Isabelle M. Côté’s research while affiliated with Simon Fraser University and other places

Biogeochemical fluxes through ecological communities underpin the functioning of ecosystems worldwide. These fluxes are often heavily influenced by small‐bodied consumers, such as insects, worms, mollusks, or small vertebrates, which transfer energy and nutrients from autotrophic sources to larger animals. Although coral reefs are one of the most productive ecosystems in the world, we know relatively little about how small consumers make energy available to larger predators and how their roles may vary across reefs. Here, we use community‐scale collections of small, bottom‐dwelling (“cryptobenthic”) reef fishes along with size spectrum analyses, stable isotopes, and demographic modeling to examine their role in harnessing and transferring carbon in two distinct coral reef habitats. Using a comprehensive dataset from Mo'orea (French Polynesia), we demonstrate that, despite only being separated by a narrow reef crest, forereef and backreef habitats harbor distinct communities of cryptobenthic fishes that play vastly divergent roles in carbon transfer. Forereef communities in Mo'orea are depauperate, largely consisting of predatory and planktivorous species that have comparatively high standing biomass (both individually and collectively). In these communities, the combination of size spectra and isotope values suggests important contributions of pelagic subsidies, but the rate of biomass production and turnover (i.e., the rate at which biomass is replenished) is relatively low. In contrast, cryptobenthic fish communities in the backreef are characterized by high abundances of the smallest bodied species, forming a traditional bottom‐heavy trophic pyramid that is fueled by benthic autotrophs. In these communities, benthic productivity fuels rapid production and turnover of fish biomass, while pelagic energy channels are notably less productive. Our integrative approach demonstrates the utility of combining multiple methods (e.g., isotopically informed demographic models) to trace energy fluxes through small consumer communities in complex ecosystems. Furthermore, our results highlight that coral reef productivity dynamics are highly habitat‐dependent and the role of the smallest coral reef consumers may be most pronounced in shallow systems with limited connectivity to the open ocean.

The nexus between changing habitats, faunal communities, and anthropogenic stressors represents an enduring conservation challenge. We propose that habitat‐mediated soundscape conservation—the ability of biogenic habitats to attenuate anthropogenic noise—plays an unrecognized role in mitigating underwater noise pollution, a pervasive disturbance that disrupts the ability of species to perceive acoustic cues and communicate. We hypothesize that noise attenuation depends on the composition and physical complexity of biogenic habitats, and severe habitat degradation can cause acoustic conditions to exceed ecological tipping points, resulting in the emergence of alternative acoustic states. We examine this concept in coral reefs and kelp forests, given that the global decline of both ecosystems provides the requisite conditions to investigate our hypothesis. We then explore why anthropogenic structures fail to provide acoustic refugia. Finally, we assess whether habitat restoration or acoustic enrichment can reestablish natural soundscapes. Our review underscores the importance of considering habitat degradation when evaluating the risk that pollutants pose to ecosystems.

Pentameric symmetry characterizes echinoderms and is most readily observed in sea stars. However, some pentamerous sea star individuals deviate from the normal 5-arm pattern, most likely as a result of errors in regeneration, but the frequency of these deviations and their ecological consequences for the individuals are poorly understood. Here, we report the extent of deviations from pentamery in multiple populations of co-occurring sea star species and tested 3 potential advantages of supernumerary arms—increased oral surface area, increased feeding, and faster righting response—in 1 species, the bat star Patiria miniata . Using underwater surveys and behavioural experiments at 16 sites in Barkley Sound, British Columbia, Canada, we found individuals with atypical arm numbers in 5 of 9 pentamerous sea star species. There were significant differences among sites and species, with site-specific mean percentages of atypical sea stars ranging from 0.8 to 14.6% and species-specific mean percentages ranging from 0 to 10%. Bat stars had the highest proportion of individuals with atypical numbers of arms, with site-specific frequencies ranging from 0 to 25%. The probability of feeding and righting speed were similar between bat stars with and without supernumerary arms, but bat stars with supernumerary arms had slightly larger oral surface areas for a given arm length, which could confer an advantage in adherence to the substrate. Although the advantages of supernumerary arms for bat stars appear to be negligible, the lack of any clear disadvantage suggests that selection against atypical variants might be weak, leading to limited selection on the accuracy of regeneration in this species.

