scholarly journals Mechanistic insights into the role of large carnivores for ecosystem structure and functioning

Ecography ◽  
2020 ◽  
Vol 43 (12) ◽  
pp. 1752-1763 ◽  
Author(s):  
Selwyn Hoeks ◽  
Mark A. J. Huijbregts ◽  
Michela Busana ◽  
Michael B. J. Harfoot ◽  
Jens‐Christian Svenning ◽  
...  
Keyword(s):  
Ecosystem Structure ◽  
Large Carnivores ◽  
Ecosystem Structure And Functioning

scholarly journals Reconstructing Bioinvasion Dynamics Through Micropaleontologic Analysis Highlights the Role of Temperature Change as a Driver of Alien Foraminifera Invasion

2021 ◽  
Vol 8 ◽  
Author(s):  
Roberta Guastella ◽  
Agnese Marchini ◽  
Antonio Caruso ◽  
Julian Evans ◽  
Miriam Cobianchi ◽  
...  
Keyword(s):  
Temporal Trends ◽  
Strong Relationship ◽  
Invasion Success ◽  
Radiometric Dating ◽  
Ecosystem Structure ◽  
Central Mediterranean ◽  
Population Outbreaks ◽  
First Arrival ◽  
Ecosystem Structure And Functioning

Invasive alien species threaten biodiversity and ecosystem structure and functioning, but incomplete assessments of their origins and temporal trends impair our ability to understand the relative importance of different factors driving invasion success. Continuous time-series are needed to assess invasion dynamics, but such data are usually difficult to obtain, especially in the case of small-sized taxa that may remain undetected for several decades. In this study, we show how micropaleontologic analysis of sedimentary cores coupled with radiometric dating can be used to date the first arrival and to reconstruct temporal trends of foraminiferal species, focusing on the alien Amphistegina lobifera and its cryptogenic congener A. lessonii in the Maltese Islands. Our results show that the two species had reached the Central Mediterranean Sea several decades earlier than reported in the literature, with considerable implications for all previous hypotheses of their spreading patterns and rates. By relating the population dynamics of the two foraminifera with trends in sea surface temperature, we document a strong relationship between sea warming and population outbreaks of both species. We conclude that the micropaleontologic approach is a reliable procedure for reconstructing the bioinvasion dynamics of taxa having mineralized remains, and can be added to the toolkit for studying invasions.

Comparison of approaches for incorporating depredation on fisheries catches into Ecopath

2020 ◽  
Author(s):  
Lyndsay Clavareau ◽  
Martin P Marzloff ◽  
Verena M Trenkel ◽  
Catherine M Bulman ◽  
Sophie Gourguet ◽  
...  
Keyword(s):  
Marine Species ◽  
Fish Population ◽  
Ecosystem Structure ◽  
Fish Stocks ◽  
Marine Predators ◽  
Target Fish ◽  
Ecosystem Structure And Functioning ◽  
Model Structures

Abstract Ecosystem-based approaches are increasingly used in fisheries management to account for the direct trophic impacts of fish population harvesting. However, fisheries can also indirectly alter ecosystem structure and functioning, for instance via the provision of new feeding opportunities to marine predators. For instance, marine depredation, where predators feed on fishery catches on fishing gear, is a behaviour developed by many marine species globally. This behaviour can modify both the ecological role of predators and fisheries performance. Yet, these ecosystem-wide effects of depredation are rarely considered holistically. In this study, we explored different ways of incorporating depredation into an Ecopath trophic model. We assessed, through a subantarctic case study, how three alternative model structures can account for depredation effects on fishery catches, predator and non-commercial prey populations, as well as target fish stocks. While none adequately addresses all facets of depredation, the alternative models can to some extent capture how depredation can lead to increased fishing pressure on stocks. As structural specificities of Ecopath prevented us from representing other depredation effects such as provisioning effects for predator populations, we conclude this study with a set of guidance to effectively capture the complex effects of depredation in marine ecosystems and fisheries models.

