Using bioenergetics and stable isotopes to assess the trophic role of rusty crayfish (Orconectes rusticus) in lake littoral zones

2006 ◽  
Vol 63 (2) ◽  
pp. 335-344 ◽  
Author(s):  
Brian M Roth ◽  
Catherine L Hein ◽  
M Jake Vander Zanden
Keyword(s):  
Stable Isotope ◽  
Trophic Position ◽  
Isotope Analysis ◽  
Freshwater Ecosystems ◽  
Prey Choice ◽  
Orconectes Rusticus ◽  
Rusty Crayfish ◽  
Littoral Habitat ◽  
Trophic Role

Crayfish often dominate freshwater ecosystems and can have strong effects on littoral habitat and biota through foraging. However, there is substantial debate regarding the trophic role of crayfish and implications of their foraging behavior on littoral ecosystems. We created a bioenergetics model for rusty crayfish (Orconectes rusticus) to determine how growth and prey choice constrain crayfish consumption, which affects littoral ecosystems. We simulated over 6400 potential rusty crayfish diets by varying the abundance of important prey. We judged how crayfish prey choice affects the amount and identity of prey that crayfish must consume to match observed growth. We compared our model predictions with stable isotope evidence from 10 northern Wisconsin lakes to determine energy sources and trophic position of rusty crayfish relative to other invertebrates. Our diet simulations and stable isotope analysis concurred that crayfish of all ages are primarily predators. Individuals that do not feed on zoobenthos must therefore consume large quantities of less desirable food such as macrophytes, which are an important component of littoral habitat.

The trophic role of Octopus insularis at a pristine tropical atoll in southwest Atlantic: a potential keystone predator?

2019 ◽  
Author(s):  
Renato Junqueira de Souza Dantas ◽  
Tatiana Silva Leite ◽  
Cristiano Queiroz de Albuquerque
Keyword(s):  
Food Web ◽  
Trophic Position ◽  
Feeding Strategy ◽  
Isotope Analysis ◽  
Carbon Sources ◽  
Trophic Levels ◽  
Isotopic Niche ◽  
Southwest Atlantic ◽  
Trophic Role

In the present study, we evaluated the trophic role of Octopus insularis Leite and Haimovici, 2008 in the food web of Rocas Atoll, a preserved insular territory in the southwest Atlantic. Using stable isotope analysis of C and N, we showed that the local trophic web comprises at least four trophic levels, where the octopus presents d13C values from -12.1 to -6.1‰, d15N values from 6.4 to 11.0‰ and occupies a trophic position (TP) between the second and third trophic levels (mean ± SD TPadditive = 3.08 ± 0.36; TPBayesian = 3.12 ± 0.17). Among other benthic/reef-associated consumers, this cephalopod stood out for its much wider isotopic niche (SEAB = 4.7890), pointing to a diet diversified in carbon sources, but focused on prey in lower TPs. Time-minimizing feeding strategy seemed almost permanent throughout the life cycle, given the great niche overlap between small and large octopuses (large: SEAB = 4.59, small: SEAB = 4.03) and their very similar trophic positions (TPadditive/TPBayesian: large = 3.27/3.26; small = 2.89/2.99). Also, as a prey, O. insularis composed 16%-24% of the diet of some benthic/demersal predators. Overall, exerting great predatory pressure on bottom-associated organisms and serving as a relevant food source for top and mesopredators, O. insularis represented a top consumer of the benthic portion of the food web and an important link between its benthic and demersal strata with potential for keystone species.

Pedogenic, palustrine and groundwater dolomite formation in non-marine bentonites (Bavaria, Germany)

Clay Minerals ◽  
2015 ◽  
Vol 50 (2) ◽  
pp. 163-183 ◽  
Author(s):  
M.H. Köster ◽  
H.A. Gilg
Keyword(s):  
Stable Isotope ◽  
Isotope Geochemistry ◽  
Isotope Analysis ◽  
X Ray Diffraction ◽  
Wetting And Drying ◽  
C3 Plant ◽  
Carbonate Formation ◽  
Data Points ◽  
Dolomite Formation

AbstractDolomite and calcite in Bavarian bentonites, southern Germany, were investigated using petrography, field-emission scanning electron microscopy and stable isotope geochemistry to explore the role of authigenic carbonate formation during bentonitization. Pedogenic, palustrine and groundwater carbonates were distinguished on the basis of X-ray diffraction, micromorphological and stable isotope analysis. The δ13CV-PDB and δ18OV-PDB values of dolomite range from −8.0% to −6.1% and −5.4% to −3.4%, respectively. Calcites show a range from −11.9% to −8.1% for carbon and from −9.1% to −6.2% for oxygen. Carbon isotope compositions imply a C3-plant-dominated carbon source and repeated wetting and drying cycles. The oxygen isotope data points to an evaporation and temperature controlled δ18OV-SMOW value of meteoric water of −7.0% to −4.8%. A syngenetic to early diagenetic timing of dolomitization is indicated, suggesting both dolomite and bentonite formation in non-saline, non-arid and repeatedly partially-oxygenated and reducing soil and groundwater environments during pedogenesis.

