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.

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.

scholarly journals Breaking out of the comfort zone: El Niño-Southern Oscillation as a driver of trophic flows in a benthic consumer of the Humboldt Current ecosystem

2017 ◽  
Vol 284 (1857) ◽  
pp. 20170923 ◽  
Author(s):  
José M. Riascos ◽  
Marco A. Solís ◽  
Aldo S. Pacheco ◽  
Manuel Ballesteros
Keyword(s):  
El Niño ◽  
Trophic Ecology ◽  
El Nino ◽  
Southern Oscillation ◽  
Trophic Position ◽  
Trophic Levels ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Strong Increase ◽  
Humboldt Current

The trophic flow of a species is considered a characteristic trait reflecting its trophic position and function in the ecosystem and its interaction with the environment. However, climate patterns are changing and we ignore how patterns of trophic flow are being affected. In the Humboldt Current ecosystem, arguably one of the most productive marine systems, El Niño-Southern Oscillation is the main source of interannual and longer-term variability. To assess the effect of this variability on trophic flow we built a 16-year series of mass-specific somatic production rate (P/B) of the Peruvian scallop ( Argopecten purpuratus ), a species belonging to a former tropical fauna that thrived in this cold ecosystem. A strong increase of the P/B ratio of this species was observed during nutrient-poor, warmer water conditions typical of El Niño, owing to the massive recruitment of fast-growing juvenile scallops. Trophic ecology theory predicts that when primary production is nutrient limited, the trophic flow of organisms occupying low trophic levels should be constrained (bottom-up control). For former tropical fauna thriving in cold, productive upwelling coastal zones, a short time of low food conditions but warm waters during El Niño could be sufficient to waken their ancestral biological features and display massive proliferations.

Trophic ecology of the chihuil sea catfish (Bagre panamensis) in the south-east Gulf of California, México

2017 ◽  
Vol 98 (4) ◽  
pp. 885-893 ◽  
Author(s):  
Víctor M. Muro-Torres ◽  
Felipe Amezcua ◽  
Raul E. Lara-Mendoza ◽  
John T. Buszkiewicz ◽  
Felipe Amezcua-Linares
Keyword(s):  
Gulf Of California ◽  
Trophic Ecology ◽  
Trophic Position ◽  
Feeding Habits ◽  
Isotope Analysis ◽  
Demersal Fish ◽  
Trophic Levels ◽  
High Plasticity ◽  
Combined Use ◽  
Ecosystem Based Fisheries Management

The trophic ecology of the chihuil sea catfish Bagre panamensis was studied through high-resolution variations in its feeding habits and trophic position (TP) in the SE Gulf of California, relevant to sex, size and season. The combined use of stomach content (SCA) and stable isotope analysis (SIA) allowed us to perform these analyses and also estimate the TP of its preys. Results of this study show that the chihuil sea catfish is a generalist and opportunistic omnivore predator that consumes primarily demersal fish and peneid shrimps. Its diet did not vary with climatic season (rainy or dry), size or sex. Results from the SIA indicated high plasticity in habitat use and prey species. The estimated TP value was 4.19, which indicates a tertiary consumer from the soft bottom demersal community in the SE Gulf of California, preying on lower trophic levels, which aids in understanding the species' trophic role in the food web. Because this species and its prey are important to artisanal and industrial fisheries in the Gulf of California, diet assimilation information is useful for the potential establishment of an ecosystem-based fisheries management in the area.

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.

Trophic ecology and foraging areas of cetaceans sampled in the coastal waters of south-eastern Brazil assessed through skin δ13C and δ15N

2021 ◽  
pp. 1-10
Author(s):  
Victor Uber Paschoalini ◽  
Genyffer Cibele Troina ◽  
Laura Busin Campos ◽  
Marcos César de Oliveira Santos
Keyword(s):  
Habitat Use ◽  
Coastal Waters ◽  
Trophic Ecology ◽  
Trophic Position ◽  
Trophic Levels ◽  
Eastern Coast ◽  
Cetacean Species ◽  
Δ13c And Δ15n ◽  
South Eastern ◽  
Eastern Brazil

