The exposure of nanoplastics was investigated by observing their interaction with Amphibalanus amphitrite (commonly known as acorn barnacles). Poly­(methyl methacrylate) (PMMA) and fluorescent perylene tetraester (PTE) dye were used to prepare highly fluorescent nanoplastic particles. At concentrations of 25 ppm, the PMMA particles showed no detrimental impact on barnacle larvae and their microalgae feed, Tetraselmis suecica and Chaetoceros muelleri. PMMA nanoplastics were ingested and translocated inside the body of the barnacle nauplii within the first 3 h of incubation. The fluorescent PMMA particles inside the transparent nauplius were tracked using confocal fluorescence microscopy. Subsequently, the nanoplastics were fed to the barnacle nauplii under two conditionsacute and chronic exposure. The results from acute exposure show that nanoplastics persist in the body throughout stages of growth and developmentfrom nauplius to cyprid and juvenile barnacle. Some egestion of nanoplastics was observed through moulting and fecal excrement. In comparison, chronic exposure demonstrates bioaccumulation of the nanoplastics even at low concentrations of the plastics. The impacts of our study using PMMA nanoparticles exceeds current knowledge, where most studies stop at uptake and ingestion. Here we demonstrate that uptake of nanoparticles during planktonic larval stages may persist to the adult stages, indicating potential for the long-term impacts of nanoplastics on sessile invertebrate communities.

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1. Giant clam populations in Singapore are endangered due to historical exploitation, habitat loss, and sediment pollution. 2. Transplanting cultured giant clams onto reefs is a potential conservation strategy. This study examined the growth and survival of three initial size classes (50.0-60.0 mm, 60.1-70.0 mm, >70 mm) of cultured juvenile fluted giant clams, Tridacna squamosa, transplanted to three reef sites under two caging treatments (caged and uncaged).3. After 145 days, there was no significant difference in clam survival within the size classes and within caging treatments across reef sites, even though environmental conditions varied greatly between sites. However, there was a significant effect of initial size class on T. squamosa survival, with higher survival with increasing size class (50.0-60.0 mm: 11.1%; 60.1-70.0 mm: 34.1%; >70.0 mm: 46.9%).4. Clams in caged treatments had significantly lower survival (16.7%) than uncaged clams (43.1%), likely due to biofouling atop caged treatments reducing light availability. Growth rates in the caged treatment (2.2 ± SD 1.8 mm month À1 ) were also lower than those in the uncaged treatment (3.9 ± SD 2.2 mm month À1 ). 5. By optimizing transplant procedures for Singapore's turbid reef conditions, T. squamosa restocking efforts could play an important role in boosting local population numbers to facilitate natural recovery.