Bioaccumulation and biomagnification of microplastics in marine organisms: a review and meta-analysis of current data

Microplastic (MP) contamination has been well documented across a range of habitats and for a large number of organisms in the marine environment. Consequently, bioaccumulation, and in particular biomagnification of MPs and associated chemical additives, are often inferred to occur in marine food webs. Presented here are the results of a systematic literature review to examine whether current, published findings support the premise that MPs and associated chemical additives bioaccumulate and biomagnify across a general marine food web. First, field and laboratory-derived contamination data on marine species were standardised by sample size from a total of 116 publications. Second, following assignment of each species to one of five main trophic levels, the average uptake of MPs and of associated chemical additives was estimated across all species within each level. These uptake data within and across the five trophic levels were then critically examined for any evidence of bioaccumulation and biomagnification. Findings corroborate previous studies that MP bioaccumulation occurs within each trophic level, while current evidence around bioaccumulation of associated chemical additives is much more ambiguous. In contrast, MP biomagnification across a general marine food web is not supported by current field observations, while results from the few laboratory studies supporting trophic transfer are hampered by using unrealistic exposure conditions. Further, a lack of both field and laboratory data precludes an examination of potential trophic transfer and biomagnification of chemical additives associated with MPs. Combined, these findings indicate that, although bioaccumulation of MPs occurs within trophic levels, no clear sign of MP biomagnification in situ was observed at the higher trophic levels. Recommendations for future studies to focus on investigating ingestion, retention and depuration rates for MPs and chemical additives under environmentally realistic conditions, and on examining the potential of multi-level trophic transfer for MPs and chemical additives have been made

Plastics for dinner: Store-bought seafood, but not wild-caught from the Great Barrier Reef, as a source of microplastics to human consumers

Seafood accounts for more than 17% of the global consumption of animal protein, with an excess of 335000 t consumed in Australia throughout 2019-2020. Recently, the presence of microplastics (MPs) within commercial seafood and the potential vectorisation of MPs to human consumers has become a significant concern for the public and the scientific community. Here, four commonly harvested wild-caught marine organisms were assessed for MP presence. These species comprise a significant proportion of the Queensland seafood industry, as well as being highly desirable to Australian consumers. The edible muscle tissue and discarded digestive tissue (GIT) of barramundi (Lates calcifer), coral trout (Plectropomus leopardus), blue leg king prawns (Melicertus latisulcatus), and Ballot's saucer scallops (Ylistrum balloti), were analysed discretely to determine the extent to which these species may be contaminated in the wild (GIT tissue), and the extent to which they themselves may act as a vector for human exposure (edible muscle tissue). Wild-caught seafood was predominantly free of MPs, with digestive tissues from two of ten coral trout containing only two fibres each. All wild-caught muscle tissue samples were free of MPs, as was the GIT of scallops, prawns, and barramundi. On the other hand, fresh, skinless barramundi muscle tissues, purchased from various commercial suppliers, were examined and found to be significantly contaminated with MPs (0.02 - 0.19 MP g-1). Overall, these results highlight the growing consensus that food can become contaminated simply by being prepared in the human environment, and the focus must shift to determining the extent of MP proliferation within the processing and point-of-sale environment

The social and mating system of the herbivorous reef fish Sparisoma viride:One-male versus multi-male groups

We present a detailed description of the social and mating system of the protogynous reef herbivore Sparisoma viride at the fringing reef of Bonaire (Netherlands Antilles). Initial phase (IP) fish and terminal phase (TP) males occur either in one- or in multi-male groups, which are compared quantitatively with respect to the use of space, size composition, social interactions and sexual activity. One-male groups consist of one TP male plus 1-14 IP females, whereas in multi-male groups up to 14 TP males and about twice as many LP fish share a common home range. The two social units further show marked differences in vertical distribution (one-male groups are restricted to depths between 3 and 22 m, multi-male groups mainly residing <3 m), size composition (a larger proportion of small adults live in multi-male groups), size and stability of the range (larger in one-male groups) and sexual activity (daily spawning of one-male group members inside their normal home range; no activity in multi-male groups on the shallow reef). Sexual activity occurred daily, throughout the year, with no evidence for tidal tracking or major seasonal or lunar patterns. The one-male groups constitute less than 20% of the adult stock but control up to 77% of the inhabited reef. As a result they have access to higher-yield food patches and to suitable spawning sites inside their home range. Although members of both units appear to defend their common home range against intruding conspecifics, the degree of territoriality is clearly higher in one-male groups. We discuss the relative importance of food, shelter, mates and mating sites as defended resources and some life history implications. The complex social and mating system of S. viride shows much resemblance to that of another Caribbean scarid, Scarus iserti. This complexity seems to reflect the capacity of individuals to flexibly adapt their feeding, mating and life history styles to an unpredictable environment. We propose that S. viride is a good study animal to test adaptive explanations for its territorial organization and complex life history patterns

