An investigation into the stability and degradation of plastics in aquatic environments using a large-scale field-deployment study.

The fragmentation of plastic debris is a key pathway to the formation of microplastic pollution. These disintegration processes depend on the materials' physical and chemical characteristics, but insight into these interrelationships is still limited, especially under natural conditions. Five plastics of known polymer/additive compositions and processing histories were deployed in aquatic environments and recovered after six and twelve months. The polymer types used were linear low density polyethylene (LLDPE), oxo-degradable LLDPE (oxoLLDPE), poly(ethylene terephthalate) (PET), polyamide-6 (PA6), and poly(lactic acid) (PLA). Four geographically distinct locations across Aotearoa/New Zealand were chosen: three marine sites and a wastewater treatment plant (WWTP). Accelerated UV-weathering under controlled laboratory conditions was also carried out to evaluate artificial ageing as a model for plastic degradation in the natural environment. The samples' physical characteristics and surface microstructures were studied for each deployment location and exposure time. The strongest effects were found for oxoLLDPE upon artificial ageing, with increased crystallinity, intense surface cracking, and substantial deterioration of its mechanical properties. However, no changes to the same extent were found after recovery of the deployed material. In the deployment environments, the chemical nature of the plastics was the most relevant factor determining their behaviours. Few significant differences between the four aquatic locations were identified, except for PA6, where indications for biological surface degradation were found only in seawater, not the WWTP. In some cases, artificial ageing reasonably mimicked the changes which some plastic properties underwent in aquatic environments, but generally, it was no reliable model for natural degradation processes. The findings from this study have implications for the understanding of the initial phases of plastic degradation in aquatic environments, eventually leading to microplastics formation. They can also guide the interpretation of accelerated laboratory ageing for the fate of aquatic plastic pollution, and for the testing of aged plastic samples.

Leaching and transformation of chemical additives from weathered plastic deployed in the marine environment.

Plastic pollution causes detrimental environmental impacts, which are increasingly attributed to chemical additives. However, the behaviour of plastic additives in the marine environment is poorly understood. We used a marine deployment experiment to examine the impact of weathering on the extractables profile, analysed by liquid chromatography-mass spectrometry, of four plastics at two locations over nine months in Aotearoa/New Zealand. The concentration of additives in polyethylene and oxo-degradable polyethylene were strongly influenced by artificial weathering, with deployment location and time less influential. By comparison, polyamide 6 and polyethylene terephthalate were comparatively inert with minimal change in response to artificial weathering or deployment time. Non-target analysis revealed extensive differentiation between non-aged and aged polyethylene after deployment, concordant with the targeted analysis. These observations highlight the need to consider the impact of leaching and weathering on plastic composition when quantifying the potential impact and risk of plastic pollution within receiving environments.

Effect-based monitoring of two rivers under urban and agricultural influence reveals a range of biological activities in sediment and water extracts.

Chemical contaminants, such as pesticides, pharmaceuticals and industrial compounds are ubiquitous in surface water and sediment in areas subject to human activity. While targeted chemical analysis is typically used for water and sediment quality monitoring, there is growing interest in applying effect-based methods with in vitro bioassays to capture the effects of all active contaminants in a sample. The current study evaluated the biological effects in surface water and sediment from two contrasting catchments in Aotearoa New Zealand, the highly urbanised Whau River catchment in Tamaki Makaurau (Auckland) and the urban and mixed agricultural Koreti (New River) Estuary catchment. Two complementary passive sampling devices, Chemcatcher for polar chemicals and polyethylene (PED) for non-polar chemicals, were applied to capture a wide range of contaminants in water, while composite sediment samples were collected at each sampling site. Bioassays indicative of induction of xenobiotic metabolism, receptor-mediated effects, genotoxicity, cytotoxicity and apical effects were applied to the water and sediment extracts. Most sediment extracts induced moderate to strong estrogenic and aryl hydrocarbon (AhR) activity, along with moderate toxicity to bacteria. The water extracts showed similar patterns to the sediment extracts, but with lower activity. Generally, the polar Chemcatcher extracts showed greater estrogenic activity, photosynthesis inhibition and algal growth inhibition than the non-polar PED extracts, though the PED extracts showed greater AhR activity. The observed effects in the water extracts were compared to available ecological effect-based trigger values (EBT) to evaluate the potential risk. For the polar extracts, most sites in both catchments exceeded the EBT for estrogenicity, with many sites exceeding the EBTs for AhR activity and photosynthesis inhibition. Of the wide range of endpoints considered, estrogenic activity, AhR activity and herbicidal activity appear to be the primary risk drivers in both the Whau and Koreti Estuary catchments.

