Impacts of microplastics on marine organisms
Most natural nano-plastics and MPs are less than 100 nm in size and are found in seawater. In general, these microscopic particles have a detectable impact on marine species (Table 2). MPs, on the other hand, cannot molecularly be degraded or assimilated after consumption because marine organisms do not have the necessary enzyme pathways to degrade the synthetic polymers, and can therefore be classified as bioinert substances (Andrady, 2011). It has long been known that ingestion of MP can cause a number of health problems. MPs are known to harm aquatic organisms in a variety of ways, including effects on growth and development, reduced food intake, gut blockage, changes in swimming behaviour, and impaired reproductive success (Lo and Chan, 2018; Lee et al. 2017; Wright et al. 2013). The ability of MPs' to bind and absorb metals and POPs (e.g., polychlorinated biphenyls, polycyclic aromatic hydrocarbons, dichloro-diphenyl-trichloroethane and polybrominated diphenyl ethers) from the ecosystem is of concern (Gewert et al. 2015; Rochman et al. 2014). The nature of polymeric materials (e.g., glassy, or rubbery), the weathering and residence time of plastic debris in seawater, and the biological colonisation of their surfaces may increase the ability to absorb MPs (Wang et al. 2016). MPs can absorb POPs in greater quantities than larger plastics due to their greater surface area to volume ratio (Cole et al. 2011), which is detrimental to the ecosystem (Gewert et al. 2015). Hirai et al. (2011) estimated the average global amount of POPs in marine plastic pellets to be 1-10,000 ng/g.
MPs can collect and store metals, most of which come from a variety of sources, including industrial wastewater, waste incineration, and antistatic coatings (Brennecke et al. 2016; Rochman et al. 2013b). Due to the widespread distribution of plastic debris and the small size of MPs, both primary and contaminated MPs can be ingested by a variety of marine animals and have potentially hazardous effects. One or more sources, such as residual monomers and additives in plastics, products formed during partial fragmentation, or substances adsorbed to them, can cause these effects. Furthermore, the number of MPs ingested, and the time they remain in the tissues or organs of an organism are critical factors in determining their potential effects (Wright et al. 2013a; Wang et al. 2016). Several studies have demonstrated that MPs, alone or in combination with other marine contaminants, pose a significant health risk to many marine biotas.
Impacts on bivalve-molluscs
There is a historical financial connection between humans and molluscs. Two of the three main groups within the phylum Mollusca are bivalves and gastropods. Molluscs provide various commercial benefits, such as fishing and mariculture, but they can also cause significant economic losses causing misery in communities that depend on this income (Levin, 2013). They are a diverse group found in a variety of aquatic habitats. They play a critical role in ecosystem engineering, by reshaping aquatic bottom conditions while also providing habitat, security, and food for a variety of other taxa (Fernández Pérez et al. 2018).
Detrimental human health consequences from MP fibres associated with the consumption of marine molluscs have attracted much attention recently. Molluscs are a group of filter feeders that are vital to both the environment and the economy. These sessile animals filter a considerable amount of water, which is absorbed and deposits a wide range of marine toxins that humans can tolerate to some level in their tissues. Bivalves such as Mytilus galloprovincialis and Mytilus edulis are heavily used in the food industry and that also serve as bioindicators of pollution (Bat et al. 2018; Capillo et al. 2018; Savorelli et al. 2017). Ostrea edulis has been contaminated by MPs, both conventional and biodegradable (Green, 2016). As bivalves filtrated their food, they may represent an important source of MPs accumulated toxins to humans (Mincarelli et al. 2021; Van Cauwenberghe and Janssen, 2014).
De Witte et al. (2014) found that M. edulis samples collected from the Belgian coast and purchased in shops contained 0.26 to 0.51 fibres per gram of tissue, with variation due to environmental availability. Mathalon and Hill (2014) found approximately 30 and 70 fibres per individual of M. edulis collected from a Nova Scotia port and purchased from an aquaculture site, respectively. Li et al. (2015) found large amounts of fibres in a variety of molluscs from a Chinese fisheries market.
MP exposure affected the homeostasis of bivalves Mytilus sp. resulting in increased energy consumption, decreased binding strength, interference with key metabolic enzymes, and increased regulation of antioxidant indicators (Green et al. 2018; Détrée and Gallardo-Escárate, 2017, 2018; Van Cauwenberghe et al. 2015). This is most likely the result of the need to assimilate inactive material while maintaining metabolic balance (von Moos et al. 2012). Changes in immunological indicators, oxidative stress, neurotoxicity and genotoxicity as well as transcriptional effects have been observed in mussels with high pyrene concentrations (Mincarelli et al. 2021). Early granulocytoma development (inflammation), an increase in haemocytes, and a significant decrease in lysosomal membrane stability (LMS) have also been noted (Browne et al. 2008). In addition, the amount of energy provided for immunological functions may be decreased, resulting in damage to all normal physiological processes. The result is the deterioration of individual fitness and ecosystem. Furthermore, the constant consumption and accumulation of MPs in bivalves shall have long-term negative consequences (Avio et al. 2015b).
Table 2. Effects of microplastics on aquatic biota.
|
Classes
|
Species
|
Exposure
time (hrs)
|
MPs
|
Effectsb
|
Ref.
|
Type
(size µm)a
|
Tested
Concentration
|
Annelida
|
Arenicola marina
|
672
|
PS (400-1300)
|
100 gL-1
|
↓ Feeding activity
|
Besseling et al. 2013
|
|
|
240
|
PVC (250)
|
n.s
|
↑ Oxidative stress
|
Browne et al. 2013
|
|
|
336
|
PE, PS (<100)
|
110 MPs g-1 of sediment
|
↑ EC
↑ Protein content
|
Van Cauwenberghe et al. 2015
|
|
|
48, 672
|
PVC (130)
|
5-50g of MPs Kg-1 of sediment
|
↓ Energy reserves
↓ Feeding activity
↑ Phagocytic activity
↑ Inflammatory response
↓ Lipid reserves
↑ MPs retention
|
Wright et al. 2013
|
|
|
744
|
PE, PVC
(1.4-707)
|
0.2-20 g of MPs Kg-1 of wet sediment
|
↑ Metabolic rates
|
