scholarly journals Stargrazing: Trophic ecology of sea stars in the Galápagos rocky subtidal zone

Author(s):  
Sofia Castelló y Tickell ◽  
Natalie H.N. Low ◽  
Robert W. Lamb ◽  
Margarita Brandt ◽  
Jon D. Witman

Abstract Sea stars (class Asteroidea) can play powerful and wide-ranging roles as consumers of algae and prey items in benthic ecosystems worldwide. In the Galápagos rocky subtidal zone, sea stars are abundant and diverse but their distribution, feeding habits and ecological impacts have received little attention. We compared diets and distributions across the six most abundant sea star species to examine functional roles of this important group. Bi-annual censuses carried out between 2006–2014 at two depths (6-8m, 12-15m) at 12 sites in Galápagos identified two abundance “hotspots” and revealed higher densities at locations with more heterogeneous benthic topographies. Field surveys revealed a high incidence of feeding (35–68% of individuals across species) and distinct diets were evident for each species in terms of food items and dietary breadth, suggesting niche partitioning. Most species can be classified as facultative herbivores, with diets dominated by crustose and turf algae supplemented by a small proportion of sessile invertebrates. The two most abundant species (Pentaceraster cumingi and Nidorellia armata) had the narrowest diets. Field prey selectivity experiments identified P. cumingi as a size-selective predator of the pencil urchin Eucidaris galapagensis. In field caging experiments, N. armata reduced biomass of unbleached crustose coralline algae and macroalgae by 72% and 52%, respectively. In the context of emerging threats such as disease, ocean acidification and climate change, a deeper understanding of distinct functional roles can inform ecological models and management plans.

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hanna Bae ◽  
In-Young Ahn ◽  
Jinsoon Park ◽  
Sung Joon Song ◽  
Junsung Noh ◽  
...  

AbstractGlacier retreat is a major long-standing global issue; however, the ecological impacts of such retreats on marine organisms remain unanswered. Here, we examined changes to the polar benthic community structure of “diatoms” under current global warming in a recently retreated glacial area of Marian Cove, Antarctica. The environments and spatiotemporal assemblages of benthic diatoms surveyed in 2018–2019 significantly varied between the intertidal (tidal height of 2.5 m) and subtidal zone (10 and 30 m). A distinct floral distribution along the cove (~ 4.5 km) was characterized by the adaptive strategy of species present, with chain-forming species predominating near the glacier. The predominant chain-forming diatoms, such as Fragilaria striatula and Paralia sp., are widely distributed in the innermost cove over years, indicating sensitive responses of benthic species to the fast-evolving polar environment. The site-specific and substrate-dependent distributions of certain indicator species (e.g., F. striatula, Navicula glaciei, Cocconeis cf. pinnata) generally reflected such shifts in the benthic community. Our review revealed that the inner glacier region reflected trophic association, featured with higher diversity, abundance, and biomass of benthic diatoms and macrofauna. Overall, the polar benthic community shift observed along the cove generally represented changing environmental conditions, (in)directly linked to ice-melting due to the recent glacier retreat.


2017 ◽  
Vol 67 (3-4) ◽  
pp. 287-300 ◽  
Author(s):  
María I. Deserti ◽  
Karina S. Esquius ◽  
Alicia H. Escalante ◽  
Fabián H. Acuña

Hydra is a genus of common, sessile, solitary freshwater cnidarians, which are defined as carnivorous and efficient predators. The purpose of this study was to obtain information on the feeding habits and diet of Hydra vulgaris collected from its natural habitat in Nahuel Rucá Lake (Buenos Aires Province, Argentina). We found three categories of food items in the coelenteron: algae, fungi, and small invertebrates. Algae dominated the diet in terms of abundance and frequency of occurrence, but their volumetric contribution was almost negligible, as was their possible nutritional value. Invertebrate prey captured, using active predation, represented the major volumetric contribution, with four different taxa found. The detection of phytoplankton in the gastral cavities reveals the input of some organisms present in the surrounding waters in addition to the invertebrates. This information is novel, since studies on the natural diet of Hydra are very scarce.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Leandro Nolé Eduardo ◽  
Flávia Lucena-Frédou ◽  
Michael Maia Mincarone ◽  
Andrey Soares ◽  
François Le Loc’h ◽  
...  

