Selvitys meriteitse Suomeen kulkeutuvien vieraslajien saapumisreiteistä

Liite 7. HAVINA-loppuraporttiin. URN:NBN:fi-fe2014062529465</a

Seafloor sediments as microplastic sinks in the northern Baltic Sea : Negligible upward transport of buried microplastics by bioturbation

Microplastics (MPs) are ubiquitous in the marine environment. High concentrations of MPs are found from seafloor sediments, which have been proposed to act as their final sinks. Because bioturbation is an important process affecting the burial of MPs, a mesocosm experiment was established to study whether sediment infauna may also promote MP return to the sediment surface. Thin layers of frozen sediment containing an environmentally realistic concentration (500 μm and 100–300 μm) were added to depths of 2 cm and 5 cm in the experimental cylinders filled with sediment. The displacement of these MPs, made of acrylonitrile butadiene styrene (ABS), by a community of common benthic invertebrates in the northern Baltic Sea (clam Limecola balthica, polychaete Marenzelleria spp., gammarid Monoporeia affinis) was studied in a 10-week experiment. After the experiment, the MPs were extracted from each sediment layer and the animals were examined for MP ingestion. The results indicated that the transportation of MPs to the sediment surface by bioturbation was negligible. Thus, in the Baltic Sea, the seafloor may act as a sink for once sedimented MPs, reducing simultaneously the MP exposure of the macrofauna feeding on the sediment surface.peerReviewe

Citizen science provides added value in the monitoring for coastal non-indigenous species

Continuous and comprehensive monitoring is one of the most important practices to trace changes in the state of the environment and target management efforts. Yet, governmental resources are often insufficient for monitoring all required environmental parameters, and therefore authorities have started to utilize citizen observations to supplement and increase the scale of monitoring. The aims of the present study were to show the potential of citizen science in environmental monitoring by utilising citizen observations of the non-indigenous Harris mud crab Rhithropanopeus harrisii in Finnish waters, where coastal monitoring is insufficient to estimate the distribution and spread of non-indigenous species. Harris mud crab has shown measurable impact locally and is considered invasive. For reporting the status of invasions to national and European authorities and planning for potential eradication efforts, up to date knowledge on NIS ranges are needed. Citizen observations on the species were collected from the first observation onwards between 2009 and 2018, at first via email and later through an active citizen observation web portal (Invasive Alien Species Portal). The outcomes of the study indicate that species-specific citizen observations can be a beneficial addition to supplement national monitoring programs to fulfil legislative reporting requirements and to target potential management. Recognizable species and geographical areas with low biodiversity provide a good opportunity to utilize citizen observations. Moreover, citizen observations may enable distribution assessments for certain species that would otherwise require excessive resources and sampling efforts. Highlights • Citizen observations are cost-efficient addition to routine monitoring. • Citizen science can provide presence data on dist inctly recognizable species. • Citizen science provides important information to target management actions. • Citizen science enables estimates for species distribution

Experimental feeding rates of gelatinous predators Aurelia aurita and Mnemiopsis leidyi at low northern Baltic Sea salinity

The effect of the northern Baltic Sea\u27s low salinity on feeding rates of a native scyphozoan Aurelia aurita and a recent invader to southern Baltic Sea, ctenophore Mnemiopsis was investigated experimentally. Incubations with Acartia spp. prey (4.19-25.16 indiv. l(-1)) were used to estimate clearance rates for both predators. Mnentiopsis leidyi digestion times were measured for several natural prey items. Wet weight (ww):length/diameter relationships as well as clearance rates (0.49 +/- 0.15 1 g(ww)(-1) h(-1) [mean +/- SE] for M. leidyi [mean oral-aboral length +/- SD = 9.6 +/- 1.5 mm]; and 0.18 +/- 0.07 1 g(ww)(-1) h(-1) [mean +/- SE] for A. aurita [mean bell diameter SD = 37.3 +/- 6.9 mm]) and digestion times at salinity 5.7 were within the ranges reported from higher salinities. These preliminary results suggest that the low salinity does not significantly depress the feeding rates or potential predatory impact of these gelatinous predators

