scholarly journals Variability of amphidromous organism isotopic niches in three Guadeloupe rivers affected by damming and water catchment

2021 ◽  
Vol 151 ◽  
Author(s):  
Lou Frotté ◽  
Loïc Michel ◽  
Gilles Lepoint ◽  
Sébastien Cordonnier ◽  
Étienne Bezault ◽  
...  
Keyword(s):  
Trophic Ecology ◽  
Natural Variability ◽  
Community Diversity ◽  
Small Rivers ◽  
Isotopic Niche ◽  
Specific Effects ◽  
River Hydrology ◽  
Adult Habitat ◽  
Three Rivers ◽  
Water Catchment

Native fauna of the tropical volcanic part of Guadeloupe is amphidromous: juveniles born in rivers but that grow in the sea need to migrate upstream to colonise their adult habitat in rivers. This migration is affected by any human-made obstacles placed in their way. Moreover, on volcanic tropical islands, streams are the main source of water catchment for the human population. This deeply affects river hydrology and characteristics. Both damming and water catchment potentially affect community diversity and species demography, but they may also alter the trophic ecology of the river fauna. Using stable isotopes and the stable isotope Bayesian ellipses approach in R (SIBER), this study aimed to assess the isotopic niche variability of riverine fauna of three persistent small rivers of Basse-Terre Island (Guadeloupe) affected by damming and water catchment. Using electrofishing, decapods and fishes (gobies) of three rivers were sampled upstream and downstream of dams. Our results demonstrated that the variability of the isotopic niches was extremely high between rivers but varied less between stations of the same river. Our results revealed complex and river-specific effects and a pattern merged with natural variability. Our two hypotheses (i.e., increase of resources upstream of dams and differential responses of trophic guilds to damming and water catchment) were only weakly supported and never in an unambiguous manner. Our study showed that it is necessary to consider the ‘noise’ generated by natural variability to observe and understand changes in the trophic ecology of associated fauna in relation to damming and water catchment.

scholarly journals Abundance and diversity of black flies (Diptera: Simuliidae) in rivers of the Andean Eastern Hills of Bogotá (Colombia),

2018 ◽  
Vol 23 (2) ◽  
pp. 291-317 ◽  
Author(s):  
Alexandra Buitrago-Guacaneme ◽  
Aura Sotelo-Londoño ◽  
Gabriel A. Pinilla-Agudelo ◽  
Alexander García-García ◽  
Ligia I Moncada ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Small Rivers ◽  
Black Flies ◽  
Benthic Organisms ◽  
Running Water ◽  
Dca Ordination ◽  
Chemical Factors ◽  
Abundance And Diversity ◽  
Three Rivers ◽  
Physical And Chemical

Black flies are abundant benthic organisms in well-oxygenated running water and are considered effective bioindicators of water quality. Information on the ecology of these organisms at the species level is important, since up to now information has mainly been available on a family level. The aim of this study was to evaluate the composition of black flies and their relationships to a group of physical and chemical factors in four small rivers of the Eastern Hills around Bogotá, Colombia. These headwaters are protected by the Empresa de Acueducto y Alcantarillado de Bogotá. Black fly larvae and pupae were collected during four sampling periods during the dry season to the early rainy season of 2012. Multivariate methods were used to determine the presence of each species in relation to dissolved oxygen, nitrates, pH, temperature, and water velocity. PCA ordination revealed a physicochemical environment with a tendency towards a certain homogeneity in the fourrivers studied. The DCA ordination confirmed that in La Vieja River the G. ortizi complex dominated while S. muiscorum was dominant in the other three rivers. Similarly, according to the NMDS, the composition of black flies in Arzobispo and Chorro de Padilla rivers was similar, while that of El Delirio and La Vieja rivers were different, especially in this last river. The rivers hadlow species richness (four species and one species complex). Simulium muiscorum was negatively correlated with dissolved oxygen, temperature and current velocity while S. ignescens was associated with slightly more oxygenated waters and S. furcilatum with fastercurrents.The low species diversity and richness for the four rivers is consistent with previous report sof low Neotropical diversity of black flies. Results showed that simuliid species could possibly be good indicators of the environmental conditions of Eastern Hills rivers around Bogotá.

scholarly journals How fishing intensity affects the spatial and trophic ecology of two gull species breeding in sympatry

2018 ◽  
Vol 75 (6) ◽  
pp. 1949-1964 ◽  
Author(s):  
Diana M Matos ◽  
Jaime A Ramos ◽  
Joana G Calado ◽  
Filipe R Ceia ◽  
Jessica Hey ◽  
...  
Keyword(s):  
Trophic Ecology ◽  
Habitat Preferences ◽  
Isotope Analysis ◽  
Demersal Fish ◽  
Trophic Niche ◽  
Isotopic Niche ◽  
Temporal Segregation ◽  
Fishery Discards ◽  
Individual Tracking ◽  
South Portugal

