Boat noise impacts risk assessment in a coral reef fish but effects depend on engine type.

This is the author accepted manuscript. The final version is available from Nature Publishing Group via the DOI in this record.Human noise pollution has increased markedly since the start of industrialization and there is international concern about how this may impact wildlife. Here we determined whether real motorboat noise affected the behavior, space use and escape response of a juvenile damselfish (Pomacentrus wardi) in the wild, and explored whether fish respond effectively to chemical and visual threats in the presence of two common types of motorboat noise. Noise from 30 hp 2-stroke outboard motors reduced boldness and activity of fish on habitat patches compared to ambient reef-sound controls. Fish also no longer responded to alarm odours with an antipredator response, instead increasing activity and space use, and fewer fish responded appropriately to a looming threat. In contrast, while there was a minor influence of noise from a 30 hp 4-stroke outboard on space use, there was no influence on their ability to respond to alarm odours, and no impact on their escape response. Evidence suggests that anthropogenic noise impacts the way juvenile fish assess risk, which will reduce individual fitness and survival, however, not all engine types cause major effects. This finding may give managers options by which they can reduce the impact of motorboat noise on inshore fish communities.We would like to thank the staff at Lizard Island for logistical support and Georgina Torras Jorda for spending many hours driving small boats around. Funding was provided by an Australian Research Council Centre of Excellence for Coral Reef Studies (EI140100117) and the Natural Environment Research Council (NE/ P001572/1)

Short-term acclimation in adults does not predict offspring acclimation potential to hypoxia

Abstract The prevalence of hypoxic areas in coastal waters is predicted to increase and lead to reduced biodiversity. While the adult stages of many estuarine invertebrates can cope with short periods of hypoxia, it remains unclear whether that ability is present if animals are bred and reared under chronic hypoxia. We firstly investigated the effect of moderate, short-term environmental hypoxia (40% air saturation for one week) on metabolic performance in adults of an estuarine amphipod, and the fitness consequences of prolonged exposure. We then reared the offspring of hypoxia-exposed parents under hypoxia, and assessed their oxyregulatory ability under declining oxygen tensions as juveniles and adults. Adults from the parental generation were able to acclimate their metabolism to hypoxia after one week, employing mechanisms typically associated with prolonged exposure. Their progeny, however, did not develop the adult pattern of respiratory regulation when reared under chronic hypoxia, but instead exhibited a poorer oxyregulatory ability than their parents. We conclude that species apparently hypoxia-tolerant when tested in short-term experiments, could be physiologically compromised as adults if they develop under hypoxia. Consequently, we propose that the increased prevalence of hypoxia in coastal regions will have marked effects in some species currently considered hypoxia tolerant

Synchronous behavioural shifts in reef fishes linked to mass coral bleaching

Mass coral bleaching causes population declines and mortality of coral reef species1 yet its impacts on behaviour are largely unknown. Here, we unite behavioural theory with community ecology to test whether bleaching-induced mass mortality of corals can cause consistent changes in the behaviour of coral-feeding fishes. We documented 5,259 encounters between individuals of 38 Chaetodon (butterflyfish) species on 17 reefs within the central Indo-Pacific, of which 3,828 were repeated on 10 reefs both before and after the global coral bleaching event in 2016. Aggression between butterflyfishes decreased by two-thirds following large-scale coral mortality, despite no significant change in fish abundance or community composition. Pairwise encounters were most likely to be aggressive between obligate corallivores and on reefs with high coral cover. After bleaching, the proportion of preferred Acropora corals in the diet decreased significantly (up to 85% fewer bites), with no increase in overall bite rate to compensate for the loss of these nutritionally rich corals. The observed reduced aggression at low resource levels due to nutritional deficit follows the predictions of the economic theory of aggressive behaviour2,3. Our results reveal synchronous changes in behaviour in response to coral mortality. Such changes could potentially disrupt territories4, leading to reorganization of ecological communities

Painted Goby Larvae under high-CO2 fail to recognize reef sounds

Atmospheric CO2 levels have been increasing at an unprecedented rate due to anthropogenic activity. Consequently, ocean pCO2 is increasing and pH decreasing, affecting marine life, including fish. For many coastal marine fishes, selection of the adult habitat occurs at the end of the pelagic larval phase. Fish larvae use a range of sensory cues, including sound, for locating settlement habitat. This study tested the effect of elevated CO2 on the ability of settlement-stage temperate fish to use auditory cues from adult coastal reef habitats. Wild late larval stages of painted goby (Pomatoschistus pictus) were exposed to control pCO2 (532 μatm, pH 8.06) and high pCO2 (1503 μatm, pH 7.66) conditions, likely to occur in nearshore regions subjected to upwelling events by the end of the century, and tested in an auditory choice chamber for their preference or avoidance to nighttime reef recordings. Fish reared in control pCO2 conditions discriminated reef soundscapes and were attracted by reef recordings. This behaviour changed in fish reared in the high CO2 conditions, with settlement-stage larvae strongly avoiding reef recordings. This study provides evidence that ocean acidification might affect the auditory responses of larval stages of temperate reef fish species, with potentially significant impacts on their survival.Fundação para a Ciência e a Tecnologia (FCT)info:eu-repo/semantics/publishedVersio

Effect of elevated CO2and small boat noise on the kinematics of predator-prey interactions.

