IDENTIFICATION, ECOLOGY AND CONTROL OF NUISANCE … · 2019. 5. 9. · ALGAL PROBLEMS Toxicity-Cyanotoxins • Cyanobacteria are the primary toxin threats to people in freshwater;

IDENTIFICATION, ECOLOGY AND

CONTROL OF NUISANCE

FRESHWATER ALGAE

KENNETH J. WAGNER, Ph.D, CLM

WATER RESOURCE SERVICES

PART 1: THE PROBLEMS

ALGAL PROBLEMS

Algal problems include:

• Ecological imbalances

• Physical impacts on the aquatic system

• Water quality alteration

• Aesthetic impairment

• Taste and odor

• Toxicity

ALGAL PROBLEMS

Ecological Imbalances

High algal densities:

• Result from overly successful growth processes and

insufficient loss processes

• Represent inefficient processing of energy by higher

trophic levels

• May direct energy flow to benthic/detrital pathways

• May actually reduce system productivity (productivity

tends to be highest at intermediate biomass)

ALGAL PROBLEMS

Aesthetic Impairment

High algal densities lead to:

• High solids, low clarity

• High organic content

• Fluctuating DO and pH

• “Slimy” feel to the water

• Unaesthetic appearance

• Taste and odor

• Possible toxicity

ALGAL PROBLEMS

Taste and Odor

• At sufficient density, all algae can produce taste and odor by virtue of organic content and decay

• Geosmin and Methylisoborneol (MIB) are the two most common T&O compounds, produced by cyanobacteria in water column or on bottom

• Additional compounds produced by golden algae and can impart cucumber, violet, spicy and fishy odors

• T&O presence does not guarantee toxicity, but with enough algae to cause T&O, toxicity should be checked

ALGAL PROBLEMS

Taste and OdorT&O by other algae

• Green algae, diatoms, dinoflagellates and euglenoids can produce fishy or septic odors at elevated densities

• Major die-off of high density algae may produce a septic smell

• Actinomycetes, a non-photosynthetic bacterium, can also produce geosmin and MIB

ALGAL PROBLEMS

Taste and Odor

Control of T&O

• Minimizing algal density and specific T&O producers is desirable for T&O control

• Activated carbon removes most T&O, but effective use is slow and increases treatment cost

• Aeration/mixing may oxidize/volatilize T&O compounds, but not completely effective

• Possible toxic link, but no severe direct health effects known from T&O; aesthetic issues can be major

ALGAL PROBLEMS

Toxicity-Cyanotoxins• Cyanobacteria are the primary toxin threats to people in freshwater; acute

toxicity is rare, but chronic effects may be significant and are difficult to

detect.

• Research (e.g., 3 papers in Lake and Reservoir Management in 2009) plus

NLA report indicate widespread occurrence of toxins but highly variable

concentrations, even within lakes, and rarely “high”.

• Water treatment in typical supply facilities is adequate to minimize risk;

the greatest risk is from substandard treatment systems and direct

recreational contact.

• Some other algae produce toxins - Prymnesium, or golden blossom, can

kill fish; marine dinoflagellates, or red tides, can be toxic to many animals

and humans.

ALGAL PROBLEMS

Toxicity-Cyanotoxins

• Dermatotoxins

– produce rashes and other skin reactions, usually within a day (hours)

• Hepatotoxins

– disrupt proteins that keep the liver functioning, may act slowly (days to weeks)

• Neurotoxins

– cause rapid paralysis of skeletal and respiratory muscles (minutes)

ALGAL PROBLEMS

Toxicity-Analytical Methods

Se

lec

tivit

y100

75

50

25

Bioassay(mouse)

mg ng pg

Sensitivity

MassSpec LC/MS

HPLC

ELISAPhosphatase Assay

ALGAL PROBLEMS

Toxicity- Key Issues

• Acute and chronic toxicity levels - how much can

be tolerated?

