Species introduced through human-related activities beyond their native range, termed alien species, have various impacts worldwide. The IUCN Environmental Impact Classification for Alien Taxa ...(EICAT) is a global standard to assess negative impacts of alien species on native biodiversity. Alien species can also positively affect biodiversity (for instance, through food and habitat provisioning or dispersal facilitation) but there is currently no standardized and evidence-based system to classify positive impacts. We fill this gap by proposing EICAT+, which uses 5 semiquantitative scenarios to categorize the magnitude of positive impacts, and describes underlying mechanisms. EICAT+ can be applied to all alien taxa at different spatial and organizational scales. The application of EICAT+ expands our understanding of the consequences of biological invasions and can inform conservation decisions.
Significance International concern about the consequences of human-induced global environmental changes has prompted a renewed focus on reducing ecological effects of biological invasions, climate ...change, and nutrient pollution. Our results show that the combined effects of nonnative species invasions and abiotic global environmental changes are often negative but no worse than invasion impacts alone. Invasion impacts are also more strongly detrimental than warming temperatures or nitrogen deposition, two common stressors. Thus, reducing the spread of invasive species is critical for mitigating harms from anthropogenic changes to global ecosystems.
The temperature tolerances of individuals in geographically separated populations of a single species can be used as indicators of each population's potential to persist or become extinct in response ...to climate change. We evaluated the population-level variation in temperature tolerance in populations of several marine invertebrate taxa, including bryozoans, tunicates, bivalves, and gastropods, separated by distances of <
200
km to >
5000
km. We then combined physiological thermotolerance data with current temperature data and climate change predictions to predict which of these populations may be most vulnerable to future changes. In a trans-continental comparison of four subtidal epibenthic species, we show that populations on the east coast of the United States, which experienced higher habitat temperatures than those on the west coast, had higher thermal tolerances but lived closer to individuals' tolerance limits. Similarly, temperature tolerances varied between western and eastern Atlantic populations of the mussel
Mytilus edulis; however, these differences only emerged after repeated exposures to high temperatures. Furthermore, the less thermotolerant
M. edulis population in the western Atlantic was more susceptible to temperature increases, as evidenced by a recent range contraction. Thus, for both the subtidal epibenthic and intertidal mussel species, we identified the western Atlantic as a ‘hot spot’ of populations susceptible to climate change compared to those in the eastern Pacific and eastern Atlantic, respectively. Finally, because current tolerances are not the sole indicators of individuals' abilities to cope with temperature increases, we also assessed the possibility for acclimatization to facilitate the persistence of populations
via the buffering of temperature effects. We show that, for four populations of intertidal
Littorina snail species in the northwest Atlantic, most populations were able to overcome geographic differences in temperature tolerance
via acclimation. When acclimation capacity is low, the potential for “rescue” may depend on the particular species' life-history strategy and dispersal ability. For example, although individuals from the coldest-adapted population of
Littorina littorea were unable to acclimate as quickly as those from more southern populations, this species has a pelagic larval stage and, thus, the greatest dispersal potential of these littorines. Together, these studies highlight the importance of considering variation in temperature tolerance between populations within species to improve the forecasting of changes in the abundances and distributions of species in response to climate warming.
► Populations within a species may differ in ability to cope with climate change. ► Geographic variation in temperature tolerance is indicative of coping ability. ► Thermal tolerance varied geographically across several invertebrate taxa. ► Western Atlantic populations were often more susceptible to climate warming. ► Coping with climate change will involve tolerance, acclimation, and dispersal.
Invasive Alien Species (IAS) are amongst the most significant drivers of species extinction and ecosystem degradation, causing negative impacts on ecosystem services and human well-being. InvasiBES, ...a project funded by BiodivERsA-Belmont Forum for 2019–2021, will use data and models across scales, habitats and species to understand and anticipate the multi-faceted impacts of IAS and to provide tools for their management. Using Alien Species Narratives as reference, we will design future intervention scenarios focused on prevention, control and eradication of IAS in Europe and the United States, through a participatory process bringing together the expertise of scientists and stakeholders. We will also adapt current impact assessment protocols to assess both the detrimental and beneficial impacts of IAS on biodiversity and ecosystem services. This information will then be combined with maps of the potential distribution of Invasive Species of Interest in Europe under current and future climate-change scenarios. Likewise, we will anticipate areas under risk of invasion by range-shifting plants of concern in the US. Finally, focusing on three local-scale studies that cover a range of habitats (freshwater, terrestrial and marine), invasive species (plants and animals) and ecosystem services (supporting, provisioning, regulating and cultural), we will use empirical field data to quantify the real-world impacts of IAS on biodiversity and ecosystem services and calculate indicators of ecosystem recovery after the invader is removed. Spatial planning tools (InVEST) will be used to evaluate the costs and benefits of species-specific intervention scenarios at the regional scale. Data, models and maps, developed throughout the project, will serve to build scenarios and models of biodiversity and ecosystem services that are relevant to underpin management of IAS at multiple scales.