Impact of accelerated weathering on the leaching kinetics of stabiliser additives from microplastics.

The release of additives from microplastics is known to harm organisms. In the environment, microplastics are exposed to weathering processes which are suspected to influence additive leaching kinetics, the extent and mechanism of which remain poorly understood. We examined the impact of weathering on stabiliser additive leaching kinetics using environmentally relevant accelerated weathering and leaching procedures. Nine binary polymer-additive formulations were specifically prepared, weathered, analysed, and evaluated for their leaching characteristics. Cumulative additive release (Ce) varied widely between formulations, ranging from 0.009 to 1162 µg/g. Values of Ce generally increased by polymer type in the order polyethylene terephthalate < polyamide 6 < polyethylene. The change in leaching kinetics after accelerated weathering was incongruous across the nine formulations, with a significant change in Ce only observed for three out of nine formulations. Physicochemical characterisation of the microplastics demonstrated that additive blooming was the primary mechanism influencing the leaching response to weathering. These findings highlight the dependency of additive fate on the polymer type, additive chemistry, and the extent of weathering exposure. This has significant implications for risk assessment and mitigation, where the general assumption that polymer weathering increases additive leaching may be too simplistic.

Solving a microplastic dilemma? Evaluating additive release with a dynamic leaching method for microplastic assessment (DyLeMMA).

Microplastics and plastic additives are contaminants of emerging environmental concern. Static leaching methods are commonly applied to assess the rate and extent of additive release from microplastics. However, this approach may not be representative of environmental conditions where near infinite dilution or percolation commonly occur. We evaluated three different approaches for assessing additive leaching under environmentally relevant sink conditions, culminating in the refinement and validation of DyLeMMA (Dynamic Leaching Method for Microplastic Assessment). Analysis was performed using a high-resolution liquid chromatography-mass spectrometry method enabling targeted quantification of additives and screening for non-intentionally added substances. Using four different plastics, sink conditions were maintained over the duration of the test, thereby avoiding solubility limited release and ensuring environmental relevance. Background contamination from ubiquitous additive chemicals was minimised, thereby providing good sensitivity and specificity. Resulting data, in the form of additive release curves, should prove suitable for fitting to release models and derivation of parameters describing additive leaching from microplastics.Key attributes of DyLeMMA:•Environmentally relevant dynamic leaching method for microplastics, demonstrated to maintain sink conditions over the test duration,•Simple, fast, and cost-effective approach without complication of using a solid phase sink,•Provide data suitable for understanding microplastic leaching kinetics and mechanisms.

Honey bee toxicological responses do not accurately predict environmental risk of imidacloprid to a solitary ground-nesting bee species.

