BBC Wildlife - UK (2020-05)

inthedaytime,with

fewerecologistsand

resourcesrequired to

accuratelymonitor

thepopulations.

Furtherafield,

eDNAanalysisis

alsorevolutionising

conservationprojects

inremoteregions

aroundtheworld.

Scientistsworking with

WWFAlaskaandthe

DepartmentofWildlife

Managementhave been

trackingpolarbears

bygatheringsamples

offurfromfootprints

inthesnow.ByanalysingtheeDNAin

thesesamples,the scientistsareableto

identifyindividual bears andhavestarted

tomapoutfamily trees. Collecting

samplesinthisway is farlessintrusive

thanthetraditional methodoffittinga

trackingcollar,and givesa moreaccurate

pictureofpopulation size.

Likewise,inthe Caribbean– where

sharksurveyspreviouslyinvolved

donningyourscuba kit, dunking

camerasoverboard or settingfishing

linestocatchandtag sharks– eDNA

analysisis having impressiveresults.

A 2017studyatFlorida International

Universityshowed that sharksare

thrivinginareasoftheoceanwhere

commercialfishinghasbeenbanned,such

astheBahamas,butinevitablystruggling

intheless-well-protectedwatersaround

JamaicaandBelize.Inanotherstudyin

NewCaledonia,moresharkspecieswere

identifiedintwoweeksofwatersample

collectionforeDNAanalysisthanintwo

years’worthofscubadivesandunderwater

filmingexpeditions.

A widerperspective

AseDNAsamplingis relativelyquickand

easy,it canpaintanaccurateportraitofan

ecosystemasa whole.Thatwasthecasein

a studycarriedoutaroundoneofthemain

riversinthenorthernPeruvianAmazon.

JustoneeDNA surveycanyieldsurprisingly

richresults.IncollaborationwithWWFPeru,

NatureMetricsanalysedeDNAsamplesfrom

40 sitesalongthe MarañónRiverBasinto

checkforthepresenceofriverdolphins,

Amazonmanatees andmigratorycatfish.

Theanalysisshowed thatmanycatfish

specieswerepresent throughoutthe

river,Amazonmanateesat 12 sites,

andriverdolphins in alllowland

sites.Thestudy also detected

thepresenceof more than

155 mammals,including

therarelyobserved night

monkeyandkinkajou,

74 amphibians, 65 birds

and6 reptiles.

WWF Peru collected samples

at 40 points and sent them

to NatureMetrics, a specialist

eDNA company in the UK,

for analysis.

“The rain had washed

DNA from the land into

the water, creating a ‘soup’

of DNA,” says CEO Kat

Bruce. “In the samples, we

found traces of more than

600 vertebrate species,

which included a lot of fish,

but also a huge variety of

terrestrial vertebrate fauna,

such as jaguars, giant

anteaters, bats and night

monkeys.” (see case study, below).

eDNA can give a heads-up about alien

invaders as well. Take the case of the

tilapia. The fish was first discovered in a

town in northern Australia in 1978, but

now rules in 20 coastal areas. It’s such a

pest that the fine for keeping one as a pet

is up to AUS$200,000, in case it escapes.

But it can be hard to calculate population

size if there aren’t yet many around. The

key is to catch an invader early, and roll

out control measures before numbers get

too high – which is what happened in the

UK with invading zebra mussels blocking

water treatment plant pipes, and Chinese

mitten crabs crumbling riverbanks with

their burrows. If eDNA sampling had been

eDNA has been

used to try and

solve the mystery

of ‘Nessie’.

eDNA makes it

easier to survey river

dolphins and night

monkeys (right).

NEWS FEATURE

34 BBC Wildlife May 2020

MarañónRiver Basin

e DNA CASE STUDY

PERU

Dolphin: Hiroya Minakuchi/Minden Pictures/FLPA; monkey: Oyvind Martinsen-

Panama Wildlife/Alamy; Loch Ness monster: Science History Images/Alamy