Climate change has driven shifts in species distributions along latitudinal and elevational gradients, and such shifts are likely to continue as warming accelerates. However, little is known about ...the response of strongly interacting species, including whether multiple, interacting species are likely to shift concordantly or whether climate change will promote community disassembly. In rocky shore ecosystems, mussels are dominant foundation species that provide habitat and increase diversity of associated species. The New Zealand mussel guild is uniquely diverse as four species can be found within 1 m
2
of shoreline. We integrated comparative ecophysiology and population ecology to evaluate whether air temperature sets elevational range limits and to quantify mussels’ warming tolerances. Air temperature appears to set upper intertidal limits across mid-intertidal species, based on findings that (1) lethal thermal limits coincided with temperatures experienced at upper tide-height limits, (2) species with higher thermal tolerances occurred higher on shore, and (3) lethal tolerances were highest at our warmest site. Based on predicted body temperatures in year 2100, mid-elevation habitat-forming mussels are likely to experience an increase in the frequency of thermal events causing 50% mortality at their upper elevation limit. Such events are predicted to occur 3.0–4.4 times more frequently in 2100 than present at a warmer site and to increase from 0 to 0.4/0.1 days per year for
Perna/Aulacomya
, but not
Mytilus
, at a cooler site. These results indicate that the mussel species’ ranges are all likely to contract at warmer sites in the future, decreasing habitat for associated organisms.
Extreme events, such as heat waves, are predicted to increase in frequency, duration, and severity as a consequence of climate change. However, global change research generally focuses on increases ...in mean temperatures and fails to address the potential impacts of increasingly severe heat waves. In addition, climate change may interact with another primary threat to biodiversity, non‐native species invasions. We assessed the impacts of a short‐term heat wave on the marine epibenthic fouling community of Bodega Harbor, California, USA, by exposing experimental mesocosms to a simulated heat wave in the laboratory and then monitoring community development in the field. We hypothesized that (1) juveniles would be more susceptible to heat waves than adults, (2) native species would be more susceptible than non‐native species, and (3) non‐native species would recover more quickly than native species. We observed no effect of the heat wave on juvenile species richness, either initially or during the recovery period, relative to communities at ambient seawater temperatures. In contrast, total adult species richness initially declined in response to the heat wave. Adult community composition also changed in heat‐wave treatments, with non‐natives representing the majority of species and occupying more cover than native species. The reduction in native richness associated with the heat wave persisted through the recovery period, whereas invasive richness was actually higher on heat‐wave versus ambient plates at 95 days. Heat waves have the potential to alter the composition of this community because of species‐, taxon‐, and/or origin‐specific responses; for example, non‐native bryozoans displayed greater resistance than native and non‐native tunicates. Recovery from the heat wave occurred via growth of resistant individuals and larval recruitment. Our study highlights the importance of considering species' and community responses to heat waves, and not just mean predicted temperature increases, to evaluate the consequences of climate change.
Ocean warming, acidification, deoxygenation and reduced productivity are widely considered to be the major stressors to ocean ecosystems induced by emissions of CO2. However, an overlooked stressor ...is the change in ocean circulation in response to climate change. Strong changes in the intensity and position of the western boundary currents have already been observed, and the consequences of such changes for ecosystems are beginning to emerge. In this study, we address climatically induced changes in ocean circulation on a global scale but relevant to propagule dispersal for species inhabiting global shelf ecosystems, using a high‐resolution global ocean model run under the IPCC RCP 8.5 scenario. The ¼ degree model resolution allows improved regional realism of the ocean circulation beyond that of available CMIP5‐class models. We use a Lagrangian approach forced by modelled ocean circulation to simulate the circulation pathways that disperse planktonic life stages. Based on trajectory backtracking, we identify present‐day coastal retention, dominant flow and dispersal range for coastal regions at the global scale. Projecting into the future, we identify areas of the strongest projected circulation change and present regional examples with the most significant modifications in their dominant pathways. Climatically induced changes in ocean circulation should be considered as an additional stressor of marine ecosystems in a similar way to ocean warming or acidification.
