scholarly journals Sargassum blooms in the Caribbean alter the trophic structure of the sea urchin Diadema antillarum

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7589 ◽  
Author(s):  
Nancy Cabanillas-Terán ◽  
Héctor A. Hernández-Arana ◽  
Miguel-Ángel Ruiz-Zárate ◽  
Alejandro Vega-Zepeda ◽  
Alberto Sanchez-Gonzalez
Keyword(s):  
Stable Isotopes ◽  
Sea Urchin ◽  
Niche Breadth ◽  
Negative Impact ◽  
Trophic Niche ◽  
Food Sources ◽  
Diadema Antillarum ◽  
Carbon And Nitrogen ◽  
Hypoxic Conditions ◽  
The Impact

The arrival of large masses of drifting Sargassum since 2011 has caused changes in the natural dynamics of Caribbean coastal ecosystems. In the summer of 2015, unprecedented and massive mats of S. fluitans and S. natans have been observed throughout the Mexican Caribbean including exceptional accumulations ashore. This study uses stable isotopes to assess the impact of Sargassum blooms on the trophic dynamics of the Diadema antillarum sea urchin, a keystone herbivore on many Caribbean reefs. Bayesian models were used to estimate the variations in the relative proportions of carbon and nitrogen of assimilated algal resources. At three lagoon reef sites, the niche breadth of D. antillarum was analysed and compared under massive influx of drifting Sargassum spp. vs. no influx of Sargassum blooms. The effects of the leachates generated by the decomposition of Sargassum led to hypoxic conditions on these reefs and reduced the taxonomic diversity of macroalgal food sources available to D. antillarum. Our trophic data support the hypothesis that processes of assimilation of carbon and nitrogen were modified under Sargassum effect. Isotopic signatures of macroalgae associated with the reef sites exhibited significantly lower values of δ15N altering the natural herbivory of D. antillarum. The Stable Isotopes Analysis in R (SIAR) indicated that, under the influence of Sargassum blooms, certain algal resources (Dictyota, Halimeda and Udotea) were more assimilated due to a reduction in available algal resources. Despite being an abundant available resource, pelagic Sargassum was a negligible contributor to sea urchin diet. The Stable Isotope Bayesian Ellipses in R (SIBER) analysis displayed differences between sites, and suggests a reduction in trophic niche breadth, particularly in a protected reef lagoon. Our findings reveal that Sargassum blooms caused changes in trophic characteristics of D. antillarum with a negative impact by hypoxic conditions. These dynamics, coupled with the increase in organic matter in an oligotrophic system could lead to reduce coral reef ecosystem function.

Determination of food sources and trophic position in Malaysian tropical highland streams using carbon and nitrogen stable isotopes

2017 ◽  
Vol 37 (2) ◽  
pp. 97-104 ◽  
Author(s):  
Dhiya Shafiqah Ridzuan ◽  
Che Salmah Md. Rawi ◽  
Suhaila Abdul Hamid ◽  
Salman Abdo Al-Shami
Keyword(s):  
Stable Isotopes ◽  
Trophic Position ◽  
Food Sources ◽  
Nitrogen Stable Isotopes ◽  
Carbon And Nitrogen ◽  
Highland Streams

scholarly journals Trophic niche breadth of pond zooplankton species using stable isotope analysis and the relationship with the abiotic and biotic factors

2019 ◽  
Vol 6 (1) ◽  
pp. 180917 ◽  
Author(s):  
Hideyuki Doi ◽  
Kwang-Hyeon Chang ◽  
Shin-ichi Nakano
Keyword(s):  
Stable Isotope ◽  
Niche Breadth ◽  
Resource Competition ◽  
Feeding Habits ◽  
Zooplankton Biomass ◽  
Trophic Niche ◽  
Zooplankton Species ◽  
Carbon And Nitrogen ◽  
Ecosystem Size ◽  
The Relationship

