scholarly journals Not all nudibranchs are carnivorous: trophic ecology of Polycerella emertoni in the Ebro Delta

2020 ◽  
Vol 645 ◽  
pp. 67-82
Author(s):  
J Camps-Castellà ◽  
M Ballesteros ◽  
R Trobajo ◽  
M Pontes ◽  
P Prado
Keyword(s):  
Trophic Ecology ◽  
Video Recording ◽  
Stomach Contents ◽  
Ebro Delta ◽  
Seasonal Abundance ◽  
Feeding Strategies ◽  
Mixing Models ◽  
Habitat Features ◽  
Feeding Activities ◽  
Multiple Feeding

Nudibranchs have always been regarded as a group of specialized predators. In Alfacs Bay (Ebro Delta, Spain), the cryptic nudibranch Polycerella emertoni is found associated with the pseudo-indigenous bryozoan Amathia verticillata, which has been thought to be its target prey. Here, we assessed the trophic ecology of P. emertoni using a combination of methods, including stable isotope analyses coupled with Bayesian mixing models, examination of stomach contents, and video recording of feeding activities. A morphological analysis of the radula was also conducted to explore a possible relationship with feeding behavior. Finally, we investigated the seasonal abundance of both species throughout an entire year in order to assess the nature and strength of their association. Contrary to current belief, our results show that P. emertoni is a micro-herbivore that feeds on the periphyton covering A. verticillata (up to 99% of the diet, according to mixing models). In particular, a diverse diatom community was observed on A. verticillata, and several of these taxa were found within the stomach contents of P. emertoni. Our results evidence a distinctive radular formula and morphology compared to other species and suggest the presence of multiple feeding strategies in nudibranchs. The high seasonal association observed between P. emertoni and A. verticillata may be attributed to mimicking habitat features as a mechanism to avoid predation. The possible effects of periphyton removal in the survival of detached fragments of A. verticillata may have implications for the dispersal of fouling species and functioning of ecosystems.

scholarly journals Resource partitioning and ecomorphological variation in two syntopic species of Lebiasinidae (Characiformes) in an Amazonian stream

2016 ◽  
Vol 46 (1) ◽  
pp. 25-36 ◽  
Author(s):  
Nathália Carina dos Santos SILVA ◽  
Aluízio José Lopes da COSTA ◽  
José LOUVISE ◽  
Bruno Eleres SOARES ◽  
Vanessa Cristine e Souza REIS ◽  
...  
Keyword(s):  
Resource Partitioning ◽  
Trophic Ecology ◽  
Species Coexistence ◽  
Stomach Contents ◽  
Relative Length ◽  
Niche Overlap ◽  
The Body ◽  
Feeding Strategies ◽  
Relative Depth ◽  
Feeding Niche

ABSTRACTResource partitioning is important for species coexistence. Species with similar ecomorphology are potential competitors, especially when phylogenetically close, due to niche conservatism. The aim of this study was to investigate the resource partitioning among populations of two species of lebiasinids (Copella nigrofasciata and Pyrrhulina aff. brevis) that co-occur in a first-order Amazonian stream, analyzing the trophic ecology, feeding strategies and ecomorphological attributes related to the use of food and space by these species. Fish were captured in May and September 2010. The stomach contents of 60 individuals were analyzed and quantified volumetrically to characterize the feeding ecology of both species. Eleven morphological attributes were measured in 20 specimens and combined in nine ecomorphological indices. Both species had an omnivorous-invertivorous diet and consumed predominantly allochthonous items. Both showed a tendency to a generalist diet, but intrapopulational variation in resource use was also detected. Overall feeding niche overlap was high, but differed between seasons: low during the rainy season and high in the dry season. In the latter, the food niche overlap was asymmetric because C. nigrofasciata consumed several prey of P. aff. brevis, which reduced its food spectrum. The ecomorphological analysis suggests that C. nigrofasciatahas greater swimming capacity (greater relative length of caudal peduncle) than P. aff. brevis, which has greater maneuverability and tendency to inhabit lentic environments (greater relative depth of the body). Our results demonstrate that these species have similar trophic ecology and suggest a spatial segregation, given by morphological differences related to locomotion and occupation of habitat, favoring their coexistence.

scholarly journals Feeding patterns of two sympatric shark predators in coastal ecosystems of an oceanic island

2017 ◽  
Vol 74 (2) ◽  
pp. 216-227 ◽  
Author(s):  
Clément Trystram ◽  
Karyne M. Rogers ◽  
Marc Soria ◽  
Sébastien Jaquemet
Keyword(s):  
Trophic Ecology ◽  
Dietary Habits ◽  
Stomach Contents ◽  
Nitrogen Isotope ◽  
Oceanic Island ◽  
Apex Predators ◽  
Coastal Habitat ◽  
Galeocerdo Cuvier ◽  
Carcharhinus Leucas ◽  
Bull Shark