Honey bees (Apis mellifera) are the current model species for pesticide risk assessments, but considering bee diversity, their life histories, and paucity of non-eusocial bee data, this approach could underestimate risk. We assessed whether honey bees were an adequate risk predictor to non-targets. We conducted oral and contact bioassays for Leioproctus paahaumaa, a solitary ground-nesting bee, and A. mellifera, using imidacloprid (neonicotinoid) and dimethoate (organophosphate). The bees responded inconsistently; L. paahaumaa were 36 and 194 times more susceptible to oral and topically applied imidacloprid than A. mellifera, but showed comparable sensitivity to dimethoate. Furthermore, the proposed safety factor of ten applied to honey bee endpoints did not cover the interspecific sensitivity difference. Our standard-setting study highlights the urgent need for more comparative inter-species toxicity studies and the development of standardized toxicity protocols to ensure regulatory pesticide risk assessment frameworks are protective of diverse pollinators.

Disentangling the influence of microplastics and their chemical additives on a model detritivore system.

Microplastics (MPs) can negatively impact freshwater organisms via physical effects of the polymer itself and/or exposure to chemicals added to plastic during production to achieve desired characteristics. Effects on organisms may result from direct exposure to plastic particles and/or chemical additives or effects may manifest as indirect effects through ecological interactions between organisms (e.g., reduced food availability that impairs a consumer). To disentangle these issues, we used a simplified freshwater food web interaction comprising microbes and macroinvertebrate detritivores to evaluate the toxicity of 1) polyvinyl chloride (PVC) MPs without added chemicals (virgin), 2) the common chemical additive dibutyl phthalate (DBP), and 3) PVC MPs with incorporated DBP. Exposure to virgin PVC MPs (0.33 and 3.3 mg/L) caused negligible ecological effect with the exception of reduced macroinvertebrate feeding rates at 3.3 mg/L. Exposure to DBP (1 mg/L) both individually and when incorporated into the PVC MPs negatively impacted all tested endpoints, including microbial and macroinvertebrate respiration, feeding rate and assimilation efficiency. DBP leached rapidly from the MPs into the water, and also accumulated in macroinvertebrates and their food, providing multiple routes of exposure. Our findings suggest that additives which are intentionally incorporated into MPs could play a key role in MP toxicity and contribute to the disruption of key ecological interactions underpinning ecosystem processes, such as leaf litter decomposition.

Plastic additives: challenges in ecotox hazard assessment.

The risk of plastic debris, and specifically micro(nano)plastic particles, to ecosystems remains to be fully characterized. One particular issue that warrants further characterization is the hazards associated with chemical additives within micro(nano)plastic as they are not chemically bound within the polymers and can be persistent and biologically active. Most plastics contain additives and are therefore potential vectors for the introduction of these chemicals into the environment as they leach from plastic, a process that can be accelerated through degradation and weathering processes. There are knowledge gaps on the ecotoxicological effects of plastic additives and how they are released from parent plastic materials as they progressively fragment from the meso to micro and nano scale. This review summarizes the current state of knowledge of the ecotoxicity of plastic additives and identifies research needs to characterize the hazard they present to exposed biota. The potential ecological risk of chemical additives is of international concern so key differences in governance between the European Union and New Zealand to appropriately characterize their risk are highlighted.

Leaching and extraction of additives from plastic pollution to inform environmental risk: A multidisciplinary review of analytical approaches.

Plastic pollution is prevalent worldwide and has been highlighted as an issue of global concern due to its harmful impacts on wildlife. The extent and mechanism by which plastic pollution effects organisms is poorly understood, especially for microplastics. One proposed mechanism by which plastics may exert a harmful effect is through the leaching of additives. To determine the risk to wildlife, the chemical identity and exposure to additives must be established. However, there are few reports with disparate experimental approaches. In contrast, a breadth of knowledge on additive release from plastics is held within the food, pharmaceutical and medical, construction, and waste management industries. This includes standardised methods to perform migration, extraction, and leaching studies. This review provides an overview of the approaches and methods used to characterise additives and their leaching behaviour from plastic pollution. The limitations of these methods are highlighted and compared with industry standardised approaches. Furthermore, an overview of the analytical strategies for the identification and quantification of additives is presented. This work provides a basis for refining current leaching approaches and analytical methods with a view towards understanding the risk of plastic pollution.