Green et al. 2016
|
Echinodermata
|
Lytechinus variegatus
|
24
|
PE
|
200 ml of MPs L-1
|
↑Anomalous larvae development
|
Nobre et al. 2015
|
|
Paracentrotuslividus
|
6-48
|
PS (0.04-0.05)
|
1-50 µg ml-1
|
↑ MPs accumulation
↑ Malformations
↑ Disruption of cell membrane
↑ Cas8 (related with apoptotic processes)
↑ Oxidative stress
↑ Abcb1 gene (involved in multidrug resistance)
|
Della Torre et al. 2014
|
|
48
|
PS (6)
|
103-105 MPs ml-1
|
↓ Fertilization rate
↓ Growth
↑ Larval development abnormalities
|
Martinez-Gomez et al. 2017
|
|
|
PE (>0-80)
|
0,005-5 g of MPs L-1
|
↑ Larval development abnormalities
|
|
Tripneustesgratilla
|
120
|
PE (10-45)
|
300 MPs ml-1
|
↓ Growth
|
Kaposi et al. 2014
|
Rotifera
|
Brachionuskoreanus
|
288
|
PS (0.05-6)
|
0.1 – 20 µg ml-1
|
↓ Growth rate
↓ Fecundity
↓ Lifespan
↑ Reproduction time
|
Jeong et al. 2016
|
Mollusca
|
Crassostrea gigas
|
1440
|
PS (2-6)
|
0.023 mg L-1
|
↑ Microalgae consumption
↑ Absorption efficiency
↑ Maintenance costs
↓ Oocyte number
↓ Sperm velocity
|
Sussarellu et al. 2016
|
|
Mytilus edulis
|
336
|
PE, PS
(<100)
|
110 MPs ml-1
|
↑ EC
|
Van Cauwenberghe et al. 2015
|
|
|
3-96
|
PE (0-80)
|
2.5 g L-1
|
↑ MPs accumulation
↑ Granulocytoma formation
↓ LMS
↓ Lysosomal integrity
|
von Moos et al. 2012
|
|
|
8
|
PS (0.03)
|
0.1-0.3 g L-1
|
↓ Filtering activity
|
Wegner et al. 2012
|
|
Mytilus galloprovincialis
|
0.5-4
|
PS (0.05)
|
1-50 µg L-1
|
↓ LMS
↓ Phagocytic activity
↑ Lysozyme release
↑ ROS
↑ NO production
↑ Apoptotic processes
↓ MMP Cytotoxicity
|
Canesi et al. 2015
|
|
|
168
|
PE, PS (<100)
|
20 g L-1
|
↓ Granulocytes
↓ LMS
↑ DNA breaks in haemocytes
↑ Nuclear anomalies
↓ AChE, Se-D-GPx, and CAT activities
↓ Lysosomal integrity
|
Avio et al. 2015a
|
|
|
24
|
PE (1-50)
|
1.5x107 MPs L-1
|
↓ PK and SD in the haemolymph and gills (genes involved in the carbon metabolism)
↑ PK and SD in the digestive gland and mantle (genes involved in the carbon metabolism)
↓ ID in the haemolymph (gene involved in the carbon metabolism)
↑ ID in the mantle (gene involved in the carbon metabolism)
↓ PGRP in the digestive gland and haemolymph (gene involved in immunity)
↑ TLR in the digestive gland and mantle (gene involved in immunity)
↑ Myticin A in the digestive gland and mantle (gene involved in immunity)
↓ Myticin A in the gills (gene involved in immunity)
↑ Myticin B in the gills, haemocytes and mantle (gene involved in immunity)
↓ Myticin B in the mantle (gene involved in immunity)
↑ Myticin B in the gills, haemocytes and mantle (gene involved in immunity)
↑ p53 in the digestive gland, mantle, gills and haemolymph (gene involved in apoptosis)
↑ FADD in the digestive gland and mantle (gene involved in apoptosis)
↑ Caspase 3/7 in the mantle (gene involved in apoptosis)
↑ SOD and CAT activities (digestive gland and mantle)
|
Détrée and Gallardo-Escárate, 2017
|
|
Scrobicularia plana
|
336
|
PS (20)
|
1 mg L-1
|
↑ SOD, CAT, GPx and GST activities (gills)
↑ SOD activity (digestive gland)
↓ CAT activity (digestive gland)
↑ GPx activity after 3 days exposure (digestive gland)
↓ GPx activity after the remaining time (digestive gland)
↓ GST (digestive gland)
↓ AChE activity (gills)
↑ LPO levels (digestive gland) Genotoxicity
|
Ribeiro et al. 2017
|
Crustacea
|
Hyalella azteca
|
240, 1008
|
PE (10-27)
|
0-100000 MPs ml-1
|
↑ Mortality
↓ Reproduction
↓ Growth
|
Au et al. 2015
|
|
|
|
PP (20-75)
|
0-90 MPs ml-1
|
↑ Mortality
↓ Growth
↓ Weight
|
|
Carcinus maenas
|
1-24
|
PS (8)
|
106-107 MPs L-1
|
↓ Hemolymph sodium ions
↑ Hemolymph calcium ions
↑ Oxygen consumption
|
Watts et al. 2016
|
|
Tigriopus japonicus
|
2 generation test
|
PS (0.05-0.5)
|
0.125-25 µg ml-1
|
↑ Mortality
↓ Survival
↓ Fecundity
|
Lee et al. 2013
|
|
Centropagestypicus
|
24
|
PS (0.4-3.8)
|
40x103-1x106 MPs ml-1
|
↓ Ingestion rates
|
Cole et al. 2013
|
|
Nephrops norvegicus
|
5760 (feeding test)
|
PP (3000-5000)
|
5 MPs feeding-1
|
↓ Feeding rate
↓ Body mass
↓ Metabolic rate
|
Welden and Cowie, 2016
|
|
Palaemonetes pugio
|
3h
|
PE,PS,PP
(30-165)
|
50 000 MPs L-1
|
↑ Mortality
|
Gray and Weinstein 2017
|
|
Gammarus fossarum
|
672
|
PA (500)
|
100-13.380 PA MPs cm-2 base area
|
↓ Assimilation efficiency
|
Blarer and Burkhardt-Holm, 2016
|
|
|
24
|
AC (Acrylic glass) (32-250)
|
10-100000 MPs individual-1
|
↓ Assimilation efficiency
↓ Wet weight gain
|
Straub et al. 2017
|
|
|
|
PES (32-250)
|
|
↓ Wet weight gain
|
|
Artemia franciscana
|
24
|
PS (0,1)
|
0,001-10 mg L-1
|
↓ Swimming speed
|
Gambardella et al. 2017
|
|
|
48
|
|
|
↑ Swimming speed
↓ AChE activity
↑ PChE and CAT activities
|
Cui et al. 2017
|
|
Daphnia galeata
|
120
|
PS (0.05)
|
5 mg L-1
|
↑ Mortality
↓ Reproduction
Abnormal development
|
|
Daphnia magna
|
504
|
PS (0.07)
|
0.22-103 mg L-1
|
↓ Reproduction
↓ Body size
↑ Mortality
|
Besseling et al. 2014
|
|
|
24,48
|
AC (Acrylic resin) (0.086-0.125)
|
0.01-1000 mg L-1
|
↑ Immobilization
|
Booth et al. 2016
|
|
|
48
|
PES (62-1400)
|
12.5-100 mg L-1
|
↑ Mortality
|
Jemec et al. 2016
|
|
|
48
|
PS (0,2)
|
1-30 mg L-1
|
↑ Immobilization
|
Kim et al. 2017
|
|
|
6,24
|
PS (0.09-0.1)
|
10 µg ml-1
|
↑ MPs retention
↑ Stress
↓ Feeding rate
↓ Survival rate
|
Nasser and Lynch, 2016
|
|
|
0.008 - 504
|
PE (1-5)
|
102-3x104 MPs L-1
|
↑ Mortality
↓ Feeding
↓ Growth
|
Ogonowski et al. 2016
|
|
|
96
|
PE (1-100)
|
12.5-400 mg L-1
|
↑ Immobilisation
|
Rehse et al. 2016
|
|
|
24,504
|
PS (0.1-2)
|
0.1-1 mg L-1
|
↓ Feeding rate
|
Rist et al. 2017
|
|
|
24
|
PS (0.052)
|
0.075-0.15 g L-1
|
↑Mortality
|
Mattsson et al. 2017
|
|
Amphibalanusamphitrite
|
48
|
PS (0.1)
|
0.001-10 mg L-1
|
↓ Swimming speed
↑ AChE, PChE and CAT activities
|
Gambardella et al. 2017
|
|
|
96
|
PE, PS, PP, PVC, PES
|
0.10 and 0.50 m2 L-1
|
↑ Mortality
↓ Settlement
|
Li et al. 2016
|
|
Calanus helgolandicus
|
24, 216
|
PS (20)
|
65-75 MPs ml-1
|
↓ Predatory performance
↓ Reproductive output
↓ Survival
Energetic depletion
|
Cole et al. 2015
|
|
Paracyclopina nana
|
24
|
PS (0.05-6)
|
0.1-20 µg mL-1
|
↑ Intracellular ROS level
↑ Phosphorylation of extracellular signal-regulated kinase (p-ERK) and p38 (p-p38)
↑ GR, GPx, GST and SOD activities
|
Jeong et al. 2017
|
|
Parvocalanuscrassirostris
|
144, 576
|
PES (5-10)
|
10000-80000 MPs mL-1
|
↓ Egg production
↓ Population size
↑ H3 (gene involved in chromatin structure of eukaryotic cells)
|
Heinder et al. 2017
|
Fish
|
Dicentrarchuslabrax
|
864
|
PE (10-45)
|
104-105 MPs g-1 of diet
|
↑ Mortality
↑ CYP P450
|
Mazurais et al. 2015
|
|
|
2160
|
PVC (300)
|
1 g kg-1 of diet
|
↑ Structural alterations of the DI
