harmful algal blooms (habs)

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Harmful Algal Blooms (HABs). Outline. Re-introduction to phytoplankton and HABs Hypoxia and disruptive blooms Toxic microalgae Regional Case Studies. “Phytoplankton” is a messy word. Literally = errant or wandering plant Often called “algae” or “microalgae” - PowerPoint PPT Presentation


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Harmful Algal Blooms (HABs)Re-introduction to phytoplankton and HABs

Hypoxia and disruptive blooms

Toxic microalgae

Regional Case Studies

OutlinePhytoplankton is a messy wordLiterally = errant or wandering plant

Often called algae or microalgae

Any single-celled organism (usually protists or bacteria) in aquatic systems that performs photosynthesis

They arent plants (but it helps to call them that)


http://farm3.static.flickr.com/http://ux.brookdalecc.edu/staff/sandyhook/taxonomyPhytoplankton are a Functional GroupGrouped by what they do, not who they areEx. Mammals are a taxonomic group, put different function (grazers, scavengers, predators)

Many problems with this grouping as wellSome live on the bottom microphytobenthosSome are predators and dont always do photosynthesis Some are parasites Incredible genetic and functional diversity



http://assets.nydailynews.comGlobal Importance45-50% of global primary productivity (fixing carbon into food)

Production of oxygen

Responsible for large fraction of global carbon burial (deep ocean)

Base of almost every aquatic food web

Role in C cycle gives them a key role in climate change

Bloom = domination by one species/group or a rapid, dense proliferation of phytoplankton (a poor definition)

Harmful for several possible reasonsProduce toxins

Hypoxia (low oxygen)

Exclusion/Shading - disruptive to other phototrophs

Physically harmful -obstruct fish gills, form large mats or foams


serc.carleton.eduHAB is also a messy word

Falkowski et al 2004Toxic or otherwise harmful species across many taxa

Variety of physiology, ecology, and toxicology to consider

Beware of broad explanations or solutions for HABsand covers a wide taxonomic rangeHABs are not newBelieved to be one or more of the Biblical Seven Deadly Plagues (Ehrenkranz and Sampson, 2008)

Red tides and toxic fish noted by Spanish explorers in 1600-1700s Florida (Tester and Steidinger 1997)

Many human mortalities from HAB shellfish poisoning in last 300 years (Lewitus et al. 2012)

Toxic bloom in California, 1961 inspired The Birds (Bargu et al. 2012)

A local jubilee of seafood is a hypoxia event

Many other historical accounts indicate hypoxia and toxic algae events

The Daily Telegraph

but they are on the riseGlobal increase in HABs was previously under debateStrong scientific consensus that HABs are increasing due to anthropogenic influence (Heisler et al. 2008)Increased eutrophication (nutrient pollution)Climate changeInvasive speciesStrong link between local nutrient pollution and increases in HABsAnderson et al. 2002

Parsons et al. 2002 Climate change likely to exacerbate HABs, particularly cyanobacteria

Paerl et al. 2011Paerl et al. 2011Phytoplankton growth generally increases with temperature

Cyanobacteria (blue-green algae) more likely to dominate due to high termperature tolerance

Many toxic cyanobacteria, also can be ecologically unfavorable (poor food source for higher trophic levels)

Warming implicated in many cyanobacteria HAB problems world wide (Ex. Lake Taihu, China)Invasions may also play a role in HAB expansionSome HABs linked to ballast water exchange (Hallegraeff, 1998) and known HAB species found in many ballast water surveys (Burkholder et al. 2007; Doblin et al. 2007)

HABs that form resting stages (cysts) or can survive long periods of darkness are prime candidates for ballast water invasion

Bio-fouling on ships may also be an important source of invasive species (Lopez-Rodas et al. 2010)



Longislandsoundstudy.netProfound ecological and economic consequences

Eutrophication implicated in the global rise in hypoxic zones (Diaz et al. 2001)

Hypoxia formation actually relies on several factors:Physical processes (i.e. wind and mixing)Nutrient inputs to supply phytoplankton growthSufficient phytoplankton growth and export to bottom watersSufficient bacterial decomposition in bottom waters to deplete oxygen

Hypoxia and Fisheries Decline

Hugo Ahlenius, UNEP/GRID-ArendalIn addition to sporadic fish kills, hypoxic zones drive down overall fisheries production (finfish and shellfish)

Louisiana Dead Zone Causes and estimated fisheries loss of 470 million pounds of seafood (Conservation and economic loss)

Most costly effect of eutrophication/ over abundance of phytoplankton

www.cop.noaa.govHABs can be dispruptive by excluding other speciesDense blooms due to eutrophication can shade other important

