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Abstract Climate change is negatively impacting ecosystems and their contributions to human well‐being, known as ecosystem services. Previous research has mainly focused on the direct effects of climate change on species and ecosystem services, leaving a gap in understanding the indirect impacts resulting from changes in species interactions within complex ecosystems. This knowledge gap is significant because the loss of a species in a food web can lead to additional species losses or “co‐extinctions,” particularly when the species most impacted by climate change are also the species that play critical roles in food web persistence or provide ecosystem services. Here, we present a framework to investigate the relationships among species vulnerability to climate change, their roles within the food web, their contributions to ecosystem services, and the overall persistence of these systems and services in the face of climate‐induced species losses. To do this, we assess the robustness of food webs and their associated ecosystem services to climate‐driven species extinctions in eight empirical rocky intertidal food webs. Across food webs, we find that highly connected species are not the most vulnerable to climate change. However, we find species that directly provide ecosystem services are more vulnerable to climate change and more connected than species that do not directly provide services, which results in ecosystem service provision collapsing before food webs. Overall, we find that food webs are more robust to climate change than the ecosystem services they provide and show that combining species roles in food webs and services with their vulnerability to climate change offer predictions about the impacts of co‐extinctions for future food web and ecosystem service persistence. However, these conclusions are limited by data availability and quality, underscoring the need for more comprehensive data collection on linking species roles in interaction networks and their vulnerabilities to climate change.
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Scientists' warning on endangered food webs
Abstract. All organisms are ultimately dependent on a large diversity of consumptiveand non-consumptive interactions established with other organisms, formingan intricate web of interdependencies. In 1992, when 1700 concernedscientists issued the first “World Scientists' Warning to Humanity”, ourunderstanding of such interaction networks was still in its infancy. Bysimultaneously considering the species (nodes) and the links that glue themtogether into functional communities, the study of modern food webs – ormore generally ecological networks – has brought us closer to a predictivecommunity ecology. Scientists have now observed, manipulated, and modelledthe assembly and the collapse of food webs under various global changestressors and identified common patterns. Most stressors, such as increasingtemperature, biological invasions, biodiversity loss, habitat fragmentation,over-exploitation, have been shown to simplify food webs byconcentrating energy flow along fewer pathways, threatening long-termcommunity persistence. More worryingly, it has been shown that communitiescan abruptly change from highly diverse to simplified stable states withlittle or no warning. Altogether, evidence shows that apart from thechallenge of tackling climate change and hampering the extinction ofthreatened species, we need urgent action to tackle large-scale biologicalchange and specifically to protect food webs, as we are under the risk of pushingentire ecosystems outside their safe zones. At the same time, we need togain a better understanding of the global-scale synergies and trade-offsbetween climate change and biological change. Here we highlight the mostpressing challenges for the conservation of natural food webs and recentadvances that might help us addressing such challenges.
