FACTSHEET

arch Scientist,

pa’

t) ae th

e oceans aat c

assiviant kelps (Macrocyst

ith d to land

tissue and

r ge soaks up

r ed.

eir scopic and

ups: the cteria) that

; the ttuce; the

clude the hyta), the

with “red tides” which are actually caused by single-celled

which can paralytic

algae ahe

of thdifferent photosynthetic pigments or chlorophylls that each alga uses and these reflect different wavelengths of light.

Where are macroalgae found? With few exceptions, macroalgae are strictly benthic plants; that is they are always attached to the seabed or a solid substratum such as natural

ts, boat hulls, jetty s, mooring lines etc. When dislodged, most

e floating ve for hours to

Caulerpa species, anchor themselves or simply by

s fronds.

Macroalgae grow both intertidally and subtidally. Because they derive their nutrients by diffusion through their tissue, the water movement across fronds has to be continually refreshed and by being anchored to the seabed, they increase their

January 2011, Hwww.industry.nsw.gov.au/publications H for updates

Primefact 947 first edition

Primary Industries Sciece & Research

Macroalgae Alan Millar, Principal Rese Royal Botanic Gardens, Sydney

shellfish poisoning. No marine macroknown to be toxic or harmful to humans. Tdifferent ‘colours’ of algae are the result

reef, rocks, shells, mangrove roopiling

What are macroalgae? Macroalgae are members of the huge grouaquatic plants know as algae (singular ‘algalgae (the primary producers of the planeprimitive photosynthetic plants that includ

of ). The re e

macroalgae have a limited lifespan as freseaweed drift and they may only liseveral months.

single celled ‘phytoplankton’ of thmulti-celled macroalgae, or seaweeds, thrange in size from microscopic to the mkelps (Durvillaea) and g

nd the an e bull is).

Only a few macroalgae, such ascan grow in soft sediments and either with long root-like rhizoidsentanglement around seagras

Macroalgae should not be confused wseagrasses. The latter are closely relateplants as they have roots, vascularproduce flowers and pollen.

Macroalgae on the other hand, derive all their nutrients directly from the surrounding watethrough their tissue, a bit like a sponmoisture, and their holdfasts are purely fophysically anchoring the thallus to the seab

While seaweeds do reproduce sexually, threproductive structures are mostly microrequire fine dissection to be revealed.

Most macroalgae fall into four basic groblue-green algae (Cyanophyta/Cyanobaare often associated with blooms in riversgreen algae (Chlorophyta) such as sea lebrown algae (Heterokontophyta) that inlarge kelps; and the red algae (Rhodopmost diverse group of all.

The red algae should not be confused

algae (phytoplankton), some species ofproduce toxins that can kill fish or cause

re se e

Figure 1 Hormosira banksii, a common brown alga on rocky intertidal shores in NSW (Millar, 2007)

p 2 Macroalgae

chances of this. When floating with the curand tides, the water imm

reediately surrounding

esed after this seaweed th

n maintai

ic otic

trsis to occur. In cle

atut in murky wate

is reduced to only a few metres.

Along the NSW coast the maximum depth fomacroalgae is about 35-45 metres.

nts them

is not replenished as rapidly.

The one notable exception is a species of Sargassum. The famous Sargasso Sea (wnorth Atlantic) is nam

tern at

n itself floats there in massive rafts and caby simple fragmentation.

Since macroalgae are true photosynthetorganisms, they can only grow in the “phof the coastal regions, where the light penesufficiently for photosynthe

” zone ates ar

rs this

r most

waters, macroalgae can survive and grow depths of over 200 metres, b

foods, pharmaceuticals and cosm

In New South Wales, as in Austravery few algae are collected for co

Figure 2 Dislodged Durvillaea potatorumwashed up on a beach (Millar, 2007)

Significance As a result of their photosynthetic activity, marine algae (macroalgae and phytoplankton) are considered to produce between 50% and 75% of the earth’s oxygen as well as taking up about 25% of the carbon dioxide.

gnificant group of pink in colour and, ntributors to the

tidal reefs as they ate (chalk) in

reat Barrier Reef marine

ium carbonate s Halimeda. In

lled macroalgal

source as food f fish, shellfish

y often act fish. As drift, seaweeds

beach on the sand, they

beach

alued at about ests are four

re metre than any

m natural stands, tis forests along

ere the seaweed grows they can be prises. In these,

ts are seeded ecial ropes that are then attached to long-

vesting.

es, the seaweed n aquaculture, is he nation’s Gross

producer of y grow many

(eg, the red dried to make nori

ge of secondary eenen and alginates

sively in making processed etics.

lia as a whole, mmercial

purposes. The reason for this is that, while NSW is high in diversity of macroalgal species, no one algal species occurs in sufficiently large amounts or grows or recruits rapidly enough to make it commercially viable for harvesting.

