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In a recent editorial, the Editors-in-Chief of Journal of Experimental Biology argued that consensus building, data sharing, and better integration across disciplines are needed to address the urgent scientific challenges posed by climate change. We agree and expand on the importance of cross-disciplinary integration and transparency to improve consensus building and advance climate change research in experimental biology. We investigated reproducible research practices in experimental biology through a review of open data and analysis code associated with empirical studies on three debated paradigms and for unrelated studies published in leading journals in comparative physiology and behavioural ecology over the last 10 years. Nineteen per cent of studies on the three paradigms had open data, and 3.2% had open code. Similarly, 12.1% of studies in the journals we examined had open data, and 3.1% had open code. Previous research indicates that only 50% of shared datasets are complete and re-usable, suggesting that fewer than 10% of studies in experimental biology have usable open data. Encouragingly, our results indicate that reproducible research practices are increasing over time, with data sharing rates in some journals reaching 75% in recent years. Rigorous empirical research in experimental biology is key to understanding the mechanisms by which climate change affects organisms, and ultimately promotes evidence-based conservation policy and practice. We argue that a greater adoption of open science practices, with a particular focus on FAIR (Findable, Accessible, Interoperable, Re-usable) data and code, represents a much-needed paradigm shift towards improved transparency, cross-disciplinary integration, and consensus building to maximize the contributions of experimental biologists in addressing the impacts of environmental change on living organisms.

In North America, studies regarding effects of CO2-induced low pH in bivalve aquaculture are largely restricted to the US Pacific coast. Studies on species from the northwest Atlantic are lacking. Furthermore, information on the roles of intergenerational exposure and biological sex in bivalve responses to low pH, particularly in an aquaculture-specific context, is scant. We tested if short-term (1 month) exposure to CO2-induced reductions in pHNBS affected the reproductive development of male and female eastern oysters (Crassostrea virginica) during hatchery-specific reproductive conditioning and whether maternal and/or paternal exposure influenced larval responses. Reduced pH (7.5–7.7) increased the rate of reproductive development in both males and females. There was no indication of intergenerational effects; adult pH conditions did not affect early larval development. In contrast, low pH conditions experienced by gametes during spawning, fertilization, and embryo incubation (48 h) resulted in higher larval survival (+6–8% from control), reduced shell height (−2 to 3 µm), and increased deformities (abnormal shell shape; +3–5%). We suggest that local adaptation to acidic land runoff may account for the positive effects of low pH observed in this study. Bioeconomic assessments are now needed to understand the implications of reduced pH on aquaculture operations in these regions of Atlantic Canada.

Ocean acidification—decreasing oceanic pH resulting from the uptake of excess atmospheric CO2—has the potential to affect marine life in the future. Among the possible consequences, a series of studies on coral reef fish suggested that the direct effects of acidification on fish behavior may be extreme and have broad ecological ramifications. Recent studies documenting a lack of effect of experimental ocean acidification on fish behavior, however, call this prediction into question. Indeed, the phenomenon of decreasing effect sizes over time is not uncommon and is typically referred to as the “decline effect.” Here, we explore the consistency and robustness of scientific evidence over the past decade regarding direct effects of ocean acidification on fish behavior. Using a systematic review and meta-analysis of 91 studies empirically testing effects of ocean acidification on fish behavior, we provide quantitative evidence that the research to date on this topic is characterized by a decline effect, where large effects in initial studies have all but disappeared in subsequent studies over a decade. The decline effect in this field cannot be explained by 3 likely biological explanations, including increasing proportions of studies examining (1) cold-water species; (2) nonolfactory-associated behaviors; and (3) nonlarval life stages. Furthermore, the vast majority of studies with large effect sizes in this field tend to be characterized by low sample sizes, yet are published in high-impact journals and have a disproportionate influence on the field in terms of citations. We contend that ocean acidification has a negligible direct impact on fish behavior, and we advocate for improved approaches to minimize the potential for a decline effect in future avenues of research.