Abstract Fisheries produce large quantities of discards, an important resource for scavenging seabirds. However, a policy reform banning discards, which is soon to be implemented within the EU, will impose a food shortage upon scavengers, and it is still largely unknown how scavengers will behave. We studied the diet (hard remains), trophic (stable isotope analysis), and foraging (individual tracking) ecology of two gull species breeding in sympatry: Audouin’s gull Larus audouinii (AG) and yellow-legged gull Larus michahellis (YLG), in South Portugal, under normal fishery activity (NFA; work days) and low fishery activity (LFA; weekends), over two consecutive years. We established a pattern of dietary, spatial, and temporal segregation between the two gull species. Under LFA, yellow-legged gulls reduced their time spent at-sea, thus foraging more in alternative habitats (e.g. refuse dumps) and widening their isotopic niche (i.e. generalist behaviour). Contrastingly, Audouin’s gull had a narrower trophic niche (i.e. specialist behaviour), foraging exclusively at-sea, reducing the amount of demersal fish and increasing the amount of pelagic fish in their diet. Under NFA, both species foraged mostly at-sea, feeding almost exclusively on fish, with increased consumption of demersal species (i.e. fishery discards). In general, yellow-legged gull had a broader trophic niche (i.e. generalist behaviour) when compared with the narrower isotopic niche of Audouin’s gull (i.e. specialist behaviour). Overall, both gull species relied heavily on fishery discards. However, there was visible dietary, spatial, and temporal segregation between the two species, associated with their dietary and habitat preferences that could be attributed to the availability of anthropogenic resources, such as fishery discards.

scholarly journals Individual niche trajectories in nesting green turtles on Rocas Atoll, Brazil: an isotopic tool to assess diet shifts over time

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Karoline Fernanda Ferreira Agostinho ◽  
Leandro Rabello Monteiro ◽  
Ana Paula Madeira Di Beneditto
Keyword(s):  
Trophic Ecology ◽  
Isotope Analysis ◽  
Trophic Niche ◽  
Northeastern Brazil ◽  
Diet Shift ◽  
Isotopic Niche ◽  
Temporal Window ◽  
Temporal Dimension ◽  
Green Turtles ◽  
Diet Shifts

Abstract In this study, multi-tissue (yolk and carapace) stable isotope analysis was used to assess individual isotopic niche trajectories of nesting green turtles on Rocas Atoll, off northeastern Brazil, and to reveal a diet shift in the temporal dimension. The diet trajectories of individual green turtles were highly directional, with a stronger component towards decreasing values of δ15N from carapace to yolk. When the green turtles are in their foraging sites (temporal window measured by the yolk samples), they are more herbivores. Conversely, in a broader temporal window, the green turtles demonstrate a carnivore-omnivore strategy, such as represented by heavier δ15N values in the carapace. This finding confirms a temporal diet shift. This is the first study that applies trophic niche trajectories for sea turtles, adding a new isotopic tool to understand the trophic ecology of these migrant animals.

Aquatic hyphomycetes in three rivers of southwestern France. II. Spatial and temporal differences between species

1998 ◽  
Vol 76 (1) ◽  
pp. 107-114
Author(s):  
Eric Fabre
Keyword(s):  
Abundant Species ◽  
Aquatic Hyphomycetes ◽  
Community Diversity ◽  
Water Filtration ◽  
Individual Species ◽  
Downstream Distance ◽  
Different Seasons ◽  
Conidial Concentration ◽  
Three Rivers ◽  
Complex Manner

Spatial and temporal changes in conidial concentration of species of aquatic hyphomycetes were studied in three southwestern French rivers (Adour, Nive, and Tech). The survey was conducted from source to mouth for a year by water filtration. Fifty-two species were identified. Alatospora acuminata and Clavariopsis aquatica were the most abundant species in all three rivers. Most other species made small contributions to the total amount of conidia, but species such as Heliscella stellata or Lemonniera aquatica occasionally may be important in a particular river. The timing of seasonal peaks of conidia concentration of some species was studied. Species were classified into three groups according to the similarity or differences among rivers. Peak conidial concentration could appear at the same season on the three rivers (e.g., Alatospora acuminata, Articulospora tetracladia, Heliscella stellata, Lemonniera aquatica, Lunulospora curvula) or in different seasons on the three rivers (e.g., Pyricularia submersa, Tetrachaetum elegans). No peak was found for Clavariopsis aquatica or Clavatospora longibrachiata on any river. Changes in conidial concentration along the three rivers were analysed. Patterns of individual species varied among rivers and seasons. During summer on the Tech River, conidial concentration of Heliscella stellata increased abruptly to the highest values of this study after having remained close to zero in the uppermost 20 km. This coincided with a drastic decrease in community diversity in these reaches. Both altitude and downstream distance influence conidial concentrations in a complex manner. Key words: Ingoldian fungi, conidia concentration, season, elevation.

