When Wolves Recolonize: Indirect Effects on the Small and Medium-Sized Mammal Community

The abundance and diversity of mammals will be greatly affected by a number of factors, including plant productivity, climate, natural disturbance, and disease. Of particular interest to conservation strategies, there is little known about the ecological role that carnivores play in maintaining ecosystem structure. Large carnivores were essentially eliminated from much of their range during the last century. Yet, a growing body of experimental evidence indicates that top carnivores are keystone species, and they play important roles in maintaining the health of Nature. The predatory activities of large carnivores produce effects that ripple through the trophic levels of an ecosystem and affect organisms that seem distantly removed, ecologically and taxonomically. But, few studies have examined the indirect impacts of predation across those trophic levels. Such studies have been deemed a high priority in the Greater Yellowstone Ecosystem. Presently, we are assessing the abundance of selected species of mammals at sites representing five major vegetation types found in the Grand Teton National Park. The five vegetation sites are sampled in areas with and without wolves. The size range of these mammals extends from voles/mice to coyotes. Small rodents are being assessed through standard capture/recapture techniques using Sherman traps. Carnivores are being estimated by genetic identification of scat. That method is non-invasive, and by walking transects two times, we can essentially estimate populations sizes using the Lincoln-Peterson statistical technique. Mammals that can not be easily trapped or identified through scat will be followed over time using indices of abundance.

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The establishment of an invasive pest mite, Raoiella indica, affects mite abundance and diversity on coconut plants

Systematic and Applied Acarology ◽

10.11158/saa.25.5.9 ◽

2020 ◽

Vol 25 (5) ◽

pp. 881-894

Author(s):

Maria Edvânia Neves Barros ◽

Debora B. Lima ◽

Jairo A. Mendes ◽

Manoel G. C. Gondim Jr. ◽

José Wagner Da Silva Melo

Keyword(s):

Invasive Species ◽

Keystone Species ◽

Invasive Pest ◽

Ecosystem Structure ◽

Feeding Mode ◽

Phytoseiid Mites ◽

Red Palm Mite ◽

Raoiella Indica ◽

Pest Mite ◽

Abundance And Diversity

The introduction and establishment of an invasive species in a new habitat represents a major threat to biodiversity and ecosystem structure. A recent example of a mite that has become an invasive species is the red palm mite, Raoiella indica Hirst (Acari: Tenuipalpidae). After its introduction in the Americas, this species has considerably expanded the number of hosts and has been reported as a key pest of some of these. In the present study we investigated the possibility of mitefauna alteration on coconut leaflets (abundance and diversity) mediated by the introduction and establishment of R. indica. A survey was conducted over a period of 1 year in two areas of coconut cultivation: one infested and one free of R. indica. The results of the present study suggest that the introduction of R. indica modifies the mitefauna existing in coconut leaflets. Differences were detected in the abundance and diversity of mites at the level of the taxonomic categories (family and species) and at the level of the trophic groups (predators, herbivores and mites with undefined feeding mode). Additionally, in plants infested by the invasive species, a similar pattern was observed between the fluctuation of the phytoseiid mites and other tenuipalpid mites. In these plants, the density of the tenuipalpid mites (including R. indica) was also the variable that most contributed to explain the fluctuation of phytoseiid mites. This suggests that the invasive species, R. indica, acts as a keystone species, structuring the mitefauna in coconut plants.

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Decoupled taxonomic and ecological recoveries from the Permo-Triassic extinction

Science Advances ◽

10.1126/sciadv.aat5091 ◽

2018 ◽

Vol 4 (10) ◽

pp. eaat5091 ◽

Cited By ~ 22

Author(s):

Haijun Song ◽

Paul B. Wignall ◽

Alexander M. Dunhill

Keyword(s):

Time Scales ◽

Carrying Capacity ◽

Mass Extinction ◽

Marine Species ◽

Taxonomic Diversity ◽

Marine Ecosystems ◽

Trophic Levels ◽

Ecosystem Structure ◽

Top Down ◽

Structure Building

The Permian-Triassic mass extinction was the worst crisis faced by life; it killed >90% of marine species in less than 0.1 million years (Ma). However, knowledge of its macroecological impact over prolonged time scales is limited. We show that marine ecosystems dominated by non-motile animals shifted to ones dominated by nektonic groups after the extinction. In Triassic oceans, animals at high trophic levels recovered faster than those at lower levels. The top-down rebuilding of marine ecosystems was still underway in the latest Triassic, ~50 Ma after the extinction, and contrasts with the ~5-Ma recovery required for taxonomic diversity. The decoupling between taxonomic and ecological recoveries suggests that a process of vacant niche filling before reaching the maximum environmental carrying capacity is independent of ecosystem structure building.

