Trophic Biology Research Articles

Sobre los caracteres taxonómicos de los Bruchidius Schilsky, 1905 ibero-baleares y canarios del grupo foveolatus (Coleoptera: Bruchidae)

A morphological study is carried out on the taxonomic characters of the species of the genus Bruchidius Schilsky, 1905, grouped in the foveolatus subgeneric group, present in the Iberian Peninsula (Spain and Portugal), the Balearic Islands, and the Canary Islands. The morphological characters and their value as a discriminating criterion of the species of the group are analyzed, as well as the concordant and discordant aspects of the known trophic biology of the different species.

Biofilter-constructed wetland-trophic pond system: A new strategy for effective sewage treatment and agricultural irrigation in rural area

Artificial ecosystems with high biological complexity are generally considered to be efficient in metabolizing substances and resistant to temperature shock. In this study, a novel near-natural system (BCT system), which consisted of simple biofilter, constructed wetland and trophic biology pond, was conducted to treat rural sewage in situ for irrigation into farmland. Water quality related to carbon and nutrients and microbial community were analyzed along the system to reveal the effect of each unit. The annual average removals of BCT system for TN, NH4+-N, TP and COD could reach 46.53%, 52.18%, 41.48%, and 53.21%, respectively. There was no significant decrease for removal efficiencies from high temperature period (HTP, ≥15 °C) to low temperature period (LTP, <15 °C). In LTP, the trophic pond (TRP) removed 34.85% of TN, 33.93% of NH4+-N, 13.71% of TP and 18.77% of COD, while the removal efficiencies of constructed wetland fluctuated greatly. The TRP facilitated the BCT system to maintain the removal capability during low temperature period. The relative abundance of denitrification functional genes in TRP increased nearly tenfold from HTP to LTP. The effluent quality from the system can meet the agricultural irrigation standards, demonstrating the effect of BCT system on sewage treatment and agricultural irrigation in rural area.

Datos sobre la biología trófica y reproductora de algunas especies de Bruchidius Shchilsky, 1905 (Coleoptera, Bruchidae)

Knowledge about biology of seed beetles (Coleoptera, Bruchidae) is scarce or non-existent in the vast majority of species of no economic interest. Data on trophic biology are confusing, mixing host species with refuge species. In recent years, an effort has been made to understand the biology of these insects, based on in vivo information. In this article we present observations on the trophic and reproductive biology of six species of the genus Bruchidius, made in the course of these studies.

Feeding Habits of Sarda chiliensis chiliensis (Cuvier, 1832) in Northern Chile and Southern Perú.

Simple SummaryKnowing the biology of fish, preferably for this study of trophic relationships, is fundamental to advance in the culture technologies of this species, since knowing what they feed on will allow us to generate a species-specific food for the species and thus be able to obtain a fast and efficient growth. The objective of this research was to analyze the feeding habits of South Pacific bonito by sex and season between summer and autumn in three locations in the South Pacific, using trophic biology techniques. A total of 1404 stomachs were analyzed, corresponding to 420 specimens from the Pozo de Lisas area, 540 specimens from the La Capilla area and 444 specimens from the Chanavayita area. Dynamic indexes of feeding analysis and trophic composition of the diet were used. Under the analysis carried out in this research, we can conclude that fish feed more during autumn; in addition, the prey hierarchy of this species was Pleuroncodes monodon and Engraulis ringes. That said, and in view of the results, it would be a generalist species.The trophic relationships of pelagic fishes with migratory traits such as the South Pacific Bonito, Sarda chiliensis chiliensis (Cuvier, 1832), have not been studied in depth in the past. The objective of the present research was to analyze the feeding habits of South Pacific Bonito by sex and to analyze a comparison between summer and autumn months in three different areas of the eastern South Pacific by applying different techniques used in trophic biology. Between December 2013 and June 2014, specimens were captured in the areas of Pozo de Lisas (Ilo, Peru), La Capilla (Arica, Chile) and Chanavayita (Iquique, Chile). The feeding dynamics and trophic composition of the diet were analyzed, as well as the feeding strategy and trophic relationships. A total of 1404 specimens were analyzed, of which 654 had stomach contents. Seven prey items were identified: (a) fish remains; (b) squid jaw remains; (c) squid gladius remains; (d) caudal fin remains; (e) Engraulis rigens; (f) Pleuroncodes monodon and (g) N/A (not determined). The Pozo de Lisas and La Capilla areas showed homogeneity in their prey items, while the Chanavayita area showed more diversity. Regarding the importance of prey items in the diet of S. chiliensis in the three localities, it would be correct to state that it is a generalist species.

