As climate change continues, anticipating species’ responses to rising temperatures requires an understanding of the drivers of thermal sensitivity, which itself may vary over space and time. We ...measured metabolic rates of three representative marine invertebrate species (hermit crabs
Pagurus hirsutiusculus
, periwinkle snails
Littorina sitkana
, and mussels
Mytilus trossulus
) and evaluated the relationship between thermal sensitivity (
Q
10
) and thermal history. We tested the hypothesis that thermal history drives thermal sensitivity and quantified how this relationship differs over time (short-term to seasonal time scales) and between species. Organisms were collected from tide pools in Sitka, Alaska where we also recorded temperatures to characterize thermal history prior to metabolic rate assays. Using respirometry, we estimated mass-specific oxygen consumption (
MO
2
) at ambient and increased temperatures for one individual per species per tide pool across three seasons. We evaluated relationships between thermal sensitivity and pool temperatures for time periods ranging from 1 day to 1 month prior to collection. For all species, thermal sensitivity was related to thermal history for the shorter time periods (1 day to 1 week). However, the direction of the relationships and most important thermal parameters (i.e., maximum, mean, or range) differed between species and seasons. We found that on average,
P. hirsutiusculus
and
L. sitkana
were more thermally sensitive than
M. trossulus
. These findings show that variability in thermal history over small spatial scales influences individuals’ metabolic response to warming and may be indicative of these species’ ability to acclimate to future climate change.
Biological processes play important roles in determining how global changes manifest at local scales. Primary producers can absorb increased CO2 via daytime photosynthesis, modifying pH in aquatic ...ecosystems. Yet producers and consumers also increase CO2 via respiration. It is unclear whether biological modification of pH differs across the year, and, if so, what biotic and abiotic drivers underlie temporal differences. We addressed these questions using the intensive study of tide pool ecosystems in Alaska, USA, including quarterly surveys of 34 pools over 1 year and monthly surveys of five pools from spring to fall in a second year. We measured physical conditions, community composition, and changes in pH and dissolved oxygen during the day and night. We detected strong temporal patterns in pH dynamics. Our measurements indicate that pH modification varies spatially (between tide pools) and temporally (across months). This variation in pH dynamics mirrored changes in dissolved oxygen and was associated with community composition, including both relative abundance and diversity of benthic producers and consumers, whose role differed across the year, particularly at night. These results highlight the importance of the time of year when considering the ways that community composition influences pH conditions in aquatic ecosystems.
Integrated assessment of biological invasions Ibáñez, Inés; Diez, Jeffrey M; Miller, Luke P ...
Ecological applications,
2014-January, 20140101, January 2014, 2014-Jan, 2014-01-00, Letnik:
24, Številka:
1
Journal Article
Recenzirano
Odprti dostop
As the main witnesses of the ecological and economic impacts of invasions on ecosystems around the world, ecologists seek to provide the relevant science that informs managers about the potential for ...invasion of specific organisms in their region(s) of interest. Yet, the assorted literature that could inform such forecasts is rarely integrated to do so, and further, the diverse nature of the data available complicates synthesis and quantitative prediction. Here we present a set of analytical tools for synthesizing different levels of distributional and/or demographic data to produce meaningful assessments of invasion potential that can guide management at multiple phases of ongoing invasions, from dispersal to colonization to proliferation. We illustrate the utility of data-synthesis and data-model assimilation approaches with case studies of three well-known invasive species-a vine, a marine mussel, and a freshwater crayfish-under current and projected future climatic conditions. Results from the integrated assessments reflect the complexity of the invasion process and show that the most relevant climatic variables can have contrasting effects or operate at different intensities across habitat types. As a consequence, for two of the study species climate trends will increase the likelihood of invasion in some habitats and decrease it in others. Our results identified and quantified both bottlenecks and windows of opportunity for invasion, mainly related to the role of human uses of the landscape or to disruption of the flow of resources. The approach we describe has a high potential to enhance model realism, explanatory insight, and predictive capability, generating information that can inform management decisions and optimize phase-specific prevention and control efforts for a wide range of biological invasions.