AbstractMesopelagic fishes are numerically the most important vertebrate group of all world’s oceans. While these species are increasingly threatened by anthropogenic activities, basic biological knowledge is still lacking. For instance, major uncertainties remain on the behaviour, ecology, and thus functional roles of mesopelagic micronektivores, particularly regarding their interactions with physicochemical features. Here, we examine the trophic ecology, habitat, and migratory behaviour of the viperfish (Chauliodus sloani)—a poorly known and abundant deep-sea species—to further understand the ecology and thus functional role of mesopelagic micronektivores. Moreover, we explore how physical drivers may affect these features and how these relationships are likely to change over large oceanic areas. The viperfish heavily preys on epipelagic migrant species, especially myctophids, and presents spatial and trophic ontogenetic shifts. Temperature restricts its vertical distribution. Therefore, its trophodynamics, migratory behaviour, and functional roles are expected to be modulated by the latitudinal change in temperature. For instance, in most tropical regions the viperfish stay full-time feeding, excreting, and serving as prey (e.g. for bathypelagic predators) at deep layers. On the contrary, in temperate regions, the viperfish ascend to superficial waters where they trophically interact with epipelagic predators and may release carbon where its remineralization is the greatest.


The Condor ◽  
2007 ◽  
Vol 109 (2) ◽  
pp. 268-275 ◽  
Author(s):  
Carola Sanpera ◽  
Xavier Ruiz ◽  
Rocío Moreno ◽  
Lluís Jover ◽  
Susan Waldron

Abstract To better understand migratory connectivity between breeding and nonbreeding populations, we analyzed mercury (Hg) and stable isotope signatures of nitrogen (δ15N), carbon (δ13C), and sulfur (δ34S) in Audouin's Gulls (Larus audouinii) breeding in two different colonies, the Ebro Delta (northeastern Spain) and the Chafarinas Islands (southwestern Mediterranean). Although abundant information is available on the biology and trophic ecology of this gull's breeding populations, little is known about migration patterns, distribution in winter, or conditions faced during the nonbreeding period. Analyses were carried out on first primary feathers, grown during the summer while gulls are on the breeding grounds, and mantle feathers, grown during the winter. Different isotopic signatures (δ15N, δ13C, and δ34S) in summer (primary) feathers from each area agree with the observed differences in diet between the two colonies. In winter (mantle) feathers, isotopic signatures did not differ, consistent with a common wintering ground and common diet, although the lack of isotopic basemaps in marine systems precludes assignment to a geographical area of reference. Future research is needed to relate isotopic signatures and Hg values in mantle feathers to trophic ecology in wintering areas. Results for Hg indicate that the excretory role played by primary feathers precludes their use as indicators of trophic ecology.


Author(s):  
Víctor M. Muro-Torres ◽  
Felipe Amezcua ◽  
Raul E. Lara-Mendoza ◽  
John T. Buszkiewicz ◽  
Felipe Amezcua-Linares

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.


Zootaxa ◽  
2018 ◽  
Vol 4483 (1) ◽  
pp. 155 ◽  
Author(s):  
LAÍS V. RAMALHO ◽  
PAUL D. TAYLOR ◽  
FERNANDO COREIXAS MORAES ◽  
RODRIGO MOURA ◽  
GILBERTO M. AMADO-FILHO ◽  
...  

