{"id":71140,"date":"2025-12-04T15:33:06","date_gmt":"2025-12-04T15:33:06","guid":{"rendered":"https:\/\/www.newsbeep.com\/us-fl\/71140\/"},"modified":"2025-12-04T15:33:06","modified_gmt":"2025-12-04T15:33:06","slug":"study-reveals-dramatic-decline-in-some-historic-sargassum-populations","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/us-fl\/71140\/","title":{"rendered":"Study reveals dramatic decline in some historic sargassum populations"},"content":{"rendered":"

Dyllan Furness<\/a>, College of Marine Science<\/p>\n

A new study led by researchers at the University of South Florida\u2019s College of Marine
\n Science has found that certain populations of the seaweed sargassum have experienced
\n a significant decline over the past decade. This was true even as an increased abundance
\n of sargassum in the tropical Atlantic caused large mats of the seaweed to inundate
\n beaches across the Caribbean and Gulf regions.\u00a0<\/p>\n

The abundance of sargassum in the Atlantic\u2019s north Sargasso Sea has plummeted since
\n 2015, according to the paper published this week in Nature Geoscience<\/a>. Sargassum from the Gulf, which annually supplies the Sargasso Sea, has also decreased
\n substantially.<\/p>\n

The findings point to ocean warming as a possible cause of the decline and suggest
\n a dramatic shift in sargassum\u2019s distribution, which could affect the health of marine
\n ecosystems.<\/p>\n

\u201cWhat is fascinating is that two opposite patterns occurred in the Atlantic Ocean,\u201d
\n said Chuanmin Hu<\/a>, professor of oceanography at the USF College of Marine Science and senior author
\n of the study. \u201cThe tropical Atlantic has seen a significant increase in sargassum
\n in the past decade, but at the same time the Sargasso Sea has a lot less sargassum
\n than it used to.\u201d<\/p>\n

Much like rainforests, large floating mats of sargassum support high levels of biodiversity.
\n They serve as an important habitat for turtles, crabs, shrimp, fish, and seabirds,
\n some of which are specially adapted to inhabit the mats of seaweed.<\/p>\n

However, once sargassum mats wash ashore and decay, they can emit a foul odor, harm
\n marine life, and disrupt coastal communities. Cleanup efforts in the United States
\n alone have cost businesses and governments millions of dollars annually<\/a>.<\/p>\n

Hu has used satellites to study sargassum since 2006 and spearheaded the discovery of the Great Atlantic Sargassum Belt in 2019<\/a>. His Optical Oceanography Lab is a global leader in sargassum research, providing
\n satellite imagery and monthly bulletins that inform stakeholders about sargassum biomass
\n seen from space.<\/p>\n

Read more: USF experts lead on sargassum research, monitoring, and prediction<\/a><\/p>\n

For the recent study, Yingjun Zhang, then a postdoctoral researcher, and Brian Barnes<\/a>, assistant research professor at the USF College of Marine Science, analyzed satellite
\n data gathered by NASA to assess changes in sargassum biomass. The lab partnered with
\n researchers at Sea Education Association<\/a> and Eckerd College<\/a>, who observed similar declines using field collected data, and provided historical
\n records, temperature tolerance information, and variety-level sargassum distribution
\n insights that were unavailable by remote sensing. Researchers from Woods Hole Oceanographic Institution<\/a> and Florida Atlantic University<\/a> also contributed to the study.<\/p>\n

The Gulf typically experiences a spring bloom of sargassum, which is carried north
\n by currents to the Sargasso Sea, where peak season occurs during late fall or early
\n winter. Lower levels of healthy sargassum in the Gulf result in a decreased abundance
\n of healthy sargassum in the Sargasso Sea.<\/p>\n

\u201cThese findings suggest we may be witnessing the early stages of a basin-scale regime
\n shift in sargassum distribution,\u201d said Zhang, now a postdoctoral scholar at the Scripps
\n Institution of Oceanography. \u201cSince a wide range of marine life relies on pelagic
\n sargassum ecosystems, this could really make a difference.\u201d<\/p>\n

Barnes said, \u201cThe regime shift also includes changes in sargassum seasonality, as
\n the once fall and winter peaks are now replaced by summer peaks in the north Sargasso
\n Sea.\u201d<\/p>\n

By analyzing three ingredients all plants depend on \u2014 light, nutrients, and temperature
\n \u2014 the researchers posit that record high temperatures in the Gulf, including more
\n frequent marine heat waves and possible nutrient competition by sargassum transported
\n from the Caribbean Sea, may have stunted the region\u2019s population of sargassum. The
\n result is weakened sargassum that struggles to survive once it arrives in the Sargasso
\n Sea.<\/p>\n

Studies have shown that waters in the Gulf warmed approximately 0.19\u00b0C (0.34\u00b0F) per decade<\/a> between 1970 and 2020, about twice the rate of the global ocean. While sargassum
\n in the Gulf prefer temperatures between 20 and 28\u00b0C (68 to 82\u00b0F), summer water temperatures
\n in the Gulf have recently exceeded 30\u00b0C (86\u00b0F).\u00a0<\/p>\n

Even the Great Atlantic Sargassum Belt, which stretches 5,000 miles across the Atlantic,
\n hasn\u2019t helped compensate for the decline in the Gulf. Sargassum from the belt may
\n be acclimated to warmer conditions or in poor health upon arrival and thus does not
\n tolerate the colder waters of the Sargasso Sea.<\/p>\n

\u201cIt’s a complex story and challenging to unravel due both to the spatial scale and
\n the fact that each variety of sargassum responds to ocean environmental conditions
\n in different ways,\u201d said Deb Goodwin, chief scientist at Sea Education Association
\n and a co-author of the study. \u201cLong-term data identifying and quantifying sargassum
\n varieties provided critical context to the satellite observations.\u201d<\/p>\n

Looking ahead, the research team aims to better understand how sargassum\u2019s shifting
\n population dynamics could impact marine ecosystems, including whether competition
\n from the Great Atlantic Sargassum Belt could drive further declines of sargassum in
\n the Gulf.<\/p>\n","protected":false},"excerpt":{"rendered":"Dyllan Furness, College of Marine Science A new study led by researchers at the University of South Florida\u2019s…\n","protected":false},"author":2,"featured_media":71141,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[13],"tags":[202,204,203,199,201,200],"class_list":["post-71140","post","type-post","status-publish","format-standard","has-post-thumbnail","category-st-petersburg","tag-st-pete","tag-st-pete-headlines","tag-st-pete-news","tag-st-petersburg","tag-st-petersburg-headlines","tag-st-petersburg-news"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us-fl\/wp-json\/wp\/v2\/posts\/71140","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us-fl\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us-fl\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-fl\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-fl\/wp-json\/wp\/v2\/comments?post=71140"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us-fl\/wp-json\/wp\/v2\/posts\/71140\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-fl\/wp-json\/wp\/v2\/media\/71141"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us-fl\/wp-json\/wp\/v2\/media?parent=71140"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-fl\/wp-json\/wp\/v2\/categories?post=71140"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-fl\/wp-json\/wp\/v2\/tags?post=71140"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}