Cnidaria

3.1.2. Cnidaria View in CoL View at ENA

Cnidarians are divided into three classes: Hydrozoa, Scyphozoa, and Anthozoa. They are widely distributed in different habitats, from seagrasses to coral reefs, from coastal areas to the deep sea, and from benthic to pelagic zones, and they are affected by MPs originating from various anthropogenic sources in many places with human impact. Hydrozoans and scyphozoans are commonly known as jellyfish, with both sessile polyp and free-living medusa forms. Although studies on the effects of MPs on the phylum Cnidaria are limited, it is possible to say that more studies have been carried out compared to Porifera. In our literature review, seven relevant studies were found (Appendix Table 1 View Table 1 ).

In the pelagic jellyfish Aurelia aureta in the North Sea, Pelagia noctiluca in the Canary Islands, Rhizostoma pulmo in the Adriatic Sea, benthic jellyfish Cassiopea xamachana in Florida, and sea anemone Actinia equina on the north coast of Spain, MPs were reported mostly in the form of fibers ( Avio et al., 2020; Iliff et al., 2020; Devereux et al., 2021; Janssens and Garcia-Vazguez, 2021; Rapp et al., 2021). The anthropogenic contaminants PE, PP, PET, cotton, rayon/viscose fibers, acrylic, cellophane, cellulose, and linen were detected ( Devereux et al., 2021; Rapp et al., 2021). In addition, jellyfish such as Aurelia aurita and Pelagia noctulica were found to be bioindicators for the determination of MPs in pelagic waters (Macali and Bergami, 2020; Rapp et al., 2021). Anthozoans, another class of Cnidaria, are a group of polyp-shaped corals and anemones, all of which are sessile. There are many experimental studies investigating the ingestion and adhesion of MPs by corals and species-specific MP uptake; the effects of MPs on corals together with chemical contaminants such as PAE, PCBs, and heavy metals; pathogen-induced diseases caused by MPs and their effects; and the symbiotic relationship between corals and Symbiodiniaceae ( Huang et al., 2021) . However, nonexperimental studies are limited. On Liugiu Island, Taiwan, MPs were detected on the surface of (0.35 ± 0.28 items/g) and inside (0.23 ± 0.17 items/g) Acropora spp. , Galaxea astreata , and Pocillopora verrucosa corals. The MPs detected were over 90% fiber and included polymers such as rayon, PES/PET, nylon, PACA, PS, PP, and PE (Lim et al., 2022). Corals obtain nutrient and energy needs through symbiotic relationships with the photosynthetic family Symbiodiniaceae . This symbiotic relationship is critical for supporting healthy coral reefs. From Hainan Island, China, it was reported that MPs can induce apoptosis in the coral Pocillopora damicornis and that the symbiotic relationship between Symbiodiniaceae and coral may be damaged (Tang et al., 2021).