Long-term stability in the richness and structure of helminth communities in eels, Anguilla anguilla, in Lough Derg, River Shannon, Ireland

2002 ◽  
Vol 76 (4) ◽  
pp. 315-322 ◽  
Author(s):  
C.R. Kennedy ◽  
C. Moriarty
Keyword(s):  
Community Diversity ◽  
Large Rivers ◽  
Small Rivers ◽  
Intestinal Helminth ◽  
Helminth Parasites ◽  
Component Community ◽  
Data Set ◽  
Helminth Communities ◽  
Composition And Structure ◽  
Acanthocephalus Lucii

AbstractA data set on intestinal helminth parasites was collected in the course of an 18 year investigation into the biology of eels in Meelick Bay, Lough Derg, River Shannon. This was used to test two hypotheses relating to the composition and structure of intestinal helminth communities, namely that eels in large rivers do not harbour richer and more diverse communities than those in small rivers but that community composition and structure are more stable over time than in small rivers. The helminth community was species poor, with only six species comprising the component community and a maximum infracommunity richness of three species. The community was overwhelmingly dominated by the acanthocephalan Acanthocephalus lucii, reflecting the importance of its intermediate host Asellus aquaticus in the eels' diet. The remaining helminth species contributed to species richness but made very little contribution to community diversity. Population levels of Acanthocephalus lucii fell and remained low between 1992 and 2000, probably reflecting increased movement of eels from other parts of the lough into Meelick Bay. Diversity values were low, but similar to those reported from other rivers in Britain and Europe. The results provided support for both hypotheses and indicated that in respect of richness, diversity and dominance, the helminth communities of eels in the River Shannon were typical of, and comparable to, those of other large rivers throughout Europe.

Aquatic hyphomycetes in three rivers of southwestern France. I. Spatial and temporal changes in conidial concentration, species richness, and community diversity

1998 ◽  
Vol 76 (1) ◽  
pp. 99-106
Author(s):  
Eric Fabre
Keyword(s):  
Species Richness ◽  
Temporal Changes ◽  
Aquatic Hyphomycetes ◽  
Population Diversity ◽  
Community Diversity ◽  
Water Filtration ◽  
Spatial And Temporal Changes ◽  
Conidial Concentration ◽  
Autumn And Winter ◽  
Three Rivers

Spatial and temporal changes in aquatic hyphomycetes communities were studied in three southwestern French rivers (Tech, Adour, and Nive). The survey was conducted from source to mouth for a year by water filtration. Changes in conidial concentration, species richness, and population diversity were analysed. Concentration of conidia of aquatic hyphomycetes generally increased in the downstream direction. However, these changes varied according to the river and the sampling date. Conidial concentration was higher during autumn than during spring and summer, but there was no difference between the beginning and the end of the leaf fall. Species richness was maximal during autumn and winter. It increased rapidly in downstream direction and reached a plateau. The diversity of conidial community of aquatic hyphomycetes generally remained constant regardless of the river sampled or the sampling date. It approached 75% of the theorical maximum possible diversity value, given the number of species and number of conidia sampled. Key words: Ingoldian fungi, community structure, season, altitude.

scholarly journals Isotopic niche reflects stress-induced variability in physiological status

2018 ◽  
Vol 5 (2) ◽  
pp. 171398 ◽  
Author(s):  
Agnes M. L. Karlson ◽  
Martin Reutgard ◽  
Andrius Garbaras ◽  
Elena Gorokhova
Keyword(s):  
Body Size ◽  
Stable Isotope ◽  
Trophic Ecology ◽  
Physiological Stress ◽  
Isotope Composition ◽  
Stress Factors ◽  
Physiological Status ◽  
Isotopic Niche ◽  
Control Groups ◽  
Oxygen Conditions