Zooplankton species have different feeding habits, but the diversity of their food resources and the factors governing them are still largely unknown. We here estimated the differences in the trophic niche breadths of dominant zooplankton species in ponds, using stable isotopes. To understand the differences in trophic niches of different zooplankton species, we measured the carbon and nitrogen stable isotope ratios and calculated the nearest-neighbour distance (NND), and standard deviation of NND (SDNND) of the bi-plot space of stable carbon and nitrogen isotopes in pond zooplankton. We tested the relationship between the NND/SDNND and environmental factors, as well as the zooplankton biomass, using generalized linear models (GLMs). For cladocerans, including Bosmina, Ceriodaphnia and Daphnia, the NNDs were significantly correlated with the biomass, pond morphology (volume and depth), total phosphorous (TP) and fish presence. For copepod species, including Eodiaptomus and cyclopoids, NNDs were significantly correlated with pond morphology, TP and fish presence, but not with biomass. In GLMs of SDNND, significant correlated factors were less than those for NND, and for some species, pond morphology and TP were significantly correlated with SDNND. Here, we found that the NND and SDNND of zooplankton species were related to various factors, including their biomass, predator presence, pond size and water quality. For cladocerans, biomass may be supported by trophic niche breadth, probably because of the consequences of resource competition. Also, predation and ecosystem size may influence trophic niche breadth due to changes in zooplankton behaviours.

The monogenean Paradiplozoon ichthyoxanthon behaves like a micropredator on two of its hosts, as indicated by stable isotopes

2018 ◽  
Vol 93 (1) ◽  
pp. 71-75 ◽  
Author(s):  
B. Sures ◽  
M. Nachev ◽  
B.M. Gilbert ◽  
Q.M. Dos Santos ◽  
M.A. Jochmann ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Trophic Level ◽  
Trophic Interactions ◽  
Carbon Sources ◽  
Food Sources ◽  
Carbon And Nitrogen ◽  
Blood Sucking ◽  
Vaal Dam ◽  
Living Organisms ◽  
Host Fishes

AbstractThe analysis of stable isotopes of carbon and nitrogen has been used as a fingerprint for understanding the trophic interactions of organisms. Most of these studies have been applied to free-living organisms, while parasites have largely been neglected. Studies dealing with parasites so far have assessed the carbon and nitrogen signatures in endoparasites or ectoparasites of different hosts, without showing general trends concerning the nutritional relationships within host–parasite associations. Moreover, in most cases such systems involved a single host and parasite species. The present study is therefore the first to detail the trophic interactions of a freshwater monogenean–host model using δ13C and δ15N, where a single monogenean species infects two distinctly different hosts. Host fishes, Labeobarbus aeneus and Labeobarbus kimberleyensis from the Vaal Dam, South Africa, were assessed for the monogenean parasite Paradiplozoon ichthyoxanthon, individuals of which were removed from the gills of the hosts. The parasites and host muscle samples were analysed for signatures of δ13C and δ15N using an elemental analyser connected to an isotope ratio mass spectrometer. Host fish appear to use partly different food sources, with L. aeneus having slightly elevated δ13C signatures compared to L. kimberleyensis, and showed only small differences with regard to their nitrogen signatures, suggesting that both species range on the same trophic level. Carbon and nitrogen signatures in P. ichthyoxanthon showed that the parasites mirrored the small differences in dietary carbon sources of the host but, according to δ15N signatures, the parasite ranged on a higher trophic level than the hosts. This relationship resembles predator–prey relationships and therefore suggests that P. ichthyoxanthon might act as a micropredator, similar to blood-sucking arthropods such as mites and fleas.

scholarly journals Vulture rescue and rehabilitation in South Africa: An urban perspective

2011 ◽  
Vol 82 (1) ◽  
Author(s):  
V. Naidoo ◽  
K. Wolter ◽  
I. Espie ◽  
A. Kotze
Keyword(s):  
Negative Impact ◽  
Food Sources ◽  
Mountain Range ◽  
Population Declines ◽  
Surgical Interventions ◽  
The Past ◽  
Safe Food ◽  
Surrounding Areas ◽  
The Impact ◽  
Apparently Healthy