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4. Communities

Ecology: A Very Short Introduction ◽

10.1093/actrade/9780198831013.003.0004 ◽

2020 ◽

pp. 48-72

Author(s):

Jaboury Ghazoul

Keyword(s):

Biological System ◽

Keystone Species ◽

Living System ◽

Ecosystem Structure ◽

Ecological Communities ◽

Cooperative Relationships ◽

Collaborative Interactions ◽

Energy Transfers ◽

Great Insight ◽

System Components

‘Communities’ begins by looking at mutualisms, collaborative interactions between species, and goes on to explore ecosystem structure and change. True mutualism is rare, and cooperative relationships easily become exploitative. Entire communities can depend on a ‘keystone’ species, the loss of which has impacts that cascade across the biological system. Succession is the sequential development of increasingly complex ecological communities. Raymond Lindeman’s great insight was to interpret complex ecosystems as flows of energy and matter between living and non-living system components. Successional processes, ecosystem structures, and energy transfers all arise from the myriad of antagonistic and mutualistic interactions among individual organisms.

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Do conservation strategies that increase tiger populations have consequences for other wild carnivores like leopards?

Scientific Reports ◽

10.1038/s41598-019-51213-w ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 3

Author(s):

Ujjwal Kumar ◽

Neha Awasthi ◽

Qamar Qureshi ◽

Yadvendradev Jhala

Keyword(s):

Species Conservation ◽

Camera Trap ◽

Conservation Strategies ◽

Spatially Explicit ◽

Large Carnivores ◽

Catchment Scale ◽

Large Carnivore ◽

Positive Growth ◽

Capture Recapture ◽

Very High

Abstract Most large carnivore populations are declining across their global range except in some well managed protected areas (PA’s). Investments for conserving charismatic apex carnivores are often justified due to their umbrella effect on biodiversity. We evaluate population trends of two large sympatric carnivores, the tiger and leopard through spatially-explicit-capture-recapture models from camera trap data in Kanha PA, India, from 2011 to 2016. Our results show that the overall density (100 km−2) of tigers ranged between 4.82 ± 0.33 to 5.21 ± 0.55SE and of leopards between 6.63 ± 0.71 to 8.64 ± 0.75SE, with no detectable trends at the PA scale. When evaluated at the catchment scale, Banjar catchment that had higher prey density and higher conservation investments, recorded significant growth of both carnivores. While Halon catchment, that had lower prey and conservation investments, populations of both carnivores remained stable. Sex ratio of both carnivores was female biased. As is typical with large carnivores, movement parameter sigma (an index for range size), was larger for males than for females. However, sigma was surprisingly similar for the same genders in both carnivores. At home-range scale, leopards achieved high densities and positive growth rates in areas that had low, medium or declining tiger density. Our results suggest that umbrella-species conservation value of tigers is likely to be compromised at very high densities and therefore should not be artificially inflated through targeted management.

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Shoot, shovel and shut up: cryptic poaching slows restoration of a large carnivore in Europe

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2011.1275 ◽

2011 ◽

Vol 279 (1730) ◽

pp. 910-915 ◽

Cited By ~ 153

Author(s):

Olof Liberg ◽

Guillaume Chapron ◽

Petter Wabakken ◽

Hans Christian Pedersen ◽

N. Thompson Hobbs ◽

...