The fossil record is the primary source of data used to study predator-prey interactions in deep time and to evaluate key questions regarding the evolutionary and ecological importance of predation. Here, we review the types of paleontological data used to infer predation in the marine fossil record, discuss strengths and limitations of paleontological lines of evidence used to recognize and evaluate predatory activity, assess the influence of environmental gradients on predation patterns, and review fossil evidence for predator behavior and prey defense. We assembled a predation database from the literature that documents a steady increase in the number of papers on predation since the 1960s. These studies have become increasingly quantitative and have expanded in focus from reporting cases of predation documented by fossils to using the fossil record of predation to test ecological and evolutionary hypotheses. The data on the fossil record of predation amassed so far in the literature primarily come from trace fossils, mostly drill holes and, to a lesser extent, repair scars, derived predominantly from the Cenozoic of Europe and North America. Mollusks are the clade most often studied as prey and inferred predators. We discuss how to distinguish biotic from abiotic damage and predatory from parasitic traces, and how to recognize failed predation. Our data show that identifying the predator is easiest when predator and prey are preserved in the act of predation or when predators were fossilized with their gut contents preserved. However, determining the culprits responsible for bite traces, drill holes, and other types of predation traces can be more problematic. Taphonomic and other factors can distort patterns of predation, but their potential effects can be minimized by careful study design. With the correct identification and quantification of fossilized traces of predation, ecological trends in predator-prey interactions may be discerned along environmental gradients in water depth, habitat, and oxygen and nutrient availability. However, so far, these trends have not been explored adequately for the fossil record. We also review the effects of climate change and ocean acidification on predator-prey interactions, but, again, few studies consider those factors from a deep-time perspective. Finally, fossils have been used successfully to infer the behavior of ancient predators and identify and interpret active and passive defense strategies employed by their prey. The marine fossil record of predation has become a major field of research over the last 50 years, but many critical gaps remain in our understanding of the evolutionary history of predator-prey interactions.

While high levels of siltation are known to be deleterious to eastern oysters (Crassostrea virginica), the collective effect of suspended and bedded sediment is understudied from the perspective of oyster farming and bed restoration. In this study, we used laboratory experiments to explore spat settlement rates on a wild bed proxy substrate (i.e., empty shells on the bottom of experimental tanks) in conditions simulating a siltation event and the presence of suspended spat collectors. Using high-frequency valvometry, we also described the behavioural effects of acute sediment burial on wild adult oysters in situ. The vast majority of larvae settled on bottom substrate as opposed to suspended collectors. Sediment negatively affected overall oyster spat settlement on bottom shell, as spat densities were ≈3 × lower when sediment was present. This negative effect was largely attributed to severely depressed spat densities on the upper side (top) of bottom shells. Settlement on the underside of bottom shell was less affected. Wild adult oyster behaviour was negatively affected by acute burial, which ultimately resulted in death. We suggest that the reduction in settlement in the presence of siltation is likely due to the combined effects of suspended sediment on cue detection and bedded sediment on substrate availability. Given that oysters are ecosystem engineers, the negative effects of siltation on both larval and adult oysters can ultimately result in cascading effects to the surrounding biological community.

16 pages, 5 figures, 2 tables, Sustained periods of anoxia, driven by eutrophication, threaten coastal marine systems and can lead to mass mortalities of even resilient animals such as bivalves. While mortality rates under anoxia are well-studied, the specific mechanism(s) of mortality are less clear. We used a suite of complementary techniques (LT50, histology, 16S rRNA amplicon sequencing, and valvometry) to show that the proliferation of anaerobic bacteria within eastern oysters (Crassostrea virginica) accelerates mortality rate under anoxic conditions. Manipulative laboratory experiments revealed that oyster survival under anoxic conditions was halved when bacteria were present compared to when they were excluded by the broad-spectrum antibiotic chloramphenicol. Histological assessments supported this mechanism and showed infiltration of bacteria in oysters that were not treated with antibiotics compared to a general lack of bacteria when oysters were treated with antibiotics. 16S rRNA amplicon sequencing failed to identify any particular genera of bacteria responsible for mortality, rather a diversity of endogenous anaerobic and/or sulfate-reducing bacteria were common among oysters. In addition, monitoring of oyster valve gaping behavior in the field revealed that oysters showed remarkable valve closure synchrony when first exposed to anoxia. However, oysters periodically opened throughout anoxia/hypoxia in both the lab and field, suggesting that the infiltration of exogenous bacteria from the environment may also influence mortality rates under natural settings. Coupled with previous studies, we posit that mass mortality events in a wide range of coastal bivalves are likely the result of co-morbidity from asphyxiation and bacterial processes, This study was funded by L'Étang Ruisseau Bar Ltd. in partnership with the Department of Fisheries and Oceans of Canada (Aquaculture Collaborative Research and Development Program, project 17-G-02 led by M.R.S.C.), a NSERC Discovery Grant to R.F. (RGPIN-2017-04294), and a Total Development Fund from the New Brunswick Department of Agriculture, Aquaculture and Fisheries to R.F.

