Trophic function in estuaries: response of macrobenthos to natural and contaminant gradients

1998 ◽  
Vol 49 (8) ◽  
pp. 833 ◽  
Author(s):  
Gary R. Gaston ◽  
Chet F. Rakocinski ◽  
Steven S. Brown ◽  
Carol M. Cleveland
Keyword(s):  
Trophic Structure ◽  
Trophic Ecology ◽  
Environmental Gradients ◽  
Clay Content ◽  
Polynuclear Aromatic Hydrocarbons ◽  
Trophic Levels ◽  
Sediment Surface ◽  
Shallow Subsurface ◽  
Community Function ◽  
Deposit Feeders

Trophic ecology of macrobenthic communities in estuaries of the northern Gulf of Mexico was used to infer community function, determine effects of contaminants on macrobenthos, and provide insight into community responses following disturbance. The taxa that numerically dominated the region included few large, deep-burrowing suspension feeders that typify estuaries elsewhere. This pattern is indicative of disturbance, and results in dominance by trophic groups that live near the sediment–water interface (early benthic-community succession). Trophic structure was significantly related to several sediment contaminants (especially metals, polynuclear aromatic hydrocarbons, DDT), and three environmental gradients (salinity, depth, and sediment silt–clay content). Generally, trophic diversity increased and proportion of subsurface-deposit feeders (SSDF) decreased with salinity, meaning that a more even distribution of trophic structure was found at high-salinity stations. The trophic shift toward dominance by shallow, subsurface-deposit feeders in contaminated habitats may have dire implications for fisheries. Several important commercial and recreational fisheries of the region depend on fish that feed primarily at the sediment surface. Higher proportion of subsurface-deposit feeders, coupled with low macrobenthic density in contaminated sediments, may imply that limited energy is transferred to higher trophic levels.

scholarly journals Oribatid mite communities in mountain scree: stable isotopes (15N, 13C) reveal three trophic levels of exclusively sexual species

2021 ◽  
Author(s):  
Ioana Nae ◽  
Augustin Nae ◽  
Stefan Scheu ◽  
Mark Maraun
Keyword(s):  
Trophic Structure ◽  
Trophic Ecology ◽  
Oribatid Mite ◽  
Reproductive Mode ◽  
Mite Species ◽  
Oribatid Mites ◽  
Trophic Levels ◽  
Resource Poor ◽  
Trophic Niches ◽  
Oribatid Mite Species

AbstractMountain scree habitats are intermediate habitats between the base of the soil and the bedrock. They are composed of a network of small cracks and voids, and are commonly situated at the lower levels of scree slopes. Their environment is defined by empty spaces inside the scree, the absence of light and photoperiod, low temperature, and resource poor conditions. Soil arthropod communities, their trophic structure as well as their use of basal resources in mountain scree are little studied despite the fact that they are important components of these systems. Here, we investigate stable isotope ratios (15N/14N, 13C/12C) of oribatid mites (Oribatida, Acari) to understand their trophic niches and their variation with depth (50 and 75 cm) at two mountain scree sites (Cerdacul Stanciului, Marele Grohotis) in the Romanian Carpathians. Further, we used existing data to investigate the reproductive mode of the species in that habitat, as this may be related to resource availability. We hypothesized that trophic niches of oribatid mites will not differ between the two mountain scree regions but will be affected by depth. We furthermore hypothesized that due to the resource poor conditions oribatid mite species will span a narrow range of trophic levels, and that species are sexual rather than parthenogenetic. Our results showed that (1) oribatid mite trophic structure only slightly differed between the two sites indicating that the trophic ecology of oribatid mites in scree habitats is consistent and predictable, (2) oribatid mite trophic structure did not differ between the two studied soil depths indicating that the structure and availability of resources that were used by oribatid mites in deeper scree habitats varies little with depth, (3) oribatid mite species spanned only three trophic levels indicating that the habitat is rather resource poor, and (4) that all studied oribatid mite species were sexual supporting the view that resource poor conditions favour sexual reproduction.

