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Micro­plastics in the ocean: bio­lo­gists study effects on mar­ine animals

22.12.2014
Uptake of large plastic items by birds and fish may cause block­age of the gastrointest­in­al tract and severe star­va­tion of the anim­als. ​“We were won­der­ing wheth­er small plastic particles have a com­par­able effect on smal­ler anim­als,” says Dr. Lars Gutow from AWI’s North Sea Office. ​“Only very lim­ited research has been done on the effects of micro­plastics on liv­ing beings. Accord­ingly, there is great uncer­tainty about the implic­a­tions for mar­ine anim­als,” the bio­lo­gist explains the motiv­a­tion for the study. Lars Gutow and his col­leagues selec­ted the iso­pod Idotea emarginata as their mod­el organ­ism for an ini­tial case study. In feed­ing exper­i­ments the research­ers offered the iso­pods arti­fi­cial algal food sup­ple­men­ted with plastic particles. The food con­tained three dif­fer­ent kinds of micro­plastics in vary­ing con­cen­tra­tions. They used indus­tri­ally pro­duced poly­styrene particles with a dia­met­er of ten micro­met­ers as well as self-made frag­ments and fibres made of poly­ethyl­ene and poly­ac­ryl, respect­ively. The research­ers stud­ied the fate of the dif­fer­ent mater­i­als under a light micro­scope, with the help of a fluor­es­cence micro­scope, and with an elec­tron micro­scope. They were able to trace the path of the micro­plastic particles through the iso­pods and determ­ine the con­cen­tra­tions of the particles in dif­fer­ent sec­tions of the digest­ive sys­tem. The study showed that the con­cen­tra­tion of micro­plastics in the faecal mater­i­al of the iso­pods was as high as in the food. The sci­ent­ists found small amounts of micro­plastics both in the stom­ach and in the gut of the anim­als. How­ever, they did not detect any micro­particles in the digest­ive glands. ​“The iso­pods inges­ted and excreted the arti­fi­cial food with the micro­plastic particles without absorb­ing or accu­mu­lat­ing the particles,” Gutow sum­mar­ises the res­ults. Thus, plastic particles in the spe­cif­ic size range stud­ied do not rep­res­ent a dir­ect mech­an­ic­al risk for iso­pods and prob­ably not for oth­er crus­ta­ceans either. ​“In the case of Idotea emarginata, the micro­plastic particles did not enter the digest­ive gland, which is the prin­ciple organ in crus­ta­ceans where diges­tion and resorp­tion of nutri­ents takes place,” states the bio­lo­gist from AWI’s North Sea Office. In a long-term exper­i­ment the sci­ent­ists could also show that iso­pods did not dis­play any long-term effects even after feed­ing on micro­plastic enriched food for six to sev­en weeks. Fit­ness para­met­ers such as sur­viv­al rate and growth did not dif­fer between anim­als that were fed with and without micro­plastics, respect­ively. In an earli­er study, how­ever, AWI bio­lo­gist Prof. Dr. Angela Köhler demon­strated that mus­sels show inflam­mat­ory reac­tions if they take up and absorb high con­cen­tra­tions of micro­plastic in an exper­i­ment. This clearly shows that dif­fer­ent anim­al spe­cies react dif­fer­ently to micro­plastics. ​“In con­trast to fil­ter feed­ing mus­sels, iso­pods of the genus Idotea prob­ably take up more fre­quently indi­gest­ible particles with their food in their nat­ur­al hab­it­at and may, thus, have adap­ted accord­ingly,” elu­cid­ates Gutow. But the bio­lo­gists are not only inter­ested in the feed­ing type: ​“We want to study sys­tem­at­ic­ally how the life style, hab­it­at, physiology and ana­tomy of dif­fer­ent mar­ine organ­isms influ­ence the uptake and util­isa­tion of micro­plastic particles in order to come up with a risk mat­rix for diverse types of organ­isms,” says Lars Gutow. ​“There­fore, it will be neces­sary to also study the pos­sible chem­ic­al (tox­ic) and bio­chem­ic­al effects in addi­tion to the phys­ic­al effects that we looked at,” he out­lines future tasks.

Ori­gin­al studies:

  • Julia Hämer, Lars Gutow, Angela Köhler and Rein­hard Saborowski, Envir­on­ment­al Sci­ence and Tech­no­logy (2014): Fate of Micro­plastics in the Mar­ine Iso­pod Idotea emarginata (DOI: 10.1021/es501385y)
  • Nadia von Moos, Patri­cia Burkhardt-Holm and Angela Köhler, Envir­on­ment­al Sci­ence and Tech­no­logy (2012): Uptake and Effects of Micro­plastics on Cells and Tis­sue of the Blue Mus­sel Mytilus edulis L. after an Exper­i­ment­al Expos­ure (DOI: 10.1021/es5302332w)

About the AWI

The Alfred Wegen­er Insti­tute con­ducts research in the Arc­tic, Ant­arc­tic and in the high and mid-lat­it­ude oceans. The Insti­tute coordin­ates Ger­man polar research and provides import­ant infra­struc­ture such as the research icebreak­er Polarstern and research sta­tions in the Arc­tic and Ant­arc­tic to the nation­al and inter­na­tion­al sci­entif­ic world. The Alfred Wegen­er Insti­tute is one of the 18 research centres of the Helm­holtz Asso­ci­ation, the largest sci­entif­ic organ­isa­tion in Ger­many. Source: idw/Al­fred-Wegen­er-Insti­tut
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