Some macroalgae respond rapidly to, and thrive within, waters that receive increased nutrients and often can be used as indicators of water quality. At certain times of the year, especially in spring when

Crustose coralline algae, a very sired seaweeds, make rocks lookwhen broken apart, are major cosediments of intertidal and subactively lay down Calcium Carbontheir tissues.

Geological cores taken on the Ghave shown that up to 70% of thesediments are made up of calcdeposits from the green algal genufact, they should probably be careefs rather than coral reefs.

Macroalgae are an important reand/or shelter for a large range oand other invertebrate species, and theas nurseries for juvenile are a vital food source for many invertebrates and, when rotting return vital nutrients back into theecosystem.

Globally, macroalgae have been v11 billion dollars annually. Kelp fortimes more productive per squaintensively farmed crop on land.

Macroalgae can be harvested frosuch as the fast-growing Macrocysthe coast of California whup to 50 cm a day. Alternatively, farmed in large aquaculture enterthe algal spores and/or young planonto splines or other structures where they are left to grow for several months before har

In countries such as the Philippinindustry, which is based largely oone of the largest contributors to tDomestic Product.

Japan is the largest grower andmacroalgae in the world and thedifferent types of seaweed for foodalgal genus Porphyra which issheets for sushi rolls) or for a ranproducts such as agar, carragwhich are used exten

Macroalgae p 3

water temperatures and day lengths coupled with some heavy rainfalls supplynutrients from runoff to the coast and estuenvironments, macroalgae can bloom in mquantities. In all instances so far studied,involved in these blooms are harmlesnative s

increaseing arias

thes, non-

pecies. They are simply responding tions as mos

d. Wi waters, they have recently occurred at

such as Port Macquarie, Port Stephens, Jervambula on the sou

f m NSW

99nti

a in tted.

12lgae a

not necessarily the most regularly seen o

s, although the red calcified algae n in tide pools a

orms.

acroalgae of NSW

s

ies

a lettuce)

mosira banksii

osa

ata

Dictyota bartaryesiana

Durvillaea potatorum (only south of Tathra)

Reds

Crustose corallines

Cryptonemia sp.

Augophyllum delicatum

ly fragile fish habitat loss may dance and

brates in some of these ones.

chanical lture, siltation,

s; s, including the ntribute to a

y Harbour is the site of the world’s aweed (Millar 2003)

and

long the NSW ction south

have increased 007).

ectly by boating- by dredging and reclamation.

as pontoons and jetties ing macroalgae.

torm events, floods, sease also

s.

ersity and , and affected by:

phy and

Regions of upwelling where nutrient-rich cold waters reach the surface at certain localised regions along a coastline,

Anthropogenic entrance modification to intermittently closed and open estuaries and lagoons (which causes decreased flushing &

,

ne sive algae

Loss of species Macroalgae are an extremethat can be easily destroyed. Thiscontribute to declines in the abun

toxic, o t

diversity of fish and inverteestuaries and nearby coastal z

Direct human impacts such as medamage, eutrophication, aquacucoastal constructions, and alteration of food web

changes in environmental conditplants do.

These major blooms are mostly natural phenomena and occur all over the worlNSW

thin places is th

along with indirect human impactimpacts of climate change, can cowidespread loss of macroalgae.

Already, SydneBay, and Merimbula and Pcoast.

