Ecologization Is Not a Metaphor: Museums in the Web of Life

Ecology and Collaboration

Ecological communities are constantly being reshaped in the face of environmental change and anthropogenic pressures. Yet, how food webs change over time remains poorly understood. Food web science is characterized by a trade‐off between complexity (in terms of the number of species and feeding links) and dynamics. Topological analysis can use complex, highly resolved empirical food web models to explore the architecture of feeding interactions but is limited to a static view, whereas ecosystem models can be dynamic but use highly aggregated food webs. Here, we explore the temporal dynamics of a highly resolved empirical food web over a time period of 18 years, using the German Bight fish and benthic epifauna community as our case study. We relied on long‐term monitoring ecosystem surveys (from 1998 to 2015) to build a metaweb, i.e. the meta food web containing all species recorded over the time span of our study. We then combined time series of species abundances with topological network analysis to construct annual food web snapshots. We developed a new approach, ‘node‐weighted’ food web metrics by including species abundances to represent the temporal dynamics of food web structure, focusing on generality and vulnerability. Our results suggest that structural food web properties change through time; however, binary food web structural properties may not be as temporally variable as the underlying changes in species composition. Further, the node‐weighted metrics enabled us to detect that food web structure was influenced by changes in species composition during the first half of the time series and more strongly by changes in species dominance during the second half. Our results demonstrate how ecosystem surveys can be used to monitor temporal changes in food web structure, which are important ecosystem indicators for building marine management and conservation plans.

Ecologists use stable isotopes (delta13C, delta15N) to better understand food webs and explore trophic interactions in ecosystems. Traditionally, delta13C vs. delta15N bi-plots have been used to describe food web structure for a single time period or ecosystem. Comparisons of food webs across time and space are increasing, but development of statistical approaches for testing hypotheses regarding food web change has lagged behind. Here we present statistical methodologies for quantitatively comparing stable isotope food web data. We demonstrate the utility of circular statistics and hypothesis tests for quantifying directional food web differences using two case studies: an arthropod salt marsh community across a habitat gradient and a freshwater fish community from Lake Tahoe, USA, over a 120-year time period. We calculated magnitude and mean angle of change (theta) for each species in food web space using mean delta13C and delta15N of each species as the x, y coordinates. In the coastal salt marsh, arthropod consumers exhibited a significant shift toward dependence on Spartina, progressing from a habitat invaded by Phragmites to a restored Spartina habitat. In Lake Tahoe, we found that all species from the freshwater fish community shifted in the same direction in food web space toward more pelagic-based production with the introduction of nonnative Mysis relicta and onset of cultural eutrophication. Using circular statistics to quantitatively analyze stable isotope food web data, we were able to gain significant insight into patterns and changes in food web structure that were not evident from qualitative comparisons. As more ecologists incorporate a food web perspective into ecosystem analysis, these statistical tools can provide a basis for quantifying directional food web differences from standard isotope data.

This chapter examines recent case studies of marine food webs to evaluate the applicability of food web theories for the marine environment. Classical macrodescriptors and recent network metrics are evaluated for each marine food web example. Food webs are defined as those which are non-estuarine, non-coastal, and larger in scale than food webs typically and classically studied (i.e., not a bay, not a river-ocean mixing zone, not a rocky inter-tidal zone, etc.). There are clear distinctions for marine food webs when compared to all terrestrial and other aquatic food webs, yet there are also clear distinctions among different types of marine food webs. The chapter notes that there are three categories of food web theories: (i) those factors and models which apply categorically to all food webs; (ii) those factors and models which can be split into simple, lowly connected, strongly interacting, clearly defined localized food webs versus complex, highly connected, weakly interacting, broader, more extensive food webs; and (iii) those factors and models which are uniquely and distinctly marine. Understanding the qualitative properties of food webs can provide further evaluation of which theories are appropriate, which are not, when each is true, and why. Finally, the chapter discusses the applications and implications of these theories for ecosystem-based natural resource management.