• Synergistic effects - those with liver or nerve

disorders at higher risk

• Exposure routes - ingestion vs. skin

• Treatment options - avoid cell lysis, remove or

neutralize toxins

ALGAL PROBLEMS

Recommended Thresholds for Concern

WHO: Mod/High risk thresholds at >20,000 – 100,000 cells/mL, >10 - 50 ug/L chl-a, >10

- 20 ppb microcystin-LR

State thresholds in NEAPMS region:

• CT: Visible scums, 70,000 cells/mL, microcystin >15 ppb

• MA, RI: 70,000 cells/mL, visible scum, microcystin >14 ppb

• VT: Visible scums or mats present

• NH: Scum present with potential toxin producer >50% of cell count or 70,000

cells/mL

• ME, PA, NJ: Using WHO thresholds

• NY: Suspicious = unverified credible visual evidence Confirmed = BG chlorophyll a >

30 ug/l or MC-LR > 4 ug/L Confirmed with high toxins = MC-LR > 20 ug/L

ALGAL PROBLEMS

Recommended Toxicity Precautions

• Monitor algal quantity and quality

• If potential toxin producers are detected, increase monitoring

and test for toxins

• For water supplies, incorporate capability to treat for toxins

(PAC or strong oxidation seem to be best)

• For recreational lakes, be prepared to warn users and/or limit

contact recreation

• Avoid treatments that rupture cells

PART 2: ALGAL FORMS

Algal Taxonomy

Just where to make the split between species or even genera is not always obvious

Layer cake

analogy from

Morales et al.

2002

Fragilaria

construens

Fragilaria

brevistriata

cruciate

biundular

elliptical

triradiate

linear

Algal TaxonomySplitters vs. Lumpers

• Lumping limits taxa, groups by “reliable”

differentiators (best if genetically based,

but was not always the case)

• Splitting proliferates taxa, separates

forms based on what may be genotypic or

phenotypic differences

• In characterizing environmental

conditions, splitting will be more useful

but requires more effort

Classification Features• Pigments

• Food storage

• Cell wall

• Flagella

o Cell structures

o Cell organization

Reproductive mode

Genetics

Culture response

Biochemistry

Cyanobacteria TaxonomyModern Classification of CyanobacteriaSubclass Synechococcophycideae

Order Synechococcales (e.g. Aphanocapsa, Coelosphaerium, Synechococcus,

Merismopedia, Snowella)

Order Pseudanabaenales (e.g. Pseudanabaena, Schizothrix, Spirulina, Planktolyngbya)

Subclass Oscillatoriophycideae

Order Chroococcales (e.g., Chroococcus, Microcystis)

Order Phormidiales (e.g., Arthrospira, Phormidium, Planktothrix)

Order Oscillatoriales (e.g., Lyngbya, Limnoraphis, Microseira, Oscillatoria)

Subclass Nostocophycideae

Order Nostocales (e.g., Nodularia, Anabaena, Dolichospermum, Aphanizomenon,

Cuspidothrix, Chrysosporum, Sphaerospermopsis, Trichormus, Anabaenopsis,

Cylindrospermum, Raphidiopsis, Gleotrichia, Rivularia, Scytonema, Tolypothrix, Stigonema)

Cyanobacteria Taxonomy

Some Major Findings of Polyphasic Analyses

• Distinction between coccoid and filamentous forms no longer

followed at the highest subclass level

• Division into subclasses based on thylakoid arrangement and

presence of differentiated cells (heterocytes/akinetes)

• Heterocytous cyanobacteria unified into one subclass

• Many genera shown to actually include more than one genus (e.g.

Anabaena, Aphanizomenon, Synechocystis, Phormidium, Lyngbya)

• Planktonic Anabaena and Aphanizomenon species closely related at

the generic level; continuum of genera in between

• Morphology based species concept for Microcystis not supported


Sphaerospermopsis aphanizomenoides Chrysosporum ovalisporum

• Anabaena and Aphanizomenon appear to constitute a gradient of multiple genera

• Anabaena do not have aerotopes, do not float, and are benthic. Anabaena with

aerotopes split off mostly into Dolichospermum with a few intermediate genera

(Sphaerospermopsis, Chrysosporum, and Trichormus) based mostly on akinete and

heterocyte features

Dolichospermum Anabaena


Cuspidothrix

Aphanizomenon

Filaments with long attenuated end cells split

from Aphanizomenon into Cuspidothrix

Separating Cyano Species

• Cell shape and Size

• Color

• Granulation

• Presence/Absence of Aerotopes

• Habitat• Cell Arrangement

• Mucilage features

• Trichome morphology

• Presence/Absence and Nature of

Sheath

• Presence/Absence of

Constrictions at Cross-walls

• Shape, Size and Location of

Heterocytes and Akinetes

• Motility

• End Cell Shape

Algal Taxonomy

Scenedesmus

Splitting by molecular analysis for other algal groups too!