Invasive species science has focused heavily on the invasive agent. However, management to protect native species also requires a proactive approach focused on resident communities and the features ...affecting their vulnerability to invasion impacts. Vulnerability is likely the result of factors acting across spatial scales, from local to regional, and it is the combined effects of these factors that will determine the magnitude of vulnerability. Here, we introduce an analytical framework that quantifies the scale‐dependent impact of biological invasions on native richness from the shape of the native species–area relationship (SAR). We leveraged newly available, biogeographically extensive vegetation data from the U.S. National Ecological Observatory Network to assess plant community vulnerability to invasion impact as a function of factors acting across scales. We analyzed more than 1000 SARs widely distributed across the USA along environmental gradients and under different levels of non‐native plant cover. Decreases in native richness were consistently associated with non‐native species cover, but native richness was compromised only at relatively high levels of non‐native cover. After accounting for variation in baseline ecosystem diversity, net primary productivity, and human modification, ecoregions that were colder and wetter were most vulnerable to losses of native plant species at the local level, while warmer and wetter areas were most susceptible at the landscape level. We also document how the combined effects of cross‐scale factors result in a heterogeneous spatial pattern of vulnerability. This pattern could not be predicted by analyses at any single scale, underscoring the importance of accounting for factors acting across scales. Simultaneously assessing differences in vulnerability between distinct plant communities at local, landscape, and regional scales provided outputs that can be used to inform policy and management aimed at reducing vulnerability to the impact of plant invasions.
AbstractClimate change threatens biodiversity worldwide, and assessing how those changes will impact communities will be critical for conservation. Dominant primary producers can alter local-scale ...environmental conditions, reducing temperature
shading and mitigating ocean acidification
photosynthesis, which could buffer communities from the impacts of climate change. We conducted two experiments on the coast of southeastern Alaska to assess the effects of a common seaweed species,
, on temperature and pH in field tide pools and tide pool mesocosms. We found that
was numerically dominant in this system, covering >60% of habitable space in the pools and accounting for >40% of live cover. However, while
had a density-dependent effect on pH in isolated mesocosms, we did not find a consistent effect of
on either pH or water temperature in tide pools in the field. These results suggest that the amelioration of climate change impacts in immersed marine ecosystems by primary producers is not universal and likely depends on species' functional attributes, including photosynthetic rate and physical structure, in addition to abundance or dominance.
Accelerating rates of climate change and a paucity of whole-community studies of climate impacts limit our ability to forecast shifts in ecosystem structure and dynamics, particularly because climate ...change can lead to idiosyncratic responses via both demographic effects and altered species interactions. We used a multispecies model to predict which processes and species' responses are likely to drive shifts in the composition of a space-limited benthic marine community. Our model was parametrized from experimental manipulations of the community. Model simulations indicated shifts in species dominance patterns as temperatures increase, with projected shifts in composition primarily owing to the temperature dependence of growth, mortality and competition for three critical species. By contrast, warming impacts on two other species (rendering them weaker competitors for space) and recruitment rates of all species were of lesser importance in determining projected community changes. Our analysis reveals the importance of temperature-dependent competitive interactions for predicting effects of changing climate on such communities. Furthermore, by identifying processes and species that could disproportionately leverage shifts in community composition, our results contribute to a mechanistic understanding of climate change impacts, thereby allowing more insightful predictions of future biodiversity patterns.
