scholarly journals Are Antarctic and sub-Antarctic marine food webs different?

2021 ◽  
Author(s):  
Iara DIamela Rodriguez ◽  
Tomas Ignacio Marina ◽  
Leonardo Ariel Saravia
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Potter Cove ◽  
Marine Food Webs ◽  
Beagle Channel ◽  
West Antarctic ◽  
Antarctic Marine ◽  
Marine Food ◽  
West Antarctic Peninsula ◽  
Mean Trophic Level

Aim: Food web structure plays an important role in determining ecosystem stability to perturbations. High latitude marine ecosystems are being affected by environmental stressors and ecological shifts. In the West Antarctic Peninsula these transformations are driven by climate change, and in the sub-Antarctic region by anthropogenic activities. Understanding the differences between these areas is necessary to monitor the changes that are expected to occur in the upcoming decades. Here, we compared the structure and stability of Antarctic and sub-Antarctic marine food webs. Location: Antarctic (Potter Cove, 25 de Mayo/King George Island, West Antarctic Peninsula) and sub-Antarctic (Beagle Channel, Tierra del Fuego, South America) regions. Time period: 1965 - 2019. Major taxa studied: from phytoplankton to fish. Methods: We compiled species trophic (predator-prey) interactions and calculated complexity (number of species and interactions, connectance), structure (mean trophic level, omnivory, degree distribution, modularity, species roles and traits) and stability (QSS) metrics. To be able to make statistical comparisons, we used a randomization algorithm (Strona Curveball) maintaining the number of prey and predators for each species and calculated metrics for each simulation. Results: The Beagle Channel food web presented higher values for complexity metrics (number of species and interactions), structure (mean trophic level, omnivory, modularity) but lower stability (QSS). Potter Cove fitted the exponential degree distribution, while Beagle Channel the power-law with exponential cutoff model. Both food webs presented the same connectance value (0.05), similar distribution of species in top, intermediate and top positions and topological roles, with only one network connector each. Main conclusions: Our results showed that Beagle Channel food web is more complex, but less stable and sensitive to the loss of its most connected species. While the Potter Cove food web presented less complexity and greater stability to perturbations.

The role of fish in the Antarctic marine food web: differences between inshore and offshore waters in the southern Scotia Arc and west Antarctic Peninsula

2002 ◽  
Vol 14 (4) ◽  
pp. 293-309 ◽  
Author(s):  
ESTEBAN BARRERA-ORO
Keyword(s):  
Food Web ◽  
Antarctic Peninsula ◽  
Demersal Fish ◽  
Pelagic Fish ◽  
West Antarctic ◽  
Antarctic Marine ◽  
Scotia Arc ◽  
West Antarctic Peninsula ◽  
The Antarctic

The role of fish in the Antarctic food web in inshore and offshore waters is analysed, taking as an example the coastal marine communities of the southern Scotia Arc (South Orkney Islands and South Shetland Islands) and the west Antarctic Peninsula. Inshore, the ecological role of demersal fish is more important than that of krill. There, demersal fish are major consumers of benthos and also feed on zooplankton (mainly krill in summer). They are links between lower and upper levels of the food web and are common prey of other fish, birds and seals. Offshore, demersal fish depend less on benthos and feed more on zooplankton (mainly krill) and nekton, and are less accessible as prey of birds and seals. There, pelagic fish (especially lantern fish) are more abundant than inshore and play an important role in the energy flow from macrozooplankton to higher trophic levels (seabirds and seals). Through the higher fish predators, energy is transferred to land in the form of fish remains, pellets (birds), regurgitation and faeces (birds and seals). However, in the general context of the Antarctic marine ecosystem, krill (Euphausia superba) plays the central role in the food web because it is the main food source in terms of biomass for most of the high level predators from demersal fish up to whales. This has no obvious equivalent in other marine ecosystems. In Antarctic offshore coastal and oceanic waters the greatest proportion of energy from the ecosystem is transferred to land directly through krill consumers, such as flying birds, penguins, and seals. Beside krill, the populations of fish in the Antarctic Ocean are the second most important element for higher predators, in particular the energy-rich pelagic Myctophidae in open waters and the pelagic Antarctic silver fish (Pleuragramma antarcticum) in the high Antarctic zone. Although the occurrence of these pelagic fish inshore has been poorly documented, their abundance in neritic waters could be higher than previously believed.

scholarly journals Architecture of Marine Food Webs: to be or not be a ‘small-world’

2018 ◽  
Author(s):  
Tomás Ignacio Marina ◽  
Leonardo A. Saravia ◽  
Georgina Cordone ◽  
Vanesa Salinas ◽  
Santiago R. Doyle ◽  
...  
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Path Length ◽  
Small World ◽  
Marine Ecosystems ◽  
Characteristic Path Length ◽  
Structural Pattern ◽  
Marine Food Webs ◽  
Marine Habitats ◽  
Marine Food