Ocean acidification is expected to affect marine organisms in the near future. Furthermore, abrupt short-term fluctuations in seawater pCO

Background The process of peer-review in academia has attracted criticism surrounding issues of bias, fairness, and professionalism; however, frequency of occurrence of such comments is unknown. Methods We evaluated 1491 sets of reviewer comments from the fields of “Ecology and Evolution” and “Behavioural Medicine,” of which 920 were retrieved from the online review repository Publons and 571 were obtained from six early career investigators. Comment sets were coded for the occurrence of “unprofessional comments” and “incomplete, inaccurate or unsubstantiated critiques” using an a-prior rubric based on our published research. Results are presented as absolute numbers and percentages. Results Overall, 12% (179) of comment sets included at least one unprofessional comment towards the author or their work, and 41% (611) contained incomplete, inaccurate of unsubstantiated critiques (IIUC). Conclusions The large number of unprofessional comments, and IIUCs observed could heighten psychological distress among investigators, particularly those at an early stage in their career. We suggest that development and adherence to a universally agreed upon reviewer code of conduct is necessary to improve the quality and professional experience of peer review.

The size and frequency of gastropod drill holes in shells of their prey are common indicators of predator-prey ecology in the fossil record. Taphonomic processes occurring after predation, however, can influence the preservation of shells in a given fossil assemblage and can thus influence ecological inferences based on preserved shells. To determine if ocean acidification (OA) has the capacity to influence prey shell taphonomy in a gastropod drilling predation system, we tested for effects of elevated pCO2 on dissolution rates, breakage force, and drill hole diameters in non-fragmented shells of two prey species of the cannibalistic naticid gastropod, Euspira heros. Drilled and non-drilled shells of Littorina littorea and E. heros were exposed to control (~300 μatm) and elevated (~800 and 4000 μatm) pCO2 treatments for five weeks. Dry shell weight and drill hole diameter (outer and inner) were recorded for individual shells before and after exposure; the force required for shell breakage was recorded at the end of the exposure period. Shell mass loss in 800 and 4000 μatm, respectively, were ~1 and 7% for E. heros, and ~0 and 4% for L. littorea, compared to ~0% in the control for both species. Shell breakage force was unaffected by elevated pCO2, but was affected by species and drill hole presence, with E. heros shells requiring a force of ~220 and 269 Newtons in drilled and non-drilled shells, respectively, compared to ~294 and 415 Newtons in L. littorea. At 4000 μatm, outer drill hole diameter significantly increased by ~12% for E. heros, while inner drill hole diameter significantly increased by ~13% in E. heros and ~10% in L. littorea. Ultimately, this study provides the first documentation of molluscan shell taphonomy in the context of OA for a gastropod drilling predation system and sets the stage for future research. © 2018. This is the authors’ accepted and refereed manuscript to the article. Locked until 17 July 2020 due to copyright restrictions. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/

In Prince Edward Island, the spring oyster fishery occurs from early May to mid-July. During this time, oysters may be harvested and held for multiple days by harvesters before being brought to oyster processors, who then relay them in seawater at leased sites. Over the past decade, however, processors have reported high mortalities of relayed catch during July. We investigated duration of air exposure as a potential driver for the high July mortalities reported by oyster processors. Wild oysters were removed from fishing beds in June and July 2017 and handled to mimic techniques used by harvesters. After removal, the oysters were exposed to atmospheric conditions (air) for 0, 24, 48, 72, or 96 h and mortality was quantified. The oysters were then placed at a holding site for 60 days and mortality was quantified on days 7, 14, 30 and 60, and condition index was measured on remaining oysters from each air exposure treatment. Increased mortality was associated with increased air exposure duration, and this effect was most pronounced during July. Oysters exposed to air for 72–96 h in June experienced mortality rates of 4–11%, while the same air exposure duration in July yielded mortality rates four times higher than in June (16–44%). Most of the associated mortality occurred during air exposure and within 7 days of placing oysters at the holding site. Condition index was also lower in July; however there was no evidence that oysters had spawned. Higher mortalities and lower condition indices in July were associated with higher average air and seawater temperatures (both ∼3 °C higher than June). These results ultimately suggest that increased air exposure can result in substantial mortality of PEI oysters fished in July, and corroborate the reports of high July mortalities from oyster processors.