Stomach contents and stable carbon and nitrogen isotope analyses (δ13C and δ15N) were used to investigate the trophic ecology of two apex predators, tiger sharks (Galeocerdo cuvier) and bull sharks (Carcharhinus leucas), from Reunion Island to describe their dietary habits at both the population and individual levels. In this oceanic island, the tiger and bull sharks were more piscivorous and teutophagous than noted in previous research from other localities. The δ13C values suggested that bull sharks depended on more neritic organic matter sources than tiger sharks, confirming a coastal habitat preference for bull sharks. Moreover, the total length of the bull shark influenced δ13C values, with smaller individuals being more coastal than larger individuals. All indicators suggest that there is a higher degree of similarity between individual tiger sharks compared with the more heterogeneous bull shark population, which is composed of individuals who specialize on different prey. These results suggest that the two species have different functions in these coastal habitats, and thus, they must be considered independently in terms of conservation and management.

scholarly journals Can mandible morphology help predict feeding habits in Antarctic amphipods?

2020 ◽  
Vol 32 (6) ◽  
pp. 496-507
Author(s):  
Loïc N. Michel ◽  
Fabienne L. Nyssen ◽  
Patrick Dauby ◽  
Marie Verheye
Keyword(s):  
Functional Groups ◽  
Trophic Ecology ◽  
Feeding Habits ◽  
Gut Contents ◽  
Ecological Niches ◽  
Feeding Strategies ◽  
Generalist Predators ◽  
Dietary Specialization ◽  
Important Place ◽  
Antarctic Amphipod

AbstractIn Antarctica, amphipods form a highly diverse group, occupy many different ecological niches and hold an important place in food webs. Here, we aimed to test whether differences in Antarctic amphipod feeding habits were reflected in their mandible morphology, and if mouthpart specialization could be used to describe amphipod trophic ecology. To do so, we compared mandible morphology in nine species spanning seven families and five functional groups (grazers, suspension feeders, generalist predators, specialist predators and scavengers). Mandible morphology adequately depicted some aspects of amphipod trophic ecology, such as the trophic level at which animals feed or their degree of dietary specialization. On the other hand, links between mandible morphology and amphipod diet were seldom unambiguous or straightforward. Similar adaptations were found in distinct functional groups. Conversely, mandible morphology could vary within a single functional group, and phylogenetic effects sometimes complicated the interpretation of form-function relationships. Overall, mandible morphology on its own was generally not sufficient to precisely predict amphipod feeding strategies. However, when combined with other methods (e.g. gut contents, trophic markers), it constitutes a valuable source of information for integrative studies of amphipod ecological diversity in the Southern Ocean.

scholarly journals Resource use by two electric fishes (Gymnotiformes) of the National Forest Saracá-Taquera, Oriximiná, Pará

2017 ◽  
Vol 15 (2) ◽  
Author(s):  
Bruno E. Soares ◽  
Daniela C. O. Rosa ◽  
Nathália C. S. Silva ◽  
Miriam P. Albrecht ◽  
Érica P. Caramaschi
Keyword(s):  
Resource Use ◽  
Niche Breadth ◽  
Feeding Strategy ◽  
Stomach Contents ◽  
Niche Overlap ◽  
Feeding Strategies ◽  
National Forest ◽  
Microhabitat Use ◽  
Use Patterns ◽  
Head Morphology

ABSTRACT Fishes of the order Gymnotiformes have high diversity of oral and head morphology, which suggests trophic specializations within each clade. The aim of this study was to describe resource use patterns by two fish species (Gymnorhamphichthys rondoni and Gymnotus coropinae) in the National Forest Saracá-Taquera, Oriximiná - Pará, analyzing microhabitat use, diet composition, feeding strategies, niche breadth and niche overlap. Stomach contents of 101 individuals (41 G. rondoni and 60 G. coropinae), sampled in 23 headwater streams were analyzed and volume of food items was quantified to characterize their feeding ecology. Gymnorhamphichthys rondoni was captured mainly on sandy bottoms, whereas G. coropinae in crevices. Both species had a zoobenthivorous diet and consumed predominantly Sediment/Detritus and Diptera larvae, but also included allochthonous prey in their diet. These species had high niche overlap, with small variations related to the higher consumption of Ceratopogonidae larvae by G. rondoni and of Chironomidae larvae by G. coropinae. Both species had a generalist feeding strategy, but G. coropinae had a broader niche breadth. Our results demonstrate that G. rondoni and G. coropinae occupy different microhabitats but rely on similar food resources.