Bryozoans are a key group of sessile invertebrates in some reef frameworks but are typically neglected in environmental monitoring programs. Abrolhos Bank (Brazil) is the largest reef complex in the South Atlantic Ocean, encompassing several reef landscapes over an area of 46,000 km2. A transition takes place across the shelf from mangroves to soft sediments, coastal shallow reefs to a volcanic archipelago – surrounded by fringing reefs – and unique mushroom-shaped biogenic structures, with mesophotic pinnacle reefs, rhodolith beds, sink-holes and shelf break deep environments. The taxonomic composition of the bryozoan fauna was studied in 11 core samples taken from shallow to mesophotic mid-shelf reefs (4–25 m deep) on Abrolhos Bank by divers using a submersible drill. Of the 20 bryozoan species sampled, 17 are new records for Abrolhos Bank and seven species are new to science: Crassimarginatella winstonae n. sp., Parasmittina distincta n. sp., Parasmittina abrolhosensis n. sp., Hemismittoidea asymmetrica n. sp., Stylopoma variabilis n. sp., Stylopoma hastata n. sp., and Plesiocleidochasma acuminata n. sp. (described by Ramalho, Taylor & Moraes). The most conspicuous species is Celleporaria atlantica. These results increase to 48 the total number of bryozoan species known in this region and reinforce the importance of this group as one of the main components apart from crustose coralline algae and corals of the reef framework-building community of Abrolhos Bank. 


2020 ◽  
Vol 32 (6) ◽  
pp. 496-507
Author(s):  
Loïc N. Michel ◽  
Fabienne L. Nyssen ◽  
Patrick Dauby ◽  
Marie Verheye

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.


2019 ◽  
Vol 70 (10) ◽  
pp. 1402 ◽  
Author(s):  
F. V. Albuquerque ◽  
A. F. Navia ◽  
T. Vaske ◽  
O. Crespo ◽  
F. H. V. Hazin

Trophic relationships of large pelagic predators can determine the structure and dynamics of oceanic food webs. The feeding habits and trophic ecology of five large pelagic fish (Acanthocybium solandri, Coryphaena hippurus, Elagatis bipinnulata, Thunnus albacares and Thunnus atlanticus) in the Saint Peter and Saint Paul Archipelago were evaluated to determine whether there is a trophic-niche overlap or resource partitioning among them. Eighty prey items found in 1528 stomachs were identified and grouped into Cephalopoda, Cnidaria, Crustacea, Gastropoda, Teleostei and Tunicata. Exocoetidae and Scombridae were the main prey in the diet of Acanthocybium solandri. In C. hippurus, Cheilopogon cyanopterus and Exocoetus volitans were the most important prey items, whereas C. cyanopterus was the main prey for T. albacares. Thunnus atlanticus consumed a great proportion of invertebrate species, with shrimps of Sergestidae family being particularly important. The gastropod Cavolinia sp. was the most important prey for E. bipinnulata. The five species had a high trophic specialisation and a high trophic level (>4.4), whereas most dietary overlaps were consistently low. The most important factor for diet dissimilarity was the consumption of Exocoetidade. All species were classified as top predators with varied diets, indicating their structural and functional importance in the food web of the Archipelago.


2019 ◽  
Vol 66 (1) ◽  
pp. 51-56
Author(s):  
Javier Sánchez-Hernández

Abstract It has been taken for granted that feeding guilds and behavior in animals are linked to the taxonomic relatedness of species, but empirical evidence supporting such relationship is virtually missing. To examine the importance of taxonomy on trophic ecology, I here present the first well-resolved dietary taxonomy analysis based on feeding guilds (predation, herbivory, and filtering) among families and genera within the fish order Perciformes. Taxonomic relatedness in feeding did not vary with ecosystem dimension (marine vs. freshwater). Although predation dominates among Perciformes fishes, this study shows that in most cases taxonomic units (family or genus) are composed by species with several feeding guilds. Related species are more similar in feeding compared with species that are taxonomically more distant, demonstrating that there is a greater variation of feeding guilds within families than genera. Thus, there is no consistency in feeding guilds between family- and genus-level taxonomy. This study provides empirical support for the notion that genera are more informative than families, underlining that family-level taxonomy should be avoided to infer feeding habits of fish species at finer taxonomic resolution. Thus, the choice of taxonomic resolution (family or genus level) in ecological studies is key to avoid information loss and misleading results. I conclude that high-rank taxonomic units (i.e., above the generic level) are not appropriate to test research hypotheses about the feeding of fish.


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