Abstract We investigated the habitat use and feeding ecology of 10 cetacean species encountered along the south-eastern coast of Brazil (24–26°S) using carbon (δ13C) and nitrogen (δ15N) stable isotopes. Hierarchical cluster analysis distinguished two main groups based on their isotopic patterns. One group included migratory baleen whales (Megaptera novaeangliae and Eubalaena australis) with the lowest δ13C and δ15N values, reflecting baseline isotopic values of their Subantarctic feeding grounds and consumption of lower trophic level prey. Resident species and those occasionally occurring in Brazilian coastal waters highly differed from the migratory whales in their isotopic values. In this group, Tursiops truncatus had the highest δ13C and δ15N values, indicating coastal habits and relatively higher trophic position. Similar δ13C values were observed in Sotalia guianensis, Pontoporia blainvillei, Orcinus orca and Steno bredanensis. However, the former two species had lower δ15N values than the latter two, indicating different trophic positions. The relatively lower δ13C values observed in Stenella frontalis suggest greater influence of pelagic prey in their diet. Furthermore, the lower δ13C values observed in Delphinus delphis and Balaenoptera edeni were associated with upwelling events that occur along the region, affecting the isotopic values of their main prey. Juvenile M. novaeangliae had higher δ13C and δ15N than the adults, which may indicate feeding in areas with different isoscapes and consumption of pelagic schooling fish with relatively higher trophic levels than krill. This study provides preliminary information that are useful to understand the habitat use and coexistence of cetacean species occurring in south-eastern Brazil.

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.

Geographic and temporal variation in the trophic ecology of a small-bodied shark: evidence of resilience to environmental change

2015 ◽  
Vol 72 (3) ◽  
pp. 343-351 ◽  
Author(s):  
Samantha E.M. Munroe ◽  
Michelle R. Heupel ◽  
Aaron T. Fisk ◽  
Colin A. Simpfendorfer
Keyword(s):  
Temporal Variation ◽  
Geographic Variation ◽  
Trophic Ecology ◽  
Prey Availability ◽  
Trophic Position ◽  
Feeding Strategies ◽  
Isotopic Niche ◽  
Shark Species ◽  
Time And Space ◽  
Over Time

Shark dietary patterns can determine how they will respond to changes in prey availability and biodiversity. Geographic variation in diet can also indicate if species have unique structuring roles or feeding strategies in different environments. Unfortunately, little is known about the diet of most shark species and how diet varies over time and space. This study used stable isotope analysis to assess the diet of the Australian sharpnose shark (Rhizoprionodon taylori). Plasma and muscle δ13C and δ15N of R. taylori were compared with δ13C and δ15N baselines from multiple embayments to determine the isotopic niche, trophic position, and benthic and pelagic contributions to diet over time and space. Overall, R. taylori had a wide trophic position range and consumed prey from benthic and pelagic sources. However, there was geographic and temporal variation in trophic position and benthic and pelagic contributions. These findings indicate R. taylori is a dietary generalist, but different populations may have unique effects on distinct ecosystems. Geographic variation in diet also suggests R. taylori may be adaptive to changes in prey availability.

scholarly journals Primary Sources and Food Web Structure of a Tropical Wetland with High Density of Mangrove Forest

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3105
Author(s):  
Victor M. Muro-Torres ◽  
Felipe Amezcua ◽  
Martin Soto-Jiménez ◽  
Eduardo F. Balart ◽  
Elisa Serviere-Zaragoza ◽  
...  
Keyword(s):  
Food Web ◽  
Gulf Of California ◽  
Trophic Ecology ◽  
Abundant Species ◽  
Trophic Levels ◽  
Isotopic Niche ◽  
Trophic Chain ◽  
Mangrove Forests ◽  
Food Web Structure ◽  
Wide Range

The trophic ecology of wetlands with mangrove forests remains poorly understood. Through the use of stomach contents analysis, stable isotope signatures, and Bayesian mixing models, the food web of a tropical wetland in the gulf of California was investigated. Consumers had heterogeneous diets, omnivores were the most abundant species (47%), followed by planktivorous (21%), minor piscivores (10%), major piscivores (10%), macrobenthivores (9%), and herbivores (3%). The values of δ13C (from −12 to −29‰) and δ15N (from 4 to 24‰) showed a wide range of isotopic values of the consumers. Most of the species had a broad isotopic niche and there was a large diet overlap of species due to the exploitation of a common set of food resources. Five trophic levels were identified, with the weakfish (Cynoscion xanthulus) as the top predator of this system with detritus coming from the mangrove as the main source that supports the food chain. This highlights the importance of the mangrove forests to such ecosystems, because not only they are the most important primary food source, but also, they offer habitat to a large suite of fauna, which are important components of the trophic chain.

