scholarly journals Predator size-structure and species identity determine cascading effects in a coastal ecosystem

2018 ◽  
Vol 8 (24) ◽  
pp. 12435-12442 ◽  
Author(s):  
John N. Griffin ◽  
Brian R. Silliman
Keyword(s):  
Size Structure ◽  
Coastal Ecosystem ◽  
Species Identity ◽  
Cascading Effects ◽  
Predator Size

Cascading effects of predators on algal size structure

2022 ◽  
Author(s):  
Allison R. Rober ◽  
Kevin S. McCann ◽  
Merritt R. Turetsky ◽  
Kevin H. Wyatt
Keyword(s):  
Size Structure ◽  
Cascading Effects

scholarly journals Hunting pressure modulates the composition and size structure of terrestrial and arboreal vertebrates in Amazonian forests

2021 ◽  
Author(s):  
Andressa B. Scabin ◽  
Carlos A. Peres
Keyword(s):  
Community Structure ◽  
Tropical Forests ◽  
Forest Canopy ◽  
Linear Models ◽  
Size Structure ◽  
Management Policy ◽  
Primary Forest ◽  
Population Declines ◽  
Hunting Pressure ◽  
Cascading Effects

AbstractOverhunting is a leading contemporary driver of tropical forest wildlife loss. The absence or extremely low densities of large-bodied vertebrates disrupts plant-animal mutualisms and consequently degrades key ecosystem services. Understanding patterns of defaunation is therefore crucial given that most tropical forests worldwide are now “half-empty”. Here we investigate changes in vertebrate community composition and size structure along a gradient of marked anthropogenic hunting pressure in the Médio Juruá region of western Brazilian Amazonia. Using a novel camera trapping grid design deployed both in the understorey and the forest canopy, we estimated the aggregate biomass of several functional groups of terrestrial and arboreal species at 28 sites along the hunting gradient. Generalized linear models (GLMs) identified hunting pressure as the most important driver of aggregate biomass for game, terrestrial, and arboreal species, as well as nocturnal rodents, frugivores, and granivores. Local hunting pressure affected vertebrate community structure as shown by both GLM and ordination analyses. The size structure of vertebrate fauna changed in heavily hunted areas due to population declines in large-bodied species and apparent compensatory increases in nocturnal rodents. Our study shows markedly altered vertebrate community structure even in remote but heavily settled areas of continuous primary forest. Depletion of frugivore and granivore populations, and concomitant density-compensation by seed predators, likely affect forest regeneration in persistently overhunted tropical forests. These findings contribute to a better understanding of how cascading effects induced by historical defaunation operate, informing wildlife management policy in tropical peri-urban, rural and wilderness areas.

scholarly journals Food Webs and Fish Size Patterns in Insular Lakes Partially Support Climate-Related Features in Continental Lakes

Water ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1380
Author(s):  
Nicolas Vidal ◽  
Susanne L. Amsinck ◽  
Vítor Gonçalves ◽  
José M. Neto Azevedo ◽  
Liselotte S. Johansson ◽  
...  
Keyword(s):  
Food Web ◽  
Size Structure ◽  
Fish Food ◽  
Fish Size ◽  
Cascading Effects ◽  
Ambient Temperatures ◽  
Climatic Regions ◽  
Remote Island ◽  
Time Substitution ◽  
Warm Lakes

Disentangling the effects of climate change on nature is one of the main challenges facing ecologists nowadays. Warmer climates forces strong effects on lake biota for fish, leading to a reduction in size, changes in diet, more frequent reproduction, and stronger cascading effects. Space-for-time substitution studies (SFTS) are often used to unravel climate effects on lakes biota; however, results from continental lakes are potentially confounded by biogeographical and evolutionary differences, also leading to an overall higher fish species richness in warm lakes. Such differences may not be found in lakes on remote islands, where natural fish free lakes have been subjected to stocking only during the past few hundred years. We studied 20 species-poor lakes located in two remote island groups with contrasting climates, but similar seasonality: the Faroe Islands (cold; 6.5 ± 2.8 °C annual average (SD) and the Azores Islands (warm; 17.3 ± 2.9 °C)). As for mainland lakes, mean body size of fish in the warmer lakes were smaller overall, and phytoplankton per unit of phosphorus higher. The δ13C carbon range for basal organisms, and for the whole food web, appeared wider in colder lakes. In contrast to previous works in continental fresh waters, Layman metrics of the fish food web were similar between the two climatic regions. Our results from insular systems provide further evidence that ambient temperatures, at least partially, drive the changes in fish size structure and the cascading effects found along latitude gradients in lakes.