scholarly journals Species- and size-related patterns in stable isotopes and mercury concentrations in fish help refine marine ecosystem indicators and provide evidence for distinct management units for hake in the Northeast Atlantic

2014 ◽  
Vol 71 (5) ◽  
pp. 1073-1087 ◽  
Author(s):  
T. Chouvelon ◽  
F. Caurant ◽  
Y. Cherel ◽  
B. Simon-Bouhet ◽  
J. Spitz ◽  
...  
Keyword(s):  
Fish Species ◽  
Trophic Level ◽  
Trophic Ecology ◽  
Marine Ecosystem ◽  
Feeding Strategies ◽  
Bay Of Biscay ◽  
Management Units ◽  
Δ13c And Δ15n ◽  
Northeast Atlantic ◽  
European Hake

Abstract Recent European environmental policies argue for the development of indicators of the ecological status of ecosystems that are easy to implement and powerful enough to detect changes quickly. For instance, some indicators that are currently proposed for monitoring foodweb structure and functioning are based on the size of organisms, using size as a proxy for trophic level. However, these indicators do not necessarily accurately reflect the underlying trophic structure and dynamics to follow. Ecological tracers (i.e. chemical parameters measured in consumer tissues to infer the trophic ecology of organisms) may serve as complementary indicators of trophic level, and may also help distinguish different populations of a species when more commonly used methods (e.g. genetic, age determination) present their own limitations. Here, we analysed the potential of muscle δ13C and δ15N values and of muscle mercury (Hg) concentrations to depict size-related trophic habits of different fish species. We expected that intra- and interspecific variation in these ecological tracers could be helpful in refining currently proposed indicators of marine ecosystems, and also help in discriminating management unitsfor some species. Four fish species were selected for their economical and/or ecological importance in the Bay of Biscay (Northeast Atlantic): whiting Merlangius merlangus, European hake Merluccius merluccius, Atlantic horse mackerel Trachurus trachurus and anglerfish Lophius piscatorius. Muscle δ13C and δ15N values segregated the species and enabled us to discriminate species-specific feeding strategies with increasing size of individuals. Fish body size was not always linearly correlated with δ15N or trophic level. In contrast, Hg concentrations and size-related Hg patterns were more similar from species to species. Interestingly, muscle δ15N values together with Hg concentrations segregated the two putative stocks of European hake within the Bay of Biscay. Hence, we propose the combined use of ecological tracers as a promising method for accurately assigning a consumer to a trophic guild, investigating Hg trophodynamics in foodwebs, and helping discriminate distinct ecological populations within a species when defining management units.

Locomotor Activity Patterns and Feeding Habits in the Prawn Palaemon Serratus (Pennant, 1777) (Decapoda, Palaemonidae) in the Alfacs Bay, Ebro Delta, Spain

Crustaceana ◽  
1996 ◽  
Vol 69 (1) ◽  
pp. 101-112 ◽  
Author(s):  
G. Guerao ◽  
C. Ribera
Keyword(s):  
Feeding Habits ◽  
Activity Patterns ◽  
Video Recording ◽  
Time Lapse ◽  
Maximum Activity ◽  
Ebro Delta ◽  
Diel Activity ◽  
Organic Debris ◽  
Endogenous Rhythmicity ◽  
Composition Changes

AbstractDiel activity rhythms of the prawn Palaemon serratus from Alfacs Bay, Ebro Delta, Spain, were studied under laboratory conditions by time-lapse video recording. The activity pattern showed endogenous rhythmicity of a circadian period with maximum activity at night. The feeding habits of P. serratus were studied using the frequency-of-occurrence method and the points method. The food of this species mainly consists of molluscs and crustaceans, and the remains of gastropods, amphipods, isopods, bivalves, mysids, copepods, and decapods were identified. The remaining items consisted of cnidarians, polychaetes, ophiuroids, plant material, sand, and unidentified organic debris. Results indicate that P. serratus is a predator of benthic invertebrates rather than a scavenger or detritus feeder. Diet composition changes with the size of the prawn.

scholarly journals Trophic ecology of Mugil liza at the southern limit of its distribution (Buenos Aires, Argentina)

2015 ◽  
Vol 63 (3) ◽  
pp. 271-277 ◽  
Author(s):  
Gustavo Thompson ◽  
Roberta Callico Fortunato ◽  
Ignacio Chiesa ◽  
Alejandra Volpedo
Keyword(s):  
Trophic Ecology ◽  
Buenos Aires ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Benthic Fauna ◽  
Fine Sand ◽  
Coarse Sand ◽  
Buenos Aires Province ◽  
Southern Limit ◽  
Rates Of Growth