Under anthropogenic climate change, living systems in the ocean are experiencing stressors including elevated temperature and decreased productivity. Here, we hypothesize a further stressor: ocean circulation change. This threatens to modify the flow pathways used by marine species for dispersing their larval stages, potentially preventing them from reaching settling grounds. Using a global simulation of an extreme climate scenario, we calculate how dispersal pathways for the entire global coastline may change over the 21st century. We highlight regions with the greatest circulation stress, where pathways run with/against climate change, and where connectivity may weaken, strengthen or alter entirely in the future.
Human impacts on ecosystems are resulting in unprecedented rates of biodiversity loss worldwide. The loss of species results in the loss of the multiple roles that each species plays or functions ...(i.e., “ecosystem multifunctionality”) that it provides. A more comprehensive understanding of the effects of species on ecosystem multifunctionality is necessary for assessing the ecological impacts of species loss. We studied the effects of two dominant intertidal species, a primary producer (the seaweed Neorhodomela oregona) and a consumer (the shellfish Mytilus trossulus), on 12 ecosystem functions in a coastal ecosystem, both in undisturbed tide pools and following the removal of the dominant producer. We modified analytical methods used in biodiversity–multifunctionality studies to investigate the potential effects of individual dominant species on ecosystem function. The effects of the two dominant species from different trophic levels tended to differ in directionality (+/−) consistently (92% of the time) across the 12 individual functions considered. Using averaging and multiple threshold approaches, we found that the dominant consumer—but not the dominant producer—was associated with ecosystem multifunctionality. Additionally, the relationship between abundance and multifunctionality differed depending on whether the dominant producer was present, with a negative relationship between the dominant consumer and ecosystem function with the dominant producer present compared to a non‐significant, positive trend where the producer had been removed. Our findings suggest that interactions among dominant species can drive ecosystem function. The results of this study highlight the utility of methods previously used in biodiversity‐focused research for studying functional contributions of individual species, as well as the importance of species abundance and identity in driving ecosystem multifunctionality, in the context of species loss.
We studied the effects of two dominant intertidal species, a primary producer (the seaweed Neorhodomela oregona) and a consumer (the shellfish Mytilus trossulus), on 12 ecosystem functions in a coastal ecosystem, both in undisturbed tide pools and following the removal of the dominant producer. We found that the dominant consumer—but not the dominant producer—was associated with ecosystem multifunctionality, and the relationship differed depending on whether the dominant producer was present. Our findings suggest that interactions among dominant species can drive overall ecosystem function.
Marine communities face continuing and accelerating climate change. Predicting which species will go extinct or persist in future climates requires assessing redistribution potential and tolerance to ...warming, both of which can depend on dispersal ability. We evaluated biophysical processes that could promote population persistence under changing climatic conditions by (1) promoting poleward dispersal in an Eastern Boundary Current region, where offshore currents flow predominantly equatorward, and (2) increasing the frequency of more thermotolerant phenotypes in marine populations. We paired intensive time-series observations (during 2014 and 2015) of recruitment and thermal tolerance limits for cohorts of marine mussels with simulated larval transport using a high-resolution, 3D coastal circulation model of the northeastern Pacific. We used the modeling results to predict the proportion of individuals in each recruiting cohort that originated from sources south or north of our study site on the USA west coast (45.50°N, 123.95°W) as well as the environmental conditions experienced in the water column. We found that the coastal upwelling index was related to origin of individuals within recruiting cohorts, with poleward recruitment predicted to increase under downwelling conditions. Furthermore, thermal tolerance limits were higher in cohorts predicted to experience higher and more variable temperatures during dispersal. These findings highlight complex links between demographic and physical transport processes as well as the potential for climate-driven changes in wind patterns to indirectly affect species’ abilities to cope with increasing temperatures.
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