Benthic Crustacean Digestion Can Modulate the Environmental Fate of Microplastics in the Deep Sea

Abstract

Microplastics (MPs) are ubiquitous contaminants of the marine environment, and the deep seafloor is their ultimate sink compartment. Manipulative and field experiments provided evidence of the ingestion of MPs by deep-sea fauna, but knowledge of MPs’ fate once ingested still remains scant. We provide evidence of MP partial retention and fragmentation mediated by digestion activity of a Norwegian langoustine, a good bioindicator for MP contamination of the deep sea. We report here that MPs in the intestines were more abundant and significantly smaller (up to 1 order of magnitude in surface) than those in the stomachs. Our results show that the stomach can act as a size-bottleneck for ingested MPs, enhancing the retention of larger particles within the stomach and promoting fragmentation into smaller plastic debris, which is then released in the intestine. Our results provide evidence that the langoustine is responsible for the fragmentation of MPs already accumulated in sediments through its scavenging activity and digestion. These findings highlight the existence of a new peculiar kind of “secondary” MPs, introduced in the environment by biological activities, which could represent a significant pathway of plastic degradation in a secluded and stable environment such as the deep sea.

Effect of microplastics in water and aquatic systems

“…In the study, 85% of the examined specimens showed higher amount of microplastics in the intestine than in the stomach with length of 0.23 ± 0.16 and 1 ± 0.16 mm, respectively, indicating that a considerable proportion of absorbed microplastics leaving the stomach are broken by gastric mills, preceded by filtering systems that discourage larger particles from accessing the intestine. These results demonstrate the presence of a new form of "secondary" microplastic releasing into the marine environment by the lobsters (Cau et al 2020). However, earlier studies (Welden and Cowie 2016) have already shown that continuous fed on plastics by lobsters results in higher mortality rate or affects their growth and reproduction.…”

“…The Norway Nephrops norvegicus lobsters are deep sea scavengers (Andrades et al 2019) that inhabits in European climatic conditions and are a strong bioindicator (Cau et al 2019) of MP pollution. Analysis performed by Italian scientists in 2020 (Cau et al 2020) found that crustaceans can modulate the deterioration of microplastics into tiny particles in which their stomach can essentially serve as a grinding mill that grinds the plastic particles into even smaller ones thus affecting the lower trophic levels of food chain. In the study, 85% of the examined specimens showed higher amount of microplastics in the intestine than in the stomach with length of 0.23 ± 0.16 and 1 ± 0.16 mm, respectively, indicating that a considerable proportion of absorbed microplastics leaving the stomach are broken by gastric mills, preceded by filtering systems that discourage larger particles from accessing the intestine.…”

Rapid fragmentation of microplastics by the freshwater amphipod Gammarus duebeni (Lillj.)

“…Also, a laboratory study with urchins, Paracentrotus lividus, attached to a polyethylene tray, showed the presence of microplastics ranging in size between 118 µm-15.8 mm 50 . Lastly, a recent monitoring study claimed that langoustines collected from the deep-sea had retained and fragmented plastics in their guts 51 . These studies suggest that digestive fragmentation can potentially play a critical role in determining the fate of plastics in the environment.…”

Eating Near the Dump: Identification of Nearby Plastic Hotspot as a Proxy for Potential Microplastic Contamination in the Norwegian Lobster (Nephrops norvegicus)

“…The dataset on MiP ingestion in N. norvegicus was retrieved from two recent studies on the topic, conducted in the area under scrutiny in the present study (Cau et al, 2020(Cau et al, , 2019. Samples used in these studies were collected in the framework of the same MEDITS campaigns, at depths between ca.…”

“…Due to their small size, MiP are potentially available for ingestion to a wide range of marine species (Jâms et al, 2020), including cetaceans (Lusher et al, 2018), seabirds (Amélineau et al, 2016), mollusks (Ward et al, 2019), echinoderms (Graham and Thompson, 2009), zooplankton (Cole et al, 2013;Desforges et al, 2015), and corals (Hall et al, 2015). Ingested MiP may accumulate within organisms, causing blockages and internal abrasions or be fragmented through the digestion process (Cau et al, 2020). In addition, plastic particles may have toxic impacts due to monomers and plastic additives that do affect endocrine functions (Oehlmann et al, 2009;Talsness et al, 2009), reduce feeding behavior (Cole and Galloway, 2015), and compromise growth and reproduction (Lee et al, 2013;Lo and Chan, 2018).…”