Outcomes of the first combined national survey of pesticides and emerging organic contaminants (EOCs) in groundwater in New Zealand 2018.

The first national survey of Emerging Organic Contaminants (EOCs) involved sampling 121 wells located throughout New Zealand and analysis for a suite of 29 EOCs. This survey was carried out in conjunction with the 2018 national survey of pesticides in groundwater, a survey that is conducted on a four-yearly basis which included the analysis of glyphosate for first time. A total of 227 EOCs were detected in the 85 wells (70%). There were 29 different EOCs in the analytical suite and 25 different EOCs were detected in at least one well. The highest concentration measured was 655 ng/L for sucralose, an artificial sweetener. These results indicate that EOCs, sourced from either animal or human effluents/activities, are making their way into shallow groundwater systems and can be detected at low concentrations. A total of 135 wells were analysed for glyphosate, glufosinate and their principal metabolites. There was only one detection of glyphosate at a concentration of 2.1 µg/L. This well showed evidence of poor wellhead protection and the contamination likely came from containers that were stored near the well. A total of 279 wells were sampled and analysed for pesticides and 68 wells (24.4%) contained detectable residues of pesticides, with 28 of these wells having two or more pesticides detected. The maximum number of pesticides detected in one well was six. None of the sampled wells exceeded the Maximum Acceptable Value (MAV) for drinking water in New Zealand and the concentrations of most of the detected pesticides were equivalent to less than 0.5% of the MAV. Comparisons with earlier National Surveys of pesticides in groundwater in New Zealand indicate the frequencies of pesticide detections have remained similar over the last 16 years, with higher detection frequencies occurring before that time.

Organic Micropollutants in Wastewater Effluents and the Receiving Coastal Waters, Sediments, and Biota of Lyttelton Harbour (Te Whakaraupo), New Zealand.

Coastal ecosystems are receiving environments for micropollutants due to high levels of associated anthropogenic activities. Effluent discharges from wastewater treatment plants are a significant source of micropollutants to coastal environments. Wastewater effluents, seawater, sediments, and green-lipped mussels (Perna canaliculus) in Lyttelton Harbour (Te Whakaraupo), Christchurch, New Zealand, were analysed for a suite of personal care products and steroid hormones during a 1-year period. In wastewater effluents, the concentration of methyl paraben (mParaben), ethyl paraben (eParaben), propyl paraben (pParaben), butyl paraben (bParaben), 4-t-octylphenol (OP), 4-methylbenzylidene camphor (4-MBC), benzophenone-3 (BP-3), benzophenone-1 (BP-1), triclosan, methyl triclosan (mTric), Bisphenol A (BPA), Estrone (E1), 17ß-estradiol (E2), 17α-ethinyl estradiol (EE2), and Estriol (E3) ranged from < 0.6 to 429 ng L-1 and was dominated by OP, 4-MBC, BP-3, triclosan, BP-1, and BPA. In seawater, 4-MBC, BP-3, BPA, and E1 were the most frequently detected contaminants (< 0.2-9.4 ng L-1). Coastal sediment samples contained mParaben, OP, 4-MBC, BP-3, BP-1, BPA, OMC, and E1 (< 0.2-11 ng g-1 d.w.), and mParaben, OP, and BP-3 were found to bioaccumulate (3.8-21.3 ng g-1 d.w.) in green lipped mussels.

Development of acute and chronic toxicity bioassays using the pelagic copepod Gladioferens pectinatus.