While many studies document effects of elevated pCO2 on coastal organisms, the environmental variability characteristic of coastal regions is often not directly tested. We tested for effects of elevated pCO2 on the valve gaping activity of adult eastern oysters ( Crassostrea virginica) in response to acute heat shock that can occur in nearshore shallow coastal waters. In two consecutive experimental trials, oysters (n = 4) wired with Hall Effect biosensors (that measured valve gaping at one-second intervals) were exposed for 10 days at six different pCO2 treatments spanning a range currently observed in nearshore coastal regions, and predicted under near-future ocean acidification . After the 10-day acclimation period, oysters from each pCO2 treatment were exposed to a 3-h heat shock assay (11-12 ➔ 30 °C) and valve gaping activity was monitored continuously. During the heat shock assays, valve gaping activity increased with increasing temperature and then ceased when temperature was reduced back to 11-12 °C; however, these valve gaping rate increases during heat shock were not characteristic of overly-stressed oysters. Exposure to elevated pCO2 had no effect on the valve gaping response of oysters to acute heat shock. Our results suggest that the valve gaping responses of adult eastern oysters to acute temperature increases are unaffected by short-term elevations in seawater pCO2. Future studies incorporating the roles of local adaptation, food availability, and direct functional consequences of valve gaping (e.g. physiological rates, predator avoidance, response to environmental toxins) are warranted.

Feeding is fundamental for all heterotrophic organisms, providing the means to acquire energy for basic life processes. Recent studies have suggested that experimental ocean acidification (OA) can alter the feeding performance of marine calcifying invertebrates, but results have been inconsistent. While several reviews pertaining to the biological effects of OA exist, none provide a synthesis of OA effects on feeding performance. Here, we provide a quantitative analysis of published experiments testing for effects of elevated CO2 on feeding rates of marine calcifying invertebrates. Results revealed that suspension-feeding molluscs and predatory and grazing echinoderms experienced depressed feeding rates under elevated CO2, while arthropods appeared unaffected; larval and juvenile animals were more susceptible to CO2 effects than adults. Feeding strategy did not appear to influence the overall taxonomic trend, nor did habitat, although exposure time did have an effect. AIC model selection revealed that Phylum best predicted effect size; life stage and exposure time were also included in candidate models. Based on these results, we synthesize potential physiological attributes of different taxa that may drive OA sensitivities in feeding rates, which could potentially result in community-level impacts. We also discuss CO2 effects on calcifier feeding in the context of elevated temperature and other global marine change stressors, and highlight other areas for future research.

In the southern Gulf of St. Lawrence (sGSL), there is a mostly supplementary fishery for sea scallops (Placopecten magellanicus) concentrated on three primary scallop beds in the Northumberland Strait. The fishery is not subject to an enforced minimum size limit and small scallops (

Soft-shell clams (Mya arenaria) can serve important ecological roles in intertidal mudflats and are an important economic and recreational resource in the northwestern Atlantic. However, environmental factors affecting newly-settled and juvenile clam abundances within a given settlement season remain uncertain. We conducted a field study assessing relationships between juvenile soft-shell clam abundance and spatial, temporal, and environmental variables in coastal mudflats of the northern shore of the Bay of Fundy. Sediment pH and low-tide water temperature (tide pools) were monitored in situ on a biweekly–monthly basis over the course of the M. arenaria settlement season in 2012 at four study sites to quantify diel variation in sediment pH and temperature. Core samples were also collected to quantify M. arenaria (

While ocean acidification (OA) effects on marine organisms are well documented, impacts of sediment acidification on infaunal organisms are relatively understudied. Here we synthesize CO2-driven sediment acidification effects on infaunal marine bivalves. While sediment carbonate system conditions can already exceed near-future OA projections, sediments can become even more acidic as overlying seawater pH decreases. Evidence suggests that infaunal bivalves experience shell dissolution, more lesions, and increased mortality in more acidic sediments; effects on heavy metal accumulation appear complex and uncertain. Infaunal bivalves can avoid negative functional consequences of sediment acidification by reducing burrowing and increasing dispersal in more acidic sediments, irrespective of species or life stage; elevated temperature may compromise this avoidance behaviour. The combined effects of sediment acidification and other environmental stressors are virtually unknown. While it is evident that sediment acidification can impact infaunal marine bivalves, more research is needed to confidently predict effects under future ocean conditions.