Keyword(s):

Canis Lupus ◽

State Space Model ◽

Total Mortality ◽

Conservation Strategies ◽

Population Recovery ◽

Large Carnivores ◽

Multiple Sources ◽

Space Model ◽

The Past ◽

Conservation Plans

Poaching is a widespread and well-appreciated problem for the conservation of many threatened species. Because poaching is illegal, there is strong incentive for poachers to conceal their activities, and consequently, little data on the effects of poaching on population dynamics are available. Quantifying poaching mortality should be a required knowledge when developing conservation plans for endangered species but is hampered by methodological challenges. We show that rigorous estimates of the effects of poaching relative to other sources of mortality can be obtained with a hierarchical state–space model combined with multiple sources of data. Using the Scandinavian wolf ( Canis lupus ) population as an illustrative example, we show that poaching accounted for approximately half of total mortality and more than two-thirds of total poaching remained undetected by conventional methods, a source of mortality we term as ‘cryptic poaching’. Our simulations suggest that without poaching during the past decade, the population would have been almost four times as large in 2009. Such a severe impact of poaching on population recovery may be widespread among large carnivores. We believe that conservation strategies for large carnivores considering only observed data may not be adequate and should be revised by including and quantifying cryptic poaching.

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Fisheries impacts on lake ecosystem structure in the context of a changing climate and trophic state

Journal of Limnology ◽

10.4081/jlimnol.2017.1640 ◽

2017 ◽

Author(s):

Tiina Nõges ◽

Orlane Anneville ◽

Jean Guillard ◽

Juta Haberman ◽

Ain Järvalt ◽

...

Keyword(s):

Water Quality ◽

Trophic State ◽

Scale Effects ◽

Trophic Levels ◽

Interactive Effects ◽

Phosphorus Loading ◽

Lake Ecosystem ◽

Ecosystem Structure ◽

Top Down ◽

Lake Basins

<p>Through cascading effects within lake food webs, commercial and recreational fisheries may indirectly affect the abundances of organisms at lower trophic levels, such as phytoplankton, even if they are not directly consumed. So far, interactive effects of fisheries, changing trophic state and climate upon lake ecosystems have been largely overlooked. Here we analyse case studies from five European lake basins of differing trophic states (Lake Võrtsjärv, two basins of Windermere, Lake Geneva and Lake Maggiore) with long-term limnological and fisheries data. Decreasing phosphorus concentrations (re-oligotrophication) and increasing water temperatures have been reported in all five lake basins, while phytoplankton concentration has decreased only slightly or even increased in some cases. To examine possible ecosystem-scale effects of fisheries, we analysed correlations between fish and fisheries data, and other food web components and environmental factors. Re-oligotrophication over different ranges of the trophic scale induced different fish responsesIn the deeper lakes Geneva and Maggiore, we found a stronger link between phytoplankton and planktivorous fish and thus a more important cascading top-down effect than in other lakes. This connection makes careful ecosystem-based fisheries management extremely important for maintaining high water quality in such systems. We also demonstrated that increasing water temperature might favour piscivores at low phosphorus loading, but suppresses them at high phosphorus loading and might thus either enhance or diminish the cascading top-down control over phytoplankton with strong implications for water quality.</p>

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Lake Michigan offshore ecosystem structure and food web changes from 1987 to 2008

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2013-0514 ◽

2014 ◽

Vol 71 (7) ◽

pp. 1072-1086 ◽

Cited By ~ 20

Author(s):

Mark W. Rogers ◽

David B. Bunnell ◽

Charles P. Madenjian ◽

David M. Warner

Keyword(s):

Food Web ◽

Functional Groups ◽

Lake Michigan ◽

Neogobius Melanostomus ◽

Trophic Levels ◽

Nutrient Concentrations ◽

Ecosystem Structure ◽

Bythotrephes Longimanus ◽

Nutrient Inputs ◽

Food Web Structure

Ecosystems undergo dynamic changes owing to species invasions, fisheries management decisions, landscape modifications, and nutrient inputs. At Lake Michigan, new invaders (e.g., dreissenid mussels (Dreissena spp.), spiny water flea (Bythotrephes longimanus), round goby (Neogobius melanostomus)) have proliferated and altered energy transfer pathways, while nutrient concentrations and stocking rates to support fisheries have changed. We developed an ecosystem model to describe food web structure in 1987 and ran simulations through 2008 to evaluate changes in biomass of functional groups, predator consumption, and effects of recently invading species. Keystone functional groups from 1987 were identified as Mysis, burbot (Lota lota), phytoplankton, alewife (Alosa pseudoharengus), nonpredatory cladocerans, and Chinook salmon (Oncorhynchus tshawytscha). Simulations predicted biomass reductions across all trophic levels and predicted biomasses fit observed trends for most functional groups. The effects of invasive species (e.g., dreissenid grazing) increased across simulation years, but were difficult to disentangle from other changes (e.g., declining offshore nutrient concentrations). In total, our model effectively represented recent changes to the Lake Michigan ecosystem and provides an ecosystem-based tool for exploring future resource management scenarios.