Well validated and reliable biological assays using local and native species are required to characterise the impacts of pollution on ecosystem health. We identified a native estuarine pelagic copepod species suitable for assessing the ecotoxicological impact of anthropogenic contaminants. Gladioferens pectinatus fulfilled the necessary-selection criteria of: wide distribution and abundance across New Zealand estuaries, ease of maintenance in the laboratory, short life cycle, sensitivity to toxicants with different modes of action, and providing reproducibility of biological response to toxicants. Measured endpoints were survival and larval development rate for the nauplii, and survival, realized offspring and total potential offspring for adults. LC50 values for the survival of G. pectinatus exposed to copper, phenanthrene and chlorpyrifos were 170 (143-193), 181.3 (131.3-231.3) and 4.3 (3.8-4.9) µg/L, respectively. The most sensitive chronic endpoint identified for G. pectinatus was the larval development rate, with EC50 values of 49.8 (45-55.3), 31.3 (24.8-44.7) and 1.97 (1.6-2.31) µg/L for copper, phenanthrene and chlorpyrifos, respectively. The acute and chronic responses obtained for G. pectinatus against the three reference toxicants are comparable with those reported for other copepod species and confirm its sensitivity and suitability to assess the toxicity of New Zealand estuarine samples.

Assessment of endocrine disruption and oxidative potential of bisphenol-A, triclosan, nonylphenol, diethylhexyl phthalate, galaxolide, and carbamazepine, common contaminants of municipal biosolids.

The use of biosolids as a soil conditioner and fertiliser is hindered by the limited knowledge on the risks of micro-contaminants they contain. This study investigated the binding of six organic contaminants commonly found in biosolids, to the estrogen (ER), androgen (AR), aryl hydrocarbon (AhR), and transthyretin (TTR) receptors and their redox activity. Triclosan (TCS), bisphenol-A (BPA), and technical nonylphenol (TNP) had affinity for the TTR with relative potencies of 0.3, 0.03, and 0.076 respectively. Further, binding to TTR was the only toxicological response observed for carbamazepine, which induced sub-maximal response and relative potency of 0.0017. Estrogenic activity was induced by BPA, galaxolide (HHCB), diethylhexyl phthalate (DEHP) and TNP with BPA having the strongest potency of 5.1 × 10-6 relative to estradiol. Only BPA showed androgenic activity but it was not quantifiable. BPA also showed anti-androgenic activity along with TCS, HHCB, and TNP in the order of TNP > HHCB > TCS ~ BPA (relative potencies 0.126, 0.042, 0.032, 0.03). No compounds exhibited anti-estrogenic or AhR activity, or were redox-active in the dithiothreitol assay. The results highlight the multiple modes of action through which these compounds may impact exposed organisms, and the concentrations at which effects may occur. This allows assessment of the likelihood of effects being observed at environmental concentrations, and the potential contribution of these compounds.

Assessment of urban stream sediment pollutants entering estuaries using chemical analysis and multiple bioassays to characterise biological activities.

Stormwater contaminants are a major source of often neglected environmental stressors because of the emphasis placed on the management of municipal and industrial wastewaters. Stormwater-derived pollutants in sediments from two New Zealand estuaries was characterised by analytical chemistry and bioassays. Contaminants were extracted from sediment using accelerated solvent extraction (ASE), recovered and concentrated by solid phase extraction (SPE), and analysed for polycyclic aromatic hydrocarbons (PAHs), selected metals, and musk fragrances. The concentrations of PAHs were below the ANZECC Interim Sediment Quality Guideline values while those of lead and zinc exceeded them in some samples. The sediment extracts containing organic contaminants exhibited acute toxicity in the zebrafish fish embryo toxicity (FET) and teratogenicity, induction of biotransformation (EROD activity), and genotoxicity (comet assay) in zebrafish. The potential of the extracts to interact with endocrine signalling processes was assessed by GeneBLAzer reporter gene bioassays and they exhibited estrogenic, androgenic, and anti-progestagenic activities.

Assessment of cytotoxicity, genotoxicity and 7-ethoxyresorufin-O-deethylase (EROD) induction in sediment extracts from New Zealand urban estuaries.