8 pages, 2 figures, 2 tables, Ocean acidification is expected to affect marine organisms in the near future. Furthermore, abrupt short-term fluctuations in seawater pCO2 characteristic of near-shore coastal regions and high-density aquaculture sites currently have the potential to influence organismal and community functioning by altering animal behaviour. While anti-predator responses in fishes exposed to elevated pCO2 are well documented, such responses in benthic marine invertebrates are poorly studied. We used high frequency, non-invasive biosensors to test whether or not short term (3-week) exposure to elevated pCO2 could impact behavioural responses to the threat of predation in adult Mediterranean mussels from Galicia on the northwestern coast of Spain. Predator alarm cues (crushed conspecifics) resulted in a prolonged (1 h) reduction in the degree of valve opening (−20%) but had no clear effect on overall valve movement activity, while elevated pCO2 did not affect either response. Our results add to the increasing body of evidence suggesting that the effects of end-of-century pCO2 levels on marine animal behaviour are likely weak. Nonetheless, longer-term exposures spanning multiple generations are needed to better understand how ocean acidification might impact behavioural responses to predation in marine bivalves, This project was funded by the Spanish government through the Ministerio de Economía y Competitividad that included European FEDER funds (projects Ref. AGL-2013-45945-R, CTM2016-76146-C3-2-R/CTM2016-76146-C3-1-R)

Startle response behaviours are important in predator avoidance and escape for a wide array of animals. For many marine invertebrates, however, startle response behaviours are understudied, and the effects of global change stressors on these responses are unknown. We exposed two size classes of blue mussels (Mytilus edulis × trossulus) to different combinations of temperature (15 and 19 °C) and pH (8.2 and 7.5 pHT) for 3 months and subsequently measured individual time to open following a tactile predator cue (i.e. startle response time) over a series of four consecutive trials. Time to open was highly repeatable in the short term and decreased linearly across the four trials. Individuals from the larger size class had a shorter time to open than their smaller-sized counterparts. High temperature increased time to open compared to low temperature, while pH had no effect. These results suggest that bivalve time to open is repeatable, related to relative vulnerability to predation and affected by temperature. Given that increased closure times impact feeding and respiration, the effect of temperature on closure duration may play a role in the sensitivity to ocean warming in this species and contribute to ecosystem level effects.

Non-consumptive effects of predators on prey populations have received increased interest in recent years. For Crassostrea virginica (Eastern Oyster), much of the focus has been on induced morphological defenses (e.g., shell thickening). Here, we provide in situ documentation of a behavioral response of Eastern Oysters (valve closure) to the threat of predation on a natural reef. This behavioral response, while intuitive, has been largely ignored in the literature despite potential impacts on individual oyster health by affecting feeding and subsequently energy assimilation, reproductive condition, and growth. In situ photographs revealed that, under natural conditions, Eastern Oysters closed during the passive presence of a crab mate-guarding pair and took ∼5 minutes to reopen to pre-predator gapes. Given that multiple oysters in our photos reacted similarly, this behavioral response may scale up to have effects on the population and the ecosystem services that Eastern Oysters provide. Ultimately, our observations open the door to a number of testable hypotheses regarding a predator's non-consumptive effects on oyster reefs.

In aquatic toxicology, methods that are chosen for exposures have profound consequences on experimental outcomes and thus can skew policy initiatives. For example, as compared to single-organism exposures, toxicity test results of group exposures may be impacted by confounding factors such as social interactions between animals or individual variation in accumulation rates. To test for differences in organismal response between group and individual toxicological exposures, we exposed Daphnia magna to copper and subsequently compared the toxicity (median lethal concentration or LC50) between groups and individuals. Results suggested that water chemistry had a larger effect on experimental outcomes than the number of animals exposed in the same tank. Methodological decisions with respect to replication type can affect toxicity tests, and LC50s calculated using different exposure types (such as group and individual exposures) may not be comparable.

Although ocean acidification will impact marine organisms in the future, few studies have addressed the effects of sedimentary porewater acidification on benthic invertebrates. This study suggests that burrowing behavior and post-settlement dispersal of juvenile bivalves are altered by porewater acidification under present day conditions. We tested the efficacy of a novel method of stabilizing porewater pH using sediment underlain with food grade gelatin in both the lab and field, and then employed this method to test if porewater acidification could alter post-settlement clam dispersal under natural conditions. In the field, clams were exposed to a gradient of porewater acidification in manipulated (CO2 added) sediments for 24 h to determine if acidification could alter dispersal patterns of juvenile clams under natural flow conditions; juvenile clam dispersal in the presence of different buffer types was also tested. In addition, juvenile clams were placed on unmanipulated, field-collected sediment cores in the lab which varied naturally with respect to acidification to test burrowing behavior in response to natural porewater pH. Gelatin stabilized porewater pH for 24–48 h and its presence did not influence clam burrowing behavior. In the field, a significant negative relationship between the percent of clams dispersed and acidification was observed, while stabilizing porewater pH significantly decreased clam dispersal. In the lab, there was a significant positive relationship between the percent of clams burrowed and porewater acidification. This study suggests that porewater acidification has the capacity to alter the burrowing behavior and dispersal patterns of juvenile bivalves under natural conditions.

