{"id":63861,"date":"2012-08-13T08:20:55","date_gmt":"2012-08-13T12:20:55","guid":{"rendered":"https:\/\/today.uconn.edu\/?p=63861"},"modified":"2012-08-16T15:26:21","modified_gmt":"2012-08-16T19:26:21","slug":"algal-bloom-species-with-two-deadly-toxins-could-disrupt-marine-food-web","status":"publish","type":"post","link":"https:\/\/today.uconn.edu\/2012\/08\/algal-bloom-species-with-two-deadly-toxins-could-disrupt-marine-food-web\/","title":{"rendered":"Algal Bloom Species with Two Deadly Toxins Could Disrupt Marine Food Web"},"content":{"rendered":"
\"The<\/a>
The algal bloom species Alexandrium, which looks like Saturn in the lower-left, and several of its single-celled predators. (Photo courtesy of Hans Dam)<\/figcaption><\/figure>\n

When tiny aquatic organisms reproduce in large amounts, algal blooms occur that take over portions of open water up to hundreds of miles in area.<\/p>\n

And when these oceanic plankton happen to be the toxic kind, they can be deadly to other living things crossing their path.<\/p>\n

One of the most poisonous and abundant of these plankton, the species Alexandrium tamarense, <\/em>produces paralytic shellfish toxin (PST), a neurotoxin that can result in death when ingested in large amounts by mammals, including humans.<\/p>\n

Now, Professor Hans Dam and his research group in the Department of Marine Sciences have shown that this microscopic alga also produces a second kind of deadly toxin, one that attacks some of the algae\u2019s tiny predators and, along with PST, could ultimately upset entire marine food chains. Dam published his findings in the May 2012 issue of the journal Aquatic Microbial Ecology<\/em><\/a>.<\/p>\n

\"Hans<\/a>
Hans Dam in a lab in Chile, where he is working with researchers at the University of Los Lagos to understand how Alexandrium may affect important commercial species. (Photo courtesy of Hans Dam)<\/figcaption><\/figure>\n

\u201cThe amazing thing is, when you look at these algae under a microscope, they\u2019re so beautiful \u2013 but they\u2019re so deadly,\u201d says Dam. \u201cWe call them the beautiful assassins.\u201d<\/p>\n

Like plants, these one-celled organisms make their own food from the light of the sun. The Alexandrium<\/em> species lives in cold seawater in the northern and southern hemispheres, and is found from the Long Island Sound up to the northernmost Canadian borders. In 2005, a major bloom \u2013 sometimes referred to as a red tide \u2013 occurred throughout the northeast coast, severely affecting the Cape Cod area.<\/p>\n

In small numbers, Alexandrium<\/em> is virtually harmless to humans, says Dam. But when they\u2019re eaten by clams, mussels, or other microorganisms \u2013 which are then eaten by small crustaceans, which are in turn eaten by larger crustaceans or fish \u2013 the toxins can build up in large amounts. So in some parts of the world, eating contaminated lobsters, clams, and fish has led to illness or death.<\/p>\n

However, says Dam, PST only affects animals that have central nervous systems.<\/p>\n

\u201cThis toxin blocks sodium channels in anything that has a well-developed nervous system,\u201d he says. \u201cBut most of the organisms in the ocean are not those kinds of organisms. They\u2019re single-celled, similar to the algae themselves, and they don\u2019t have a well-developed nervous system.\u201d<\/p>\n

Scientists had begun to notice that even though Alexandrium<\/em>\u2019s toxin isn\u2019t supposed to affect single-celled animals, when the alga was in the vicinity of some of its one-celled predators, some of those predators got sick and died. Dam\u2019s post-doctoral researcher Hayley Flores showed in laboratory experiments that in fact the alga produces a different toxin, called a reactive oxygen species, that kills its predators by popping their cell membrane.<\/p>\n

\u201cIf you only have one cell, losing your cell membrane is all it takes to kill you,\u201d says Dam. \u201cThis new mechanism of toxicity, combined with the other, is pretty evil.\u201d<\/p>\n

Dam speculates that this ability to harm both large and small oceanic predators could lead to disruptions in the marine food web during large Alexandrium<\/em> blooms.<\/p>\n

\u201cThese small predators that are being affected by the reactive oxygen species are the things that typically eat large amounts of the algae and keep them from growing like crazy,\u201d says Dam. \u201cThis brings up a whole new line of inquiry for us: What will actually control these algae in the future?\u201d<\/p>\n

Dam notes that although harmful algal blooms have been linked to human activities, such as pollution runoff from rivers, there are many different factors that could affect the blooms, and scientists still aren\u2019t sure exactly how they begin. He speculates that the algae may have become more toxic over time, which has led to their proliferation.<\/p>\n

His group will next try to understand how the alga produces the reactive oxygen species and whether it also affects multicellular animals. He\u2019s also working with researchers at the University of Los Lagos in Chile to understand how Alexandrium<\/em> may affect important commercial species such as salmon and king crab. And his group recently received funding from Connecticut Sea Grant to study the effects of temperature on plankton in the Long Island Sound.<\/p>\n

Dam says that even though humans have little to fear, the marine world could see shifts based on just this one group of species.<\/p>\n

\u201cIf it\u2019s killing multicellular animals with one toxin and small protists with another,” he says, “it could be the killer of the ocean world.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"

A study led by marine scientist Hans Dam found that a tiny aquatic organism called Alexandrium has the ability to harm both large and small predators.<\/p>\n","protected":false},"author":37,"featured_media":63859,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_crdt_document":"","wds_primary_category":0,"wds_primary_series":0,"wds_primary_attribution":0,"footnotes":""},"categories":[1],"tags":[],"magazine-issues":[],"coauthors":[63],"class_list":["post-63861","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized"],"pp_statuses_selecting_workflow":false,"pp_workflow_action":"current","pp_status_selection":"publish","acf":[],"publishpress_future_action":{"enabled":false,"date":"2026-05-03 05:41:52","action":"change-status","newStatus":"draft","terms":[],"taxonomy":"category","extraData":[]},"publishpress_future_workflow_manual_trigger":{"enabledWorkflows":[]},"_links":{"self":[{"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/posts\/63861","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/users\/37"}],"replies":[{"embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/comments?post=63861"}],"version-history":[{"count":5,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/posts\/63861\/revisions"}],"predecessor-version":[{"id":64262,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/posts\/63861\/revisions\/64262"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/media\/63859"}],"wp:attachment":[{"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/media?parent=63861"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/categories?post=63861"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/tags?post=63861"},{"taxonomy":"magazine-issue","embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/magazine-issues?post=63861"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/coauthors?post=63861"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}