Insights into the ocean’s biological carbon pump: What makes marine snow falling into the deep ocean?

2021 ◽  
Author(s):  
Frederic Le Moigne
Keyword(s):  
Carbon Cycle ◽  
Global Analysis ◽  
Deep Ocean ◽  
Ecosystem Structure ◽  
Faecal Pellets ◽  
Surface Ocean ◽  
Mesopelagic Zone ◽  
Carbon Pump ◽  
Biological Carbon Pump

<p>The oceanic biological carbon pump (BCP) regulates the Earth carbon cycle by transporting part of the photosynthetically fixed CO<sub>2</sub> into the deep ocean. Suppressing this mechanism would result in an important increase of atmospheric CO<sub>2</sub> level. The BCP occurs mainly in the form of organic carbon particles (POC) sinking out the surface ocean. Various types of particles are produced in surface ocean. They all differ in production, sinking and decomposition rates, vertically and horizontally. The amount of POC transported to depths via these various export pathways as well as their decomposition pathways all have different ecological origins and therefore may response differently to climate change. Here I will briefly review some of the processes driving both particle export out of the euphotic zone (0-100m) as well as particles transport within the mesopelagic zone (100-1000m). In the early 2000s, strong correlations between POC and mineral (calcite an opal) fluxes observed in the deep ocean have inspired the inclusion of “ballast effect” parameterizations in carbon cycle models. These relationships were first considered as being universal. However global analysis of POC and mineral ballast fluxes showed that mineral ballasting is important in regions like the high-latitude North Atlantic but that in most places (some of which efficiently exporting) the unballasted fraction often dominates the export flux. In such regions, we later showed that zooplankton-mediated export (presence of faecal pellets) and surface microbial abundance were important drivers of the efficiency of particles export. Similar trends were found globally by including bacteria and zooplankton abundances to a global reanalysis of the global variations of the POC export efficiency. This implies that the whole ecosystem structure from bacteria to fishes, rather than just the phytoplankton community, is important in setting the strength of the biological carbon pump. Further down in the water column (mesopelagic zone), processes impacting the transport of particles are less clear. Sinking particles experience a number of biotic and abiotic transformations during their descent. These includes solubilization, remineralisation, fragmentation, ingestion/active transport, breakdown among others. While some potential factors such as O<sub>2</sub> concentration and temperature have been proposed as powerful controls, global evidences are often inconsistent. In the award talk, I will review current challenges related to the role of particles consumption by zooplankton and fishes as well as the role of particles attached prokaryotes (bacteria and archaea) in setting the efficiency of the carbon transport in the mesopelagic zone.</p>

scholarly journals The MARAS dataset, vegetation and soil characteristics of dryland rangelands across Patagonia

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Gabriel Oliva ◽  
Eder dos Santos ◽  
Osiris Sofía ◽  
Fernando Umaña ◽  
Virginia Massara ◽  
...  
Keyword(s):  
Soil Analysis ◽  
Soil Surface ◽  
Surface Characteristics ◽  
Spatial Pattern Analysis ◽  
Ecosystem Structure ◽  
Species List ◽  
Plant Soil ◽  
Rangeland Monitoring ◽  
Ecosystem Structure And Functioning ◽  
Line Intercept

Abstract We present the MARAS (Environmental Monitoring of Arid and Semiarid Regions) dataset, which stores vegetation and soil data of 426 rangeland monitoring plots installed throughout Patagonia, a 624.500 km2 area of southern Argentina and Chile. Data for each monitoring plot includes basic climatic and landscape features, photographs, 500 point intercepts for vegetation cover, plant species list and biodiversity indexes, 50-m line-intercept transect for vegetation spatial pattern analysis, land function indexes drawn from 11 measures of soil surface characteristics and laboratory soil analysis (pH, conductivity, organic matter, N and texture). Monitoring plots were installed between 2007 and 2019, and are being reassessed at 5-year intervals (247 have been surveyed twice). The MARAS dataset provides a baseline from which to evaluate the impacts of climate change and changes in land use intensity in Patagonian ecosystems, which collectively constitute one of the world´s largest rangeland areas. This dataset will be of interest to scientists exploring key ecological questions such as biodiversity-ecosystem functioning relationships, plant-soil interactions and climatic controls on ecosystem structure and functioning.