Breaching of coastal causeways and dikes (embankments) is a common method used to restore estuaries and marshes to a more natural state. Here, we reviewed literature pertaining to embankment breaches to assess the effectiveness of this restoration method and to provide practical advice for future breaches. While all methods of embankment breaching can be successful, active measures appear to be more successful than allowing breaches to occur naturally. Restoring tidal flow sooner, and to a greater degree, will speed recovery of impacted systems. Overall, recovery is often quick, with hydrology changing immediately. Sedimentation and erosion patterns also change soon after breaching, but it can take up to 15 years for sediment elevation to stabilize, and 60–100 years for equilibrium conditions to develop. Marsh plant communities recover rapidly, with most systems almost fully recovering within 5–20 years. Fish, bird, and invertebrate communities also mostly recover within five years. Unfortunately, recovery is often not complete. Even with large investments of time and money, systems can still exhibit variation from reference habitats in their biotic and abiotic conditions up to 130 years post breach. In some cases, this may be due to embankment remnants still impacting the system. Conversely, the systems may have changed too much, and/or global climate change may have altered successional pathways to such a degree that recovery to pre-disturbance conditions is unlikely. Regardless, breaching of coastal embankments often restores conditions that are more natural and increases estuary similarity to reference systems. As such, breaching is a useful prescription for coastal restoration, one that can deliver a considerable return on investment.

Jeff C. Clements reckons with a recent set of reviewer comments that used ‘being critical’ as a justification to be mean. Jeff C. Clements reckons with a recent set of reviewer comments that used ‘being critical’ as a justification to be mean.

Through physical manipulation, oyster growers can modify the morphological features of young oysters in order to improve their robustness and resiliency to predation. In this study, the efficacy of a novel passive culturing technique using floating buckets that “bounce” oysters prior to the benthic grow-out phase for enhancing shell thickness and strength, while not compromising oyster shape, was investigated. Using a field experiment, we quantified and compared the shell thickness (mm), compressive strength (Newtons), and shape (fan ratios and cup ratios) of juvenile oysters subjected to this bouncing technique with oysters grown in floating bags, the current industry standard. Results indicated that bouncing increased shell thickness and strength for oysters >45 mm shell height compared to control oysters, but also decreased shell thickness and strength for oysters

Apart from ocean acidification, hypoxia is another stressor to marine organisms, especially those in coastal waters. Their interactive effects of elevated CO2 and hypoxia on the physiological energetics in mussel Mytilus edulis were evaluated. Mussels were exposed to three pH levels (8.1, 7.7, 7.3) at two dissolved oxygen levels (6 and 2 mg L−1) and clearance rate, absorption efficiency, respiration rate, excretion rate, scope for growth and O: N ratio were measured during a14-day exposure. After exposure, all parameters (except excretion rate) were significantly reduced under low pH and hypoxic conditions, whereas excretion rate was significantly increased. Additive effects of low pH and hypoxia were evident for all parameters and low pH appeared to elicit a stronger effect than hypoxia (2.0 mg L−1). Overall, hypoxia can aggravate the effects of acidification on the physiological energetics of mussels, and their populations may be diminished by these stressors.

An inability to focus during a weekend trip forced Jeff Clements to ponder often-overlooked drivers of academic mental health. An inability to focus during a weekend trip forced Jeff Clements to ponder often-overlooked drivers of academic mental health.

Bivalve farming can contribute to nutrient removal in coastal and estuarine systems, as bivalves directly incorporate nutrients into their tissues and shells. We conducted a meta-analysis to compare the nitrogen removal potential (NRP; i.e., percentage of nitrogen in tissues and shells) of mussels, Mytilus edulis, and oysters, Crassostrea virginica. We then used species-specific NRPs to determine and compare the total and per-hectare NRPs for four shellfish aquaculture methods used in two Atlantic Canadian provinces – New Brunswick (NB) and Prince Edward Island (PEI) – based on current harvest biomasses. Finally, we determined the contribution of current shellfish farming to nitrogen load mitigation for a subset of bays in NB and PEI. Results revealed that on a per-weight basis, NRP was similar for the tissues of mussels and oysters, while mussel shells had a significantly higher percentage of nitrogen than oyster shells. Collectively, shellfish harvesting has the capacity to remove a mean annual total of 99088 kg and 204571 kg of nitrogen from NB and PEI, respectively. Given current harvesting practices for four culture methods employed in the region, suspended mussel culture provides the greatest NRP per hectare of farm area, followed in sequence by suspended mussel and oyster mixed culture, suspended oyster culture, and bottom oyster culture. Preliminary analysis suggested that harvests in the region typically remove