Vieraslajien havaitseminen Suomen merialueen seurannoissa

Julkaisussa kuvataan merialueemme keskeiset biologiset seurannat sekä niiden tuottama tieto Suomessa tavattujen meriympäristön vieraslajien levinneisyydestä ja runsaudesta. Kolmasosaa tunnetuista vieraslajeistamme ei ole tavattu seurannoissa koskaan, ja vain parin vieraslajin esiintymisestä saadaan nykyseurannoilla suhteellisen hyvä käsitys. Heikoimmin vieraslajiryhmistä tulivat esille kalat, matalien pohjien selkärangattomat ja kovien pohjien kiinni-istuvat pohjaeläimet. Kasviplankton- ja pohjaeläinseurannat ovat alueellisesti melko kattavia rannikollamme. Eläinplankton-, kala- ja makrofyyttiyhteisöjen (vesikasvit ja makrolevät) osalta seuranta on alueellisesti rajoittunut lähinnä eteläiselle merialueelle. Suuri osa vieraslajihavainnoista on peräisin seurantojen ulkopuolisista hankkeista ja kertaluontoisista tutkimuksista. Myös rannikon velvoitetarkkailut tuottavat havaintoja vieraslajeista. Vieraslajien nykyistä parempi havaitseminen vaatii osin pyyntimenetelmien kehittämistä ja osin näytteenottoverkon täydentämistä. Lisäksi viranomaisten ylläpitämien seurantojen tulosten tallentamisessa ja aineistojen saavutettavuudessa on parantamisen varaa. Tietoa vieraslajeista ja niiden tunnistamisesta tulisi toimittaa potentiaalisille vieraslajihavaintojen tuottajille, kuten kalastajille, konsulteille ja näytteiden määrittäjille, ja havaintojen ilmoittamismahdollisuuksia kehittää

Bioturbation transports secondary microplastics to deeper layers in soft marine sediments of the northern Baltic Sea

Microplastics (MPs) are observed to be present on the seafloor ranging from coastal areas to deep seas. Because bioturbation alters the distribution of natural particles on inhabited soft bottoms, a mesocosm experiment with common benthic invertebrates was conducted to study their effect on the distribution of secondary MPs (different-sized pieces of fishing line < 1 mm). During the study period of three weeks, the benthic community increased MP concentration in the depth of 1.7-5.1 cm in the sediment. The experiment revealed a clear vertical gradient in MP distribution with their abundance being highest in the uppermost parts of the sediment and decreasing with depth. The Baltic clam Macoma balthica was the only study animal that ingested MPs. This study highlights the need to further examine the vertical distribution of MPs in natural sediments to reliably assess their abundance on the seafloor as well as their potential impacts on benthic communities

Microplastic ingestion by small coastal fish in the northern Baltic Sea, Finland

Highlights • Microplastics were found in 9% of all sampled fish. • Fish caught within the urban area of Helsinki displayed the highest occurrence of plastic ingestion (27.5%). • No relationship was found between microplastic occurrence in fish and plastic concentration in seawater. • This study is the first assessment on microplastic ingestion by coastal fish in Finland.Microplastic (MP) ingestion by four species of small coastal fish from the northern Baltic Sea was investigated. The digestive tract contents of 424 specimens, caught across eight sampling sites along the Finnish coastline were analysed for the occurrence of MP ingestion. MP were found in 38 fish individuals (9% of sampled fish). Specimens from the urban area of Helsinki displayed the highest prevalence of ingested plastics (27.5%). No relationship was found between the size or species of the fish and the presence of ingested MP particles nor the amount of MP in seawater. The comparison to a previous study conducted using the same research methods indicates that the ingestion of MP is more common in coastal fish than in offshore fish in the northern Baltic Sea

Bioturbation transports secondary microplastics to deeper layers in soft marine sediments of the northern Baltic Sea

Microplastics (MPs) are observed to be present on the seafloor ranging from coastal areas to deep seas. Because bioturbation alters the distribution of natural particles on inhabited soft bottoms, a mesocosm experiment with common benthic invertebrates was conducted to study their effect on the distribution of secondary MPs (different-sized pieces of fishing line <1 mm). During the study period of three weeks, the benthic community increased MP concentration in the depth of 1.7-5.1 cm in the sediment. The experiment revealed a clear vertical gradient in MP distribution with their abundance being highest in the uppermost parts of the sediment and decreasing with depth. The Baltic clam Macoma balthica was the only study animal that ingested MPs. This study highlights the need to further examine the vertical distribution of MPs in natural sediments to reliably assess their abundance on the seafloor as well as their potential impacts on benthic communities.Peer reviewe

Size matters more than shape: Ingestion of primary and secondary microplastics by small predators

Experimental studies have shown how microplastics are taken up by various aquatic organisms. Most of these studies have been carried out with small ( 200 μm and ABS > 100 μm) in comparison to primary microplastic beads (90 μm). Our results show that fragments of secondary plastics may end up in the food web but only in small amounts, and that the size of the fragments more than their shape is a crucial nominator influencing the numbers of plastics ingested. Future research aiming to resolve the effects of microplastics in the ecosystems should concentrate on environmentally relevant plastics and concentrations.Peer reviewe