Microplastics contamination in aquaculture-rich regions: A case study in Gresik, East Java, Indonesia.

The widespread use of plastic has resulted in the accumulation of plastic waste across a range of sizes, notably including microplastics (MPs). The introduction of MPs into aquatic ecosystems can lead to the contamination of organisms, mainly fish. This study reports for the first time a quantitative and qualitative analysis conducted on the abundance of MPs encountered in water and sediment of milkfish aquaculture ponds in Gresik, East Java, Indonesia. Water and sediment samples were collected at three stations between February to April 2021. The abundance of MPs was analyzed through the application of one-way ANOVA tests and Pearson's correlation analysis. The results identified four types of MPs: fragments, fibers, films, and pellets. The highest abundance of MPs in both water (10.40 particle/L) and sediment samples (1.15 particle/g) was observed in March. The predominant MPs size in the water samples is 100-500 µm, while it is below 100 µm in the sediment. The color of the MPs varied across eight colors: black, purple, red, blue, yellow, pink, green, and transparent. The identification of MPs polymers was found to be polypropylene (PP), Polyurethane (PU), Polycarbonate (PC), Polyethylene terephthalate (PETE), High-density polyethylene (HDPE), and low-density polyethylene (LDPE). The presence of MPs in the water column and sediments was correlated with human activities around the ponds. Hence, the abundance of MPs is a source of pollution that has the potential to damage the nutritional quality of farmed milkfish. This study provides important information for the local governments to develop waste management policies for a cleaner environment and improved human health.

Microplastics in the surface sediments from the eastern waters of Java Sea, Indonesia.

Background: This study aimed to investigate the abundance of microplastics in the eastern water of Java Sea. The study areas are well known for the high population and high industrial activities that can contribute to the plastic pollution. Methods: Microplastics were sampled from the surface sediments at five different stations representing different local activities: fish landing area (St 1), mangrove forest (St 2), abandoned shrimp pond (St 3), river mouth (St 4) and open sea (St 5). Results: Three types of microplastics were found; the most common was plastic fragments (54.34±6.39%) followed by fibers (41.45±4.59%) and films (4.21±3.90%). The highest abundance of microplastics was observed in the mangrove area (896.96±160.28 particles/kg), dominated with fragments and fibers. Films were found in greatest quantities in the fish landing area, but compared to the other types of microplastics, the abundance was much lower (80.73±37.62 particles/kg). Domestic wastes and fisheries activities were the main causes of the high microplastics in the study areas. Conclusions: The results of this study showed that microplastic pollution is a serious problem that needs to be paid attention not only from the government but also from the local people. Plastics management waste is needed.

Metallothionein expression on oysters ( Crassostrea cuculata and Crassostrea glomerata) from the southern coastal region of East Java.

Background: This study aimed to analyse levels of heavy metals (Pb, Hg and Cd) in the aquatic body, gills and stomach of the oysters Crassostrea cuculata and Crassostrea glomerata, the metallothionein (MT) level in the gills and stomach of both oysters, and relationships between heavy metals level (Pb, Hg and Cd) in the gills and stomach to MT level in both types of oysters. Methods: The research method utilized was a descriptive method. The oyster samples were taken from three stations: Sendang Biru, Popoh and Prigi beaches. MT values were assessed using confocal laser scanning microscopy. The heavy metal levels were assessed using atomic absorption spectrophotometry method. Results: Both oyster heavy metal content obtained in the southern coastal waters exceeded the safe limit set by the State Minister of Environment No. 51 of 2004. In general, the expression of MT was found to be higher in gastric tissue compared to gill tissue. Conclusions: The relationship between levels of the heavy metals Pb, Hg, and Cd in oyster gills and stomach has a strong relationship with MT levels in the gills and stomach in both types of oysters.