Onshore–offshore distribution of Thecosomata (Gastropoda) in the Benguela Current upwelling region off Namibia: species diversity and trophic position

2013 ◽  
Vol 93 (6) ◽  
pp. 1625-1640 ◽  
Author(s):  
Rolf Koppelmann ◽  
Björn Kullmann ◽  
Niko Lahajnar ◽  
Bettina Martin ◽  
Volker Mohrholz
Keyword(s):  
Species Diversity ◽  
Surface Waters ◽  
Diel Vertical Migration ◽  
Food Source ◽  
Trophic Position ◽  
Standing Stock ◽  
Open Ocean ◽  
Benguela Current ◽  
Trophic Role

Many Thecosomata (Gastropoda) produce an aragonite shell and are potentially threatened by the increasing ocean acidification. Information about these species is very important for future monitoring of the fate of this group. This paper investigates the distribution, species composition and trophic role of Thecosomata along a transect from the coast into the open ocean off Walvis Bay, Namibia, in September 2010 and January/February 2011. Twenty species were detected, but three taxa (Limacina bulimoides, Limacina inflata and Desmopterus papilio) dominated the community with more than 80% of the total standing stock. Diel vertical migration was observed for both Limacina taxa with higher concentrations in surface waters during night. Desmopterus papilio revealed almost no day/night differences. The highest diversities and abundances were detected at the slope and offshore stations, indicating the oceanic preference of this group; some taxa aggregated at the shelf–open ocean interface. δ15N measurements confirmed the first trophic level of this group; however, significant differences were detected between seasons with higher values in February 2011. This can be related to differences in seston values as the primary food source. Possible biogeochemical causes for these differences like an exhaustion of the nitrate pool or denitrification processes under suboxic conditions are discussed.

scholarly journals Estimation of nutrient contributions from the ocean across a river basin using stable isotope analysis

2015 ◽  
Vol 12 (7) ◽  
pp. 5535-5557
Author(s):  
K. Nakayama ◽  
Y. Maruya ◽  
K. Matsumoto ◽  
M. Komata ◽  
K. Komai ◽  
...  
Keyword(s):  
Stable Isotope ◽  
River Basin ◽  
Stable Isotope Analysis ◽  
Chum Salmon ◽  
Ursus Arctos ◽  
Isotope Analysis ◽  
Oncorhynchus Gorbuscha ◽  
River Ecosystem ◽  
River Channels

Abstract. Since marine derived nutrients (MDN) are transported not only in river channels but also across the entire river basin, including via ground water and migratory animals, it is necessary to investigate the contribution of MDN to the forest floor (soils) in order to quantify the true role of MDN at the river ecosystem scale. This study investigated the contribution of pink (Oncorhynchus gorbuscha) and chum salmon (O. keta) to total oceanic nitrogen (TN) input across a river basin using stable isotope analysis (SIA) of nitrogen (δ15N). The contribution of TN entering the river basin by salmon was 23.8 % relative to the total amount of TN exported from the river basin, providing a first estimate of MDN export for a river basin. The contribution of nitrogen from the ocean to the river basin soils was between 22.9 and 23.8 %. Furthermore, SIA showed that the transport of oceanic TN by sea eagles (Haliaeetus spp.) was greater than that by bears (Ursus arctos), which had previously been that bears are thought to be the major animal transporter of nutrients in the northern part of Japan.

scholarly journals Feeding Ecology of Three Euphausiid Species in the North Pacific Ocean Inferred From 18S V9 Metabarcoding and Stable Isotope Analysis

2021 ◽  
Vol 8 ◽  
Author(s):  
Fanyu Zhou ◽  
Junya Hirai ◽  
Koji Hamasaki ◽  
Sachiko Horii ◽  
Atsushi Tsuda
Keyword(s):  
Stable Isotope ◽  
Stable Isotope Analysis ◽  
Feeding Ecology ◽  
North Pacific ◽  
Prey Availability ◽  
Trophic Position ◽  
Isotope Analysis ◽  
Trophic Levels ◽  
Gut Contents ◽  
North Pacific Subtropical Gyre