Eastern oysters (Crassostrea virginica) are ecosystem engineers that are important to the ecological and economic sustainability of Atlantic Canada’s estuarine resources. Recently, there has been an increased industry demand for oyster spat (i.e., newly-settled larvae), which is often collected using artificial spat collectors suspended in the water column. Little is known, however, about the interactions between artificial spat collectors and naturally occurring substrates, and whether or not such collectors can affect oyster recruitment to wild beds which are simultaneously fished. In the laboratory, we mimicked the typical set-up of artificial spat collectors used in Atlantic Canada to measure differences in spat recruitment between locally-used artificial collectors and natural shell substrate under real-life spat-collection scenarios. Larvae were allowed to settle on various substrates where they occur in a natural system and were subsequently counted. In both single substrate and choice experiments, results indicated that oyster larvae recruited in higher numbers to natural shell substrate located on the benthic surface compared to suspended shell; and there were no significant differences among suspended substrates. This experiment provides evidence supporting existing theories around recruitment behaviour by oyster larvae, mainly that settling oysters tend to sink before they settle, suggesting that spat collectors in the wild may have little effect on wild recruitment. With increasing densities of artificial collectors in estuarine systems to meet system demands, however, further research is needed to investigate the potential draw of oyster larvae away from benthic oyster beds under more realistic natural conditions before broad conclusions regarding spat collector effects on wild oyster populations can be achieved. Crown Copyright © 2019 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/).

The effects of short-term (7 days) experimental ocean acidification (−0.4 pH units) and warming (+5 °C) on anti-predator defenses of two sympatric Mytilus species from China, M. coruscus and M. edulis, in the presence and absence of predator cues were investigated. Results suggested species-specific independent negative effects of acidification and warming on the number and weight of byssal threads, the force of thread attachment, and total thread plaque area. Similar negative effects were observed for clustering behaviour, with acidification and warming independently increasing the number of solitary individuals and decreasing the percentage of mussels in clusters. Acidification effects on byssus were strongly exacerbated when predators were present. Ultimately, this study suggests that short-term exposure to experimental warming and acidification can negatively impact anti-predator defense strategies in mussels with potential ramifications for predator-prey interactions and ecological functioning in systems where mussel beds play a key ecological role.

Transgenerational effects of multiple stressors on marine organisms are emerging environmental themes. We thus experimentally tested for transgenerational effects of seawater acidification and hypoxia on the early development traits of the mussel Mytilus edulis. Fertilization rate, embryo deformity rate, and larval shell length were negatively impacted by acidification, while hypoxia had little effect except for increasing deformity rates under control pH conditions. Offspring from low pH/O2 parents were less negatively affected by low pH/O2 conditions than offspring from control parents; however, low pH/O2 conditions still negatively affected developmental traits in offspring from acclimated parents compared to control seawater conditions. Our results demonstrate that experimental seawater acidification and hypoxia can adversely affect early developmental traits of M. edulis and that parental exposure can only partially alleviate these impacts. If experimental observations hold true in nature, it is unlikely that parental exposure will confer larval tolerance to ocean acidification for M. edulis.

Shifting environmental conditions resulting from anthropogenic climate change have recently garnered much attention in the aquaculture industry; however, ocean acidification has received relatively little attention. Here, we provide an overview of ocean acidification in the context of North American aquaculture with respect to potential impacts and mitigation strategies. North American shellfish farms should make ocean acidification an immediate priority, as shellfish and other calcifying organisms are of highest concern in an increasingly acidifying ocean and negative effects have already been felt on the Pacific coast. While implications for various finfish have been documented, our current understanding of how acidification will impact North American finfish aquaculture is limited and requires more research. Although likely to benefit from increases in seawater CO2, some seaweeds may also be at risk under more acidic conditions, particularly calcifying species, as well as non-calcifying ones residing in areas where CO2 is not the primary driver of acidification. Strategies to mitigate and adapt to the effects of acidification exist on the regional scale and can aid in identifying areas of concern, detecting changes in seawater carbonate chemistry early enough to avoid catastrophic outcomes, and adapting to long-term shifts in oceanic pH. Ultimately, ocean acidification has already imposed negative impacts on the aquaculture industry, but can be addressed with sufficient monitoring and the establishment of regional mitigation plans.

