Niche differentiation of bottlenose dolphin species in South Australia revealed by stable isotopes and stomach contents

2011 ◽  
Vol 38 (4) ◽  
pp. 261 ◽  
Author(s):  
Susan E. Gibbs ◽  
Robert G. Harcourt ◽  
Catherine M. Kemper
Keyword(s):  
Stable Isotope ◽  
Stomach Content ◽  
Bottlenose Dolphin ◽  
South Australia ◽  
Stomach Contents ◽  
Primary Source ◽  
Niche Differentiation ◽  
Numerical Abundance ◽  
Significant Difference ◽  
Management And Conservation

Context Animal species with overlapping ranges are common worldwide, but how these species coexist is less obvious. Dolphins are protected in Australia and yet little information is available on their resource use which is essential for successful management and conservation. Aim The aim of this study was to determine the degree of overlap in diet and feeding ecology of the two Tursiops spp. that have overlapping ranges in South Australia. Methods Stomach content (91 Tursiops sp. and 14 T. truncatus) and stable isotope (δ13C, δ15N) analyses (39 Tursiops sp. and 14 T. truncatus) were conducted. Carcasses of dolphins were opportunistically collected between 1974 and 2005. Diet was quantified by frequency of occurrence (FOO) and numerical abundance (NA) of prey. Key results Delta13C from teeth revealed distinct differences in primary source of carbon, corresponding to coastal (Tursiops sp. n = 39,  = –12.24, s.d. = 1.32) and offshore habitats (T. truncatus n = 14,  = –14.21, s.d. = 0.55). Differences in δ15N revealed Tursiops sp. ( = 11.66, s.d. = 0.58) feeds at a lower trophic level than T. truncatus ( = 14.29, s.d. = 0.88). Stomach content analyses for Tursiops sp. corroborated stable isotope results. There was a significant difference between the diets of Tursiops sp. from north Spencer Gulf and south Spencer Gulf (ANOSIM R = 0.249, P = 0.001). Prey were generally demersal in habit with the most important from the cephalopod families Octopodidae, Sepiidae and Loliginidae and fish families Carangidae, Clupeidae, Terapontidae and Apogonidae. For T. truncatus there were insufficient stomach contents for assessment. Conclusions South Australian bottlenose dolphin species exhibit distinct niche differentiation with clear evidence of regional variation in the diet of Tursiops sp. Implications The between and within species diet differentiation demonstrated, highlights the importance of regional management. Such results are internationally significant as coastal and offshore forms of Tursiops spp. occur worldwide.

Sources of variability and comparability between salmonid stomach contents and isotopic analyses: study design lessons and recommendations

2011 ◽  
Vol 68 (1) ◽  
pp. 137-151 ◽  
Author(s):  
Mark R. Vinson ◽  
Phaedra Budy
Keyword(s):  
Stable Isotope ◽  
Study Design ◽  
Stomach Content ◽  
Stomach Contents ◽  
Stomach Content Analysis ◽  
Diet Overlap ◽  
Target Species ◽  
Relative Information ◽  
Isotopic Analyses ◽  
Diet Analyses

We compared sources of variability and cost in paired stomach content and stable isotope samples from three salmonid species collected in September 2001–2005 and describe the relative information provided by each method in terms of measuring diet overlap and food web study design. Based on diet analyses, diet overlap among brown trout, rainbow trout, and mountain whitefish was high, and we observed little variation in diets among years. In contrast, for sample sizes n ≥ 25, 95% confidence interval (CI) around mean δ15Ν and δ13C for the three target species did not overlap, and species, year, and fish size effects were significantly different, implying that these species likely consumed similar prey but in different proportions. Stable isotope processing costs were US$12 per sample, while stomach content analysis costs averaged US$25.49 ± $2.91 (95% CI) and ranged from US$1.50 for an empty stomach to US$291.50 for a sample with 2330 items. Precision in both δ15Ν and δ13C and mean diet overlap values based on stomach contents increased considerably up to a sample size of n = 10 and plateaued around n = 25, with little further increase in precision.