Political ecology has recently seen a long-overdue movement toward studies of environmental conflicts in advanced capitalist societies, far from the rural African, Latin American, and Asian societies that constitute the great majority of studies in the field. This shift has raised questions about the commonalities and differences between ‘first-world’ and ‘third-world’ political ecologies - questions that present broader challenges and opportunities for the field. The question of commonalities and difference in ‘first-world’ and ‘third-world’ political ecologies is hemispheric, recent research in political ecology consists primarily of local-scale studies, leaving the field poorly positioned to address such broad-scale comparative questions. Appropriately, local political ecology studies challenge the stability of the ‘first world’ and ‘third world’ as meaningful geographic frames posed in these questions; but in dismantling these frames without suggesting alternatives for broader-scale analysis there is danger of moving political ecology toward even greater emphasis on specificity and difference and pushing consideration of broader-scale processes farther into the background. This is a serious challenge in a field already criticized for sprawling incoherence. This article argues that one response to these challenges is to reconsider the concept of ‘regional’ political ecologies. Regional approaches can retain the greatest strengths of recent political ecology in revealing the importance of local-scale social dynamics while situating these dynamics within broader scales of regional (and global) processes - providing greater coherence while avoiding such problematic frames as the ‘first’ and ‘third’ world. To illustrate, a brief case study and discussion are presented that consider a regional political ecology of the rural American West.

Measuring ecological and economic impacts of invasive species is necessary for managing invaded food webs. Based on abundance, biomass and diet data of autochthonous and allochthonous fish species, we proposed a novel approach to quantifying trophic interaction strengths in terms of number of individuals and biomass that each species subtract to the others in the food web. This allowed to estimate the economic loss associated to the impact of an invasive species on commercial fish stocks, as well as the resilience of invaded food webs to further perturbations. As case study, we measured the impact of the invasive bass Micropterus salmoides in two lake communities differing in food web complexity and species richness, as well as the biotic resistance of autochthonous and allochthonous fish species against the invader. Resistance to the invader was higher, while its ecological and economic impact was lower, in the more complex and species-rich food web. The percid Perca fluviatilis and the whitefish Coregonus lavaretus were the two species that most limited the invader, representing meaningful targets for conservation biological control strategies. In both food webs, the limiting effect of allochthonous species against M. salmoides was higher than the effect of autochthonous ones. Simulations predicted that the eradication of the invader would increase food web resilience, while that an increase in fish diversity would preserve resilience also at high abundances of M. salmoides. Our results support the conservation of biodiverse food webs as a way to mitigate the impact of bass invasion in lake ecosystems. Notably, the proposed approach could be applied to any habitat and animal species whenever biomass and diet data can be obtained.

Reducing methylmercury accumulation in the food webs of San Francisco Bay and its local watersheds

Species invasions represent a significant global challenge in terms of both ecological and economic impact. The incursion of smooth cordgrass Spartina alterniflora and the expansion of Pacific oysters Magallana gigas in coastal areas has resulted in significant alterations to the habitat, which has affected the structure of animal communities. Nevertheless, there remains a paucity of empirical studies examining the mechanisms and impacts of both species on food webs. This study focuses on the intertidal zone of Bohai Bay, China, and assesses the impact of the S. alterniflora invasion and the M. gigas reef on food webs. We constructed quantitative food webs from field data, categorizing habitats into pre-S. alterniflora invasion (uninvaded mudflat), post-S. alterniflora invasion (S. alterniflora-dominated), and post-M. gigas appearance (S. alterniflora-M. gigas co-dominated) periods. We found that the presence of S. alterniflora and M. gigas complicated the food web structure by increasing its links and link density. Analyzed from an energy cycling perspective, S. alterniflora reduced mudflat food web energy cycling, while oysters increased post-S. alterniflora invasion energy flow. Additionally, S. alterniflora invasion decreased local stability of the mudflat food web, which was further reduced by M. gigas aggregations. It is noteworthy that S. alterniflora was incorporated into the food web as a primary producer, primarily mediating trophic interactions. In contrast, M. gigas mainly influenced the food web through non-trophic interactions from habitat modification. The present study offers an empirical case study of the impact of habitat-modifying species on food webs.