Multiple studies across a variety of scientific disciplines have shown that the number of times that a paper is shared on Twitter (now called X) is correlated with the number of citations that paper receives. However, these studies were not designed to answer whether tweeting about scientific papers causes an increase in citations, or whether they were simply highlighting that some papers have higher relevance, importance or quality and are therefore both tweeted about more and cited more. The authors of this study are leading science communicators on Twitter from several life science disciplines, with substantially higher follower counts than the average scientist, making us uniquely placed to address this question. We conducted a three-year-long controlled experiment, randomly selecting five articles published in the same month and journal, and randomly tweeting one while retaining the others as controls. This process was repeated for 10 articles from each of 11 journals, recording Altmetric scores, number of tweets, and citation counts before and after tweeting. Randomization tests revealed that tweeted articles were downloaded 2.6–3.9 times more often than controls immediately after tweeting, and retained significantly higher Altmetric scores (+81%) and number of tweets (+105%) three years after tweeting. However, while some tweeted papers were cited more than their respective control papers published in the same journal and month, the overall increase in citation counts after three years (+7% for Web of Science and +12% for Google Scholar) was not statistically significant (p > 0.15). Therefore while discussing science on social media has many professional and societal benefits (and has been a lot of fun), increasing the citation rate of a scientist’s papers is likely not among them.

Understanding the density-dependent impacts of an invasive predator is integral for predicting potential consequences for prey populations. Functional response experiments are used to assess the rate of prey consumption and a predator’s ability to search for and consume prey at different resource densities. However, results can be highly context-dependent, limiting their extrapolation to natural ecosystems. Here, we examined how simulated habitat complexity, through the addition of substrate in which prey can escape predation, affects the functional response of invasive European green crabs ( Carcinus maenas ) foraging on two different bivalve species. Green crabs feeding on varnish clams ( Nuttallia obscurata ) shifted from a Type II hyperbolic functional response in the absence of substrate to density-independent consumption when prey could bury. Green crabs ate few Japanese littleneck clams ( Venerupis philippinarum ) under all densities, such that no functional response curve of any type could be produced and their total consumption was always density independent. However, the probability of at least one Japanese littleneck clam being consumed increased significantly with initial clam density and crab claw size across all treatments. At mean crab claw size and compared to trials without substrate, the proportion of varnish clams consumed were 4.2 times smaller when substrate was present, but substrate had a negligible effect (1.2 times) on Japanese littlenecks. The proportion of varnish clams consumed increased with crab claw size and were higher across both substrate conditions than the proportion of Japanese littlenecks consumed; however, the proportion of Japanese littleneck clams consumed increased faster with claw size than that of varnish clams. Our results suggest that including environmental features and variation in prey species can influence the density-dependent foraging described by functional response experiments. Incorporating replicable features of the natural environment into functional response experiments is imperative to make more accurate predictions about the impact of invasive predators on prey populations.

Organisms that settle and grow on other organisms (i.e., epibionts) are often costly to their hosts in terms of locomotion, growth, and/or reproduction. Such costs can potentially result in biotic resistance against invasion when native epibionts colonise non-native hosts, but examples are rare. Here, we examine the extent to which native acorn barnacles Balanus glandula that grow on the non-native Japanese mud snail, Batillaria attramentaria, may offer biotic resistance against this invader. We conducted population surveys, mark-recapture experiments, and behavioural observations in British Columbia, Canada, to measure the effects of barnacles on the movement, growth, and recapture rate, a potential proxy of short-term survival, of mud snails. One-third of mud snails carried barnacles, the weight of which sometimes exceeded the weight of the mud snail carrying them. Barnacle presence, weight, and the ratio of barnacle to snail weight all decreased the probability that mud snails would move, which could have implications for the foraging success of mud snails carrying barnacles. The slopes of the relationship between shell weight and length were similar for mud snails with and without barnacles, suggesting a lack of effect on growth allometry. The probability of recapture was 36% higher for mud snails without barnacles in one of two trials (i.e., 68% probability of recapture for snails without barnacles vs 50% for snails with barnacles), which reflects weak evidence for a small detrimental effect on mud snails carrying barnacles. Overall, native barnacles appear to offer some, though weak, biotic resistance to invasive mud snails, providing new insight into the potential for ecosystems to resist invasions through epibiotic interactions.