Macroalgae in NSW There are approximately 800 species omacroalgae presently documented fro

4b; nent he

Some of the large brown algae acoastline are experiencing a range retraas seawater surface temperaturesover the last 60-70 years (Millar 2

Macroalgae can be damaged dirrelated activities and

(Millar 1990; Millar & Kraft 1993, 1994a, 1www.aussiealgae.org). The Australian cohosts the richest marine macroalgal florworld with some 3000 species documen

The southern coast of Australia has aboutthese species. The most common macroa

00 of re

Foreshore structures suchcan indirectly impact by shad

as they st easily

Natural disturbances such as sextreme wave-action, predation and di

only grow subtidally. Those that are mseen by beachcombers are the greens and

d a drift

may contribute to macroalgal los

Subtidal macroalgal species divdistribution is de

brown(corallines) are often seeafter heavy st

n s pendent on

The diversity of the seabed topogrageology,

Some common m

Greens

Caulerpa specie

Codium spec

Ulva species (se

Browns

Hor

Phyllospora com

Ecklonia radi

Sargassum species

first recorded extinction of a sedue to dredging, trawling, siltationseabed/habitat destruction.

Figure 3 Augophyllum delicatum (Millar, 2007)

p 4 Macroalgae

increased residence times),

Point sources of pollution from indusdischarge, discharge from sewage tre

trial atm

d dum

rms,

st species.

roalga

ats ove

ds the

h as jettadin

ds.

ct

sh deckin to underlyin

lking through macroalgal areas tide.

Avoid digging for bait in macroalgal beds

Promptly report sewer overflows.

Maintain septic tanks and pumps so thatdo not leak.

ent ping plants, sewage overflow events an

of nutrient rich wastewater,

Natural climatic events such as sto

The introduction of alien or pe

How can you help protect macroalgae? Some simple ways to help protect mac

Avoid anchoring in, or mooring bomacroalgal beds.

e are:

r,

Avoid travelling across macroalgal beboats at low tide in order to minimise

in

potential for propeller damage.

Design waterfront structures suc ies, g or

s are

boat ramps and seawalls to avoid shphysical damage to macroalgal be

Ensure dredging and reclamation projesensitive to adjacent macroalgae beds.

Replace decking of jetties with me ng g

at low

to allow sunlight penetratiomacroalgal beds.

Avoid wa

.

they

Figure 4 Ecklonia radiata, the common subtidal kelp along most of the NSW coast (Thiebaud 2007)

&I NSW) has and marine

ae, under the s Management Act 1994. Any development

ae must be

ble to the protection n the Department’s

.gov.au or can be see below.

acroalgae species:

Bennetts seaweed (Vanvoorstia bennettiana) is inct (see Primefact 186) and marine

is critically

ct sets out provisions groves,

ether alive or under the Act means

up, reaching or

of it. A permit is required from I&I NSW to harm on, including macroalgae.

arming marine , without a permit 110,000 for a

t issue permits for ead macroalgae from the water.

red for the purpose of ation.

permitted from eserves or rtment of

nd Water website d areas;

rsons to remove up to 20kg/day of dead, unattached, drift seaweed (wrack) from beaches or the intertidal zone for personal use (e.g., as compost, fertiliser) without a permit. If a person or organisation wishes to collect quantities of wrack exceeding 20 kg/day, then a permit will be required under Clause 66 of the Fisheries Management (Aquaculture) Regulation 2002. A permit may be issued on a case-by-case basis for a period of a year or more.

Protection of macroalgae in NSW Industry & Investment NSW (Imanagement responsibility for fishvegetation, including macroalgFisherieor activity that may harm macroalgreferred to I&I NSW.

Policies and guidelines applicaof macroalgae can be found owebsite at www.industry.nswobtained from I&I NSW offices –

In NSW there are two species of mcurrently on the list of threatened

presumed extbrown algae (Nereia lophocladia) endangered (see Primefact 192).

Harming macroalgae The Fisheries Management Ato protect marine vegetation (manseagrasses and macroalgae whdead) from ‘harm’. ‘Harm’gather, cut, pull up, destroy, poison, digremove, injure, prevent light from otherwise harm the marine vegetation, or any part

marine vegetati

The maximum penalty for hvegetation, including macroalgaeis $220,000 for a Corporation or $person.

Collecting macroalgae I&I NSW will generally nocollecting live or dExemptions may be considescientific research or marine life rehabilitCollecting will generally not beSanctuary Zones within Aquatic RMarine Parks (see the NSW DepaEnvironment Climate Change afor the location of these protectewww.environment.nsw.gov.au).