This is the author accepted manuscript. The final version is available from Royal Society via the DOI in this record.Oceans of the future are predicted to be more acidic and noisier, particularly along the productive coastal fringe. This study examined the independent and combined effects of short-term exposure to elevated CO2and boat noise on the predator-prey interactions of a pair of common coral reef fishes (Pomacentrus wardiand its predator,Pseudochromis fuscus). Successful capture of prey by predators was the same regardless of whether the pairs had been exposed to ambient control conditions, the addition of either playback of boat noise, elevated CO2(925 µatm) or both stressors simultaneously. The kinematics of the interaction were the same for all stressor combinations and differed from the controls. The effects of CO2or boat noise were the same, suggesting that their effects were substitutive in this situation. Prey reduced their perception of threat under both stressors individually and when combined, and this coincided with reduced predator attack distances and attack speeds. The lack of an additive or multiplicative effect when both stressors co-occurred was notable given the different mechanisms involved in sensory disruptions and highlights the importance of determining the combined effects of key drivers to aid in predicting community dynamics under future environmental scenarios.Funding was provided by an Australian Research Council Centre of Excellence for Coral Reef Studies (EI140100117), an ARC discovery (M.I.M.) and a NERC Knowledge Exchange Fellowship (for S.D.S.; NE/J500616/2)

Behavioural impairment in reef fishes caused by ocean acidification at CO2 seeps

Experiments have shown that the behaviour of reef fishes can be seriously affected by projected future carbon dioxide (CO(2)) concentrations in the ocean1, 2, 3, 4. However, whether fish can acclimate to elevated CO(2) over the longer term, and the consequences of altered behaviour on the structure of fish communities, are unknown. We used marine CO(2) seeps in Papua New Guinea as a natural laboratory to test these questions. Here we show that juvenile reef fishes at CO(2) seeps exhibit behavioural abnormalities similar to those seen in laboratory experiments. Fish from CO(2) seeps were attracted to predator odour, did not distinguish between odours of different habitats, and exhibited bolder behaviour than fish from control reefs. High CO(2) did not, however, have any effect on metabolic rate or aerobic performance. Contrary to expectations, fish diversity and community structure differed little between CO(2) seeps and nearby control reefs. Differences in abundances of some fishes could be driven by the different coral community at CO(2) seeps rather than by the direct effects of high CO(2). Our results suggest that recruitment of juvenile fish from outside the seeps, along with fewer predators within the seeps, is currently sufficient to offset any negative effects of high CO(2) within the seeps. However, continuous exposure does not reduce the effect of high CO(2) on behaviour in natural reef habitat, and this could be a serious problem for fish communities in the future when ocean acidification becomes widespread as a result of continued uptake of anthropogenic CO(2) emissions

Effects of elevated CO(2) on fish behaviour undiminished by transgenerational acclimation

Behaviour and sensory performance of marine fishes are impaired at CO(2) levels projected to occur in the ocean in the next 50–100 years, and there is limited potential for within-generation acclimation to elevated CO(2). However, whether fish behaviour can acclimate or adapt to elevated CO(2) over multiple generations remains unanswered. We tested for transgenerational acclimation of reef fish olfactory preferences and behavioural lateralization at moderate (656 μatm) and high (912 μatm) end-of-century CO(2) projections. Juvenile spiny damselfish, Acanthochromis polyacanthus, from control parents (446 μatm) exhibited an innate avoidance to chemical alarm cue (CAC) when reared in control conditions. In contrast, juveniles lost their innate avoidance of CAC and even became strongly attracted to CAC when reared at elevated CO(2) levels. Juveniles from parents maintained at mid-CO(2) and high-CO(2) levels also lost their innate avoidance of CAC when reared in elevated CO(2), demonstrating no capacity for transgenerational acclimation of olfactory responses. Behavioural lateralization was also disrupted for juveniles reared under elevated CO(2), regardless of parental conditioning. Our results show minimal potential for transgenerational acclimation in this fish, suggesting that genetic adaptation will be necessary to overcome the effects of ocean acidification on behaviour