Euphausiids are abundant micronekton and important links between higher and lower trophic levels in marine ecosystems; however, their detailed diets cannot be fully understood by conventional microscopy, especially in subtropical areas. Here, we report the euphausiid community structure in the California Current (CC) area and the eastern/western North Pacific subtropical gyre (ESG and WSG) and detail the feeding ecology of the dominant species (Euphausia pacifica, E. brevis, and E. hemigibba) in each region using a combined approach of gut content analysis via 18S V9 metabarcoding and stable carbon and nitrogen isotope analysis. A pronounced omnivorous feeding of all studied euphausiid species was supported by both methods: phytoplanktonic taxonomic groups (Dinophyta, Stramenopiles, and Archaeplastida), Copepoda, and Hydrozoa were detected in the gut contents; all the three euphausiid species displayed an intermediate trophic position between the net plankton (0.2–1.0 mm) and the myctophid fish (15.2–85.5 mm). However, Hydrozoa found in euphausiid gut contents likely derived from a potential cod-end feeding, based on isotope analysis. E. pacifica in the CC province ingested more autotrophic prey, including pelagophyte and green algae, due to a greater abundance of Stramenopiles and Archaeplastida in shallow layers of CC water. On the other hand, non-autotrophic prey such as mixotrophic Kareniaceae dinoflagellates, Pontellidae and Clausocalanidae copepods, and Sphaerozoidae rhizarian contributed more to the diets of E. brevis and E. hemigibba because of a lower chlorophyll a concentration or potentially a scarcity of autotrophic prey availability in ESG and WSG. The feeding patterns of dominant euphausiid species conducting filter feeding were thus largely determined by phytoplankton prey availability in the environments. Dietary difference across three species was also indicated by stable isotope analysis, with a lower mean trophic level of E. pacifica (2.32) than E. brevis (2.48) and E. hemigibba (2.57). These results verify direct trophic interactions between euphausiids and primary production and suggest that the omnivorous feeding habit is a favorable character for dominant Euphausia species.

scholarly journals Stable isotope analyses reveal unique trophic role of reef manta rays ( Mobula alfredi ) at a remote coral reef

2019 ◽  
Vol 6 (9) ◽  
pp. 190599 ◽  
Author(s):  
Lauren R. Peel ◽  
Ryan Daly ◽  
Clare A. Keating Daly ◽  
Guy M. W. Stevens ◽  
Shaun P. Collin ◽  
...  
Keyword(s):  
Coral Reef ◽  
Stable Isotope ◽  
Trophic Ecology ◽  
Sample Treatment ◽  
Stable Isotope Analyses ◽  
Isotopic Signatures ◽  
Freeze Dried ◽  
Isotope Analyses ◽  
Trophic Role

Stable isotope analyses provide the means to examine the trophic role of animals in complex food webs. Here, we used stable isotope analyses to characterize the feeding ecology of reef manta rays ( Mobula alfredi ) at a remote coral reef in the Western Indian Ocean. Muscle samples of M. alfredi were collected from D'Arros Island and St. Joseph Atoll, Republic of Seychelles, in November 2016 and 2017. Prior to analysis, lipid and urea extraction procedures were tested on freeze-dried muscle tissue in order to standardize sample treatment protocols for M. alfredi . The lipid extraction procedure was effective at removing both lipids and urea from samples and should be used in future studies of the trophic ecology of this species. The isotopic signatures of nitrogen (δ 15 N) and carbon (δ 13 C) for M. alfredi differed by year, but did not vary by sex or life stage, suggesting that all individuals occupy the same trophic niche at this coral reef. Furthermore, the isotopic signatures for M. alfredi differed to those for co-occurring planktivorous fish species also sampled at D'Arros Island and St. Joseph Atoll, suggesting that the ecological niche of M. alfredi is unique. Pelagic zooplankton were the main contributor (45%) to the diet of M. alfredi , combined with emergent zooplankton (38%) and mesopelagic prey items (17%). Given the extent of movement that would be required to undertake this foraging strategy, individual M. alfredi are implicated as important vectors of nutrient supply around and to the coral reefs surrounding D'Arros Island and St. Joseph Atoll, particularly where substantial site fidelity is displayed by these large elasmobranchs.

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