SouthAfrica is home to 9 vulture species, of which 7 are endangered. While the cause of the population declines remains largely speculative, a vast amount of effort has been dedicated towards the protection of populations by ensuring sustainable and safe food sources for the various colonies. Limited focus was placed in the past on efforts related to the rescue and/or rehabilitation (R&R) of injured birds and the release of these birds back into the wild. This paper provides an overview of the causes, the impact and success of 3 organisations involved in R&R efforts of vultures in the Magaliesberg mountain range and surrounding areas over a period of 10 years. Study material included 162 Cape griffon (CGV) and 38 African white-backed (AWBV) vultures. Datasets include the number, sex and age of birds received, the reason the vultures were brought in for R&R, surgical interventions performed and outcomes of rescue efforts. The CGV dominated the rehabilitation attempts. Results further show that a large number of apparently healthy birds were presented for veterinary treatment. The R&R data clearly indicate that the major cause of injuries was birds colliding with overhead pylons, as a high number of soft tissue and skeletal injuries were observed. The study also shows that successful releases of rescued birds are possible. It is concluded that urbanisation has had a major negative impact on vultures around the Magaliesberg mountain range.

scholarly journals Floral Resource Partitioning between Centris (Heterocentris) analis (Fabricius, 1804) and Centris (Heterocentris) terminata Smith, 1874 (Hymenoptera, Apidae, Centridini), in an Urban Fragment of the Atlantic Forest

Sociobiology ◽  
2017 ◽  
Vol 64 (3) ◽  
pp. 292 ◽  
Author(s):  
Reinanda Lima ◽  
Maria Ferreira-Caliman ◽  
Marcos Da Costa Dórea ◽  
Caroline Tito Garcia ◽  
Francisco De Assis Ribeiro Dos Santos ◽  
...  
Keyword(s):  
Atlantic Forest ◽  
Urban Areas ◽  
Niche Breadth ◽  
Niche Overlap ◽  
Trophic Niche ◽  
Food Sources ◽  
Floral Resources ◽  
Pollen Types ◽  
Getulio Vargas ◽  
Floral Resource

The knowledge on plant species used for the collection of floral resources is crucial to understanding interactions between plants and bees. The aim of the present study was to identify floral resources used by Centris analis and Centris terminata to provision brood cells and determine the niche breadth and overlap of these two species in a fragment of the Atlantic Forest in Brazil. This study was conducted at the Universidade Federal da Bahia and Parque Zoobotânico Getúlio Vargas, both of which are located in urban areas of the city of Salvador in the state of Bahia. Twelve and eight pollen types were identified in C. analis and C. terminata nests, respectively. The most frequent pollen types were from species of Malpighiaceae and Fabaceae. A larger trophic niche breadth was found in the Parque Zoobotânico Getúlio Vargas for C. analis and in the Universidade Federal da Bahia for C. terminata. Pianka’s index demonstrated trophic niche overlap between C. analis and C. terminata, which was greater in the Parque Zoobotânico Getúlio Vargas. This study is the first to provide data on plants used as food sources by species of the genus Centris in a fragment of the Atlantic Forest situated within urban areas.   

scholarly journals Temporal variability modulates pH impact on larval sea urchin development

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Kit Yu Karen Chan ◽  
Chun Sang Daniel Tong
Keyword(s):  
Climate Change ◽  
Sea Urchin ◽  
Initial Conditions ◽  
Negative Impact ◽  
Shape Change ◽  
Global Climate ◽  
Larval Mortality ◽  
Initial Ph ◽  
The Impact

Abstract Coastal organisms reside in highly dynamic habitats. Global climate change is expected to alter not only the mean of the physical conditions experienced but also the frequencies and/or the magnitude of fluctuations of environmental factors. Understanding responses in an ecologically relevant context is essential for formulating management strategies. In particular, there are increasing suggestions that exposure to fluctuations could alleviate the impact of climate change-related stressors by selecting for plasticity that may help acclimatization to future conditions. However, it remains unclear whether the presence of fluctuations alone is sufficient to confer such effects or whether the pattern of the fluctuations matters. Therefore, we investigated the role of frequency and initial conditions of the fluctuations on performance by exposing larval sea urchin Heliocidaris crassispina to either constant or fluctuating pH. Reduced pH alone (pH 7.3 vs 8.0) did not affect larval mortality but reduced the growth of larval arms in the static pH treatments. Changes in morphology could affect the swimming mechanics for these small organisms, and geometric morphometric analysis further suggested an overall shape change such that acidified larvae had more U-shaped bodies and shorter arms, which would help maintain stability in moving water. The relative negative impact of lower pH, computed as log response ratio, on larval arm development was smaller when larvae were exposed to pH fluctuations, especially when the change was less frequent (48- vs 24-h cycle). Furthermore, larvae experiencing an initial pH drop, i.e. those where the cycle started at pH 8.0, were more negatively impacted compared with those kept at an initial pH of 7.3 before the cycling started. Our observations suggest that larval responses to climate change stress could not be easily predicted from mean conditions. Instead, to better predict organismal performance in the future ocean, monitoring and investigation of the role of real-time environmental fluctuations along the dispersive pathway is key.