Food sources of common dolphinfish (Coryphaena hippurus) based on stomach content and stable isotopes analyses

2014 ◽  
Vol 95 (3) ◽  
pp. 579-591 ◽  
Author(s):  
A. Tripp-Valdez ◽  
F. Galván-Magaña ◽  
S. Ortega-García
Keyword(s):  
Stable Isotope ◽  
Stomach Content ◽  
Gulf Of California ◽  
Stomach Contents ◽  
Isotopic Analysis ◽  
Stomach Content Analysis ◽  
Food Sources ◽  
Important Prey ◽  
Opportunistic Predator ◽  
Ecological Importance

Dolphinfish (Mahimahi) are a high-demand resource for sport and coastal fisheries, mainly in the Pacific Ocean. Due to their economic and ecological importance, studies of their biology are very important to understand their function in ecosystems. We used stable isotope and stomach content analyses to determine the most important prey of the common dolphinfish, as well as the trophic level of this species in two areas of the southern Gulf of California. Stomach contents of 445 specimens were analysed. Using both techniques, we found that the most important prey for dolphinfish in the southern Gulf of California were three invertebrate species followed by fish. This contrasts with results from other authors who found that this species was mainly piscivorous in other locations. Stomach content analysis indicated differences in prey biomass by area, season and size class. The isotopic analysis did not show significant differences between seasons or sexes. Both stomach contents and stable isotope analyses showed that although this predator consumed a wide prey spectrum, only a few prey items made up the bulk of the diet, which resulted in a low SD in δ15N values and low Levin's index values. We conclude that this fish is an opportunistic predator that may consume a wide prey spectrum, but that it mainly consumes prey that are abundant in the area, such as crustaceans and cephalopods in the Gulf of California.

scholarly journals Diet of Leptobotia elongata revealed by stomach content analysis and inferred from stable isotope signatures

2015 ◽  
Vol 98 (8) ◽  
pp. 1965-1978 ◽  
Author(s):  
L. Li ◽  
Q. Wei Wei ◽  
J. Ming Wu ◽  
H. Zhang ◽  
Y. Liu ◽  
...  
Keyword(s):  
Content Analysis ◽  
Stable Isotope ◽  
Stomach Content ◽  
Stomach Content Analysis ◽  
Stable Isotope Signatures

scholarly journals Offshore wind farms and the attraction–production hypothesis: insights from a combination of stomach content and stable isotope analyses

Hydrobiologia ◽  
2021 ◽  
Author(s):  
Ninon Mavraki ◽  
Steven Degraer ◽  
Jan Vanaverbeke
Keyword(s):  
Stable Isotope ◽  
Stomach Content ◽  
Wind Farms ◽  
Offshore Wind ◽  
Artificial Reefs ◽  
Dietary Composition ◽  
Trachurus Trachurus ◽  
Offshore Wind Farms ◽  
Scomber Scombrus ◽  
Isotope Analyses

AbstractOffshore wind farms (OWFs) act as artificial reefs, attracting high abundances of fish, which could potentially increase their local production. This study investigates the feeding ecology of fish species that abundantly occur at artificial habitats, such as OWFs, by examining the short- and the long-term dietary composition of five species: the benthopelagic Gadus morhua and Trisopterus luscus, the pelagic Scomber scombrus and Trachurus trachurus, and the benthic Myoxocephalus scorpioides. We conducted combined stomach content and stable isotope analyses to examine the short- and the time-integrated dietary composition, respectively. Our results indicated that benthopelagic and benthic species utilize artificial reefs, such as OWFs, as feeding grounds for a prolonged period, since both analyses indicated that they exploit fouling organisms occurring exclusively on artificial hard substrates. Trachurus trachurus only occasionally uses artificial reefs as oases of highly abundant resources. Scomber scombrus does not feed on fouling fauna and therefore its augmented presence in OWFs is probably related to reasons other than the enhanced food availability. The long-termed feeding preferences of benthic and benthopelagic species contribute to the hypothesis that the artificial reefs of OWFs could potentially increase the fish production in the area. However, this was not supported for the pelagic species.

scholarly journals Estimation of the feeding record of pregnant Antarctic minke whales (Balaenoptera bonaerensis) using carbon and nitrogen stable isotope analysis of baleen plates