Trophic structure of a fish community along environmental gradients of a subtropical river (Paraitinga River, Upper Tietê River Basin, Brazil)

Hydrobiologia ◽  
2007 ◽  
Vol 598 (1) ◽  
pp. 373-387 ◽  
Author(s):  
Katharina Eichbaum Esteves ◽  
Ana Valéria Pinto Lobo ◽  
Marcos Daniel Renó Faria
Keyword(s):  
River Basin ◽  
Fish Community ◽  
Trophic Structure ◽  
Environmental Gradients ◽  
Tietê River

scholarly journals Uptake and trophic changes in polybrominated diphenyl ethers in the benthic marine food chain in southwestern British Columbia, Canada

FACETS ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 20-51
Author(s):  
Brenda Burd ◽  
Chris Lowe ◽  
Carmen Morales-„Caselles ◽  
Marie Noel ◽  
Peter Ross ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Polybrominated Diphenyl Ethers ◽  
Dry Weight ◽  
Trophic Levels ◽  
Marine Food Chain ◽  
Deposit Feeders ◽  
Diphenyl Ethers ◽  
Bottom Fish ◽  
Harbour Sediment ◽  
Marine Food

We examined the physical and geochemical effects of sediment on the uptake of polybrominated diphenyl ethers (PBDEs) into marine sediment feeders and their transfer to higher trophic fauna. Sediment PBDEs increased with % total organic carbon (%TOC), organic carbon (OC) flux and grain size (%fines). Tissue PBDE variance was best explained ( R2 = 0.70) by sediment acid volatile sulfides (AVS), PBDEs, and organic lability and input, with the highest values near wastewater outfalls. Dry weight tissue/sediment PBDEs declined with increasing sediment PBDEs, resulting in tissue dilution (ratio <1) at >10 000 pg/g in harbours. Ratios also decreased with increasing %fines, resulting in regional differences. These patterns imply that high levels of fines and high sediment concentrations make PBDEs less bioavailable. Dry weight PBDEs increased >100× between background deposit feeders and predators (polychaetes, crabs, bottom fish, seal), but lipid normalized PBDEs barely increased (<1.3%), suggesting remarkably high uptake in low-lipid sediment feeders, and that PBDEs don’t accumulate at higher trophic levels, but lipid content does. Filter feeders had lower lipid-normalized PBDEs than deposit feeders, highlighting the importance of food resources in higher trophic fauna for bioaccumulation. The most profound congener change occurred with sediment uptake, with nona/deca-BDEs declining and tetra-hexa-BDEs increasing. Harbour sediment feeders had more deca-BDEs than other samples, suggesting PBDEs mostly pass unmodifed through them. Deca-BDEs persist patchily in all tissues, reflecting variable dependence on sediment/pelagic food.

scholarly journals Breaking out of the comfort zone: El Niño-Southern Oscillation as a driver of trophic flows in a benthic consumer of the Humboldt Current ecosystem

2017 ◽  
Vol 284 (1857) ◽  
pp. 20170923 ◽  
Author(s):  
José M. Riascos ◽  
Marco A. Solís ◽  
Aldo S. Pacheco ◽  
Manuel Ballesteros
Keyword(s):  
El Niño ◽  
Trophic Ecology ◽  
El Nino ◽  
Southern Oscillation ◽  
Trophic Position ◽  
Trophic Levels ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Strong Increase ◽  
Humboldt Current

The trophic flow of a species is considered a characteristic trait reflecting its trophic position and function in the ecosystem and its interaction with the environment. However, climate patterns are changing and we ignore how patterns of trophic flow are being affected. In the Humboldt Current ecosystem, arguably one of the most productive marine systems, El Niño-Southern Oscillation is the main source of interannual and longer-term variability. To assess the effect of this variability on trophic flow we built a 16-year series of mass-specific somatic production rate (P/B) of the Peruvian scallop ( Argopecten purpuratus ), a species belonging to a former tropical fauna that thrived in this cold ecosystem. A strong increase of the P/B ratio of this species was observed during nutrient-poor, warmer water conditions typical of El Niño, owing to the massive recruitment of fast-growing juvenile scallops. Trophic ecology theory predicts that when primary production is nutrient limited, the trophic flow of organisms occupying low trophic levels should be constrained (bottom-up control). For former tropical fauna thriving in cold, productive upwelling coastal zones, a short time of low food conditions but warm waters during El Niño could be sufficient to waken their ancestral biological features and display massive proliferations.