I&I NSW will allow pe

Macroalgae p 5

Contact details For further scientific information about macr

ct the author or:

Leader, Aquatic Ecosystems ent NSW

lgaor c

gement istact I&I NSW’s Aq

t regional offices:

ager – North Region

1200

n

2315 1232

y Region

NSW

0 Phone: (02) 9527 8411

nager – South Region stment NSW

and King, R.J. (1990). Bioln

Huisman, J.M. (2000). Marine plants of Australia. University of Western Australia Press, Nedlands, Western Australia. 300 pp.

Huisman, J.M. (2006). Algae of Australia: Nemaliales. Australian Biological Resources Study, Canberra. 164 pp.

Kraft, G.T. (2007). Algae of Australia: Marine Benthic Algae of Lord Howe Island and the

. Green algae. Australian Biological Resources Study, Canberra.

007) (eds). Canberra,

pp.

ine red algae of the Coffs South Wales.

3-593.

03). The world’s first recorded ings of the 17th . pp. 313-318.

Millar, A.J.K. (2007). The Flindersian and Peronian ntroduction. pp.

ical Resources Study,

ater, D.W. (2005). The ny of the

uth Wales, orfolk Islands.

3). Catalogue of e (Rhodophyta) ing Lord Howe

Pacific. Australian

a). Catalogue of om New South

including Lord Howe Island, south-western y 7: 1-46.

Catalogue of (Chlorophyta) from

cluding Lord Howe Island, ralian Systematic

ent of Primary NSW DPI). (2006). Protected marine

getation. atened_species/

tation

artment of Industry

oalgae 356 pp.

McCarthy, P.M. & Orchard, A.E. (2in NSW, conta

Dr Bob Creese Research Industry & InvestmLocked Bag 1 Nelson Bay NSW 2315 Phone: (02) 4916 3806

Report activities that are harming macroacontacting your nearest Fisheries Office Fishers Watch Hotline on 1800 043 536.

e by

Harbour Region, northern New Australian Systematic Botany 3: 29

Millar, A.J.K. (20

alling

sues

extinction of a seaweed. ProceedInternational Seaweed SymposiumOxford University Press, Oxford.

For further information about manainvolving macroalgae, con uatic

Provinces. In Algae of Australia; I554-559. Australian Biolog

Habitat Protection Uni

Conservation ManIndustry & Investment NSW

1243 Bruxner HighwayWollongbar NSW 2477 Phone: (02) 6626 Conservation Manager – Central Regio

NSW Industry & Investment Bag 1 Locked

Nelson Bay NSWPhone: (02) 4982

Conservation Manager – SydneIndustry & Investment PO Box 21 Cronulla NSW 223

Conservation MaIndustry & InvePO Box 97 Huskisson NSW 2540 Phone: (02) 4441 8969

Further reading www.aussiealgae.org

www.algaebase.org

Clayton, M.N. ogy of e. 501

www.fisheries.nsw.gov.au/thregeneral/protected_marine_vege

© State of New South Wales through Dep

Marine Plants. Longman Cheshire, Melbourpp.

southern Great Barrier Reef. 1

Algae of Australia: Introduction. ABRSCSIRO Publishing, Melbourne. 727

Millar, A.J.K. (1990). Mar

Canberra.

Millar, A.J.K. & Freshwmorphology and molecular phyloge

red algal order gelidiales from New Soincluding Lord Howe and NAustralian Systematic Botany 18: 1-49.

Millar, A.J.K. and Kraft, G.T. (199marine and freshwater red algafrom New South Wales, includIsland, south-western Systematic Botany 6: 1-90.

Millar, A.J.K. and Kraft, G.T. (1994marine brown algae (Phaeophyta) frWales,Pacific. Australian Systematic Botan

Millar, A.J.K. and Kraft, G.T. (1994b). the marine benthic green algaeNew South Wales, insouth-western Pacific. AustBotany 7: 419-453.

New South Wales DepartmIndustries (ve

and Investment (Industry & Investment NScopy, distribute and ot

W) 2011. You may herwise freely deal with this publication

for any purpose, provided that you attribute Industry & Investment NSW as the owner.

ISSN 1832-6668

Disclaimer: The information contained in this publication is based on knowledge and understanding at the time of writing (January 2011). However, because of advances in knowledge, users are reminded of the need to ensure that information upon which they rely is up to date and to check currency of the information with the appropriate officer of Industry & Investment NSW or the user’s independent adviser.

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