Polar Biology ◽  
2021 ◽  
Vol 44 (3) ◽  
pp. 621-629
Author(s):  
Mayuka Uchida ◽  
Ippei Suzuki ◽  
Keizo Ito ◽  
Mayumi Ishizuka ◽  
Yoshinori Ikenaka ◽  
...  
Keyword(s):  
Growth Rate ◽  
Stable Isotope ◽  
Antarctic Krill ◽  
Isotope Analysis ◽  
Stomach Contents ◽  
Annual Growth Rate ◽  
Pleuragramma Antarcticum ◽  
Minke Whales ◽  
Balaenoptera Bonaerensis ◽  
The Antarctic

AbstractAntarctic minke whales (Balaenoptera bonaerensis) are migratory capital breeders that experience intensive summer feeding on Antarctic krill (Euphausia superba) in the Southern Ocean and winter breeding at lower latitudes, but their prey outside of the Antarctic is unknown. Stable isotope analyses were conducted on δ13C and δ15N from the baleen plates of ten pregnant Antarctic minke whales to understand the growth rate of the baleen plate and their diet in lower latitudes. Two to three oscillations along the length of the edge of the baleen plate were observed in δ15N, and the annual growth rate was estimated to be 75.2 ± 20.4 mm, with a small amplitude (0.97 ± 0.21 ‰). Bayesian stable isotope mixing models were used to understand the dominant prey that contributed to the isotopic component of the baleen plate using Antarctic krill from the stomach contents and reported values of Antarctic coastal krill (Euphausia crystallorophias), Antarctic silver fish (Pleuragramma antarcticum), Australian krill spp., and Australian pelagic fish spp.. The models showed that the diet composition of the most recent three records from the base of the baleen plates (model 1) and the highest δ15N values in each baleen plate (model 2) were predominantly Antarctic krill, with a contribution rate of approximately 80%. The rates were approximately 10% for Antarctic coastal krill and less than 2.0% for the two Australian prey groups in both models. These results suggest that pregnant Antarctic minke whales did not feed on enough prey outside of the Antarctic to change the stable isotope values in their baleen plates.

scholarly journals Survival of patients with synchronous brain metastases: an epidemiological study in southeastern Michigan

2000 ◽  
Vol 9 (2) ◽  
pp. 1-5 ◽  
Author(s):  
Ajith J. Thomas ◽  
Jack P. Rock ◽  
Christine C. Johnson ◽  
Linda Weiss ◽  
Gordon Jacobsen ◽  
...  
Keyword(s):  
Brain Metastases ◽  
Median Survival ◽  
Cancer Diagnosis ◽  
Systemic Disease ◽  
Primary Source ◽  
Primary Site ◽  
Unknown Primary ◽  
Primary Cancer ◽  
Significant Difference ◽  
Frequent Site

Object It has been suggested that synchronous brain metastases (that is, those occurring within 2 months of primary cancer diagnosis) are associated with a shorter survival time compared with metachronous lesions (those occurring greater than 2 months after primary cancer diagnosis). In this study the authors used data obtained from the National Cancer Institute's Surveillance, Epidemiology, and End Results Program to determine the incidence of synchronous brain metastases and length of survival of patients in a defined population of southeastern Michigan residents. Methods Data obtained in 2682 patients with synchronous brain metastases treated from 1973 to 1995 were reviewed. Study criteria included patients in whom at least one brain metastasis was diagnosed within 2 months of the diagnosis of primary cancer and those with an unknown primary source. The incidence per 100,000 increased fivefold, from 0.69 in 1973 to 3.83 in 1995. The most frequent site for the primary cancer was the lung (75.4%). The second largest group (10.7%) consisted of patients in whom the primary site was unknown. The median survival length was 3.3 months. There was no significant difference in the median survival in patients with primary lung/bronchus and those with an unknown primary site (3.2 months and 3.4 months, respectively). Conclusions Patients who present with synchronous lesions have a poor prognosis, and the predominant cause of death, in greater than 90% of cases, is related to systemic disease; however, despite poor median survival lengths, certain patients will experience prolonged survival.