High community diversity may either prevent or promote the establishment of exotic species. The biotic resistance hypothesis holds that species-rich communities are more resistant to invasion than ...species-poor communities due to mechanisms including greater interspecific competition. Conversely, the invasional meltdown hypothesis proposes that greater exotic diversity increases invasibility via facilitative interactions between exotic species. To evaluate the degree to which biotic resistance or invasional meltdown influences marine community structure during the assembly period, we studied the development of marine epibenthic “fouling” communities at two southern California harbors. With a focus on sessile epibenthic species, we found that fewer exotic species established as total and exotic richness increased during community assembly and that this effect remained after accounting for space availability. We also found that changes in exotic abundance decreased over time. Throughout the assembly period, gains in exotic abundance were greatest when space was abundant and richness was low. Altogether, we found greater support for biotic resistance than invasional meltdown, suggesting that both native and exotic species contribute to biotic resistance during early development of these communities. However, our results indicate that biotic resistance may not always reduce the eventual dominance of exotic species.
Impacts of increases in extreme heat events under climate change may differ across ontogeny for species with complex life cycles. Different life stages may (1) experience unequal levels of ...environmental stress that vary across space and time (exposure) and (2) have different stress tolerances (sensitivity). We used a field experiment to investigate whether exposure, sensitivity, and overall mortality risk differed between life stages of a marine foundation species (the mussel Mytilus californianus) across thermal conditions that vary in space (habitat, elevation, and site) and time (season) in southern California, USA. We deployed temperature loggers to document habitat‐specific exposure patterns, conducted laboratory thermal tolerance assays to calculate sensitivity, and performed field surveys to determine whether risk patterns were reflected in distributions. Exposure to extreme temperatures was highest in solitary habitats and during spring. Juvenile mussels were more sensitive to extreme heat than adults, and sensitivity for both life stages was highest in December and March. Risk was largely seasonal for juveniles but was more temporally variable for adults. Spatial occurrence patterns were congruent with risk assessments for both life stages (i.e., higher occurrence in lower risk habitats). These results highlight the importance of incorporating life stage and temporal dynamics when predicting impacts of climate change.
Existing projections of climate change impacts focus primarily on direct abiotic impacts on individuals and populations. However, these models often ignore species interactions, which are vital for ...determining community composition and structure. To evaluate both direct and indirect effects of climate change on species distributions, we applied the Menge–Sutherland model, which describes the relative role of predation and environmental stress in regulating community structure. Using a space‐for‐time approach, we tested the predictions that (1) predators are more strongly impacted by increasing environmental stress than prey (as described in the Menge–Sutherland model) and (2) incorporating indirect (predator) effects increases our ability to predict impacts of increased temperature on prey distributions. We surveyed vertical distributions of predators (sea stars) and a foundational prey species (mussels) at 20 intertidal sites spanning a thermal gradient along the West Coast of the United States. Using generalized linear models and structural equation models, we found that as temperature increased, the upper limits of foundational prey species decreased (a direct effect), while prey lower limits also shifted downward, due to an indirect effect of temperature on predator distributions. Under future climate change, mussel ranges may undergo vertical shifts toward subtidal habitats, allowing for localized persistence of mussels and associated species. Our model comparisons indicate that this framework—incorporating both direct and indirect environmental stress effects within a classic community regulation model—can improve prediction of responses to warming. Community regulation models could be expanded to inform management and conservation efforts during unprecedented climate and ecological change.
Science instructors are increasingly incorporating teaching techniques that help students develop core competencies such as critical-thinking and communication skills. These core competencies are ...pillars of career readiness that prepare undergraduate students to successfully transition to continuing education or the workplace, whatever the field. Course-based undergraduate research experiences that culminate in written research papers can be effective at developing critical-thinking and communication skills but are challenging to implement as class size (and student-to-instructor ratio) grows. We developed a hierarchical mentoring program in which graduate student mentors guided groups of four to five undergraduate students through the scientific process in an upper-level ecology course. Program effectiveness was evaluated by grading final research papers (including previous year papers, before the program was implemented) and surveys (comparing to a course that did not implement the program). Results indicated that primary benefits of hierarchical mentoring were improvements in perceived and demonstrated ability in data analysis and interpretation, leading to a median increase in paper score of ~10% on a 100-point scale. Future directions indicated by our study were a need to incorporate more approaches (e.g., low-stakes writing exercises) and resources into a revised program to improve outcomes for students whose primary language is not English.
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