Sediments represent a major sink for contaminants resulting from industrial and agricultural activities - especially lipophilic substances. This study exclusively used in vitro methodologies to characterize specific toxicity effects of contaminants in sediment extracts from two urban New Zealand estuaries. Sediment extracts were prepared and tested for a range of biological endpoints. The micronucleus and comet assays in V79 cells were used to assess genotoxicity. Induction of 7-ethoxyresorufin-O-deethylase in piscine RTL-W1 cells was determined to estimate dioxin-like toxicity. Cytotoxic potentials were analyzed by neutral red uptake and MTT reduction. There was evidence of strong dioxin-like toxicity and moderate cytotoxicity. Genotoxicity was distinct in the micronucleus assay, but low in the comet assay. The results indicate the presence of chemicals in the sediments with the potential to pose a risk through multiple mechanisms of toxicity, the identities and amounts of which will be disclosed in a parallel study alongside with in vivo toxicity data.

The impact of variations of influent loading on the efficacy of an advanced tertiary sewage treatment plant to remove endocrine disrupting chemicals.

The impact of changes in influent load on the removal of endocrine disrupting chemicals (EDCs) by sewage treatment has not been fully characterised. This study assessed the efficacy of an advanced tertiary sewage treatment plant (STP) to remove EDCs during normal and peak flow events of sewage influent using trace chemical analysis of selected EDCs and four estrogenic in vitro bioassays. During the summer holiday season, influent volume increased by 68%, nutrient concentrations by at least 26% and hydraulic retention time was reduced by 40% compared with base flow conditions. Despite these pressures on the treatment system the concentrations and mass loading of estrone, 17ß-estradiol, estriol, Bisphenol A, 4-t-octylphenol and technical nonylphenol were not significantly higher (p>0.05) during the peak flow conditions compared with base flow conditions. Chemical analysis and in vitro bioassays showed that the efficacy of the STP in removing EDCs was not affected by the different loadings between baseline and peak flow regimes. This study demonstrates that large flow variations within the design capacity of advanced multi-stage STPs should not reduce the removal efficacy of EDCs.

Characterisation of microcontaminants in Darwin Harbour, a tropical estuary of northern Australia undergoing rapid development.

The detection of microcontaminants in aquatic environments raises concerns about their potential to exert ecotoxicological effects and impact human health. In contrast to freshwater habitats, little information is available on environmental concentrations in urban estuarine and marine environments. This study investigated an extensive range of organic and inorganic microcontaminants in the Darwin Harbour catchment, a tropical estuary in northern Australia undergoing rapid urbanisation and industrial development. We sampled wastewater effluent and surface water from seven sites in Darwin Harbour for pharmaceuticals and personal care products, alkylphenols, hormones, pesticides, herbicides and metals. In vitro bioassays were used to estimate the (anti)estrogenic and (anti)androgenic activities of samples. Seventy-nine of 229 organic microcontaminants analysed were detected at concentrations ranging from 0.01 to 20 µg/L, with acesulfame, paracetamol, cholesterol, caffeine, DEET and iopromide detected at the highest concentrations in wastewater effluent (20 µg/L, 17 µg/L, 11 µg/L, 11 µg/L, 10 µg/L and 7.6 µg/L, respectively). Levels of estrogenic activity ranged from estradiol equivalency quotients (EEQs) of <0.10 to 6.29±0.16 ng/L while levels of androgenic activity ranged from dihydrotestosterone equivalency quotients (DHTEQs) of <3.50 to 138.23±3.71 ng/L. Environmental concentrations of organic microcontaminants were comparable to ranges reported from aquatic environments worldwide with sewage effluent discharges representing the dominant source of entry into Darwin Harbour. The measured concentration range of DEET was higher than ranges reported in previous studies.

Personal care products and steroid hormones in the Antarctic coastal environment associated with two Antarctic research stations, McMurdo Station and Scott Base.