The Canadian Department of National Defence (DND) has approved the resumption of military activities within ‘Whiskey Hotel’, a 330 km2 area in the Strait of Juan de Fuca that overlaps the critical habitat of endangered Southern Resident Killer Whales in the northeast Pacific Ocean. Multiple Canadian and United States defense organizations use the area for training. The renewal of small-arms training follows a three-year cessation self-imposed by DND to allow a third-party consultant to investigate the risk in-air and underwater training noises pose to marine mammals. Here, we summarize the findings and limitations of the commissioned report and discuss the broader implications for mitigating aquatic noise pollution. The report evaluated the potential for marine mammals to experience injury, behavioral disturbances, and acoustic masking, and proposed mitigation measures (e.g., avoidance zones) to limit impacts. However, the narrow scope of the commissioned report prevented the investigation of the potential effects on non-mammalian taxa and the inclusion of vessel noise generated during training. Resuming military activities within the habitats of imperiled species is contentious among stakeholders. Nevertheless, the DND’s approach to examining noise pollution employs at least two of the precautionary principle’s four components, and their decision to commission a third-party investigation and implement mitigation strategies represents a framework rarely applied when evaluating the impacts of pollutants. The importance of this approach is magnified given the absence of federal underwater noise regulations, the pending development of Canada’s Ocean Noise Strategy, and multiple nations seeking to balance industrial and military activities with environmental stewardship.

Predicting the impacts of predatory invasive species is important for prioritising conservation interventions. Functional response experiments, which examine consumption by predators in relation to prey density, are a useful way to assess the potential strength of novel predator-prey relationships. However, such experiments are often conducted without consideration of sex or only with males to reduce invasion risk. Here, we compared the functional responses of male and female European green crabs ( Carcinus maenas ), a global invader, feeding on varnish clams ( Nuttallia obscurata ) to test whether the two sexes have similar potential for impact. We also examined potential correlates of predation behaviour by measuring sex-specific movement and prey choice. Both sexes displayed a Type II hyperbolic functional response, which can destabilise prey populations at low prey densities. However, males and females exhibited some differences in foraging behaviour. Female green crabs had slightly lower attack rates, which were not linked to sex differences in movement, and slightly longer handling times, which were not linked to sex differences in prey choice. These small, non-significant differences nevertheless translated into significantly greater functional response ratios, which are used to predict the ecological impact of invasive species, for males than females. There was no difference in the proportion of clams consumed between males and females with similar crusher claw heights, but females have smaller crusher claws on average, hence they consumed a smaller proportion of clams. Repeated surveys of four populations of European green crabs established in British Columbia, Canada, showed that sex ratio is highly variable. Taken together, these results and population-level modelling suggest that trying to evaluate the potential impact of European green crabs on clam populations by sampling only males could result in overestimation, even in populations that have male-biased sex-ratios. Consumer sex might generally be an important feature to consider when using functional response experiments to forecast the impact of new invasive species, especially those with marked sexual dimorphism that affect foraging.

Ocean warming and marine heatwaves induced by climate change are impacting coral reefs globally, leading to coral bleaching and mortality. Yet, coral resistance and resilience to warming are not uniform across reef sites and corals can show inter- and intraspecific variability. To understand changes in coral health and to elucidate mechanisms of coral thermal tolerance, baseline data on the dynamics of coral holobiont performance under non-stressed conditions are needed. We monitored the seasonal dynamics of algal symbionts (family Symbiodiniaceae) hosted by corals from a chronically warmed and thermally variable reef compared to a thermally stable reef in southern Taiwan over 15 months. We assessed the genera and photochemical efficiency of Symbiodiniaceae in three coral species: Acropora nana, Pocillopora acuta, and Porites lutea . Both Durusdinium and Cladocopium were present in all coral species at both reef sites across all seasons, but general trends in their detection (based on qPCR cycle) varied between sites and among species. Photochemical efficiency ( i.e. , maximum quantum yield; F v /F m ) was relatively similar between reef sites but differed consistently among species; no clear evidence of seasonal trends in F v /F m was found. Quantifying natural Symbiodiniaceae dynamics can help facilitate a more comprehensive interpretation of thermal tolerance response as well as plasticity potential of the coral holobiont.