AbstractThe search for general properties in network structure has been a central issue for food web studies in recent years. One such property is the small-world topology that combines a high clustering and a small distance between nodes of the network. This property may increase food web resilience but make them more sensitive to the extinction of connected species. Food web theory has been developed principally from freshwater and terrestrial ecosystems, largely omitting marine habitats. If theory needs to be modified to accommodate observations from marine ecosystems, based on major differences in several topological characteristics is still on debate. Here we investigated if the small-world topology is a common structural pattern in marine food webs. We developed a novel, simple and statistically rigorous method to examine the largest set of complex marine food webs to date. More than half of the analyzed marine networks exhibited a similar or lower characteristic path length than the random expectation, whereas 39% of the webs presented a significantly higher clustering than its random counterpart. Our method proved that 5 out of 28 networks fulfilled both features of the small-world topology: short path length and high clustering. This work represents the first rigorous analysis of the small-world topology and its associated features in high-quality marine networks. We conclude that such topology is a structural pattern that is not maximized in marine food webs; thus it is probably not an effective model to study robustness, stability and feasibility of marine ecosystems.

scholarly journals Microplastics in gentoo penguins from the Antarctic region

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Filipa Bessa ◽  
Norman Ratcliffe ◽  
Vanessa Otero ◽  
Paula Sobral ◽  
João C. Marques ◽  
...  
Keyword(s):  
Food Webs ◽  
Temporal Trends ◽  
The Arctic ◽  
Polymer Composition ◽  
Antarctic Region ◽  
Invasive Approach ◽  
Marine Food Webs ◽  
Antarctic Marine ◽  
Marine Food ◽  
The Antarctic

Abstract There is growing evidence that microplastic pollution (<5 mm in size) is now present in virtually all marine ecosystems, even in remote areas, such as the Arctic and the Antarctic. Microplastics have been found in water and sediments of the Antarctic but little is known of their ingestion by higher predators and mechanisms of their entry into Antarctic marine food webs. The goal of this study was to assess the occurrence of microplastics in a top predator, the gentoo penguin Pygoscelis papua from the Antarctic region (Bird Island, South Georgia and Signy Island, South Orkney Islands) and hence assess the potential for microplastic transfer through Antarctic marine food webs. To achieve this, the presence of microplastics in scats (as a proof of ingestion) was investigated to assess the viability of a non-invasive approach for microplastic analyses in Antarctic penguins. A total of 80 penguin scats were collected and any microplastics they contained were extracted. A total of 20% of penguin scats from both islands contained microplastics, consisting mainly of fibers and fragments with different sizes and polymer composition (mean abundance of microplastics: 0.23 ± 0.53 items individual−1 scat, comprising seven different polymers), which were lower values than those found for seabirds in other regions worldwide. No significant differences in microplastic numbers in penguin scats between the two regions were detected. These data highlight the need for further assessment of the levels of microplastics in this sensitive region of the planet, specifically studies on temporal trends and potential effects on penguins and other organisms in the Antarctic marine food web.

Land–Sea Interactions and Consequences for Sub-Antarctic Marine Food Webs

Ecosystems ◽  
2015 ◽  
Vol 18 (5) ◽  
pp. 752-768 ◽  
Author(s):  
Anne M. Treasure ◽  
James J. Ruzicka ◽  
Coleen L. Moloney ◽  
Leigh J. Gurney ◽  
Isabelle J. Ansorge
Keyword(s):  
Food Webs ◽  
Marine Food Webs ◽  
Antarctic Marine ◽  
Marine Food

scholarly journals Trophic transfer of microplastics and mixed contaminants in the marine food web and implications for human health

2018 ◽  
Author(s):  
Maddison Carbery ◽  
Wayne O'Connor ◽  
Palanisami Thavamani
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Human Health ◽  
Trophic Transfer ◽  
The Real ◽  
Marine Food Web ◽  
Marine Food Webs ◽  
Bioaccumulation Factors ◽  
Mixed Contaminants ◽  
Marine Food

Plastic litter has become one of the most serious threats to the marine environment. Over 690 marine species have been impacted by plastic debris with small plastic particles being observed in the digestive tract of organisms from different trophic levels. The physical and chemical properties of microplastics facilitate the sorption of contaminants to the particle surface, serving as a vector of contaminants to organisms following ingestion. Bioaccumulation factors for higher trophic organisms and impacts on wider marine food webs remain unknown. The main objectives of this review were to discuss the factors influencing microplastic ingestion; describe the biological impacts of associated chemical contaminants; highlight evidence for the trophic transfer of microplastics and contaminants within marine food webs and outline the future research priorities to address potential human health concerns. Controlled laboratory studies looking at the effects of microplastics and contaminants on model organisms employ nominal concentrations and consequently have little relevance to the real environment. Few studies have attempted to track the fate of microplastics and mixed contaminants through a complex marine food web using environmentally relevant concentrations to identify the real level of risk. To our knowledge, there has been no attempt to understand the transfer of microplastics and associated contaminants from seafood to humans and the implications for human health. Research is needed to determine bioaccumulation factors for popular seafood items in order to identify the potential impacts on human health.

Polychloronaphthalenes and Other Dioxin-like Compounds in Arctic and Antarctic Marine Food Webs

2002 ◽  
Vol 36 (16) ◽  
pp. 3490-3496 ◽  
Author(s):  
Simonetta Corsolini ◽  
Kurunthachalam Kannan ◽  
Takashi Imagawa ◽  
Silvano Focardi ◽  
John P. Giesy
Keyword(s):  
Food Webs ◽  
Marine Food Webs ◽  
Antarctic Marine ◽  
Marine Food
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