↓ Regular structure of serosa, muscularis mucose and submucosa/mucosa
Occurrence of rodlet cells in the intestinal mucosa
|
Peda et al. 2016
|
|
Pomatoschistusmicrops
|
96
|
PE (1-5)
|
0.184 mg L-1
|
↓ AChE activity
|
Oliveira et al. 2012
|
|
|
96
|
PE (1-5)
|
0.184 mg L-1
|
↓ AChE activity
|
Oliveira et al. 2013
|
|
|
0.002 (predatory test)
|
PE
(450-500)
|
100 MPs L-1
|
↓ Predatory performance
↓Predatory efficiency
|
de Sá et al. 2015
|
|
|
96
|
PE (1-5)
|
0.184 mg L-1
|
↓ AChE activity
|
Luis et al. 2015
|
|
Sparus aurata
|
720 (40-150)
|
PVC (40-150)
|
100-500 mg of MPs Kg-1 of individual
|
↑ ASP and CK activities (serum parameters)
↑ albumin and globulin (serum parameters)
↓ Glucose (serum parameters)
↑ Peroxidase activity and skin mucus IgM (Humoral immune parameters)
↑ Phagocytic capacity
↓ prdx5 and hsp90 (genes related to stress)
↑ prdx1, prdx3, and ucp1 (genes related to stress)
|
Espinosa et al. 2017
|
PE-Polyethylene; PS-Polystyrene; PP-Polypropylene; PVC-Polyvinylchloride; PLA-Biodegradable plastic; AC-Acrylic; PES-Polyester.
|
The feeding ability of Pacific oyster (Crassostrea gigas) larvae was not affected by different sizes of polystyrene microbeads (Cole and Galloway, 2015). This could be due to the simplicity of the oyster's digestive tract, which allows less MP to be retained as they are more easily ingested. The Pacific oyster C. gigas (Alfaro-Núñez et al. 2021; Revel et al. 2020) and the blue mussel Mytilus sp. exhibited no adverse effects, but the black-lipped pearl oyster Pinctada margaritifera had problems with energy balance and reproduction (Revel et al. 2019; Gardon et al. 2018).
The main effect of MPs ingestion in M. galloprovincialis is cell destruction in response to oxidative damage (Sureda et al. 2018; Pagano et al. 2017). Experiments in the marine mussel M. galloprovincialis exposed to PE MPs showed a range of adverse effects in molluscs, including immunological responses, oxidative damage, and cytotoxicity (Avio et al. 2015a). Enzymatic changes were observed in the marine mollusc M. galloprovincialis following exposure to PS and PE MP (Avio et al. 2015a). Two mollusc species showed additional ecotoxicological consequences after exposure to PS MPs. Increased neurotoxicity and genotoxicity were found in a Scrobicularia plana research (Ribeiro et al. 2017).
Impacts on gastropods-molluscs
Non-filter-feeding, larger organism like gastropods feed on certain amounts of MPs fibre to ensure retention through ingestion and impact analysis (Ehlers et al. 2020; Jabeen et al. 2018). Radix balthica has been recorded to eat a biofilm of MPs fibres during feeding. Subsequently, MPs fibres were gradually absorbed into a fibre-free medium via faeces, which took three days (Ehlers et al. 2020). Planorbella campanulata was exposed to exceptionally high levels of polyester textiles in the marine environment, and the fibres accumulated in the snail's mouth, resulting in a higher mortality rate than in control snails (Philips et al. 2020). As a result, degradation at local hot spots with high fibre concentrations can lead to blockage of feeding and death of snails. In addition, snails produced more offspring when treated with polyester fibres. This is thought to be because death triggers an increase in offspring or because the chemicals evaporated from the fibres have estrogenic effects (Philips et al. 2020). Ingestion of polystyrene microbeads by veliger of the marine gastropod Crepidula onyx resulted in a slowed development rate as well as premature settling on the seafloor (Lo and Chan, 2018), which may negatively impact post-settlement efficacy. Moreover, those individuals subjected to the microbeads only during the larval stage grew more slowly 65 days after MPs removal. This highlights the potential for adverse long-term effects of early-life exposure on development. In contrast, the adult stage was unaffected at environmentally relevant MP concentrations.
Impacts on Arthropoda
Filter and deposit-feeding decapods passively ingest MP fibres, while selectively feeding decapods aggressively feed on them. Consumption of MP fibres by isopods and predatory crustaceans has been studied by adding fibres to their food (Watts et al. 2015; Hamer et al. 2014). When the number of fibres eaten was measured in different parts of the gastrointestinal tract and in faeces, there was no evidence of aggregation within the digestive system (Watts et al. 2015; Hamer et al. 2014). MPs of various shapes and sizes were exposed to dagger shrimp (Palaemonetes pugio) in the water column (Gray and Weinstein, 2017). Due to water flow, all MPs became attached to the gill region, while shrimp that were picky foragers, ingested the MPs. Considering the short exposure time, shrimp died within the first three hours after treatment and during the subsequent 96-hour depuration period. The different sizes of polypropylene fibres tested triggered mortality, and mortality rates for fibres were higher than for fragments of different sizes (Gray and Weinstein, 2017).
The high lethality of MP fibres has been linked to intestinal tissue damage from engulfment (Gray and Weinstein, 2017). The higher toxicity of fibres, on the other hand, could be related to their weathered state. After a 96-hour exposure, untreated polyester fibres did not cause increased mortality in grass shrimp (Leads et al. 2019; Gray and Weinstein, 2017). The differences in lethality could be attributed to the different plastic fibres used or the degree of degradation of the fibres, indicating the effects of fibre properties on decapods (Leads et al. 2019; Gray and Weinstein, 2017). In a later two-day test with bacteria (Vibrio campbellii), shrimp exposed to polyester did not die, which was related to the fact that the polyester fibres degraded relatively quickly within 48 hours, reducing their immunotoxicity (Leads et al. 2019).
Individual fitness of several crab species was affected by exposure to MP fibres over a prolonged period of time (Watts et al. 2015). Horn et al. (2019) reported higher mortality in Emerita analoga that were treated with 1 mm thick polypropylene fibres. This indicated that Pacific mole crabs and other non-selective feeders cannot tell the difference between plastic and food, which puts them at risk when fibre content increase in the environment (Horn et al. 2019). Similarly, exposed E. analoga exhibited lower clutch retention and higher heterogeneity in embryonic development. Ingested MP fibres may affect reproduction, or the colour associated with these fibres may be leached (Horn et al. 2019).