The isotopic niche has become an established concept in trophic ecology. However, the assumptions behind this approach have rarely been evaluated. Evidence is accumulating that physiological stress can affect both magnitude and inter-individual variability of the isotopic signature in consumers via alterations in metabolic pathways. We hypothesized that stress factors (inadequate nutrition, parasite infestations, and exposure to toxic substances or varying oxygen conditions) might lead to suboptimal physiological performance and altered stable isotope signatures. The latter can be misinterpreted as alterations in isotopic niche. This hypothesis was tested by inducing physiological stress in the deposit-feeding amphipod Monoporeia affinis exposed to either different feeding regimes or contaminated sediments. In the amphipods, we measured body condition indices or reproductive output to assess growth status and δ 13 C and δ 15 N values to derive isotope niche metrics. As hypothesized, greater isotopic niche estimates were derived for the stressed animals compared to the control groups. Moreover, the δ 15 N values were influenced by body size, reproductive status and parasite infestations, while δ 13 C values were influenced by body size, oxygen conditions and survival. Using regression analysis with isotope composition and growth variables as predictors, we were able to discriminate between the amphipods exposed to nutritionally or chemically stressful conditions and those in the control groups. Thus, interpretation of isotopic niche can be confounded by natural or anthropogenic stressors that may induce an apparent change in isotopic niche. These findings stress the importance of including measures of growth and health status when evaluating stable isotope data in food web studies.

scholarly journals Isotopic niche provides an insight into the ecology of a symbiont during its geographic expansion

2021 ◽  
Author(s):  
Enrique González-Ortegón ◽  
Marta Perez-Miguel ◽  
Jose I Navas ◽  
Pilar Drake ◽  
Jose A Cuesta
Keyword(s):  
Host Species ◽  
Trophic Ecology ◽  
Trophic Levels ◽  
Isotopic Niche ◽  
Species Overlap ◽  
Scrobicularia Plana ◽  
New Locations ◽  
Pea Crab ◽  
Geographic Expansion ◽  
Insight Into

Abstract The study of the recent colonization of a symbiont and its interaction with host communities in new locations is an opportunity to understand how they interact. The use of isotopic ratios in trophic ecology can provide measurements of a species’ isotopic niche, as well as knowledge about how the isotopic niches between symbiont and host species overlap. Stable isotope measurements were used to assess the sources of carbon assimilated by the host species (the bivalves Mytilus galloprovincialis and Scrobicularia plana) and their associated symbiont pea crab Afropinnotheres monodi, which occurs within these bivalves’ mantle cavities. The mixing model estimates suggest that all of them assimilate carbon from similar sources, particularly from pseudofaeces and particulate organic matter in this symbiotic system based on filter feeding. The symbiotic species occupy comparable trophic levels and its association seems to be commensal or parasitic depending on the duration of such association. The pea crab A. monodi reflects a sex-specific diet, where males are more generalist than the soft females because the latter’s habitat is restricted to the host bivalve. The high isotopic overlap between soft females and M. galloprovincialis may reflect a good commensal relationship with the host.

scholarly journals Not all jellyfish are equal: isotopic evidence for inter- and intraspecific variation in jellyfish trophic ecology

2015 ◽  
Author(s):  
Nicholas E.C. Fleming ◽  
Chris Harrod ◽  
Jason Newton ◽  
Jonathan D.R. Houghton
Keyword(s):  
Trophic Ecology ◽  
Functional Group ◽  
Trophic Position ◽  
Seasonal Succession ◽  
Deep Ocean ◽  
Trophic Levels ◽  
Foraging Strategies ◽  
Isotopic Niche ◽  
Ecosystem Models ◽  
Temporal Shifts

Jellyfish are highly topical within studies of pelagic food-webs and there is a growing realisation that their role is more complex than once thought. Efforts being made to include jellyfish within fisheries and ecosystem models are an important step forward, but our present understanding of their underlying trophic ecology can lead to their over-simplification in these models. Gelatinous zooplankton represent a polyphyletic assemblage spanning >1,400 species that inhabit coastal seas to the deep-ocean and employ a wide variety of foraging strategies. Despite this diversity, many contemporary modelling approaches include jellyfish as a single functional group feeding at one or two trophic levels at most. Recent reviews have drawn attention to this issue and highlighted the need for improved communication between biologists and theoreticians if this problem is to be overcome. We used stable isotopes to investigate the trophic ecology of three co-occurring scyphozoan jellyfish species (Aurelia aurita, Cyanea lamarckii and C. capillata) within a temperate, coastal food-web in the NE Atlantic. Using information on individual size, time of year and δ13C and δ15N stable isotope values we examined: (1) whether all jellyfish could be considered as a single functional group, or showed distinct inter-specific differences in trophic ecology; (2) Were size-based shifts in trophic position, found previously in A. aurita, a common trait across species?; (3) When considered collectively, did the trophic position of three sympatric species remain constant over time? Differences in δ15N (trophic position) were evident between all three species, with size-based and temporal shifts in δ15N apparent in A. aurita and C. capillata. The isotopic niche width for all species combined increased throughout the season, reflecting temporal shifts in trophic position and seasonal succession in these gelatinous species. Taken together, these findings support previous assertions that jellyfish require more robust inclusion in marine fisheries or ecosystem models.

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