Predatory open access (OA) journals can be defined as non-indexed journals that exploit the gold OA model for profit, often spamming academics with questionable e-mails promising rapid OA publication for a fee. In aquaculture—a rapidly growing and highly scrutinized field—the issue of such journals remains undocumented. We employed a quantitative approach to determine whether attributes of scientific quality and rigor differed between OA aquaculture journals not indexed in reputable databases and well-established, indexed journals. Using a Google search, we identified several non-indexed OA journals, gathered data on attributes of these journals and articles therein, and compared these data to well-established aquaculture journals indexed in quality-controlled bibliometric databases. We then used these data to determine if non-indexed journals were likely predatory OA journals and if they pose a potential threat to aquaculture research. On average, non-indexed OA journals published significantly fewer papers per year, had cheaper fees, and were more recently established than indexed journals. Articles in non-indexed journals were, on average, shorter, had fewer authors and references, and spent significantly less time in peer review than their indexed counterparts; the proportion of articles employing rigorous statistical analyses was also lower for non-indexed journals. Additionally, articles in non-indexed journals were more likely to be published by scientists from developing nations. Worryingly, non-indexed journals were more likely to be found using a Google search, and their articles superficially resembled those in indexed journals. These results suggest that the non-indexed aquaculture journals identified herein are likely predatory OA journals and pose a threat to aquaculture research and the public education and perception of aquaculture. Several points of reference from this study, in combination, may help scientists and the public more easily identify these possibly predatory journals, as these journals were typically established after 2010, publishing

Pre-spawning blue mussels (Mytilus edulis) appear sensitive to elevated temperature and robust to elevated pCO2; however, the effects of these stressors soon after investing energy into spawning remain unknown. Furthermore, while studies suggest that elevated pCO2 affects the byssal attachment strength of Mytilus trossulus from southern latitudes, pCO2 and temperature impacts on the byssus strength of other species at higher latitudes remain undocumented. In a 90 day laboratory experiment, we exposed post-spawning adult blue mussels (M. edulis) from Atlantic Canada to three pCO2 levels (pCO2 ~625, 1295 and 2440 μatm) at two different temperatures (16°C and 22°C) and assessed energetic reserves on Day 90, byssal attachment strength on Days 30 and 60, and condition index and mortality on Days 30, 60 and 90. Results indicated that glycogen content was negatively affected under elevated temperature, but protein, lipid, and overall energy content were unaffected. Reduced glycogen content under elevated temperature was associated with reduced condition index, reduced byssal thread attachment strength, and increased mortality; elevated pCO2 had no effects. Overall, these results suggest that the glycogen reserves of post-spawning adult M. edulis are sensitive to elevated temperature, and can result in reduced health and byssal attachment strength, leading to increased mortality. These results are similar to those reported for pre-spawning mussels and suggest that post-spawning blue mussels are tolerant to elevated pCO2 and sensitive to elevated temperature. In contrast to previous studies, however, elevated pCO2 did not affect byssus strength, suggesting that negative effects of elevated pCO2 on byssus strength are not universal.

Pre-spawning blue mussels (Mytilus edulis) appear sensitive to elevated temperature and robust to elevated pCO2; however, the effects of these stressors soon after investing energy into spawning remain unknown. Furthermore, while studies suggest that elevated pCO2 affects the byssal attachment strength of Mytilus trossulus from southern latitudes, pCO2 and temperature impacts on the byssus strength of other species at higher latitudes remain undocumented. In a 90 day laboratory experiment, we exposed post-spawning adult blue mussels (M. edulis) from Atlantic Canada to three pCO2 levels (pCO2 ~625, 1295 and 2440 μatm) at two different temperatures (16°C and 22°C) and assessed energetic reserves on Day 90, byssal attachment strength on Days 30 and 60, and condition index and mortality on Days 30, 60 and 90. Results indicated that glycogen content was negatively affected under elevated temperature, but protein, lipid, and overall energy content were unaffected. Reduced glycogen content under elevated temperature was associated with reduced condition index, reduced byssal thread attachment strength, and increased mortality; elevated pCO2 had no effects. Overall, these results suggest that the glycogen reserves of post-spawning adult M. edulis are sensitive to elevated temperature, and can result in reduced health and byssal attachment strength, leading to increased mortality. These results are similar to those reported for pre-spawning mussels and suggest that post-spawning blue mussels are tolerant to elevated pCO2 and sensitive to elevated temperature. In contrast to previous studies, however, elevated pCO2 did not affect byssus strength, suggesting that negative effects of elevated pCO2 on byssus strength are not universal.