Ziajahromi et al. (2017) found that water fleas (Ceriodaphnia dubia) did not consume polyester fibres from water, but tactile contact with the fibres was associated with reduced development, reproduction, and aberrant swimming behaviour. Hyalella azteca exposed to high fibre concentrations exhibited dramatically slower growth and weighed 50% less than controls (Au et al. 2015). The effects of PP MPs on H. azteca, revealed more harmful than PE MPs (Au et al. 2015). Daphnia magna was found to be dead after consuming polyester fibres present in the water column for 48 hours (Jemec et al. 2016). MPs caused immobility (Rehse et al. 2016), mortality (Aljaibachi and Callaghan, 2018) and reproductive failure (Pacheco et al. 2018) in the planktonic crab D. magna, with transgenerational effects such as of lower growth and reproduction (Martins and Guilhermino, 2018).
Impacts on fish
Humans and all living organisms require a lot of protein, and fish is a good source of it. Therefore, the presence of MPs in fish and their potential consequences deserve special attention (Wang et al. 2020a). MPs have been found in a variety of fish species caught in the oceans, and seas (Alfaro-Núñez et al. 2021; Bessa et al. 2018; Pazos et al. 2017). Fish ingests MPs by mistaking them for natural prey, by deliberate ingestion during foraging, and by direct ingestion of animals containing MPs (Ghosh et al. 2021; Ory et al. 2017; Lusher et al. 2013). In practise, fish ingested MP fibres at various life stages from larval to sexual maturity (Gove et al. 2019; Kühn et al. 2018; Mizraji et al. 2017). Fibres were the most common MP form in larvae and juveniles, raising concerns about younger life stages that are particularly susceptible to ingesting MPs fibres (Barboza et al. 2020). According to the dispersal patterns of fibres, the ingestion of MPs fibres by fish from the Mediterranean Sea was positively related to coastal human population, river inputs, and shipping routes (Sbrana et al. 2020).
In a study of Pomatoschistus microps, MPs with chromium (VI) resulted in neurotoxicity and death, among other effects (Luis et al. 2015). PE MPs has been shown to cause neurotoxicity in fish (Luis et al. 2015) and a loss of predatory performance and efficacy in P. microps (de Sá et al. 2015). Mortality has been reported in the European bass, D. labrax (Mazurais et al. 2015). MPs are neurotoxic; impair energy-related enzymes, negatively affecton swimming performance, and cause oxidative stress and lipid peroxidation in juvenile D. labrax (Barboza et al. 2018a).
Oryzias lapites, a Japanese medaka fish was found to contain chemical contaminants (PAHs, PCBs and PBDEs) that accumulate in the body, as evidenced by bioaccumulation. Liver stress and early tumour formation were reported after animals were exposed to both pieces of primary and marine plastic pieces for a short time (Rochman et al. 2013b). After exposure scanning electron microscopy revealed structural damage in the gills, including epithelial denudation at the gill arches, fusion of the main lamellae, and increased mucus production (Hu et al. 2020). Polyethylene with absorbed chemical pollutants from marine waters can disrupt hormonal system function in adult O. lapites fish (Rochman et al. 2014). In males, gene expression of choriogenin (ChgH) was down regulated, while in females, gene expression of vitellogenin (VTgI), ChgH, and oestrogen receptor (ER) were down regulated. The main concern should be the long-term effects of exposure during the early developmental stages of an organism, which could jeopardize reproductive success and threaten biota (Rochman et al. 2014).
Omnivorous fish (Girella laevifrons) accumulated large amounts of red MPs fibre instead of the red algae they regularly eat. Specimens with higher amounts of MPs fibre in their digestive system were found to present poorer body condition (Mizraji et al. 2017), suggesting that ingested fibre may directly affect fitness. In the wild, a decline in predatory activity may reduce the ability of juvenile gobies to capture prey and escape from predators. As a result, there is a possibility that individual health and thus population fitness may be threatened, affecting in juvenile development rates and species survival (Mizraji et al. 2017).
MPs significantly reduced swimming speed and resistance time of young European seabass, D. labrax (Barboza et al. 2018b). Additionally, behavioural abnormalities such as sluggish and irregular swimming activity were observed. These results highlight the importance of assessing the combined effects of MPs and other environmental contaminants, focusing on the behaviour of fish and other marine animals, and using fish responses as a susceptible endpoint to determine the effects of contamination by MPs (Barboza et al. 2018b).
Impacts on Annelida
Annelids are marine worms that irrigate and provide oxygen and promote the growth of crops and algae. The ecological role of marine worms in oceanic reefs is to provide food for aquatic species higher up the food chain (von Palubitzki and Purschke, 2020). Species inhabiting sediments can be affected by MPs, which, depending on the degree and concentration of exposure, can lead to serious changes such as alteration of gut microbiota, suppression of growth, and reproduction of collembolan in the soil (Zhu et al. 2018). In response to high doses of HDPE, PLA, and PVC in sandy sediments, respiration rates of Arenicola marina increase (Green et al. 2016). Decreases in energy reserves have also been noted, which may be due to inflammatory responses in tissues, as well as decreased food intake to decolonize or deposit of MPs in digestive cavities (Wright et al. 2013). As a result, stress may affect the health and behaviour of the polychaete A. marina, such as feeding performance and sediment transformation, negatively impacting ecological processes (Green et al. 2016). In addition, A. marina accumulated nonylphenol and triclosan from PVC when exposed to high levels of plastics, resulting in immune system impairment physical stress, and death (Browne et al. 2013). Exposure to PS MPs has ecotoxicological effects on the polychaete A. marina, including reduced feeding activity and lysosomal membrane stability (Besseling et al. 2013). When A. marina was exposed to PS MPs, it was noted an increase in energy consumption (Wright et al. 2013). Lipid stores of A. marina exposed to sediment PVC were emptied, and an inflammatory response was observed.
Impacts on Echinodermata
Echinoderms are a vital component of the ocean food web, as well as a source of food and medicine for humans (PiRuby, 2018). PE MPs have been shown to alter larval growth of Tripneustes gratilla without affecting its persistence in echinoderms (Kaposi et al. 2014). For Lytechinus variegatus larvae, Nobre et al. (2015) confirmed these results. In the echinoderm Paracentrotus lividus, Della Torre et al. (2014) described the effects of PS MPs on gene expression and counted an upregulation of the gene Abcb1 involved in shielding and confrontation with multiple agents (Shipp and Hamdoun, 2012).
MPs affected oceanic planktotrophic pluteus larvae of the sea urchin P. lividus (Messinetti et al. 2018). When sea urchins, Lytechinus variegatus, were exposed to seepage generated from unused polyethylene beads, abnormal embryonic development increased by 66.5 percent (Nobre et al. 2015). Compounds leached from the primary plastic components were responsible for these physical and biological effects. This demonstrates the susceptibility of early life stages to exposure to internal and external MP and the unknown long-term effects on organismal ontogeny (Nobre et al. 2015).
