Striv­ing to pre­serve taonga species

The Royal So­ci­ety re­cently launched a lec­ture se­ries high­light­ing the re­search car­ried out by fe­male sci­en­tists. Will Harvie re­ports on the work of an en­vi­ron­men­tal chemist and a con­ser­va­tion ge­neti­cist.

The Dominion Post - - Catalyst -

Some years ago, Dr Sally Gaw and PhD stu­dent Phil Em­net spent 12 months mon­i­tor­ing Christchurch’s Lyt­tel­ton Har­bour for emerg­ing con­tam­i­nants.

They were look­ing for the com­pounds found in ev­ery­day items such as soaps, sham­poos and phar­ma­ceu­ti­cals that might be show­ing up in ma­rine en­vi­ron­ments and might be caus­ing harm.

Oth­ers were al­ready mon­i­tor­ing known prob­lems, such as petroleum com­pounds. Gaw and her team of en­vi­ron­men­tal chemists were look­ing for the chem­i­cals lit­tle is known about. There was some over­seas re­search avail­able on these chem­i­cals but it was patchy and more data were needed, es­pe­cially in the New Zealand con­text.

They strongly sus­pected some of these com­pounds were ‘‘can­di­dates for fu­ture reg­u­la­tion’’, Gaw told a Royal So­ci­ety Te Apa¯ rangi au­di­ence in Christchurch ear­lier this month.

They tested the three waste­water treat­ment plants emp­ty­ing into the har­bour, the sea wa­ter it­self, sed­i­ments and had a go look­ing for these chem­i­cals in mus­sels.

‘‘We were try­ing to get an idea of what might be there and what we could an­a­lyt­i­cally do at the uni­ver­sity at the time,’’ she said.

And they found these com­pounds in the waste­water, in­clud­ing preser­va­tives, some anti-mi­cro­bials found in tooth­pastes, UV fil­ters from sun­screens, hu­man hor­mones in­clud­ing from con­tra­cep­tives, and plas­tics.

The sea wa­ter and sed­i­ment tests also re­turned many of the com­pounds but some­what dif­fer­ently. The mus­sel tests also re­turned pos­i­tives but there were prob­lems with the data and fur­ther work will start next year on shell­fish.

While the re­sults were spe­cific to Lyt­tel­ton, it’s be­lieved the same sorts of com­pounds are prob­a­bly found in ma­rine en­vi­ron­ments around the coun­try.

Armed with the knowl­edge that these groups of chem­i­cals were present, Gaw and PhD stu­dent Ni­cole McRae tested the ef­fects of an anti-in­flam­ma­tory drug called voltaren (di­clofenac) on inanga (white­bait).

They se­lected voltaren be­cause it’s one of the few emerg­ing com­pounds that’s al­ready been placed on in­ter­na­tional watch lists as a ‘‘con­tam­i­nant of con­cern’’, Gaw said. It’s likely to be reg­u­lated in the fu­ture, she pre­dicted.

White­bait is a taonga species, of course, but it’s use­ful to sci­ence be­cause it’s dif­fer­ent from fish species tested for voltaren over­seas. It has skin rather than scales, for ex­am­ple, so the path­way to con­tam­i­na­tion might be dif­fer­ent.

They found a ‘‘tox­i­co­log­i­cally rel­e­vant re­sponse. The fish weren’t happy. They were show­ing signs that they were be­ing af­fected at en­vi­ron­men­tally rel­e­vant lev­els,’’ Gaw said.

Other stu­dents of Gaw’s have found mi­croplas­tics in sed­i­ments and green lipped mus­sels from the Can­ter­bury re­gion.

Gaw added that over­seas re­search strongly sug­gests po­lar fleece cloth­ing is a sig­nif­i­cant source of plas­tic con­tam­i­na­tion. She and col­leagues weren’t look­ing for po­lar fleece, but it ‘‘gen­er­ates a very, very large num­ber of fi­bres. It would prob­a­bly have been bet­ter if po­lar fleece had never been in­vented, in terms of what’s be­ing shed into the en­vi­ron­ment,’’ she said.

Ge­nomics and the kak¯ı egg dump

Re­searchers at DOC’s kakı¯ cap­tive breed­ing pro­gramme in the Macken­zie Coun­try had a prob­lem. Two birds, one ju­ve­nile and one adult, didn’t look en­tirely like kakı¯, also known as black stilt.

The were per­haps more rem­i­nis­cent of poaka, an Aus­tralian im­port that’s closely re­lated and also breeds on Macken­zie Coun­try riverbeds near Twizel.