Pharmaceutical and personal care products (PPCPs) are a major source of micropollutants to the aquatic environment. Despite intense research on the fate and effects of PPCPs in temperate climates, there is a paucity of data on their presence in polar environments. This study reports the presence of selected PPCPs in sewage effluents from two Antarctic research stations, the adjacent coastal seawater, sea ice, and biota. Sewage effluents contained bisphenol-A, ethinylestradiol, estrone, methyl triclosan, octylphenol, triclosan, and three UV-filters. The maximum sewage effluent concentrations of 4-methyl-benzylidene camphor, benzophenone-1, estrone, ethinylestradiol, and octylphenol exceeded concentrations previously reported. Coastal seawaters contained bisphenol-A, octylphenol, triclosan, three paraben preservatives, and four UV-filters. The sea ice contained a similar range and concentration of PPCPs as the seawater. Benzophenone-3 (preferential accumulation in clams), estradiol, ethinylestradiol, methyl paraben (preferential accumulation in fish, with concentrations correlating negatively with fillet size), octylphenol, and propyl paraben were detected in biota samples. PPCPs were detected in seawater and biota at distances up to 25 km from the research stations WWTP discharges. Sewage effluent discharges and disposal of raw human waste through sea ice cracks have been identified as sources of PPCPs to Antarctic coastal environments.

Degradation rate of sodium fluoroacetate in three New Zealand soils.

The degradation rate of sodium fluoroacetate (SFA) was assessed in a laboratory microcosm study incorporating 3 New Zealand soil types under different temperature (5 °C, 10 °C, or 20 °C) and soil moisture (35% or 60% water holding capacity) conditions using guideline 307 from the Organisation for Economic Co-operation and Development. A combination of nonlabeled and radiolabeled (14) C-SFA was added to soil microcosms, with sampling and analysis protocols for soil, soil extracts, and evolved CO(2) established using liquid scintillation counting and liquid chromatography-mass spectrometry. Degradation products of SFA and their rates of formation were similar in the 3 soil types. The major degradation pathway for SFA was through microbial degradation to the hydroxyl metabolite, hydroxyacetic acid, and microbial mineralization to CO(2), which constituted the major transformation product. Temperature, rather than soil type or moisture content, was the dominant factor affecting the rate of degradation. Soil treatments incubated at 20 °C displayed a more rapid loss of (14)C-SFA residues than lower temperature treatments. The transformation half-life (DT50) of SFA in the 3 soils increased with decreasing temperature, varying from 6 d to 8 d at 20 °C, 10 d to 21 d at 10 °C, and 22 d to 43 d at 5 °C.

Development of acute and chronic sediment bioassays with the harpacticoid copepod Quinquelaophonte sp.

Reliable environmentally realistic bioassay methodologies are increasingly needed to assess the effects of environmental pollution. This study describes two estuarine sediment bioassays, one acute (96 h) and one chronic (14 d), with the New Zealand harpacticoid copepod Quinquelaophonte sp. utilising behavioural and reproductive endpoints. Spiked sediments were used to expose Quinquelaophonte sp. to three reference compounds representing important categories of estuarine chemical stressors: zinc (a metal), atrazine (a pesticide), and phenanthrene (a polycyclic aromatic hydrocarbon). Acute-to-chronic ratios (ACR) were used to further characterise species responses. Acute sediment (sandy and low total organic content) 96 h EC50 values for the sublethal inhibition of mobility for zinc, atrazine and phenanthrene were 137, 5.4, and 2.6 µg/g, respectively. The chronic EC50 values for inhibition of reproduction (total offspring) were 54.5, 0.0083, and 0.067 µg/g for zinc, atrazine, and phenanthrene, respectively. For phenanthrene, a potentially novel mode of action was identified on reproduction. Quinquelaophonte sp. was found to be more sensitive than several other estuarine species indicating choice of test organism is important to characterising the effects of environmentally relevant levels of contamination. The bioassay sediment results demonstrate the sensitivity and suitability of Quinquelaophonte sp. as a tool for the assessment use of estuarine health.