Impacts on Nematoda
Nematoda is one of the most diverse taxonomic groups on the planet. Marine nematodes play an important role in the marine ecosystem by recycling carbon and nutrients needed for other marine organisms (Yeates et al. 2009). In the nematode Caenorhabditis elegans, systemic inflammatory permeability and the development of Reactive Oxygen Species (ROS) have been observed with increasing MP levels, but this has not yet converted into morbidity (Zhao et al. 2017; Dong et al. 2018). The function of translocation in ion transport was underlined by enhanced deleterious effects in acs-22 mutants with higher gut flora (Qu et al. 2018). Toxicity tests performed at environmentally relevant concentrations of MPs showed crucial negative effects on particularly sensitive endpoints and species in a variety of situations (Qu et al. 2018). Finally, for pelagic marine species, the Predicted No Effect Concentration (PNEC) was estimated to be 6650 particles m-3, which is likely to be exceeded at hotspot sites (Everaert et al. 2018).
Impacts on phytoplankton
Phytoplankton is the mainstay of the entire marine food chain and provides the primary food source for much of the ocean’s biodiversity. The impact of MPs on microalgae is also becoming an increasingly important issue of global concern (Cunha et al. 2020; Ansari et al. 2021). Microalgae are an important source of energy for most marine ecosystems, feeding a wide range of organisms from tiny zooplankton to molluscs and crustaceans (Glibert, 2019). These species are the next in the food web to be preyed upon. Phytoplankton are credited with generating half of the Earth's photosynthetic activity and thus much of the new biomass that is converted to chemical energy by the sun’s energy and underpins trophic webs. Because of their important, there is concern about the adverse effects of micro and nanoplastics on them (Koenigstein, 2020).
It is known that algae cells of the genera Chlorella and Scenedesmus can aggregate and absorb nanoplastic beads (0.02 m) due to their shape and motility, leading to a reduction in photosynthesis and the development of oxidative damage (Bhattacharya et al. 2010). The physicochemical properties of MP’s and the physical and metabolic properties of algae appear to be responsible for this adsorption; in particular, a strong attraction between algae and positively charged plastic particles has been described (Bhattacharya et al. 2010). Sjollema et al. (2015) found no suppression of photosynthesis in the marine flagellate Dunaliella tertiolecta when exposed to different types of plastic particles of different sizes. Uncharged polystyrene beads inhibited microalgae development by 45%, but only at very high levels (250 mg/L). The negative effect increased with decreasing particle size (Sjollema et al. 2015).
Impacts on zooplankton
Zooplankton is considered a vital diet source for various secondary marine organisms. It serves as a pathway for MPs to enter the food web and reach the higher trophic levels (Botterell et al. 2019). Zooplankton can exhibit different feeding behaviours depending on species, life stage, and prey accessibility (Cole et al. 2013). Prey selection is influenced by the size of the hunter relative to the prey, their swimming behaviour, and the susceptibility of each prey type to the predator once encountered. A combination of mechano- and chemoreceptors also aid in the selection of suitable prey (Cole et al. 2013). MPs are likely ingested through unselective feeding techniques, such as suspension feeding, where prey are often not selectively eaten (Cole et al. 2013). Some zooplankton species may alter their feeding habits to prefer one algal species to another, and plastic pellets can be mistaken as a prey. In addition, when exposed to MPs and algal prey, the copepod Calanus helgolandicus preferred algal prey of smaller size (Cole et al. 2015). This change in feeding behaviour suggests that copepods alter their feeding habits to avoid ingesting MPs. MPs have not been found in all zooplankton species. Cole et al. (2013) reported ingestion of MPs in Parasagitta sp. and Siphonophorae sp. across a size range. However, both species are raptors, and active foragers require an animal prey response, which may explain why immobile MP prey did not tempt them (Table 3).
Table 3. Impacts of microplastics in marine copepods.
|
Species
|
MPs
Type
|
Size(nm)
|
Concentration
|
Effects
|
References
|
Acartia clause
Calanus helgolandicus
Centropages typicus
Temora longicomis
|
Fluorescent polystyrene beads
|
0.4-30.6
|
635-1 x 106 beads/ mL
|
- There is proof of size-based selectivity in copepods.
- Fecal pellets packed with MPs are consumed by copepods.
- Algal feeding is considerably reduced when exposed to 7.3 µm MPs (> 4000 beads/mL).
|
Cole et al. 2013
|
Acartia tonsa
Calanus helgolandicus
|
Polystyrene beads,
Fibres, and fragments
|
20, 20 x
10, and < 20
|
80 MPs/mL
|
- Variable species of copepods have different bioavailability of MPs depending on their sound structure.
-In the presence of the infochemical dimethyl sulfide, copepods' ingestion rate of MPs can significantly rise.
|
Botterell et al. 2020
|
Acartia sp.
Eurytemora ajfinis
Limnocalanus macrurus
|
Fluorescent
polystyrene
microspheres
|
10
|
1 x 103, 2 x 103 or 1 x 104 particles/mL
|
- The amount of microsphere consumed is related to the concentration.
- After 12 hours, E. ajfinis ingests microspheres.
|
Setala et al. 2014
|
Calanus finmarchicus
|
Nylon MP granules or Fibres
|
10-30 or
10 x 30
|
50 MPs/mL
|
-Exposure to polyester fibres reduces algal intake rates by C. finmarchicus by 40% on average, although no effect is seen with nylon granules.
-C. finmarchicus revealed to nylon MPs molt considerably faster than control C. finmarchicus.
|
Cole et al. 2019
|
Calanus finmarchicus
Calanus glacialis
Calanus hyperboreus
|
Polyethylene spheres
|
20
|
200 and 2000
MPs/L
|
- MPs had no effect on copepods' fecal pellets growth rate.
- Copepods that were exposed to MPs experienced stress-induced reproduction.
|
Rodriguez-Torres
et al. 2020
|
Calanus finmarchicus
Pseudocalanus sp.
Acartia longiremis
|
Polystyrene beads
Polystyrene fragments
|
15 and 30
< 30
|
50-200 beads/
fragments/mL
|
- Both A. longiremis and C. finmarchicus can eat MPs, albeit A. longiremis only eats the smaller (15-µm) particles and C. finmarchicus eats both sizes, whilst Pseudocalanus sp. cannot eat any MPs.
- Copepods consume older MPs than new ones.
|
Vroom et al. 2017
|
Calanus helgolandicus
|
Fluorescent PE
microspheres
Nylon Fibres
Polyethylene
terephthalate Fibres
Nylon fragments
|
10-32
|
100
MPs/mL
|
- Copepods exposed to MP fibres have a larger effect on their eating than copepods exposed to pieces.
- Feces having small polyethylene sink at a slower pace than controls, but when high-density MPs are mixed into the fecal pellets, the sinking rates dramatically increase.
|
Coppock et al.
2019
|
Calanus helgolandicus
|
Polystyrene beads
|
20
|
75 MPs/ mL
|
-Microbead exposure reduces algal cell intake by 89 percent and carbon biomass ingestion by 60 percent in C. helgolandicus, respectively.
-Long-term exposure to polystyrene beads reduces reproductive output considerably, but has no effect on egg formation rates, breathing, or longevity.
|
Cole et al. 2015
|
Paracyclopina nana
|
Polystyrene
microbeads
|
0.05, 0.5, 6
|
10 ng/mL
|
- The 0.05 µm pellets can be found everywhere over P. nana's body, whilst the other two sizes are predominantly found in the digestive systems.
- When compared to the other two sizes (0.5 and 6 µm), the 0.05 µm nanobeads have a longer retention duration in the body.
- In copepods, MPs lead to oxidative stress.
|
Jeong et al. 2017
|
Parvocalanus
crassirostris
|
Polyethylene
terephthalate
|
5-10
|
1 x 104-8 x 104
particles/mL
|
- Egg production is lowered in a dose-dependent approach after 5-days of exposure to MPs.