Ingestion and depuration of microplastics by a planktivorous coral reef fish, Pomacentrus amboinensis

Microplastics are ubiquitous contaminants in marine environments and organisms. Concerns about potential impacts on marine organisms are usually associated with uptake of microplastics, especially via ingestion. This study used environmentally relevant exposure conditions to investigate microplastic ingestion and depuration kinetics of the planktivorous damselfish, Pomacentrus amboinensis. Irregular shaped blue polypropylene (PP) particles (longest length 125–250 μm), and regular shaped blue polyester (PET) fibers (length 600–700 μm) were selected based on physical and chemical characteristics of microplastics commonly reported in the marine environment, including in coral reef ecosystems. Individual adult damselfish were exposed to a single dose of PP particles and PET fibers at concentrations reported for waters of the Great Barrier Reef (i.e., environmentally relevant concentrations, ERC), or future projected higher concentrations (10x ERC, 100x ERC). Measured microplastic concentrations were similar to their nominal values, confirming that PP particles and PET fibers were present at the desired concentrations and available for ingestion by individual damselfish. Throughout the 128-h depuration period, the 88 experimental fish were sampled 2, 4, 8, 16, 32, 64, and 128-h post microplastic exposure and their gastrointestinal tracts (GIT) analyzed for ingested microplastics. While damselfish ingested both experimental microplastics at all concentrations, body burden, and depuration rates of PET fibers were significantly larger and longer, respectively, compared to PP particles. For both microplastic types, exposure to higher concentrations led to an increase in body burden and lower depuration rates. These findings confirm ingestion of PP particles and PET fibers by P. amboinensis and demonstrate for the first time the influence of microplastic characteristics and concentrations on body burden and depuration rates. Finally, despite measures put in place to prevent contamination, extraneous microplastics were recovered from experimental fish, highlighting the challenge to completely eliminate contamination in microplastic exposure studies. These results are critical to inform and continuously improve protocols for future microplastics research, and to elucidate patterns of microplastic contamination and associated risks in marine organisms

2017 Scientific Consensus Statement: land use impacts on the Great Barrier Reef water quality and ecosystem condition, Chapter 1: the condition of coastal and marine ecosystems of the Great Barrioer Reef and their responses to water quality and disturbances

The condition of coastal and marine ecosystems on the Great Barrier Reef and their responses to water quality and disturbances. The Great Barrier Reef marine ecosystems and their associated catchments are part of a dynamic, interconnected system. This chapter provides an up-to-date review of the state of knowledge relating to the conditions and trends of key Great Barrier Reef coastal and marine ecosystems, including current knowledge on key drivers of change and activities leading to pressures and impacts on these ecosystems. Drivers include the impacts of land run-off, coastal development activities and other disturbances such as extreme weather events that influence Great Barrier Reef water quality and the health of marine and coastal ecosystems

Hepatic transcriptomic profiles from barramundi, Lates calcarifer, as a means of assessing organism health and identifying stressors in rivers in northern Queensland

Resource managers need to differentiate between sites with and without contaminants and those where contaminants cause impacts. Potentially, transcriptomes could be used to evaluate sites where contaminant-induced effects may occur, to identify causative stressors of effects and potential adverse outcomes. To test this hypothesis, the hepatic transcriptomes in Barramundi, a perciforme teleost fish, (Lates calcarifer) from two reference sites, two agriculturally impacted sites sampled during the dry season, and an impacted site sampled during the wet season were compared. The hepatic transcriptome was profiled using RNA-Seq. Multivariate analysis showed that transcriptomes were clustered based on site and by inference water quality, but not sampling time. The largest differences in transcriptomic profile were between reference sites and a site sampled during high run-off, showing that impacted sites can be identified via RNA-Seq. Transcripts with altered abundance were linked to xenobiotic metabolism, peroxisome proliferation and stress responses, indicating putative stressors with the potential for adverse outcomes in barramundi