Las reflexiones que aquí se presentan nacen de las preocupaciones del área de investigación de “entramados comunitarios y formas de lo político” en torno a lo que hoy en América Latina significa defender la vida para un amplio y variado abanico de procesos organizativos y luchas comunitarias en medio de las renovadas dinámicas de apropiación, despojo, devastación y degradación de las naturalezas humanas y no humanas que las violentas lógicas de acumulación impulsan sin parar. Esta inquietud nos ha llevado a la tarea de dotarnos de una mirada analítica, ecológica, holística y relacional en torno a la noción de vida, que hemos ido componiendo en diálogo con la perspectiva de la ecología-mundo, la ecología política latinoamericana y la apuesta de algunas tradiciones del feminismo por poner en el centro la vida. En este texto, a modo de síntesis parciales, presentamos lo que, desde nuestras propias inquietudes políticas, implica pensar la vida, el Capitaloceno y las disputas planteadas por una multiplicidad de luchas en defensa de lo común con base en diversas investigaciones en diferentes países de América Latina, en particular en México y Bolivia, pero también en Ecuador, Guatemala, Colombia y Uruguay. El texto se compone de tres apartados. En el primero, explicamos qué entendemos por condición de interdependencia y cómo, a partir de esta idea, recuperamos la noción de trama/tejido de la vida propuesta por diferentes autores. En el segundo, nos preguntamos por la vida que el proyecto moderno-capitalista ha ido produciendo a partir de la lógica de dominio de carácter antropocéntrico, patriarcal y colonial y los modos en los que se ha buscado reorganizar la condición de interdependencia, poniendo a trabajar a las naturalezas humanas y no humanas para garantizar la lógica de acumulación. Un ejemplo a través del cual ilustramos estas dinámicas es la gestión capitalista de las relaciones de interdependencia en torno al agua en tiempos neoliberales. Y finalmente, exponemos sobre la base de numerosas investigaciones, enfocadas principalmente en experiencias comunitarias en oposición a algún proyecto extractivista, nuestro acercamiento al antagonismo social y la disputa que entablan las luchas por lo común en América Latina para defender la vida y gestionar las relaciones de interdependencia en contradicción con los términos de coproducción capitalistas.

This chapter argues for the relevance of a wisdom approach to philosophical theology for the ecological crisis. This approach—drawing upon the work of Foucault, Hadot, and Latour—frames exercises of reading and writing within the context of a way of life. These intellectual exercises play a role in webs of life and are potential sites for change. On this account, philosophical theology is not simply concerned with knowledge, information, or the formulation of doctrine, but is centered on practices of care embedded in political and ecological structures. The introduction illustrates the contemporary relevance of these practices by placing them in dialogue with political ecology and political theology.

Environmental issues have become increasingly prominent in local struggles, national debates, and international policies. In response, scholars are paying more attention to conventional politics and to more broadly defined relations of power and difference in the interactions between human groups and their biophysical environments. Such issues are at the heart of the relatively new interdisciplinary field of political ecology, forged at the intersection of political economy and cultural ecology. This volume provides a toolkit of vital concepts and a set of research models and analytic frameworks for researchers at all levels. The two opening chapters trace rich traditions of thought and practice that inform current approaches to political ecology. They point to the entangled relationship between humans, politics, economies, and environments at the dawn of the twenty-first century and address challenges that scholars face in navigating the blurring boundaries among relevant fields of enquiry. The twelve case studies that follow demonstrate ways that culture and politics serve to mediate human-environmental relationships in specific ecological and geographical contexts. Taken together, they describe uses of and conflicts over resources including land, water, soil, trees, biodiversity, money, knowledge, and information; they exemplify wide-ranging ecological settings including deserts, coasts, rainforests, high mountains, and modern cities; and they explore sites located around the world, from Canada to Tonga and cyberspace

Mercury and selenium biomagnification in a Brazilian coastal food web using nitrogen stable isotope analysis: A case study in an area under the influence of the Paraiba do Sul River plume