But the eggs had been re­trieved from a kakı¯ nest. What was go­ing on?

Dr Tammy Steeves and her team of con­ser­va­tion ge­neti­cists at the Uni­ver­sity of Can­ter­bury used DNA to sort out what these two un­ex­pected birds were.

Us­ing straight­for­ward com­par­isons of chick DNA to parental DNA, they first deter­mined the two were not kakı¯.

Nor it turns out, were they poaka, also known as pied stilt.

In­stead, they were kakı¯-poaka hy­brids, which was OK (but not great) as the two species are ca­pa­ble of in­ter­breed­ing.

But that didn’t solve the prob­lem of why the two hy­brids were in kakı¯ nests.

The an­swer, Steeves told the Royal So­ci­ety lec­ture in Christchurch, was prob­a­bly some­thing called an ‘‘egg dump’’.

They be­lieve a poaka or kakı¯poaka hy­brid sim­ply laid an egg in a kakı¯ nest.

‘‘We don’t know how of­ten this hap­pens in kakı¯ or closely re­lated birds,’’ Steeves said, ‘‘but I can say we are pick­ing up these [hy­brids] from time to time’’.

That’s im­por­tant be­cause the kakı¯ cap­tive breed­ing pro­gramme and Steeves and col­leagues’ DNA re­search are im­por­tant to the sur­vival of the crit­i­cally en­dan­gered bird.

Kakı¯ used to be wide­spread on the North and South Is­lands. By 1981, there were 23 known adults. By 2017, there were 106 known adults. So they’re an­other taonga species.

Early match-mak­ing re­lied on pedi­grees, knowl­edge about the an­ces­try of each bird. Ge­netic tools came along and told re­searchers bird DNA com­prises about 1 bil­lion base pairs and hu­man DNA has about 3 bil­lion base pairs.

Ge­netic re­search, how­ever, re­lied on a hand­ful of mark­ers, Steeves said. It was hoped these mark­ers would pro­vide a good in­di­ca­tion of the amount of poaka DNA in kakı¯. But no­body knew for sure.

‘‘What if we missed some­thing? What if kakı¯ aren’t as ge­net­i­cally pure as we think?’’ she asked.

An­swers may be at hand. In re­cent years, the re­lated sci­ence of ge­nomics has led to maps of many more than a hand­ful of DNA mark­ers. In some species, the en­tire genome has been mapped. Work to map the en­tire genome of kakı¯ and poaka is cur­rently un­der­way at the Uni­ver­sity ot Otago.

‘‘We are at the stage now where we lit­er­ally need to watch this re­search be­cause we don’t know if we will find ev­i­dence of poaka DNA in kakı¯,’’ Steeves said.

But wait, some spillover might be ben­e­fi­cial. Kakı¯ evolved in Aotearoa and are naive about mam­malian preda­tors. Poaka evolved among Aus­tralian mam­malian preda­tors and are less naive. Maybe a lit­tle poaka DNA would help kakı¯ sur­vive.

It’s hoped ge­nomic re­search will shed light on some other ap­par­ent truths es­tab­lished by the less pow­er­ful ge­netic re­search.

It showed that the more closely re­lated two birds were, the fewer chicks they hatched. And the op­po­site was true as well: less re­lated birds hatched more chicks.

The ge­nomic data on kakı¯ hasn’t come back yet but early in­di­ca­tions are that the ge­netic ap­proach has worked and more chicks are hatch­ing. How­ever, the way for­ward is with ge­nomics, Steeves said.

There was a diver­sity as­pect to this as well. Ge­netic re­search showed match-mak­ing two dis­tantly re­lated kakı¯ cre­ated more diver­sity in off­spring.

More diver­sity is val­ued be­cause it cre­ates re­silience.

If the en­vi­ron­ment ever changes again (due to cli­mate change, for ex­am­ple), then a pop­u­la­tion with low diver­sity would have an even tougher time sur­viv­ing.

Again the ge­nomic re­search should in­di­cate whether this ap­proach to in­creas­ing diver­sity is work­ing, Steeves said.

❚ Drs Gaw and Steeves spoke in the open­ing lec­ture in a Royal So­ci­ety ini­tia­tive called Great Kiwi Re­search: Shar­ing Women’s Dis­cov­er­ies. Five more lectures will be held on the North Is­land next month. See roy­al­so­ci­ety.org.nz

DAVID HALLETT

Black stilt/kak¯ı at Lake Tekapo. The en­dan­gered kak¯ı were bred in cap­tiv­ity at Twizel.

Dr Sally Gaw.

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