likely to occur in summer due to lower wave energy, while in winter there are stronger energy pulses with higher magnitudes and a northeastern wind direction. Onshore sargasso dynamics had already been described before for Puerto Morelos by Garcia-Sanchez et al (2020) and Rutten et al (2021) who reported similar interannual variability in the influx to that reported in this work, although over shorter observation periods. Rutten et al (2021) reported that the greatest sargasso beachings were in 2018 and 2019 and that 2016 was a mild year; this pattern is mostly consistent with the sargasso coverage time series reported, although in 2020 offshore sargasso coverages are comparable to those of 2019 (Figure 5).…”

“…In summer (July-September), the greatest and most frequent sargasso coverage occurs offshore, coinciding with onshore beaching events. The greatest sargasso coverages close to shore were found in calm maritime conditions (≤0.2-kW/m 2 winds), with the dominant winds coming from east/eastsoutheast (Rutten et al, 2021; this study). However, when oceanographic conditions are more variable, there are notable differences between sargasso available at sea and the wrack cast.…”

“…A considerable sargasso biomass remain in the lagoon, if the rafts continue to arrive, and only when the wrack input ceases the energetic hydrodynamic conditions flush out the wrack from the lagoon, over a period of days. However, flushing during higher-energy events also pushes part of the wrack up to the beach dune or drives it partially offshore where it settles on the lagoon floor, especially when it is already in a partially decomposed state (Rutten et al, 2021).…”

“…Putman et al (2020) and Rutten et al (2021) explained the influence of waves, wind, and tides on the sargasso dynamics close to shore and governing its beach casting; we described graphically the mean oceanographic conditions (wind and wave power). To do this, daily mean wave, wind power, and direction were obtained for eight sampling nodes along the Mexican Caribbean coast (N1: 21°N 86.5°W; N2: 20.5°N 87°W; N3: 20.5°N 86.5°W; N4: 20°N 87°W; N5: 19.5°N 87°W; N6: 19°N 87.5°W; N7: 18.5°N 87.5°W and N8: 18°N 87.5°W; Figure 3) from ERA5 climate reanalysis (https://climate.copernicus.eu/ climate-reanalysis) using marine climate data for 2018 and 2019.…”

Pesticide upsurge, cross-contamination and biodiversity: case studies from the Caribbean Coast Human-Environment Observatory

“…The large amounts of seaweed biomass washed up along the coastlines have direct and indirect consequences for beaches [Williams and Feagin, 2010, Innocenti et al, 2018, Rutten et al, 2021 and for the functioning and resilience of nearshore ecosystems [Van Tussenbroek et al, 2017, Cabanillas-Teran et al, 2019. The mass stranding of these brown algae (Figure 5) also has significant negative impacts on livelihoods, public health, tourism, fisheries and the coastal economy [Resiere et al, 2018, Schuhmann et al, 2022.…”