The objective of our paper is to develop a mechanistic conceptual framework for how food webs recover from natural physical disturbances. We summarize our work on the effect of hurricanes on island food webs and review other studies documenting how other types of physical disturbances (including fires, floods, and volcanic eruptions) alter food-web interactions. Based on these case studies, we propose that four factors play an important role in food-web succession: (1) disturbance intensity, (2) sequential recovery/colonization of successively higher trophic levels, (3) tradeoffs between growth rate of organisms at different successional stages and susceptibility to consumers, and (4) detritus including autochthonous and allochthonous sources. Studies on river flooding and islands disturbed by hurricanes indicate that energy flow is higher and trophic cascades are stronger during recovery than when the food web is at a steady state. We suggest that as consumer species colonize during succession, they may change the species or phenotypic composition of their food supply from highly vulnerable to less vulnerable items, thereby weakening both bottom-up and top-down effects throughout the food web. High inputs of detritus caused by disturbances can amplify bottom-up effects during early succession, and subsequently alter top-down effects.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 398:93-107 (2010) - DOI: https://doi.org/10.3354/meps08335 Carbon transfer in a herbivore- and microbial loop-dominated pelagic food webs in the southern Barents Sea during spring and summer Frederik De Laender*, Dick Van Oevelen, Karline Soetaert, Jack J. Middelburg NIOO-KNAW, Centre for Estuarine and Marine Ecology, Korringaweg 7, PO Box 140, 4401 Yerseke, The Netherlands *Email: frederik.delaender@ugent.be ABSTRACT: We compared carbon budgets between a herbivore-dominated and a microbial loop-dominated food web and examined the implications of food web structure for fish production. We used the southern Barents Sea as a case study and inverse modelling as an analysis method. In spring, when the system was dominated by the herbivorous web, the diet of protozoa consisted of similar amounts of bacteria and phytoplankton. Copepods showed no clear preference for protozoa. Cod Gadus morhua, a predatory fish preying on copepods and on copepod-feeding capelin Mallotus villosus in spring, moderately depended on the microbial loop in spring, as only 20 to 60% of its food passed through the microbial loop. In summer, when the food web was dominated by the microbial loop, protozoa ingested 4 times more bacteria than phytoplankton and protozoa formed 80 to 90% of the copepod diet. Because of this strong link between the microbial loop and copepods (the young cod’s main prey item) young cod (<3 yr) depended more on the microbial loop than on any other food web compartment, as >60% of its food passed through the microbial loop in summer. Adult cod (≤3 yr) relied far less on the microbial loop than young cod as it preyed on strictly herbivorous krill in summer. Food web efficiency for fish production was comparable between seasons (~5 × 10–4) and 2 times higher in summer (5 × 10–2) than in spring for copepod production. KEY WORDS: Food web · Microbial loop · Protozoa · Copepods · Gadus morhua Full text in pdf format Supplementary Material PreviousNextCite this article as: De Laender F, Van Oevelen D, Soetaert K, Middelburg JJ (2010) Carbon transfer in a herbivore- and microbial loop-dominated pelagic food webs in the southern Barents Sea during spring and summer. Mar Ecol Prog Ser 398:93-107. https://doi.org/10.3354/meps08335Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 398. Online publication date: January 05, 2010 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2010 Inter-Research.

Summary 1. A food web is presented which describes trophic interactions among the herbivores, parasitoids, predators and pathogens associated with broom, Cytisus scoparius (L.) Link. The data come from published work on the community at a single site. The web comprises a total of 154 taxa: one plant, 19 herbivores, 66 parasitoids, 60 predators, five omnivores and three pathogens. There are 370 trophic links between these taxa in the web. The taxa form 82 functionally distinct groups, called trophic species. 2. Predators consumed significantly more species than did parasitoids: a median of two prey species per species of predator (range = 1–9), compared to a median of one host species per species of parasitoid (range = 1–4). Significant differences in the number of species consumed were also found among the five predator groups: birds (median = 4), spiders (median = 5), Coleoptera (median = 1), Diptera (median = 2) and Hemiptera (median = 7). 3. Vulnerability, measured by numbers of consumer species, was significantly affected by the herbivores’ feeding styles: externally feeding herbivores were most vulnerable and the concealed herbivores were least vulnerable. Miners were vulnerable to the most parasitoid species and externally feeding herbivores were the most vulnerable to predators. 4. Resource species had a median vulnerability of 13 consumer species, a figure far higher than that in most published food webs. No significant relationship was found between species’ vulnerability to predators and vulnerability to parasitoids. However, there was a strong negative relationship between the percentage mortality due to predation and percentage mortality due to parasitism. 5. The broom food web contains nine orders of insects, a figure higher than previously recorded. The web also contains vertebrates, arachnids, bacteria and fungi. Most of the interactions between the orders were weak. Connectance was calculated for the complete web, the parasitoid sub‐web and the predator sub‐web. The connectance of the predator sub‐web, a value of 0·0364, was more than an order of magnitude larger than the connectance of the entire web (0·0156) or the parasitoid sub‐web (0·018). 6. The body lengths of 52 species in the food web were estimated from field guides or museum specimens. Larger predators consumed smaller prey in 93% of predator–prey interactions. Smaller parasitoids consumed larger hosts in 79% of parasitoid–host interactions. Parasitoids were significantly smaller than predators. 7. The 52 species were arranged in order of increasing body length along the columns and down the rows of a food web matrix. The predator sub‐web was predominantly upper triangular with 8% of non‐zero elements falling below the leading diagonal. The parasitoid sub‐web was predominantly lower triangular with 21% non‐zero elements falling above the leading diagonal. The entire web contains entries both above and below the main diagonal and thus violates a central assumption of the cascade model.