- In contrast to the control, exposure to MPs (2 x104 plastics/mL) for 6-d reduces population size by 75%, whereas populations exposed for a longer period of time (24-d) exhibit more severe depletion (i.e., 60 percent of control).
|
Heindler et al.
2017
|
Pseudodiaptomus
annandalei
|
Monodisperse
Polystyrene microspheres
|
0.5, 2, and
10
|
20, 200, and 2 x
103 µ/L
|
- MPs of three sizes were consumed by P. annandalei. MPs with diameters of 0.5 and 2 micrometers were consumed at higher rates than MPs with diameters of 10 micrometers.
- P. annandalei ingested MPs through fecal pellets.
|
Cheng et al. 2020
|
Temora turbinata
Tignopus fulvus
Tignopus japonicus
|
Polystyrene
microbeads
Polyethylene
MPs
Polystyrene
Microbeads
|
20
1-5
0.05,
0.5,
6
|
100 and 1 X 103
beads/mL
0-1-10 mg/L
9.1x 1011 particles/ml.
9.1x 10s particles/ml.
5.25 x 105 particles/mL
|
- Microbeads have a considerable impact on copepod swimming behavior.
- In the marine ecosystem, MPs can be transported from copepods to jellyfish ephyryae.
- When compared to the control, exposure to 0.5- and 6-µm polystyrene microbeads dramatically reduces fecundity at concentrations (1.25-25 mg/L), however 0.05-µm PS nanobeads have no effect on this feature.
|
Suwaki et al. 2020
Costa et al. 2020;
Lee et al. 2013
|
Tignopus japonicus
|
Polystyrene beads
|
6
|
0.023 and 0.23
mg/L
|
- MPs (0.23 mg/L) caused a significant decrease in life expectancy, nauplii/clutch number, and fertility.
-MPs had a considerable intergenerational transmission proteome plasticity in copepods due to their two-generational influence.
|
Zhang et al. 2019
|
Tigriopus japonicus
|
Polystyrene
Microbeads
|
0.05 and 10
|
20 mg/L
|
- Intake of both small and large MPs causes an excessive production of reactive O2 species, as well as a considerable impact on the antioxidant defense system.
|
Choi et al. 2020
|
Tigriopus japonicus
|
Polyethylene and
polyamide-nylon 6
MPs
|
10–30 and
5–20
|
0,12.5, 25, 50,100, 200, and 400 mg/
L
|
- In T. japonicus, MPs had a deleterious effect on eating, reproduction, and longevity.
- MPs had no effect on the body size of T. japonicus after one generation.
|
Yu et al. 2020
|
MP fibres made up 43.9-93% of MP items in zooplankton, which is similar to amounts identified in different organisms like clams, shrimps, and fish (Zheng et al. 2020). The majority of laboratory studies have exposed copepods to MPs, concluding they can be consumed by a variety of copepods (Botterell et al. 2020; Zhang et al. 2019). Choi et al. (2018) reported that Cyprinodon variegatus larvae readily ate irregular polyethylene forms. Desforges et al. (2015) discovered that the copepod Neocalanus cristatus preferred to eat particles with a diameter of 556 micrometres. Vroom et al. (2017) studied the ingestion of MPs as well as microbeads.
Copepods in contact to nylon pieces or fibres reduced their food ingestion in treatments with suspended fibres, but not in the fragment’s treatments (Coppock et al. 2019). Reduced food ingestion and the resulting decrease in existing energy will have a long-term impact on fitness (Watts et al. 2015). When the maritime copepods C. helgolandicus and T. japonicas were exposed to PS MPs, it was found a reduction in survival and productiveness (Cole et al. 2015; Lee et al. 2013). In the small crustaceans A. franciscana and Paracyclopina nana, some changes in enzymes were identified (Gambardella et al. 2017; Jeong et al. 2017). Irregular shaped MPs harmed the larvae's swimming behaviour, reducing the total distance travelled and maximum velocity (Yu et al. 2020; Wang et al. 2020b).
Impacts on algae
Algae capture and utilise energy from sunlight, and biochemically transform carbon dioxide (CO2) and water (H2O) to make organic matter. They are regarded as an essential component to the health of the world's oceans (Singh and Singh, 2014). This cycle contributes to the ocean's life balance. Algae can also be used as a source of food and medicine for people. MPs caused morphological alterations, lower growth, and photosynthetic activity is lowered (Table 4) in the microalgae Chlorella pyrenoidosa (Mao et al. 2018). MPs, for example, increased the toxicity of the medicine doxycycline in the marine microalgae Tetraselmis chuii and the restricted chemical methamphetamine in the green algae C. pyrenoidosa (Qu et al. 2020; Prata et al. 2018).
Table 4. Impacts of microplastics on marine algae.
|
Species
|
MPs type
|
Duration of
exposure
|
Endpoints
|
Effects
|
References
|
Skeletonema
costatum
|
polyvinyl chloride (PVC)
|
96h
|
Growth inhibition
|
There was a 39.7% growth reduction in 1 µm particle exposure, but no influence on algal growth. There is a lot of absorption and aggregation.
|
Zhang et al.
2017
|
Tetraselmis chuii
|
fluorescent red polyethylene
|
96h
|
Growth inhibition
|
No significant growth rate inhibition
|
Davarpanah and Guilhermino, 2015
|
Oxyrrhis marina
|
virgin and
fluorescent polystyrene
|
60 min
|
Uptake and motility
|
Increased uptake; bio-fouling formation
|
Lyakurwa, 2017
|
Rhodomonas baltica
|
virgin and
fluorescent polystyrene
|
60 min
|
Uptake and motility
|
Increased uptake; bio-fouling formation
|
Lyakurwa, 2017
|
Impacts on birds
Ingestion of plastic impacts seabirds around the world. Wilcox et al. (2015) estimated that by 2050 plastic will be found in the gastrointestinal tract of 99% of all seabird species and that 95% of individual members of avian species will have ingested plastics (>5 mm). Moreover, studies have shown that young seabirds consumed more MPs than adult seabirds (Kuhn and van Franeker, 2012; Provencher et al. 2014). Juvenile fulmars (Fulmarus glacialis) were found to have a greater amount of plastic in their stomachs than adult birds (Kuhn and van Franeker, 2012). Studies of seabirds off the Norway coast confirmed this, with ingested MPs having minor effect on tissue (Herzke et al. 2016). MPs have also been detected in the vomit and faeces of wild Cinclus cinclus (D'Souza et al. 2020), Scomber scombrus, and in caged Halichoerus grypus (Nelms et al. 2018).
Impacts on Mammalia
Cetacean species such as baleen whales have been reported to consume MPs (Simmonds, 2012). Macro filters large organisms from the seawater column, such as whales, due to their non-selective feeding behaviour ingest MPs. Stomachs of Pontoporia blainvillei, Mesoplodon mirus, Balaenoptera borealis, and B. acutorostrata, respectively, have been detected with MPs particles (Baulch and Perry, 2014; Lusher et al. 2015). A variety of synthetic polymers and particle morphologies have been found in the guts of Megaptera novaeangliae (Besseling et al. 2015). Ingestion of MPs and entanglement of plastic debris can cause both acute and chronic injury in cetaceans and increase contaminant exposure, leading to severe illness, and eventual death (Baulch and Perry, 2014). The presence of high levels of MP in the gastrointestinal tract of baleen whales could impede digestive processes and block the intestinal tract (Simmonds, 2012; Besseling et al. 2015). High concentrations of phthalates and OCs have been shown to impair antioxidant defences and other systems that prevent cellular damage in B. physalus, leading to oxidative stress and possible hormonal system abnormalities (Fossi et al. 2016). In addition, microscopic plastic particles have the potential to clog the filtration systems of organisms (Simmonds, 2012). The fate of MPs in the body of mammals is shown in Fig. 6.
