Verification of Sargassum natans (Linnaeus) Gaillon (Heterokontophyta: Phaeophyceae) from the Sargasso Sea off the coast of Brazil, western Atlantic Ocean

Abstract

The Sargasso Sea, named due to the floating presence of Sargassum fluitans and S. natans, is usually reported for the tropical region of the Northern Hemisphere. On 14 July 2011, at 02°45’ N and 48°28’ W, samples of pelagic seaweed masses were collected by the Patrol Ship Bracuí of the Brazilian Navy. The seaweed was identified as S. natans, previously considered as of doubtful occurrence in Brazil.

Comparative mitochondrial and chloroplast genomics of a genetically distinct form of Sargassum contributing to recent “Golden Tides” in the Western Atlantic

“…As satellite observations cannot differentiate between the distinct species of Sargassum , much confusion originated from these original publications regarding the probable source populations responsible for the accumulations. Our results, coupled with the modeling results, as well as visual sightings of large mats of Sargassum in the South Atlantic off of Africa and Brazil (De Széchy et al., ) support the hypothesis that a genetically distinct population of S. natans VIII always occurred in the NERR but never experienced the proper set of conditions to form large accumulations like the ones that are causing the recent strandings. Parr () consistently reported S. natans VIII from the Caribbean, but always in small amounts.…”

“…Although typically found offshore, unusual accumulations of Sargassum dubbed “golden tides” (Smetacek & Zingone, ), began washing ashore on islands in the Caribbean during 2011 then again in 2014 and 2015, burying beaches, impacting coastal fisheries, restricting harbors, and smothering sea turtle nests (Maurer et al., ). Reports of golden tides like those in the Caribbean have also been reported in western Africa and Brazil (De Széchy, Guedes, Baeta‐Neves, & Oliveira, ; Smetacek & Zingone, ) impacting tourism, food security, and the limited budgets of coastal towns trying to remove the rotting biomass from their beaches. Whether these golden tides represent changes in distribution of existing biomass or result from unusual accumulations due to higher growth rates (“blooms”) has not been established, but the most popular hypothesis is that nutrients supplied by the Amazon and Congo River basins, and also equatorial and coastal upwelling regions along west Africa are allowing fast‐growing Sargassum to reach very high concentrations in an area known as the North Equatorial Recirculation Region (NERR, Figure ), with subsequent flushing toward the Caribbean (Johnson, Ko, Franks, Moreno, & Sanchez‐Rubio, ).…”

Pelagic Sargassum in the Tropical North Atlantic

“…Pelagic Sargassum was also spotted by aircraft offshore of northeastern Brazil where not previously observed (de Széchy et al 2012). The quantity and the frequency of occurrence of pelagic Sargassum in the beach stranding events created immediate problems for fishery and tourism industries of nations on both sides of the tropical Atlantic, and ecological impacts remain largely unknown.…”

Predicting Sargassum blooms in the Caribbean Sea from MODIS observations

“…Since 2011, massive Sargassum beaching events have occurred in the Caribbean Islands, causing significant environmental and economic problems [ Gower et al ., ; Maurer et al ., ]. Similar beaching events have also been reported in western Africa and northern Brazil [ Oyesiku and Egunyomi , ; Széchy et al ., ]. Although pelagic Sargassum provides an important ecological function in the open ocean [ Council , ; Rooker et al ., ; Witherington et al ., ; Lapointe et al ., ; Doyle and Franks , ], large amount of Sargassum deposition on beaches can negatively impact the local economy, ecology, and environment [ Siuda et al ., ; Hu et al ., ].…”