• Green algae order Chlorococcales split into Chlorellales and Sphaeropleales

• Green algae genus Scenedesmus split into Scenedesmus, Acutodesmus and Desmodesmus

• Green algae genus Pediastrum split into at least 3 genera

Bottom line is that taxonomy is now based on molecular techniques more than visual

features, but we still have to do identification by eye. Molecular determination are therefore

walked back to find visual features we can use whenever possible, but it compromises

identification certainty.

DesmodesmusAcutodesmus

Algal FormsAlgal “Blooms”

Water discoloration usually defines bloom conditions

Many possible algal groups can “bloom”

Taste and odor sources, possible toxicity

Potentially severe use impairment

Algal FormsAlgal Mats

Can be bottom or

surface mats - surface

mats often start on the

bottom

Usually green or blue-

green algae

Possible taste and odor

sources

Potentially severe use

impairment

Algal Types: Planktonic Blue-greensAphanizomenon

(Cuspidothrix)

Microcystis

Dolichospermum

(Anabaena)

Woronichinia

Algal Types: Planktonic Blue-greens

Planktothrix

(Oscillatoria)

Limnoraphis

(Lyngbya)

Planktolyngbya

(Lyngbya)


Gloeotrichia


Rhaphidiopsis

(Cylindrospermopsis)

•A sub-tropical alga with toxic

properties is moving north.

•Most often encountered in

turbid reservoirs in late

summer, along with a variety

of other bluegreens.

Algal Types: Mat Forming Blue-greens

Oscillatoria

Lyngbya/Plectonema

Algal Types: Planktonic Greens

Lagerheimia

Oocystis

Order Chlorellales

(previously Chlorococcales)

Chlorella

Dictyosphaerium

Gloeocystis

Algal Types: Planktonic GreensPediastrum

Desmodesmus

(Scenedesmus)

Schroederia

Order Sphaeropleales

(previously Chlorococcales)

Pseudopediastrum

(Pediastrum)

Monactinus (Pediastrum)

Acutodesmus (Scenedesmus)

Algal Types: Planktonic Greens

Chlamydomonas

Pyramichlamys

Carteria

Eudorina

Volvox

Order Volvocales

Algal Types: Mat Forming Greens

Cladophorales, with

Cladophora (above),

Rhizoclonium and

Pithophora

Zygnematales, with

Spirogyra (above),

Mougeotia and

Zygnema

Hydrodictyon,

an unusual

type of

Chlorococcales

Oedogoniales,

with

Oedogonium

and

Bulbochaete


Zygnematales - Unbranched filaments, highly

gelatinous (slimy to the touch)

Mougeotia

Spirogyra

Zygnema

Mats trap

gases and

may float

to surface

Cladophorales - Large, multinucleate cells, reticulate chromatophores,

filamentous forms (coarser feel)

Pithophora

RhizocloniumCladophora



Hydrodictyon

Oedogonium

Bulbochaete

Algal Types: Planktonic Diatoms

Aulacoseira

(Melosira)

Asterionella

Cyclotella

Algal Types: Planktonic Diatoms

Fragilaria

Tabellaria

Nitzschia

Algal Types: Plankton Goldens

Synura

Prymnesium

Chrysosphaerella

Dinobryon

Algal Types: Mat Forming Goldens

Tribonema

Vaucheria

Algal Types: Other Plankton

Ceratium

Peridinium

Euglena

Trachelomonas

Phacus

Euglenoids

Dinoflagellates

Field vs. Microscope (courtesy of West Bishop of SePRO)