Impacts on marine reptiles (sea turtles)
Plastic pollution is a serious threat to all living organisms in the oceans, including sea turtles (Duncan et al. 2021), which are susceptible to a variety of anthropogenic stressors, including ingestion and entanglement with plastics (Nelms et al. 2015). MPs deposits in sediments can reduce thermal diffusivity, increase heat capacity, and permeability, which can affect embryos of all seven turtle species (Alfaro-Núñez et al. 2015). Loggerhead turtles (Caretta caretta) have been observed to nest on beaches that are contaminated with plastics, causing hatchlings to get caught and increasing travel time to the ocean, potentially increasing predation and decreasing survival (Aguilera et al. 2018). Consumption of plastic may increase susceptibility to diseases such as fibropapillomatosis (FP), a neoplastic disease documented in all sea turtles species (Nelms et al. 2015; Alfaro-Núñez et al. 2014). Finally, consumption of plastic by sea turtles can damage the digestive system, clogging the digestive tract and reducing feeding, stimuli, and gastrointestinal capacity, leading to food dilution and starvation, and eventual death (Nelms et al. 2015).
Stranding has recently been recognized as a significant risk to numerous marine animals and is a major reason of turtle death in several locations (Camedda et al. 2014; Jensen et al. 2013; Casale et al. 2010). In addition, entanglement with abrasions or loss of limbs due to necrosis can limit the turtle’s ability to feed competently or flee from pressure, resulting in death due to malnutrition or drowning (Nelms et al. 2015; Camedda et al. 2014). The list of the sea turtles entangled in plastic debris is given in Table 5.
Table 5. Entanglement of marine turtles in plastic debris.
|
Species
|
Ocean basin
|
Debris type
|
Pelagic juvenile
|
Neritic juvenile
|
Adult
|
Study area
|
References
|
Loggerhead (Caretta caretta)
|
Atlantic Ocean
|
Fishing
|
X
|
✓
|
✓
|
Northeastern (Boa Vista, Cape Verde Islands)
|
Lopez-Jurado et al. 2003
|
Fishing/land-based
|
X
|
✓
|
✓
|
Northeastern (Terceira Island, Azores)
|
Barreiros and Raykov, 2014
|
Mediterranean Sea
|
Land-based
|
X
|
✓
|
X
|
Tyrrhenian sea (Island of Panarea, Sicily)
|
Bentivegna, 1995
|
Fishing/land-based
|
✓
|
✓
|
✓
|
Central Mediterranean (Italy)
|
Casale et al. 2010
|
Green (Chelonia mydas)
|
Indian Ocean
|
Fishing
|
X
|
✓
|
X
|
Northeastern (Darwin, Australia)
|
Chatto, 1995
|
Fishing
|
n.a.
|
n.a.
|
n.a.
|
Northeastern (Australia)
|
Wilcox et al. 2013
|
Hawksbill (Eretmochelys imbricata)
|
Indian Ocean
|
Fishing
|
X
|
✓
|
X
|
Northeastern (Darwin, Australia)
|
Chatto, 1995
|
Fishing
|
n.a.
|
n.a.
|
n.a.
|
Northeastern (Australia)
|
Wilcox et al. 2013
|
Olive ridley (Lepidochelys olivacea)
|
Indian Ocean
|
Fishing
|
n.a.
|
n.a.
|
n.a.
|
Northeastern (McCluer Island, Australia)
|
Jensen et al. 2013
|
Fishing
|
n.a.
|
n.a.
|
n.a.
|
Northeastern (Australia)
|
Wilcox et al. 2013
|
Fishing
|
X
|
X
|
✓
|
Northeastern (Australia)
|
Chatto, 1995
|
Atlantic Ocean
|
Fishing
|
X
|
✓
|
✓
|
Southwestern (Brazil)
|
Santos et al. 2012
|
Flatback (Natator depressus)
|
Indian Ocean
|
Land-based
|
X
|
✓
|
X
|
Northeastern (Darwin, Australia)
|
Chatto, 1995
|
Fishing
|
n.a.
|
n.a.
|
n.a.
|
Northeastern (Australia)
|
Wilcox et al. 2013
|
Multiple
|
Fishing
|
n.a.
|
n.a.
|
n.a.
|
Northeastern (Australia)
|
Wilcox et al. 2014
|
Impacts on coral
The first study on the consequences of MPs consumption in corals was published in 2015 by Hall et al. (2015). Blue MPs can be ingested by Dipsastrea pallida at feeding rates of 1.2-55 g plastic cm-2h-1. Ingestion and exposure of MPs have negative effects on the symbiosis between corals and zooxanthellae (Huang et al. 2020). MP aging characteristics contribute to plastic ingestion by a variety of corals and have additional negative consequences. Table 6 summarizes what is known about the various effects of MPs on coral species.
Table 6. Impacts of microplastics on corals.
|
Species
|
MPs exposure
|
Impacts
|
References
|
Polymer
|
Size
|
Concentration
|
Duration
|
Seriotopora
caliendrum
|
PS
|
3, 6 μm
|
--
|
30 h
|
MPs enter the tentacle layer, which is occupied by symbionts, disrupting and disrupting typical coral-symbiont connections.
|
Okubo et al. 2020
|
Stylophora
pistillata
|
PE
|
106-125µm
|
5000, 50000
items/L
|
4 weeks
|
Photosynthetic efficiency is harmed; metabolite profiles of coral are altered in a minor but important way; and host-symbiont communication is affected.
|
Lanctôt et al. 2020
|
Zoanthus
sociatus
|
LDPE, PVC
|
63-125μm
|
1, 10 mg/L
(~0.5×105-4
×105, ~ 0.7×105-1.5 × 105 items/L)
|
96 h
|
High corals adherence and oxidative damage are caused, although photosynthetic efficiency is increased and no energetic expenditures are incurred.
|
Rocha et al. 2020
|
Danafungiascruposa
|
Virgin PE microbeads;
biofouled PE and PP
fragments collected
from Great Pacific
Garbage Patch
|
212-355,
600-710,
850-1000 μm microbeads; 200-500,
500-800, 800-1000µm
|
2996±5 beads/1.5L
bag; 2997±6
beads/1.5L bag, 3005±35 biofoule fragments/1 5L bag, 1480±11 beads+ 1506±14 biofouled
fragments/1.5L bag
|
2 days
|
Active swallowing and passive adherence to coral surfaces are the main mechanisms of interacting between corals and MPs; passive adhesion is the primary method; corals eat and store more biofouled MPs.
|
Corona et al. 2020
|
Astroides
calycularis
|
PE obtained from plastic bags
|
2-3 mm
|
20 items
|
30 min; 30 min; 90 min
|
Coral eating efficiency is reduced, and plankton eating does not provide adequate energy.
|
Savinelli et al. 2020
|
Symbiodini
aceae algae
(Cladocopium
goreaui)
inhabiting
in scleractinian corals
|
PS
|
1 μm
|
5 mg/L (9.0×109
items/L)
|
7 days
|
MP exposure prevents algae growth and density; greatly increases chlorophyll after 7 days without changing photocatalytic efficiency; suppresses detoxifying activity, nutrient absorption, and photosynthetic efficiency; and increases oxidative stress, apoptosis level, and ion transportation.
