Microplastic abundance in the water, seagrass, and sea hare Dolabella auricularia in Pramuka Island, Seribu Islands, Jakarta Bay, Indonesia

Abstract

This research focused on the amount of abundance of microplastics in the sea hare Dolabella auricularia as well as the seagrass fields along the southern coast of Pramuka Island. Sampling of 8 individuals of Dolabella auricularia along with seagrass Cymodocea rotundata leafblades was done at the southern coast of Pramuka Island, after which the samples were preserved and brought to a laboratorium in Depok for microplastic analysis. The sea hares’ digestive tracts were extracted and dissolved in strong nitric acid. A 1 cm2 portion of a seagrass leaf blade was cut for observation. Prepared samples were observed under a monocular microscope and further analysis was done. Microplastic fibers and film particles were found in highest abundance within the digestive tracts of each sample of Dolabella auricularia as well as on the seagrass surface where the sea hare obtains its algae from, with fragment particles found in much lower amounts. Overall, number of microplastics was found between 40.1 to 73.7 particles/g weight of sea hare digestive tract and the estimated amount of microplastic found at seagrass leafblade was 185 particles/cm2. Results provide evidence that microplastics in the ocean brought by water currents could adsorb on to algae through which it enters the food chain as it is consumed by marine biota.

Microplastics: impacts on corals and other reef organisms

“…Habitat-forming species may also influence the translocation of suspended MNPs into the food chain. Particles that have settled on the surface of Nansha Islands, South China Sea Fish <500 mm 1 -14 MP per individual [50] seagrasses and macroalgae can be ingested by herbivores [74], and then either transferred back into the sediments via faeces, or transferred up the food chain (Figure 2).…”

“…Examples of species from other ecosystems have identified ingestion by both bivalves and gastropods [ 144 ], and particles may translocate from the guts to other organs [ 145 ]. The coral reef sea hare, Dolabella auricularia , has been found to be exposed to MNPs via their diet due to the particles becoming entrained and adhered to the surface of the seagrass they graze on [ 74 ]. Taxa such as Tridacna which play various ecological roles in the coral reef ecosystem [ 146 ] may be subject direct impacts of MNPs and also via their impact on the symbiont–host relationship [ 79 , 80 , 85 , 89 , 93 , 96 ].…”

Short communication: Environment and morphometric of sea hare Dolabella auricularia from shrimp pond, Sorong, West Papua, Indonesia

“…Dolabella auricularia has several characteristics, including living in waters with warm temperatures; having purple ink which serves as protection from attacks by predators; consuming green and brown algae such as Sargassum sp. ; nocturnal; actively consuming algae at night; having green and brown colors according to its natural food sources; and as a decoration in the aquarium (Gosliner et al 2015;Manullang et al 2016;Nimbs et al 2017;Priscilla et al 2019).…”

Komposisi Dan Kelimpahan Mikroplastik Berdasarkan Lapisan Kedalaman Perairan Teluk Kendari

“…Komposisi mikroplastik di perairan laut menjadi sangat penting diperhitungkan jika jumlahnya semakin melimpah karena berpengaruh terhadap kualitas perairan. Berbagai studi diantaranya Cordova dan Hernawan (2018), Hafidh et al (2018), Priscilla et al (2019) dan Layn dkk. (2020) menunjukkan bahwa komposisi jumlah dan kelimpahan mikroplastik cukup bervariasi di perairan laut dan teluk.…”

“…Berdasarkan data tersebut berturut-turut diperoleh kelimpahan mikroplastik dari yang tertinggi ke terendah berkisar antara 72,5-165,0 Partikel/L (lapisan permukaan), 45,5-111,5 Partikel/L (dasar perairan) dan 52,0-91,0 Partikel/L (kolom perairan). Pada berbagai kondisi lapisan kedalaman, nilai tersebut relatif rendah dari 185 partikel/L yang diperoleh Priscilla et al (2019) 2018) juga mengemukakan bahwa aliran arus permukaan secara temporal memainkan peran dalam pola akumulasi mikroplastik, serta sebagai gaya penggerak yang mempengaruhi distribusi partikel perairan pada jarak 10-50 km dari pantai. Hal itu pula yang menyebabkan kelimpahan mikroplastik tertinggi yang ditemukan pada Stasiun III dan IV berada pada dasar perairannya, atau dapat dikatakan bahwa kelimpahan mikroplastik pada kedua stasiun tersebut mengalami peningkatan seiring dengan bertambahnya kedalaman.…”