Algae name Phylum Characteristics

Lyngbya/

Plectonema

Mat forming

Cyanophyta

Filamentous, toxin/taste and odor

producer, mucilaginous, mat-former


Microcystis,

Dolichospermum,

Aphanizomenon,

Planktothrix

Planktonic

Cyanophyta

Colonial, filamentous, toxin producer,

mucilaginous, planktonic, scum-former


Euglena Euglenophyta Unicellular, potential toxin-producer,

planktonic, scum-former, flagellated


Spirogyra

“silk algae”

Chlorophyta Filamentous, mucilaginous, mat-former

(also Mougeotia and Zygnema)


Pithophora

“Horsehair algae”

Chlorophyta Filamentous, mat-former, branched,

also may get similar growths from

Cladophora and/or Rhizoclonium


Prymnesium parvum Haptophyta Unicellular, toxin producer, planktonic,

flagellated (rare in northeastern USA)


Nostoc Cyanophyta Colonial, soft gel, potential toxins

(like Anabaena in gelatin)


Didymosphenia

“Rock Snot”

Bacillariophyta Mucilaginous, mat-former, stalked, mainly

in flowing water, invasive


Chara

“Muskgrass”

Charophyta Plant-like, smelly, rough texture

(Nitella is similar, without smell)

PART 3: THE ECOLOGICAL

BASIS FOR ALGAL CONTROL

ALGAL ECOLOGY

Key Processes Affecting Abundance

Growth Processes

• Primary production – controlled by light and nutrients, algal physiology

• Heterotrophy – augments primary production, dependent upon physiology and environmental conditions

• Release from sediment – recruitment from resting stages, related to turbulence, life strategies

ALGAL ECOLOGY


Loss Processes

• Physiological mortality – inevitable but highly variable

timing – many influences

• Grazing – complex algae-grazer interactions

• Sedimentation/burial – function of turbulence, sediment load,

algal strategies

• Hydraulic washout/scouring – function of flow, velocity,

circulation, and algal strategy

ALGAL ECOLOGY


• Light – differential use of light by algae by virtue of different

pigments in cells

• Temperature – differentially affects metabolism of food storage

products

• pH – affects forms of carbon available, differential use of carbon

forms by algal groups

• Mixing – differential effects as some algae settle faster, some can

swim, some can float

• Grazing by zooplankton – some algae are more edible than others

ALGAL ECOLOGY

Phytoplankton Succession - Notes

• Biomass can vary by 1000X over time, function of growth and loss

processes interacting with other influences on algae

• Primary productivity and biomass may not correlate due to time

lags, cell size and nutrient or light limitations

• Highest productivity normally at intermediate biomass (Chl a = 10

ug/L)

• High pH during blooms may trigger resting cyst formation

ALGAL ECOLOGY

Trophic Gradients

• Based on decades of study, more

P leads to more algae

• More algae leads to lower water

clarity, but in a non-linear pattern

0102030405060708090

100110120130140150160170180190200

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200

Ch

l (u

g/l)

TP (ug/l)

Total Phosphorus vs. Chlorophyll a

0

1

2

3

4

5

6

7

8

9

10

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200S

DT

(m

)TP (ug/l)

Total Phosphorus vs. Secchi Disk Transparency

ALGAL ECOLOGY

Trophic Gradients

• As algal biomass

rises, a greater

% of that

biomass is

cyanobacteria.

So more P =

more algae +

more cyanos.From Canfield et al.

1989 as reported in

Kalff 2002

ALGAL ECOLOGY

Trophic Gradients

• High P also leads to more cyanobacteria, from considerable empirical

research. Key transition range is between 10 and 100 ug/L

(10 ug/L) (100 ug/L)From Watson et al. 1997 L&O 42(3): 487-495

The End

QUESTIONS?

After that, we

might need

another one

of these…

Documents

IDENTIFICATION, ECOLOGY AND CONTROL OF NUISANCE … · 2019. 5. 9. · ALGAL PROBLEMS Toxicity-Cyanotoxins • Cyanobacteria are the primary toxin threats to people in freshwater;