|
Su et al. 2020
|
Stylophora
pistillata
|
Beach-collected foam
PS containing
brominated flame
retardant
hexabromocyclododecan
es (HBCDD)
|
Leachate
from
0.6g/L
0.5-1mm
cubic
fragments
(sliced
from
>2 cm
beach-collected
macro debris) for 21
days
|
Leachate spiked with α-, β-, and
γ-HBCDD
|
5 days
|
Photosynthetic capability, symbiont frequency, and chlorophyll content of corals are all affected to a lesser extent, as is coral polyp contraction.
|
Aminot et al. 2020
|
Acropora
tenuis
|
PE microbeads;
weathered PP collected
from beach
|
1, 6 µm
PE microbead; 0.5, 1,
2 mm2
weathered PP
|
25-200 microbeads/
L; 5-50 pieces/L
|
2.5 h; 24 h
|
Cause minor disruptions to coral fertilization, embryo abnormalities, and larval settling; do not significantly impede the success of important early-life coral activities.
|
Berry et al. 2019
|
Acropora
muricata,
Pocillopora
verrucosa, Porites
lutea, Heliopora
coerulea
|
HDPE
|
1, 8 µm
|
0.25 mg/L (200
items/L)
|
6 months
|
Bleaching, tissue damage, and parasites alter symbiont photosynthetic effectiveness but have no effect on symbiont concentrations or chlorophyll levels.
|
Reichert et al.
2019
|
Lophelia
pertusa,
Madrepora
oculata
|
LDPE (with the natural
formation of surface
microbial biofilm
preincubated for two months)
|
10×10 cm
PE macroplastics; 500
μm microbeads
|
--; 350 items/L
|
5 months
|
MP films reduce prey acquisition and growth rates in the coral Lophelia pertusa, causing the polyp "cap" structure to overgrow; had no effect on the growth and eating of the coral Madrepora oculate.
|
Mouchi et al.
2019
|
Acropora
formosa
|
LDPE
|
<100, 100-200, 200-500 μm
|
0.05, 0.1 and
0.15 g/L
|
14 days
|
Bleaching and necrosis release zooxanthellae in considerable amounts.
|
Syakti et al. 2019
|
Astrangia
poculata
|
Blue PE microbeads
(with the formation of
surface microbial
biofilm incubated for
4-8 h; pre-spiked in the
Escherichia coli cell
cultures for 9 days)
|
170.5-23
0.8 µm
|
0.2 g/L; 10-25
microbeads with the Escherichia
coli biofilm
|
90 min
(feeding) +24 h (recovery in clean
seawater); 4 weeks (E. coli biofilm
microbead
feeding)
|
Consumed MPs remain in the gastrovascular cavity's mesenterial tissues, reducing subsequent brine shrimp egg eating; co-ingestion of microbeads with E. coli cells results in coral mortality after four weeks.
|
Rotjan et al. 2019
|
Montipora
capitata,
Pocillopora
damicornis
|
PE microbeads
|
150-180
µm
|
2000 items/L
under 27°C or increased 30°C
|
10 days
|
Under heat stress, greatly limit Artemia nauplii feeding but not MP consumption.
|
Axworthy
and Padilla-Gamiño, 2019
|
Pocillopora
damicornis
|
PS
|
1 μm
|
50 mg/L (9×1010
items/L)
|
24 h
|
There are no noteworthy effects of symbiont zooxanthellae abundance; chronic MP exposure increases stress response and antioxidant enzyme activities; detoxifying and immune responses are suppressed.
|
Tang et al. 2018
|
Lophelia
pertusa
|
LDPE (with the natural
formation of surface
microbial biofilm
pre-incubated for two
months)
|
10×10 cm
LDPE
macroplastics; 500
μm microbeads
|
--; 350 items/L
|
2 months
|
Lower coral skeletal development rates considerably; enhance polyp activities and decrease prey catch rates; MPs have no effect on polyp behaviour or prey capture rates, but they do lower calcification.
|
Chapron et al.
2018
|
Montastraea cavernosa,
Orbicella
faveolata
|
PE microbeads (with
the natural formation of
surface microbial
biofilm pre-incubated
for six weeks); Polyester
microFibres
|
PE (90-106 μ
m, 212-250 μ
m, 425-500 μ
m, 850-1000
μm, 1.7-2.0 mm 2.4-2.8 mm);
Polyester
(3-5 mm)
|
30 mg/L
|
48 h
|
There are no calcification consequences.
|
Hankins et al.
2018
|
Acropora
humilis,
Acropora
millepora,
Pocillopora
verrucosa,
Pocillopora
damicornis,
Porites lutea,
Porites
cylindrica
|
Pristine PE
(with the natural
formation of surface
microbial biofilm during
exposure periods)
|
37-163 μm
|
4000 items/L
|
4 weeks
|
Mucus formation, proliferation, involvement with tentacles or mesenterial filaments; bleaching and organ collapse.
|
Reichert et al.
2018
|
Favites
chinensis
|
Fluorescent carboxylate
microspheres; microbeads
from commercial
facewash
|
3, 6, 11 μm;
3-60 μm
|
--
|
2 days;
9 days
|
Intake of MPs and Artemia nauplii with MPs significantly reduces symbiotic algae's infectivity in the host and affects the commencement of symbiotic partnerships.
|
Okubo et al. 2018
|
Astrangia
poculata
|
Microbe-free plastic
mixtures (including
HDPE,LDPE,PP,PET,P
C,PVC,PS);
Sunlight-weathered and
biofouled plastic
mixtures (including PS,
LDPE,HDPE)
|
500-1000
μm; 125-1000 μm
|
--
|
24 h
|
Corals swallow different kinds of MPs due to phagostimulants in plastic leachates; corals consume more microbe-free MPs than biofouled MPs.
|
Allen et al. 2017
|
Dipsastrea
pallida
|
Blue PP
|
10-2000 μm
|
0.395 g/L; 0.197 and 0.24 g/L
|
48 h; 12 and
3 h
|
MPs are mistaken for prey; swallowed MPs remain in the coral gut cavity's mesenterial tissue for more than 24 hours.
|
Hall et al. 2015
|
Impact on human health
Humans are vulnerable to the hazardous effects of MPs, which have been shown to contain toxins, neurotoxic chemicals, and endocrine disruptors (Rochman et al. 2013a; Wright and Kelly, 2017; Galloway and Lewis, 2016; Hahladakis et al. 2018). Ingestion, dermal absorption, and inhalation are the three ways by which plastics and their compounds can enter the human body. One of the most common pathways through which MPs enter the human body is through the consumption of seafood and meals (Alfaro-Núñez et al. 2021; Smith et al. 2018; Wright and Kelly, 2017). Consequently, MPs act as a conduit for toxic contaminants from marine organisms into the human body (Fig. 7), and pose a major threat to human well-being (Smith et al. 2018). The existence of MPs in faeces of pregnant women was studied by Ar et al. (2020). All stool samples contained microplastics, according to their results. The number of microplastics detected ranged from 5 to 21, with fibres, fragments, and films being the most common. The length of MPs ranged from 0.2 to 4.9 mm. Ingested microplastics have been found to be excreted in faeces, but the residues are collected in the body and cause long-term health damage (Ar et al. 2020). The long term and detrimental effects of MPs in human health are still not fully understood and currently are being studied by many research groups worldwide.