scholarly journals Balanced harvesting is the bioeconomic equilibrium of a size-structured Beverton-Holt model

2016 ◽  
Vol 74 (1) ◽  
pp. 112-120 ◽  
Author(s):  
Michael J. Plank
Keyword(s):  
Single Species ◽  
Size Spectrum ◽  
Ecosystem Structure ◽  
Fishing Mortality ◽  
Biomass Transfer ◽  
Body Sizes ◽  
Relative Production ◽  
Ecosystem Structure And Functioning ◽  
Classical Size ◽  
Spectrum Model

Balanced harvesting (BH) was introduced as an alternative strategy to size-at-entry fishing with the aim of maintaining ecosystem structure and functioning. BH has been criticized on a number of grounds, including that it would require an infeasible level of micromanagement and enforcement. Recent results from a size-spectrum model show that the distribution of fishing mortality across body sizes that emerges from the behaviour of a large number of fishing agents corresponds to BH in a single species. Size-spectrum models differ from classical size-structured models used in fisheries as they are based on a bookkeeping of biomass transfer from prey to predator rather than a von Bertalanffy growth model. Here we investigate a classical Beverton-Holt model coupled with the Gordon-Schaefer harvesting model extended to allow for differential fishing pressure at different body sizes. This models an open-access fishery in which individual fishing agents act to maximize their own economic return. We show that the equilibrium of the harvesting model produces an aggregate fishing mortality that is closely matched to the production at different body sizes, in other words BH of a single species. These results have significant implications because they show that the robustness of BH does not depend on arguments about the relative production levels of small versus large fish.

scholarly journals A feeding guild indicator to assess environmental change impacts on marine ecosystem structure and functioning

2020 ◽  
Vol 57 (9) ◽  
pp. 1769-1781 ◽  
Author(s):  
Murray S. A. Thompson ◽  
Hugo Pontalier ◽  
Michael A. Spence ◽  
John K. Pinnegar ◽  
Simon P. R. Greenstreet ◽  
...  
Keyword(s):  
Environmental Change ◽  
Marine Ecosystem ◽  
Ecosystem Structure ◽  
Feeding Guild ◽  
Ecosystem Structure And Functioning

Fire history in China during the Holocene and its response to the changes in environmental and anthropogenic factors

2020 ◽  
Author(s):  
Xin Xu ◽  
Fang Li ◽  
Zhongda Lin ◽  
Xiang Song
Keyword(s):  
Fire History ◽  
Driving Forces ◽  
Terrestrial Ecosystem ◽  
Anthropogenic Factors ◽  
Ecosystem Structure ◽  
The Holocene ◽  
Historical Changes ◽  
Proxy Records ◽  
Country Level ◽  
Ecosystem Structure And Functioning

<p>Fire is an intrinsic feature of terrestrial ecosystem, and a key Earth system process that strongly affects ecosystem structure and functioning , carbon and nutrient cycles, climate, air quality and society. Although local and regional paleo-fires in China have been investigated based on one or several fire-proxy records, so far China’s fire history at the country level and its driving forces remain unknown. The present study, for the first time, reconstructs China’s fire history based on charcoal and black carbon records at 107 sites through the Holocene (12 ka BP to the present in this study), and investigates fire historical changes and dominant drivers. Results show that fire activity over China gradually decline from the Early Holocene (12 ka BP) to the Middle Holocene (7.3 ka BP), followed by a sharp rise till the present age. The historical changes are mainly regulated by moisture change through the whole Holocene, and also affected by population growth and agriculture expansion over the past 2 ka.</p>

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