Dietary composition of endangered seahorses determined by stable isotope analysis

2017 ◽  
Vol 68 (5) ◽  
pp. 831 ◽  
Author(s):  
S. Valladares ◽  
D. X. Soto ◽  
M. Planas
Keyword(s):  
Stable Isotope ◽  
Environmental Changes ◽  
Conservation Status ◽  
Management Strategies ◽  
Isotope Analysis ◽  
Primary Source ◽  
Habitat Characteristics ◽  
Conservation Actions ◽  
Isotope Mixing Models ◽  
North Western

The lack of integrated measures for assessing the feeding ecology of seahorses may restrict the effectiveness of conservation actions on wild populations of worldwide threatened seahorse species. Identifying dietary sources will allow researchers to determine their degree of vulnerability to environmental changes, redefine their conservation status and apply appropriate management strategies. The resource use of the seahorse Hippocampus guttulatus inhabiting coastal waters of Galicia (north-western Iberian Peninsula) was assessed for three populations and 2 years using stable isotope mixing models. The Bayesian mixing model (MixSIAR) estimated the relative contributions of the dietary sources to the seahorse diet and revealed that Caprellidea were the primary source, followed by Gammaridea and Caridea. Mysidae and Annelida represented the less dominant prey. This prey preference can be explained by the foraging behaviour of seahorses. Different contributions of Gammaridea and Caridea to the diet were found among sites, indicating different habitat characteristics and hence different habitat use by seahorses within each site. In addition, differences were encountered among sexes. Caprellidea was the dominant prey for females, whereas Gammaridea was the dominant prey for males. The findings of the present study will contribute to the knowledge of feeding patterns of H. guttulatus, providing relevant data for conservation of this endangered species.

scholarly journals FEEDING HABITS AND HELMINTH PARASITES OF SARDINE (S. PILCHARDUS) AND ANCHOVY (E. ENCRASICOLUS) IN THE ADRIATIC SEA

2015 ◽  
Vol 17 (1) ◽  
pp. 216 ◽  
Author(s):  
B. ZORICA ◽  
V. ČIKES KEČ ◽  
O. VIDJAK ◽  
I. MLADINEO ◽  
D. EZGETA BALIČ
Keyword(s):  
Diet Composition ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Stomach Content Analysis ◽  
Helminth Parasites ◽  
Significant Difference ◽  
Prey Composition ◽  
One Year ◽  
Paratenic Hosts ◽  
Hysterothylacium Aduncum

We examined the stomach contents of two of the most economically and ecologically important small pelagic fish species, the sardine, Sardina pilchardus and the anchovy, Engraulis encrasicolus, obtained monthly from commercial purse-seine catches operating on Croatian fishing grounds during a one-year period (January–December, 2011). Both species generally showed a similar diet, with copepod and decapod larvae as dominant prey groups. The composition of anchovy and sardine stomach contents was not size- or sex-related, but throughout the year, a significant difference in diet composition was observed for each species as well as between species. Two gastrointerstinal helminths; the digenean Parahemiurus merus and nematode Hysterothylacium aduncum, were recorded during the stomach content analysis. Differences in population dynamics between the two parasites are congruent with differences in the prey composition of sardine and anchovy, reflecting fine-tuned interactions in the trophic web between parasites and intermediate or paratenic hosts included in the sardine and anchovy diet.

scholarly journals ANALYSIS OF COST AND RETURNS IN RICE PRODUCTION BY USAID-MARKETS II PROJECT PARTICIPANTS AND NON-PARTICIPANTS IN EBONYI STATE, NIGERIA

2021 ◽  
Vol 21 (1) ◽  
pp. 1-7
Author(s):  
Ogechi Cordelia Nwahia
Keyword(s):  
Research Work ◽  
Primary Source ◽  
Sampling Procedure ◽  
Study Data ◽  
Rice Production ◽  
Farm Income ◽  
International Agencies ◽  
Significant Difference ◽  
Project Participants ◽  
The Government

This research work focused on analysis of cost and returns in rice production by USAID-MARKETS II project participants and non-participants in Ebonyi state, Nigeria. Multi-stage sampling procedure was employed to select 239 participants, and 252 non- participants for the study. Data were collected from primary source, and analyzed using Z statistic, Net Farm Income (NFI) and Returns Per Naira Invested (RNI). The result reveals that the Net Farm Income (NFI) obtained by USAID-MARKETS II project participants, and non-participants were N493, 067.55/ha, and N353, 408. 12/ha respectively while the return on investment obtained by them were N3.28k, and N3.05k respectively. There was a significant difference between the profits obtained by them. Therefore, this study recommended that the teaming unemployed Nigerian youth should be encourage by the government, and international agencies through provision of grant/loan to take up rice farming as a business.

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