Micro­plastics enter­ing ocean food web through zooplankton

In a sci­entif­ic paper released June 12 in the inter­na­tion­al journ­al Archives of Envir­on­ment­al Con­tam­in­a­tion and Tox­ic­o­logy, Dr. Ross and his co-authors, Jean-Pierre Des­forges and Moira Gal­braith, report on micro­plastic particles found in two key spe­cies of zooplank­ton found in the North­east Pacific Ocean: cope­pods and euphausiids. The find­ings show plastic in one out of every 34 cope­pods, and in one in every 17 euphausiids. It’s the first indis­put­able evid­ence that spe­cies at the bot­tom of the food web are mis­tak­ing plastic for food, which raises troub­ling ques­tions about spe­cies that rely on these inver­teb­rates for food, such as sal­mon. ​“Zooplank­ton rep­res­ent a crit­ic­al energy source in the world’s oceans and a vital food for many fish and mar­ine mam­mal spe­cies. Most sal­mon spe­cies feed heav­ily on cope­pods and euphausiids dur­ing their juven­ile and adult life stages. The poten­tial trans­fer of micro­plastics in the food web, from zooplank­ton to Pacific sal­mon that ingest them, would be a great con­cern giv­en the import­ance of sal­mon in our region­al eco­sys­tems,” said Dr. Ross. ​“These particles could pose a ser­i­ous risk of phys­ic­al harm to the mar­ine anim­als that con­sume them, poten­tially block­ing their gut or leach­ing chem­ic­als into their bod­ies.” Micro­plastics refer to barely vis­ible lit­ter in the form of small frag­ments, fibres and gran­ules. They may be delib­er­ately man­u­fac­tured, as is the case with microbeads in exfo­li­ants or tooth­pastes, or may res­ult from the break­down of lar­ger pieces of plastic or tex­tiles. The micro­plastics found in the zooplank­ton in this study con­sisted of small frag­ments and fibers, but not the delib­er­ately designed microbeads that may sink to the sed­i­ments in the ocean. The study focused on four major areas in Brit­ish Columbi­a’s coast: Strait of Geor­gia, west coast Van­couver Island, north­ern Van­couver Island/​Haida Gwaii and off­shore Pacific. The highest con­cen­tra­tions observed were in the Strait of Geor­gia for both spe­cies of zooplank­ton. ​“We believe micro­plastic inges­tion by zooplank­ton to be a big­ger prob­lem near urb­an areas,” Dr. Ross noted. The authors estim­ate using find­ings in zooplank­ton that juven­ile sal­mon in the Strait of Geor­gia may be ingest­ing two to sev­en micro­plastic particles per day, and return­ing adult sal­mon are ingest­ing up to 91 particles per day. The Strait of Geor­gia is a cru­cial feed­ing ground for sal­mon, not­ably tiny smolts as they migrate out to the ocean. Dr. Ross’ team also notes the data can be used to estim­ate what lar­ger mar­ine mam­mals might ingest based on their feed­ing rates on zooplank­ton. Using this meth­od, they estim­ate a hump­back, which is a baleen whale, could ingest more than 300,000 micro­plastic particles per day. In order to meas­ure the pres­ence of micro­plastics, zooplank­ton samples were col­lec­ted and placed in glass-coated polypro­pyl­ene well plates and immersed in nitric acid. The plates were then covered and heated, until all the tis­sue of the zooplank­ton was diges­ted by the hot acid. The only things remain­ing behind were then examined under a micro­scope for the pres­ence of micro­plastics. This study fol­lows on Dr. Ross’ report last year of wide­spread con­tam­in­a­tion of sea­wa­ter in the North­east Pacific Ocean. He joined the Van­couver Aquar­i­um in 2014 to launch its Ocean Pol­lu­tion Research Pro­gram, which con­ducts inter­na­tion­al-caliber sci­entif­ic research on pol­lu­tion, ran­ging from mar­ine debris to the impact of hydro­car­bons on the coastal envir­on­ment­al. The Ocean Pol­lu­tion Research Pro­gram is part of the Van­couver Aquarium’s Coastal Ocean Research Insti­tute.

Coastal Ocean Research Institute

Estab­lished to meas­ure and mon­it­or the health of coastal eco­sys­tems on Canada’s West Coast, the Coastal Ocean Research Insti­tute, part of Van­couver Aquar­i­um Mar­ine Sci­ence Centre, is a multi-dis­cip­lin­ary, col­lab­or­a­tion-based Insti­tute estab­lished to increase dia­logue and inform policy. The Research Insti­tute is grate­ful for its gen­er­ous found­ing fund­ing part­ners Sitka Found­a­tion and North Growth Found­a­tion.

Van­couver Aquar­i­um Mar­ine Sci­ence Centre

The Van­couver Aquar­i­um Mar­ine Sci­ence Centre is a non-profit soci­ety ded­ic­ated to the con­ser­va­tion of aquat­ic life. www​.vanaqua​.org Source: Van­couver Aquar­i­um Mar­ine Sci­ence Centre