Comparative dietary ecology of turtles (Chelodina burrungandjii and Emydura victoriae) across the Kimberley Plateau, Western Australia, prior to the arrival of cane toads

2016 ◽  
Vol 67 (11) ◽  
pp. 1611 ◽  
Author(s):  
N. N. FitzSimmons ◽  
P. Featherston ◽  
A. D. Tucker
Keyword(s):  
Land Use ◽  
Food Webs ◽  
Western Australia ◽  
Prey Availability ◽  
Food Sources ◽  
Dietary Ecology ◽  
Aquatic Food ◽  
Land Use Practices ◽  
Prey Items ◽  
Specific Food

Food webs in north-western Australian rivers exist in dynamic environments and will be influenced by land use practices, invasion of toxic cane toads (Rhinella marina) and the effects of climate change on river flows. Baseline studies are needed to understand aquatic food webs before these impacts. In the present study, we investigated the diets of two turtles (Emydura victoriae and Chelodina burrungandjii) in four upland rivers across a gradient of rainfall and land uses in the Kimberley Plateau of Western Australia. We captured turtles by snorkelling and recovered their prey by stomach lavage. We enumerated 2720 prey items from 390 E. victoriae samples and 308 prey items from 155 C. burrungandjii samples. Prey compositions distinguished E. victoriae as an omnivorous generalist relying on a diversity of animal and plant prey and C. burrungandjii as a piscivorous specialist, but with both species as likely predators of toxic cane toad eggs or tadpoles. Comparisons among the rivers showed variation in diets for both species that reflect differences in prey availability and location-specific food webs. Terrestrially based food sources were observed in 26% of E. victoriae samples and 3% of C. burrungandjii samples, which indicates the importance of the aquatic–terrestrial interface and land use practices within these rivers.

scholarly journals Fatty Acid Composition at the Base of Aquatic Food Webs Is Influenced by Habitat Type and Watershed Land Use

PLoS ONE ◽  
2013 ◽  
Vol 8 (8) ◽  
pp. e70666 ◽  
Author(s):  
James H. Larson ◽  
William B. Richardson ◽  
Brent C. Knights ◽  
Lynn A. Bartsch ◽  
Michelle R. Bartsch ◽  
...  
Keyword(s):  
Land Use ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Food Webs ◽  
Acid Composition ◽  
Habitat Type ◽  
Watershed Land Use ◽  
Aquatic Food Webs ◽  
Aquatic Food

Ecosystem differences in the trophic enrichment of 13C in aquatic food webs

1997 ◽  
Vol 54 (6) ◽  
pp. 1255-1258 ◽  
Author(s):  
R L France ◽  
R H Peters
Keyword(s):  
Food Webs ◽  
Trophic Position ◽  
Open Ocean ◽  
Food Sources ◽  
Regression Equations ◽  
Combining Data ◽  
Trophic Enrichment ◽  
Aquatic Food ◽  
Alternative Food Sources ◽  
Estuarine Coastal

Data from 35 published studies were collated to examine patterns in the trophic enrichment of 13C of consumers. Because both delta 13C and delta 14N vary systematically across ecosystems, it was necessary to standardize for such differences before combining data from numerous sources. Relationships of these measures of ecosystem-standardized delta 13C to ecosystem-standardized trophic position ( DELTA delta 15N) for freshwater, estuarine, coastal, and open-ocean and for all aquatic ecosystems yielded regression equations of low predictive capability (average of 20% explained variance in delta 13C). However, differences were observed in the slopes between delta 13C and standardized trophic position when data were examined study-specifically: the average trophic fractionation of 13C was found to increase from + 0.2omicron for freshwater to + 0.5omicron for estuarine to + 0.8omicron for coastal, and to + 1.1omicron for open-ocean food webs. This ecosystem-specific gradient in 13C enrichment for consumers supports previous findings of a similar continuum existing for zooplankton - particulate organic matter differences in delta 13C. Possible mechanisms to explain these ecosystem-specific patterns in 13C enrichment may be related to the relative importance of detritus, heterotrophic respiration, partial reliance on alternative food sources, and lipid influences in the different ecosystems.

Carbon sources for aquatic food webs of riverine and lacustrine tropical waterholes with variable groundwater influence

2017 ◽  
Vol 68 (3) ◽  
pp. 442 ◽  
Author(s):  
N. E. Pettit ◽  
D. M. Warfe ◽  
P. G. Close ◽  
B. J. Pusey ◽  
R. Dobbs ◽  
...  
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Isotope Analysis ◽  
Carbon Sources ◽  
Freshwater Wetlands ◽  
Food Sources ◽  
Web Studies ◽  
Aquatic Food Webs ◽  
Aquatic Food ◽  
Groundwater Reserves