AbstractIn order to get to know the habitat and feeding habits of Mugil liza on the southern coast of Buenos Aires province, 65 specimens obtained at two sampling sites - the San Blas bay (SBB) and the mouth of the Quequén-Salado river (QSR) - during spring (November 2012) and summer (February 2013) were analyzed. Specimens were measured, sexed and weighed, their stomachs were removed and their stomach contents weighed and analyzed under the stereoscopic microscope. The specimens were adults, 28-49 cm in length and weighing 380-1100 g. Population growth was higher in the SBB (TW: 0.003*TL3.36), than in RQS (TW: 0.045*TL2.61). About 98% of the stomachs had some content, their repletion rate being of between 0.4 and 1.2%. About 75% of the stomachs contained very fine sand with few benthic organisms (algae, copepods, foraminifera), whereas the remaining 25% of stomachs contained coarse sand and a greater presence of benthic fauna (amphipods, bivalves, gastropods and coral organisms). The linear relationship between the weight of stomach contents and the total weight and length of the fish showed that the rates of growth (slope) were the same at both sites, but intercept values were significantly higher for San Blas bay (test parallelism; p < 0.001).

Trophic ecology of a benthic intertidal hydroid, Tubularia crocea, at Mar del Plata, Argentina

2005 ◽  
Vol 85 (2) ◽  
pp. 307-312 ◽  
Author(s):  
Gabriel N. Genzano
Keyword(s):  
Trophic Ecology ◽  
Feeding Rate ◽  
Prey Availability ◽  
Stomach Contents ◽  
Dry Weight ◽  
Benthic Organisms ◽  
Food Items ◽  
The Mean ◽  
The Relationship ◽  
Prey Items

The trophic ecology and seasonal changes in the diet of the intertidal hydrozoan Tubularia crocea were studied analysing the enteron contents of hydranths collected each season of the year. The relationship between feeding rate, prey availability, and re-suspension processes caused by tidal currents was also assessed. The most prevalent food items were diatoms and crustaceans. The most remarkable differences occurred during summer, when crustaceans were more abundant than diatoms. Conversely, diatoms were the most abundant prey during other seasons, and they were almost the only prey found during winter. There was no relationship between abundances of primary prey items in the water column and their occurrences in stomach contents. Instead, most prey items consisted of benthic organisms, primarily two species of diatoms (Grammatophora marina and Licmophora abreviatta) and fragments (usually appendages) of the amphipods Caprella sp. and Jassa falcata. Most food items were digested within 4–4·5 hours. The mean number of items captured per polyp per day was determined to be 115·2±19·2 in summer, 93·6±14·4 in autumn, 76·8±21·6 in winter and 199·2±31·2 in spring. Prey biomass (dry weight) polyp−1 d−1 was 5·1 μg in summer, 2·3 μg in autumn, 1·8 μg in winter, and 6·3 μg in spring. These values, in relation to hydranth biomass (55·3 μg; dry weight), were equivalent to a food intake polyp−1 d−1 of 9·3%, 4·2%, 3·2% and 11·5% of its own weight, respectively.

The influence of sex and reproductive state on diet preference in four terrestrial mammals of the French Guianan rain forest

1997 ◽  
Vol 75 (6) ◽  
pp. 929-935 ◽  
Author(s):  
O. Henry
Keyword(s):  
Stomach Contents ◽  
Reproductive Activity ◽  
Relative Energy ◽  
Feeding Strategies ◽  
Mammal Species ◽  
Protein Requirements ◽  
Terrestrial Mammals ◽  
Pregnant Females ◽  
Diet Preference ◽  
Gravid Females

The diets of males and pregnant and nonpregnant females were studied in four French Guianan mammal species, three rodents and one artiodactyl, illustrating a gradient of size, mass, and gestation, and thus of energy and protein requirements. In the rodents (Oryzomys capito, Proechimys cuvieri, Dasyprocta leporina), males were more frugivorous than females, whereas the reverse was the case in the artiodactyl (Tayassu tajacu). For all species, males ate the most pulp, while pregnant females focused on seeds or animal matter. Nevertheless, males and females appeared to be opportunistic foragers, with similar feeding strategies throughout the year. A comparative analysis of stomach contents showed that the diets of males and nonpregnant females were quite comparable, while significant differences occurred in gravid females (especially of the two smallest species). Intra-individual differences gradually decreased from O. capito to T. tajacu, possibly as a result of closer male and female cohabitation as well as lower relative energy and protein requirements for pregnant females of the larger species. Finally, for the two smallest species, reproductive activity was correlated with seed and (or) animal matter intake.

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