Fate of Nanoplastics in Marine Larvae: A Case Study Using Barnacles, Amphibalanus amphitrite

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

Proportion of larvae settled onto Singapore's coral reefs.

<p>Percent of total number of <i>T. squamosa</i> larvae released from various regional donor reefs that reached recipient reefs around Singapore's Southern Islands.</p

Mortality rates for <i>Tridacna</i> larvae.

<p>Where data for <i>Tridacna squamosa</i> were deficient, larval mortality at 5 larval stages was extrapolated from published and unpublished reports of other giant clam species. Data have been reworked to fit into the model, <i>k</i> = −In(1−p_m)/(<i>D</i>/24) in which <i>D</i> is stage duration and p_m is the proportion of dead larvae.</p

Contour plots of settler density.

<p>Distribution patterns of giant clam larvae on local coral reefs at the end of transport phase for the three spawning periods: A) 22 January, B) 10 April and C) 18 June 2004.</p

Singapore regional model.

<p>This model is composed of 3 domains. A) The overall outer domain including Peninsular Malaysia and the 8 regional release points (green dots). The red and blue domains represent the refined grid resolutions for Singapore's coastal waters. B) The blue grid encompasses the waters surrounding Singapore's Southern Islands. The red dots represent the 28 release points (i.e. the positions of <i>T. squamosa</i> in Singapore).</p

Source-sink dynamics for Singapore's coral reefs.

<p>Summation matrix of settled larvae (per 10,000 m²) showing the potential sources (rows) versus sinks (column) among the Southern Islands coral reefs. Source sites are arranged according to the descending shortest straight-line distance to the mainland.</p

Egg dispersal potential of individual giant clams among the Southern Islands reefs.

<p>Only clams with more than one egg per m² arriving onto a reef within the first 6 hours were considered to constitute successful transport.</p

Singapore's Southern Islands.

<p>Coral reef areas (in colour) among Singapore's Southern Islands used to estimate transport success. Each colour corresponds to a distinct potential sink site.</p