Made worse by overfishing/loss of key grazers

Coral reefs

Macroalgae such as kelp

Usac.org.ukParticularly damaging to seagrassMicroalage and macroalgae have caused much of seagrass die-off (Duarte 1995; Hauxwll et al 2003) due to shading

Eutrophication can shift overall production from benthos to water column. Loss of benthic production enhances resuspension making seagrass recovery harder (Olesen 1996)

News.fiu.orgor by being a poor food sourceSome species are harmful by displacing better food sources

Cyanobacteria lack essental fatty acids (e.g. sterols) give them poor nutritional quality for zooplankton (Martin-Creuzberg et al. 2008) and bivalves (Basen et al. 2012)

Toxic cyanos such as Microcystis produce colonies near zooplankton and reduced grazing


Newswise.comMacIntyre et al 2004or both!Aureococcus anophagefferens The Brown Tide

Blooms originated due to eutrophication

Tiny cells were a poor food source for bay scallops and grazers. Dense blooms out-competed other phytoplankton

Like seagrass problem, shifting biomass from benthos (microphytobenthos growing on bottom) to water column

Destablizes sediment, more resuspension

Dark environment perfect of Aureococcus (adapted to low light)

Persistent blooms wiped out bay scallop industry in New YorkAlternate Stable States


Stable StateTipping PointTwo Stable StatesIn reality, ecological disturbance changes the shape of the curves

Process can be irreversible on short time-scales (human time)In a stable state, ecosystem can receive some amount of disturbance, but will tend to return to natural state

If disturbed enough, dominance of stable state species is lost

Conditions shift to favor a new stable community Toxin-producing HABsLarge mortalities of fish or shellfish

Mortalities of wildlife such as birds or marine mammals

Direct toxic effects to humans

Human poisonings through contaminated seafood

Large economic impacts due to monitoring, medical costs, fisheries closures

Challenge: Aside from understanding HAB ecology and toxin production, must also assess trophic transfer, biotransfomation , and pharmacology of toxins


Most toxin producers are dinoflagellates


Comenius.susqu.eduMost ecological, human health, and economic costs are due to dinoflagellate HABs

Pose unique challenges for HAB research

They are mixotrophic (act as plants and animals), more difficult to describe ecology

Some cause harm at very low concentrations, hard to detect

They have enormous genomes, difficult for full sequencing

With some important exceptions

wikipediaGulfbase.orgPseudo-nitzchia the toxic diatomMicrocystis colony forming cyanobacteria that produces neuro- and hepatotoxinsPrymnesium parvum Small prymnesiophyte that produces parvotoxins, plagues aquaculture systems

Variety of toxins and diseasesSaxitoxins Paralytic Shellfish Poisoning (PSP)Alexandrium (a dinoflagellate) and some cyanosMajor problem in Northeast U.S. and Pacific Northwest

Brevetoxins Neurotoxic Shellfish Poisoning (NSP) Caused by Karenia (dino)Major problem for wildlife, tourism, and fisheries in Florida

Ciguatoxins Ciguatera Fish Poisoning (CFP)Gambierdiscus (dino) Only in tropics, poorly understoodMost common disease due to HABs, 2nd most common illness due to fish

Domoic acid Amnesic Shellfish Poisoning (ASP)Pseudo-nitzschia (diatom) Global problem for wildlife and shellfish

Okadaic acid Diarrheic Shellfish Poisoning (DSP)Emerging problem in Gulf of Mexico and Pacific NW

Whoi.eduAll structures Botana 2008Pseudo-nitzschia


Texas PWD

Diatom that occurs in temperate waters worldwide, dominant community member

Major bloom former in northern Gulf of Mexico

Produces domoic acid, accumulates in prey species and poisons their consumers.

Similarities in bloom conditionsPulses of nutrientsMixingUpwelling, estuaries, oceanic fronts

Appears to have a ruderal (weedy) growth strategy (MacIntyre et al. 2011)

A persistent threat to fisheries and wildlife

APFirst human poisonings raise attention1987, Prince Edward Island, CA3 killed, ~10 brain damaged, ~100 sickenedConsumption of domoic acid contaminated blue musselsCauses many shellfish closures in Pacific NorthwestPoisonings since in wildlifeFrequent sea lion mortalities (Scholin et al. 200)Bird mortalities (Work et al. 1993)Possible whale and dolphin illnesses (Twiner et al. 2009; Fire et al. 2011

Found in commercial fisheries in GOM (Liefer et al. 2013; Del Rio et al. 2012)

Liefer et al. 2013Gambierdiscus and Ciguatera

Maria Faust - NMNHUniversity of


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