Food web studies integrate ecological information and provide understanding of ecosystem function. Aquatic ecosystems of the Kimberley region (north-western Australia) have high conservation significance as hotspots for maintaining local and regional biodiversity. This study investigated the influence of waterhole type and persistence on the strength of consumer reliance on local energy resources for aquatic food webs. Changes in water isotopic composition indicated groundwater inputs were enough to overcome evaporative losses in some waterholes. Other waterholes had varying levels of isotope enrichment suggesting insufficient groundwater input to ‘compensate’ for evaporative loss. C and N isotope analysis indicated considerable overlap among energy sources in waterholes between macrophytes and periphyton but gradient analysis indicated that periphyton is a major carbon source for aquatic consumers. Groundwater-fed waterholes appeared to have higher quality food sources (indicated by lower C:N ratios), but there was minimal evidence that direct groundwater contributions were related to food web processes. Nonetheless, in a region where groundwater is influential in maintaining aquatic habitats, future development of groundwater reserves will likely affect the ecological and cultural value of freshwater wetlands by either reducing their permanence or size or indirectly through possible alteration to the role of periphyton in supporting the food web.

Accelerating Change

2018 ◽  
Author(s):  
Erin Stewart Mauldin
Keyword(s):  
Land Use ◽  
African Americans ◽  
Labor Relations ◽  
Cotton Production ◽  
Economic Independence ◽  
Contract Negotiations ◽  
Reduced Frequency ◽  
Ecological Event ◽  
Land Use Practices ◽  
Ecological Regime

Emancipation proved to be a far-reaching ecological event. Whereas the ecological regime of slavery had reinforced extensive land-use practices, the end of slavery weakened them. Freedpeople dedicated less time to erosion control and ditching and used contract negotiations and sharecropping arrangements to avoid working in a centrally directed gang. Understandably, freedpeople preferred to direct their own labor on an individual plot of land. The eventual proliferation of share-based or tenant contracts encouraged the physical reorganization of plantations. The combination of these two progressive alterations to labor relations tragically undermined African Americans’ efforts to achieve economic independence by tightening natural limits on cotton production and reducing blacks’ access to the South’s internal provisioning economy. The cessation, or even reduced frequency, of land maintenance on farms exacerbated erosion, flooding, and crops’ susceptibility to drought.

Deferring Crisis

2018 ◽  
Author(s):  
Erin Stewart Mauldin
Keyword(s):  
Land Use ◽  
Environmental Impacts ◽  
Shifting Cultivation ◽  
Crop Production ◽  
Animal Husbandry ◽  
Antebellum South ◽  
Westward Expansion ◽  
The Cost ◽  
Land Use Practices ◽  
Ecological Regime

This chapter explores the ecological regime of slavery and the land-use practices employed by farmers across the antebellum South. Despite the diverse ecologies and crop regimes of the region, most southern farmers employed a set of extensive agricultural techniques that kept the cost of farming down and helped circumvent natural limits on crop production and stock-raising. The use of shifting cultivation, free-range animal husbandry, and slaves to perform erosion control masked the environmental impacts of farmers’ actions, at least temporarily. Debates over westward expansion during the sectional crisis of the 1850s were not just about the extension of slavery, they also reflected practical concerns regarding access to new lands and fresh soil. Both were necessary for the continued profitability of farming in the South.

scholarly journals Elevated temperature and browning increase dietary methylmercury, but decrease essential fatty acids at the base of lake food webs

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pianpian Wu ◽  
Martin J. Kainz ◽  
Fernando Valdés ◽  
Siwen Zheng ◽  
Katharina Winter ◽  
...  
Keyword(s):  
Climate Change ◽  
Fatty Acids ◽  
Organic Matter ◽  
Food Webs ◽  
Essential Fatty Acids ◽  
Trophic Levels ◽  
Climate Change Scenarios ◽  
Essential Nutrients ◽  
Aquatic Food Webs ◽  
Aquatic Food

AbstractClimate change scenarios predict increases in temperature and organic matter supply from land to water, which affect trophic transfer of nutrients and contaminants in aquatic food webs. How essential nutrients, such as polyunsaturated fatty acids (PUFA), and potentially toxic contaminants, such as methylmercury (MeHg), at the base of aquatic food webs will be affected under climate change scenarios, remains unclear. The objective of this outdoor mesocosm study was to examine how increased water temperature and terrestrially-derived dissolved organic matter supply (tDOM; i.e., lake browning), and the interaction of both, will influence MeHg and PUFA in organisms at the base of food webs (i.e. seston; the most edible plankton size for zooplankton) in subalpine lake ecosystems. The interaction of higher temperature and tDOM increased the burden of MeHg in seston (< 40 μm) and larger sized plankton (microplankton; 40–200 μm), while the MeHg content per unit biomass remained stable. However, PUFA decreased in seston, but increased in microplankton, consisting mainly of filamentous algae, which are less readily bioavailable to zooplankton. We revealed elevated dietary exposure to MeHg, yet decreased supply of dietary PUFA to aquatic consumers with increasing temperature and tDOM supply. This experimental study provides evidence that the overall food quality at the base of aquatic food webs deteriorates during ongoing climate change scenarios by increasing the supply of toxic MeHg and lowering the dietary access to essential nutrients of consumers at higher trophic levels.

Sign in / Sign up

Export Citation Format

Share Document