Trophic ecology of the chihuil sea catfish (Bagre panamensis) in the south-east Gulf of California, México

2017 ◽  
Vol 98 (4) ◽  
pp. 885-893 ◽  
Author(s):  
Víctor M. Muro-Torres ◽  
Felipe Amezcua ◽  
Raul E. Lara-Mendoza ◽  
John T. Buszkiewicz ◽  
Felipe Amezcua-Linares
Keyword(s):  
Gulf Of California ◽  
Trophic Ecology ◽  
Trophic Position ◽  
Feeding Habits ◽  
Isotope Analysis ◽  
Demersal Fish ◽  
Trophic Levels ◽  
High Plasticity ◽  
Combined Use ◽  
Ecosystem Based Fisheries Management

The trophic ecology of the chihuil sea catfish Bagre panamensis was studied through high-resolution variations in its feeding habits and trophic position (TP) in the SE Gulf of California, relevant to sex, size and season. The combined use of stomach content (SCA) and stable isotope analysis (SIA) allowed us to perform these analyses and also estimate the TP of its preys. Results of this study show that the chihuil sea catfish is a generalist and opportunistic omnivore predator that consumes primarily demersal fish and peneid shrimps. Its diet did not vary with climatic season (rainy or dry), size or sex. Results from the SIA indicated high plasticity in habitat use and prey species. The estimated TP value was 4.19, which indicates a tertiary consumer from the soft bottom demersal community in the SE Gulf of California, preying on lower trophic levels, which aids in understanding the species' trophic role in the food web. Because this species and its prey are important to artisanal and industrial fisheries in the Gulf of California, diet assimilation information is useful for the potential establishment of an ecosystem-based fisheries management in the area.

Topographic and edaphic effects on the distribution of terrestrially reproducing anurans in Central Amazonia: mesoscale spatial patterns

2007 ◽  
Vol 23 (5) ◽  
pp. 539-547 ◽  
Author(s):  
Marcelo Menin ◽  
Albertina P. Lima ◽  
William E. Magnusson ◽  
Fabiano Waldez
Keyword(s):  
Leaf Litter ◽  
Environmental Gradients ◽  
Free Water ◽  
Clay Content ◽  
Soil Characteristics ◽  
Environmental Predictors ◽  
Anuran Species ◽  
Habitat Variation ◽  
Central Amazonia ◽  
Edaphic Variables

Many studies suggest that edaphic variables are major determinants of frog distributions. However, leaf-litter depth and soil characteristics are influenced by distance from streams, so the apparent relationship between edaphic characteristics and species distributions could be an artefact of the dependence of species on free water for reproduction. Therefore, we investigated the effect of edaphic variables on the mesoscale distribution of frog species not dependent on free water for reproduction. We evaluated the effects of soil texture, pH, slope, number of trees and leaf-litter volume on the distribution of nine terrestrially reproducing anuran species in the Reserva Ducke, a 100-km2 terra firme forest preserve in central Amazonia. Diurnal and nocturnal assemblages of anuran species were sampled in 72 plots systematically distributed across the reserve. We sampled the diurnal anuran assemblage by visual encounter in 250 × 1-m plots and the nocturnal assemblage in 250 × 20-m plots using both auditory and visual surveys. The majority of terrestrially breeding anuran species were influenced by topographic and/or edaphic variables, such as slope, soil clay content and pH. However, responses to environmental predictors differed among species. Most species occurred throughout all environmental gradients and relationships with soil characteristics were subtle, indicating that these species occur in the majority of habitats in Reserva Ducke. The results of this study indicate that terrestrially breeding frogs are habitat generalists that show little mesoscale beta diversity associated with habitat variation.

Trophic ecology of the blue shark (Prionace glauca) based on stable isotopes (δ13C and δ15N) and stomach content

2015 ◽  
Vol 96 (7) ◽  
pp. 1403-1410 ◽  
Author(s):  
Sandra Berenice Hernández-Aguilar ◽  
Ofelia Escobar-Sánchez ◽  
Felipe Galván-Magaña ◽  
Leonardo Andrés Abitia-Cárdenas
Keyword(s):  
Stable Isotope ◽  
Stomach Content ◽  
Trophic Ecology ◽  
Baja California ◽  
Marine Ecosystem ◽  
Isotope Analysis ◽  
Trophic Levels ◽  
Baja California Sur ◽  
Δ13c And Δ15n ◽  
Prionace Glauca