scholarly journals Reconstructing the diet, trophic level, and migration pattern of Mysticete whales based on baleen isotopic composition

2020 ◽  
Author(s):  
Philip M. Riekenberg ◽  
Jaime Camalich ◽  
Elisabeth Svensson ◽  
Lonneke L. IJsseldijk ◽  
Sophie M.J.M. Brasseur ◽  
...  
Keyword(s):  
Trophic Level ◽  
Trophic Position ◽  
Feeding Habits ◽  
Trophic Levels ◽  
Isotopic Niche ◽  
Physiological Changes ◽  
Temporal Sampling ◽  
Fin Whales ◽  
And Migration ◽  
Migration Pathways

AbstractBaleen from mysticete whales is a well-preserved proteinaceous material that can be used to identify migrations and feeding habits for species whose migration pathways are unknown. Analysis of δ13C and δ15N from bulk baleen has been used to infer migration patterns for individuals. However, this approach has fallen short of identifying migrations between regions as it is difficult to determine variations in isotopic shifts without temporal sampling of prey items. Here we apply analysis of δ15N values of amino acids to five baleen plates belonging to three species, revealing novel insights on trophic position, metabolic state, and migration between regions. Humpback and minke whales had higher reconstructed trophic levels than fin whales (3.4-3.5 versus 2.7-2.9, respectively) as expected due to different feeding specialization. Isotopic niche areas between baleen minima and maxima were well separated, indicating regional resource use for individuals during migration that aligned with isotopic gradients in Atlantic Ocean particulate organic matter. δ15N values from phenylalanine confirmed regional separation between the niche areas for two fin whales as migrations occurred and elevated glycine and threonine δ15N values revealed physiological changes due to fasting. Simultaneous resolution of trophic level and physiological changes allow for identification of regional migrations in mysticetes.

scholarly journals Trophic Ecology of Juvenile Southern King Crab Associated with Kelp Forest: Evidence of Cannibalism

Diversity ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 556
Author(s):  
Luis Miguel Pardo ◽  
Claudia Andrade ◽  
Lisette Zenteno-Devaud ◽  
Bastián Garrido ◽  
Cristóbal Rivera
Keyword(s):  
Fishery Management ◽  
Trophic Ecology ◽  
Trophic Position ◽  
Feeding Strategy ◽  
Isotope Analysis ◽  
Kelp Forest ◽  
Niche Shift ◽  
Kelp Forests ◽  
Isotopic Niche ◽  
King Crab

The southern king crab, Lithodes santolla, is a well-known predator/scavenger species during its adult phase but its feeding strategy in early stages is less studied. This information is important to understand their role in ecosystems and to improve fishery management (i.e., stock enhancement). Based on stomach contents and stable isotope analysis, we determined variation in the composition of diet and niche overlap in vagile and cryptic phase collected within and outside a kelp forest, Macrocystis pyrifera, of Aguila Bay at the Magellan Strait in Patagonia, Chile. Results of juvenile stomach content analysis showed 60% dissimilarity between cryptic and vagile juvenile phases. Algae dominated the volumetric contribution in cryptic juveniles while crustacean dominated the diet in vagile phase. Exoskeleton of other king crabs occurred in 43% of juveniles with crustaceans in their stomach. This fact confirms cannibalistic behavior in the wild in this species, which is consistent with findings in massive laboratory cultures. There was no evidence of isotopic niche shift between cryptic and vagile juvenile phases. Overlapping isotopic niches of different-sized juveniles suggest that they exploit similar food resources. However, vagile individuals occupy a higher trophic position than cryptic individuals, which could suggest a switch in dietary preference, from detritivorous/herbivory within kelp forests to omnivory outside of kelp forests, and an increase in the level of cannibalism in vagile juveniles.

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