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Fish and seagrass communities vary across a marine reserve boundary, but seasonal variation in small fish abundance overshadows top-down effects of large consumer exclosures

10.31230/osf.io/kudq5 ◽

2018 ◽

Author(s):

James Douglass ◽

Richard Paperno ◽

Eric A. Reyier ◽

Anson H. Hines

Keyword(s):

Seasonal Variation ◽

Trophic Levels ◽

Fish Abundance ◽

Predatory Fish ◽

Gut Contents ◽

Spatial And Temporal Variation ◽

Small Fish ◽

Ecosystem Structure ◽

Top Down ◽

Exclusion Experiment

A growing number of examples indicate that large predators can alter seagrass ecosystem structure and processes via top-down trophic interactions. However, the nature and strength of those interactions varies with biogeographic context, emphasizing the need for region-specific investigations. We investigated spatial and temporal variation in predatory fish and seagrass communities across a Marine Protected Area (MPA) boundary in the Banana River Lagoon, Florida (USA), assessing trophic roles of intermediate consumers, and performing a large-consumer exclusion experiment in the MPA. Large, predatory fishes were most abundant within the MPA, while some mid-sized fishes were more abundant outside it. Small, seagrass-resident fishes, epifaunal invertebrates, and macrophytes also differed across the MPA boundary, but varied more among individual sites and seasonally. We cannot conclusively attribute these patterns to MPA status because we lack data from prior to MPA establishment and lack study replication at the level of MPA. Nevertheless, other patterns among our data are consistent with hypothesized mechanisms of top-down control. E.g., inverse seasonal patterns in the abundance of organisms at adjacent trophic levels, coupled with stable C and N isotope and gut contents data, suggest top-down control of crustacean grazers by seasonal recruitment of small fishes. Large-consumer exclosures in the MPA increased the abundance of mid-sized predatory and omnivorous fishes, but had few impacts on lower trophic levels. Results suggest that large-scale variation in large, predatory fish abundance in this system does not strongly affect seagrass-resident fish, invertebrate, and algal communities, which appear to be driven more by habitat structure and seasonal variation in small fish abundance.

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Effect of fishing intensity and selectivity on trophic structure and fishery production

10.31230/osf.io/hr6cu ◽

2018 ◽

Author(s):

Shijie Zhou ◽

Anthony D. M. Smith

Keyword(s):

Growth Rate ◽

Population Growth ◽

Food Chain ◽

Population Growth Rate ◽

Trophic Structure ◽

Total Yield ◽

Trophic Levels ◽

Total Biomass ◽

Ecosystem Structure ◽

Fishing Strategies

Fishing intensity and selectivity patterns affect ecosystem structure and fisheries yield, the 2 fundamental performance measures in the ecosystem approach to fisheries. We used a simple multispecies predation model to explore the effect of alternative fishing strategies on a 3‑trophic-level food chain. Fishing strategies included highly selective fishing, nonselective fishing, and balanced harvesting that harvests all species at an instantaneous fishing mortality rate either proportional to intrinsic population growth rate or proportional to current population growth rate. The results showed that harvesting species at higher trophic levels has a low impact on total biomass but results in very low yields and severe impacts on trophic structure. Selectively harvesting species at the bottom of the food chain reduces the biomass of all fish, results in high yields, and is the only strategy that maintains unfished trophic structure. Non-selective fishing produces high total yield, but can cause extinction of fish at high trophic levels, and severely alters the trophic structure. Balanced harvest strategies produce higher total yield than harvesting species only at the bottom of the food chain, and have a smaller impact on trophic structure than selectively harvesting the top predator or nonselective fishing, but cannot fully maintain trophic structure. While these findings from a very simple model can provide insight into results from more complex models, analysis of sensitivity to structural assumptions in such simple models will be required to shed further light on the dynamic consequences of fishing across multiple trophic levels.

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