Occupying the upper levels of trophic webs and thus regulating prey at lower levels, sharks play an important role in the trophic structure and energy dynamics of marine ecosystems. In recent years, the removal of these individuals from upper trophic levels as a result of overfishing has negatively affected ecosystems. We analysed the diet of blue sharks (Prionace glauca) caught off the west coast of Baja California Sur, Mexico, during the months of February–June in 2001, 2005 and 2006. We employed both stomach content and stable isotope analyses as each method provides distinct yet important information regarding the role of blue sharks in marine food webs, allowing us to estimate the relative contribution of different prey items to this predator's diet. Of the 368 stomachs analysed, 210 contained food (57%) and 158 (43%) were empty. Based on stomach contents and the index of relative importance (IRI), the pelagic red crab (Pleuroncodes planipes) was the most important prey, followed by the squids Gonatus californiensis (34.1%) and Ancistrocheirus lesueurii (10.4%). The mean (±SD) values for δ15N (16.48 ± 0.94‰) and δ13C (−18.48 ± 0.63‰) suggest that blue sharks prefer feeding in oceanic waters. The trophic level based on stomach content analysis was 4.05, while that based on the stable isotope analysis was 3.8, making blue sharks top consumers in the marine ecosystem of Baja California Sur, Mexico.

The role of Spadefoot Toad tadpoles in wetland trophic structure as influenced by environmental and morphological factors

2011 ◽  
Vol 89 (1) ◽  
pp. 47-59 ◽  
Author(s):  
D. M. Ghioca-Robrecht ◽  
L. M. Smith
Keyword(s):  
Body Size ◽  
Great Plains ◽  
Trophic Structure ◽  
Trophic Levels ◽  
Wetland Ecosystems ◽  
Southern Great Plains ◽  
Larval Amphibians ◽  
Spadefoot Toad ◽  
Spea Bombifrons ◽  
And Function

Larval amphibians reach high densities in playa wetlands in the Southern Great Plains (SGP), USA, and thus may influence the entire structure and function of these ecosystems. We investigated whether both carnivorous and omnivorous morphotypes of Spadefoot Toad tadpoles (New Mexico Spadefoot, Spea multiplicata (Cope, 1863), and Plains Spadefoot, Spea bombifrons (Cope, 1863)) would exhibit a macrophagous feeding behavior that would allow them to occupy several trophic levels in playas. We also compared tadpole diets and foregut widths as influenced by the land use surrounding playas (cultivated versus grassland watersheds), year (dry versus wet year), and body size (snout-to-vent length). Tadpole diets were dominated by detritus and diatoms and tadpole foreguts increased with body size. Generally, more arthropods and less cyanobacteria were found in Spea tadpole diets as tadpoles grew larger, suggesting they influence different trophic levels with age. Foreguts were wider in carnivores than omnivores, suggesting carnivores had increased ability to ingest larger prey. Also, omnivores had wider foreguts in cropland than grassland playas, suggesting they ingest larger food items in cropland playas. From estimates of the amounts of invertebrates, detritus, and algae consumed by Spea tadpoles, we demonstrate that these larvae influence the entire trophic structure of wetland ecosystems.

scholarly journals Different environmental gradients affect different measures of snake β-diversity in the Amazon rainforests

2018 ◽  
Author(s):  
Rafael de Fraga ◽  
Miquéias Ferrão ◽  
Adam J Stow ◽  
William E Magnusson ◽  
Albertina P Lima
Keyword(s):  
Amazon Basin ◽  
Prey Availability ◽  
Environmental Gradients ◽  
Geographic Distance ◽  
Clay Content ◽  
Tree Cover ◽  
Β Diversity ◽  
Temperature And Precipitation ◽  
Nesting Sites ◽  
Conservation Actions

Mechanisms generating and maintaining biodiversity at regional scales may be evaluated by quantifying β-diversity along environmental gradients. Differences in assemblages result in biotic complementarities and redundancies among sites, which may be quantified through multi-dimensional approaches incorporating taxonomic β-diversity (TBD), functional β-diversity (FBD) and phylogenetic β-diversity (PBD). Here we test the hypothesis that snake TBD, FBD and PBD are influenced by environmental gradients, independently of geographic distance. The gradients tested are expected to affect snake assemblages indirectly, such as clay content in the soil determining primary production and Height Above the Nearest Drainage (HAND) determining prey availability, or directly, such as percentage of tree cover determining availability of resting and nesting sites, and climate (temperature and precipitation) causing physiological filtering. We sampled snakes in 21 sampling plots, each covering 5 km2, distributed over 880 km in the central-southern Amazon Basin. We used dissimilarities between sampling sites to quantify TBD, FBD and PBD, which were response variables in multiple-linear-regression and RDA models. We show that patterns of snake community composition based on TBD, FBD and PBD are associated with environmental heterogeneity in the Amazon. Despite positive correlations between all β-diversity measures, TBD responded to different environmental gradients compared to FBD and PBD. Our findings suggest that multi-dimensional approaches are more informative for ecological studies and conservation actions compared to a single diversity measure.

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