scholarly journals Seasonal feeding habits and ontogenetic diet shift of black bullhead (Ameiurus melas) in Lake Sava (Serbia)

2021 ◽  
pp. 45-45
Author(s):  
Milica Jacimovic ◽  
Jasmina Krpo-Cetkovic ◽  
Stefan Skoric ◽  
Marija Smederevac-Lalic ◽  
Aleksandar Hegedis
Keyword(s):  
Niche Breadth ◽  
Negative Impact ◽  
Feeding Habits ◽  
Fish Fauna ◽  
Trophic Niche ◽  
Diet Analysis ◽  
Diet Shift ◽  
Trophic Diversity ◽  
Black Bullhead ◽  
Ontogenetic Diet Shift

The black bullhead is an invasive species that forms dense populations and has a negative impact on the native ichthyofauna. Recent studies indicate that it is one of the most dominant invasive fish species in Serbian waters. Feeding habits based on stomach contents of individuals caught in Lake Sava were analyzed as a first step towards evaluating its possible negative impact on the native fish fauna of the lake. The following indices for diet analysis were applied: vacuity index, frequency of occurrence, numerical abundance and prominence value. Trophic niche breadth and seasonal trophic diversity were calculated using the Shannon?s index. The diet spectrum comprised 16 different prey categories from five groups: Mollusca, Crustacea, Insecta, Teleostei and plants. Fish were the main prey in all seasons, followed by aquatic invertebrates. Plant material and terrestrial insects were used as food in relatively small quantities. Predation on fish eggs was also detected. Our research confirmed that this species is an opportunistic generalist. An ontogenetic diet shift was also detected. The lowest value of trophic diversity was found in age 1+ individuals (H=1.39), while the highest was found in age 3+ individuals (H=2.00). The widest niche breadth was recorded in spring 2011 (H=2.12).

scholarly journals The niche of shrimp stocks (Xiphopenaeus kroyeri Heller, 1862) from southeastern Brazil: a stable isotope approach

2020 ◽  
Vol 12 (9) ◽  
pp. 16173-16176
Author(s):  
Keltony De Aquino Ferreira ◽  
Leandro Rabello Monteiro ◽  
Ana Paula Madeira Di Beneditto
Keyword(s):  
Stable Isotopes ◽  
Rio De Janeiro ◽  
Food Sources ◽  
Southeastern Brazil ◽  
Isotopic Niche ◽  
Trophic Diversity ◽  
Carbon And Nitrogen ◽  
Xiphopenaeus Kroyeri ◽  
Espirito Santo ◽  
Janeiro State

The penaeid shrimp Xiphopenaeus kroyeri is the second most important species of crustacean in Brazilian fisheries. Stable isotopes of carbon and nitrogen are chemical proxies to provide quantitative information about the consumer isotopic niche, which is associated with its feeding ecology and ecological niche in the environment. This study evaluated the niche dimensions of X. kroyeri from different stocks through stable isotopes determinations.   Shrimps were sampled in four fishing areas from southeastern Brazil (Vitória and Anchieta, in Espírito Santo State, and Atafona and Farol de São Tomé, in Rio de Janeiro State). The stable isotopes of carbon and nitrogen were determined in the abdominal muscle. Quantitative metrics of the isotopic niche estimated the trophic diversity and trophic redundancy among stocks. Shrimp stocks from Espírito Santo State had highest trophic diversity, indicating greater variety of food sources and wider utilization of the available food sources. The shrimps from Rio de Janeiro State had highest trophic redundancy, revealing a more homogeneous dietary pattern.  The isotopic niche approach allowed the discrimination of X. kroyeri stocks distributed in southeastern Brazil, and the results will be helpful to assist fisheries management.

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