scholarly journals Prey size diversity hinders biomass trophic transfer and predator size diversity promotes it in planktonic communities

2016 ◽  
Vol 283 (1824) ◽  
pp. 20152129 ◽  
Author(s):  
Carmen García-Comas ◽  
Akash R. Sastri ◽  
Lin Ye ◽  
Chun-Yi Chang ◽  
Fan-Sian Lin ◽  
...  
Keyword(s):  
Size Structure ◽  
Prey Size ◽  
Interactive Effect ◽  
Trophic Transfer ◽  
Trophic Levels ◽  
Transfer Efficiency ◽  
Nutrient Concentrations ◽  
Predator Size ◽  
Trade Offs ◽  
Size Diversity

Body size exerts multiple effects on plankton food-web interactions. However, the influence of size structure on trophic transfer remains poorly quantified in the field. Here, we examine how the size diversity of prey (nano-microplankton) and predators (mesozooplankton) influence trophic transfer efficiency (using biomass ratio as a proxy) in natural marine ecosystems. Our results support previous studies on single trophic levels: transfer efficiency decreases with increasing prey size diversity and is enhanced with greater predator size diversity. We further show that communities with low nano-microplankton size diversity and high mesozooplankton size diversity tend to occur in warmer environments with low nutrient concentrations, thus promoting trophic transfer to higher trophic levels in those conditions. Moreover, we reveal an interactive effect of predator and prey size diversities: the positive effect of predator size diversity becomes influential when prey size diversity is high. Mechanistically, the negative effect of prey size diversity on trophic transfer may be explained by unicellular size-based metabolic constraints as well as trade-offs between growth and predation avoidance with size, whereas increasing predator size diversity may enhance diet niche partitioning and thus promote trophic transfer. These findings provide insights into size-based theories of ecosystem functioning, with implications for ecosystem predictive models.

scholarly journals Protection of large predators in a marine reserve alters size-dependent prey mortality

2017 ◽  
Vol 284 (1847) ◽  
pp. 20161936 ◽  
Author(s):  
Rebecca L. Selden ◽  
Steven D. Gaines ◽  
Scott L. Hamilton ◽  
Robert R. Warner
Keyword(s):  
Size Structure ◽  
Sea Urchins ◽  
Marine Reserves ◽  
Marine Reserve ◽  
Mortality Rates ◽  
Kelp Forests ◽  
Size Dependent ◽  
Predator Size ◽  
Top Predators ◽  
Large Predators

Where predator–prey interactions are size-dependent, reductions in predator size owing to fishing has the potential to disrupt the ecological role of top predators in marine ecosystems. In southern California kelp forests, we investigated the size-dependence of the interaction between herbivorous sea urchins and one of their predators, California sheephead ( Semicossyphus pulcher ). Empirical tests examined how differences in predator size structure between reserve and fished areas affected size-specific urchin mortality. Sites inside marine reserves had greater sheephead size and biomass, while empirical feeding trials indicated that larger sheephead were required to successfully consume urchins of increasing test diameter. Evaluations of the selectivity of sheephead for two urchin species indicated that shorter-spined purple urchins were attacked more frequently and successfully than longer-spined red urchins of the same size class, particularly at the largest test diameters. As a result of these size-specific interactions and the higher biomass of large sheephead inside reserves, urchin mortality rates were three times higher inside the reserve for both species. In addition, urchin mortality rates decreased with urchin size, and very few large urchins were successfully consumed in fished areas. The truncation of sheephead size structure that commonly occurs owing to fishing will probably result in reductions in urchin mortality, which may reduce the resilience of kelp beds to urchin barren formation. By contrast, the recovery of predator size structure in marine reserves may restore this resilience, but may be delayed until fish grow to sizes capable of consuming larger urchins.

Species identity drives ecosystem function in a subsidy-dependent coastal ecosystem

Oecologia ◽  
2021 ◽  
Author(s):  
Kyle A. Emery ◽  
Jenifer E. Dugan ◽  
R. A. Bailey ◽  
Robert J. Miller
Keyword(s):  
Ecosystem Function ◽  
Coastal Ecosystem ◽  
Species Identity

CASCADING EFFECTS OF FISHING CAN ALTER CARBON FLOW THROUGH A TEMPERATE COASTAL ECOSYSTEM

2008 ◽  
Vol 18 (8) ◽  
pp. 1874-1887 ◽  
Author(s):  
Anne K. Salomon ◽  
Nick T. Shears ◽  
Timothy J. Langlois ◽  
Russell C. Babcock
Keyword(s):  
Carbon Flow ◽  
Coastal Ecosystem ◽  
Cascading Effects ◽  
Flow Through
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