Difference in the colonization of meiofaunal biofouling on the plastic plates submersed in the Jangmok Bay

Abstract

We investigated the difference in the meiofaunal biofouling on the four polymer types of plastic plates in order to understand which organisms attach to plates from surrounding water and how recruiters colonize on plates according to polymer types and exposure period. The plastic plates (30 cm × 30 cm) consisting of PE (polyethylene), PP (polypropylene), PET (polyethylene terephthalate) and EPS (expanded polystyrene) had been submerged vertically at a depth of 1 m in Jangmok Bay from July to October 2021. The plates were retrieved at interval of 2 weeks for 12 weeks and the scrubbed organisms were sieved using 40, 60, 300 and 1,000 μm sieves and preserved for microscopic analysis. During this study, a total of 43 taxa had recruited on plates. In the 40-60 μm size group, copepods (harpacticoids), gastropods, bivalves, maxillopods (cyprids), amphipods, nematodes and polychaetes recruited in week 2 and their occupancy was different for each polymer types. The abundance of 40–60 μm peaked at week 4 regardless of polymer types (mean: 774 inds. m-2). In weeks 4-6, bivalves and nematodes were dominant and EPS had highest abundance than the others (mean: 995 inds. m-2). Nematodes dominated from the week 8 to the end of this experiment (week 12) regardless of polymer types. In the 60-300 μm size group, cnidarians, amphipods, maxillopods, copepods, bivalves, gastropods, polychaetes, nematodes and others (unidentified eggs) appeared in week 2. But bivalves had the highest density, following by nematodes on all plates throughout the experiment. And the abundance of 60 - 300 μm (mean: 5,674 inds. 0.1 m-2) was always higher than the abundance of 40-60 (mean: 312 inds. 0.1 m-2) and 300-1,000 μm (mean: 1,463 inds. 0.1 m-2) until week 8. EPS had the highest abundance in each week except week 2 (mean: 9,452 inds. 0.1 m-2). In the 300-1,000 μm size group, cnidarians, amphipods, maxillopods, copepods, bivalves, gastropods, polychaetes, others (unidentified eggs) and crustacean larvae appeared in week 2, and amphipods had higher density except PP. In all plates, bivalves dominated in week 4. The occupancy of cnidarians increased and peaked at week 6 and then decreased afterwards, but the occupancy of crustacean larvae increased from the week 6 to the end on all plates. PP had the highest abundance during this study except week 4 (mean: 4,396 inds. m-2). In week 12, the abundance of 300-1,000 μm on PP, PE and PET plates were higher than that of 60-300 μm. These findings suggested that recruiters showed different preference on the polymer types of plates in the initial stage of colonization, while the difference of colonization according to polymer types did not exist at a late phase of exposure. And the abundance of meiofaunal biofouling showed that each size group had the different preference for polymer types and exposure periods: The 60-300 μm size group prefer EPS in weeks 4-12 and 300-1,000 μm size group prefer PP except week 4, respectively.