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- Award ID(s):
- 1754221
- PAR ID:
- 10165673
- Date Published:
- Journal Name:
- Web Ecology
- Volume:
- 20
- Issue:
- 1
- ISSN:
- 1399-1183
- Page Range / eLocation ID:
- 1 to 10
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Food webs show the architecture of trophic relationships, revealing the biodiversity and species interactions in an ecosystem. Understanding which factors modulate the structure of food webs offers us the ability to predict how they will change when influential factors are altered. To date, most of the research about food webs has focused on species interactions whereas the influences of surrounding environments have been overlooked. Here, using network analysis, we identified how the structure of aquatic food webs varied across a range of geophysical conditions within a whole stream system. Within a headwater basin in the Cascade Mountain Range, Oregon, USA, macroinvertebrate and vertebrate composition was investigated at 18 sites. Predator–prey interactions were compiled based on existing literature and dietary analysis. Several structural network metrics were calculated for each food web. We show that the structure of food webs was predictable based on geophysical features at both local (i.e., slope) and broader (i.e., basin size) spatial extents. Increased omnivory, greater connectance, shorter path lengths, and ultimately greater complexity and resilience existed downstream compared to upstream in the stream network. Surprisingly, the variation in food web structure was not associated with geographic proximity. Structural metric values and abundance of omnivory suggest high levels of stability for these food webs. There is a predictable variation in the structure of food webs across the network that is influenced by both longitudinal position within streams and patchy discontinuities in habitat. Hence, findings illustrate that the slightly differing perspectives from the River Continuum Concept, Discontinuity Patch Dynamics, and Process Domains can be integrated and unified using food web networks. Our analyses extend ecologists’ understanding of the stability of food webs and are a vital step toward predicting how webs and communities may respond to both natural disturbances and current global environmental change.more » « less
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Some organisms can produce their own food through a process called photosynthesis. These organisms transform light energy, carbon dioxide, and water into sugars, which allow them to grow their bodies, reproduce, and be a source of energy for other organisms. Studying photosynthesis in nature and in the laboratory has given scientists important insights into the effects of climate change on plants and other photosynthetic organisms. For example, such studies help scientists understand whether there will continue to be enough food for humans to eat as the climate changes. In this article, we discuss the importance of photosynthetic organisms; how light energy, carbon dioxide, and water are transformed into sugar during photosynthesis; the challenges that today’s land plants face; and how and why scientists measure photosynthesis in plants.more » « less
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Abstract While climate change is altering ecosystems on a global scale, not all ecosystems are responding in the same way. The resilience of ecological communities may depend on whether food webs are producer‐ or detritus‐based (i.e. ‘green’ or ‘brown’ food webs, respectively), or both (i.e. ‘multi‐channel’ food web).Food web theory suggests that the presence of multiple energy pathways can enhance community stability and resilience and may modulate the responses of ecological communities to disturbances such as climate change. Despite important advances in food web theory, few studies have empirically investigated the resilience of ecological communities to climate change stressors in ecosystems with different primary energy channels.We conducted a factorial experiment using outdoor stream mesocosms to investigate the independent and interactive effects of warming and drought on invertebrate communities in food webs with different energy channel configurations. Warming had little effect on invertebrates, but stream drying negatively impacted total invertebrate abundance, biomass, richness and diversity.Although resistance to drying did not differ among energy channel treatments, recovery and overall resilience were higher in green mesocosms than in mixed and brown mesocosms. Resilience to drying also varied widely among taxa, with larger predatory taxa exhibiting lower resilience.Our results suggest that the effects of drought on stream communities may vary regionally and depend on whether food webs are fuelled by autochthonous or allochthonous basal resources. Communities inhabiting streams with large amounts of organic matter and more complex substrates that provide refugia may be more resilient to the loss of surface water than communities inhabiting streams with simpler, more homogeneous substrates.more » « less
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null (Ed.)Abstract Analyses of ancient food webs reveal important paleoecological processes and responses to a range of perturbations throughout Earth's history, such as climate change. These responses can inform our forecasts of future biotic responses to similar perturbations. However, previous analyses of ancient food webs rarely accounted for key differences between modern and ancient community data, particularly selective loss of soft-bodied taxa during fossilization. To consider how fossilization impacts inferences of ancient community structure, we (1) analyzed node-level attributes to identify correlations between ecological roles and fossilization potential and (2) applied selective information loss procedures to food web data for extant systems. We found that selective loss of soft-bodied organisms has predictable effects on the trophic structure of “artificially fossilized” food webs because these organisms occupy unique, consistent food web positions. Fossilized food webs misleadingly appear less stable (i.e., more prone to trophic cascades), with less predation and an overrepresentation of generalist consumers. We also found that ecological differences between soft- and hard-bodied taxa—indicated by distinct positions in modern food webs—are recorded in an early Eocene web, but not in Cambrian webs. This suggests that ecological differences between the groups have existed for ≥48 Myr. Our results indicate that accounting for soft-bodied taxa is vital for accurate depictions of ancient food webs. However, the consistency of information loss trends across the analyzed food webs means it is possible to predict how the selective loss of soft-bodied taxa affects food web metrics, which can permit better modeling of ancient communities.more » « less
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.5194/we-20-1-2020