Feeding of Atlantic bluefin tuna Thunnus thynnus around the Canary Islands assessed from stomach content and stable isotope analyses

The Canary archipelago, which is part of the Atlantic biogeographical region of Macaronesia, provides suitable habitat for tropical and temperate-water large pelagic species. Atlantic bluefin tuna (ABFT) Thunnus thynnus occur year round in the Canary Islands. Life history traits of ABFT, specifically foraging patterns, have not been studied thus far in this region. We investigated ABFT trophic biology, combining stomach content and stable isotope analyses. A high proportion (~77%) of the stomachs contained prey, indicating active foraging. The diet primarily consisted of fishes, among which the snipefish Macroramphosus sp. was the major prey. Cephalopods and crustaceans were less important diet components. Moreover, a well-preserved specimen of Cory’s shearwater Calonectris borealis was found in a stomach sampled in 2018. Besides natural prey, 16.7% of the stomachs contained plastic debris. Inter-annual isotopic differences were detected in liver tissue samples, reflecting a dietary shift in 2018, where δ15N values were lower than in 2016 and 2017. Isotopic niche width estimations from stable isotope Bayesian ellipse in R and kernel utilization density analyses suggested a more diverse diet in 2017. Corrected and Bayesian standard ellipse area values from muscle and liver data indicated that the diet of ABFT in the Canary Islands is more euryphagous than in the Strait of Gibraltar (East Atlantic) but more stenophagous than it is in the Gulf of Saint Lawrence (West Atlantic). The present results show that the Canary archipelago represents a foraging ground for ABFT in spring.

Trophic biology of the twospot livebearer, Pseudoxiphophorus bimaculatus, an invasive fish in Teuchitlán River, central Mexico

espanolEl rio Teuchitlan se considera un hotspot de diversidad de peces con 3 especies endemicas. Pseudoxiphophorus bimaculatus fue introducido en el sistema fluvial, aunque se desconoce su impacto trofico en el rio Teuchitlan. Se determino la importancia de cada articulo alimenticio con el indice de importancia relativa, el comportamiento trofico usando el indice de omnivoria, la posicion trofica usando el programa TrophLab y la amplitud de nicho trofico de la especie usando el indice estandarizado de Levin. Realizamos analisis de Permanova para comparar la dieta entre clases de talla, sitios y estaciones. Analizamos 631 contenidos estomacales de P. bimaculatus. La especie consume principalmente insectos terrestres, pero con tendencia a la herbivoria en algunos sitios, se presento un comportamiento trofico generalista en la estacion humeda y especialista en la estacion seca, ocupando diferentes niveles troficos y mostrando amplitud de nicho trofico variable. Esta estrategia de alimentacion flexible permite a P. bimaculatus explotar recursos de diferentes niveles troficos. El alto consumo (%RII > 50) de insectos terrestres podria indicar que P. bimaculatus puede transportar energia aloctona al rio. Ademas, el alto potencial invasivo de la especie es un grave riesgo para los ecosistemas de agua dulce del centro de Mexico, una region que ha sido reconocida como un hotspot muy importante para la conservacion de peces de agua dulce. EnglishThe Teuchitlan River in Mexico is a hotspot of fish diversity, with 3 endemic species. Pseudoxiphophorus bimaculatus has been introduced into the river, but its trophic impact on the system is unknown. We determined the importance of each food item in the diet of P. bimaculatus with a relative importance index, their feeding behavior using an omnivorous index, the trophic position with the TrophLab program, and the niche breadth using the standardized Levin index. We performed Permanova analyses to compare diet between size classes, sites, and seasons. We analyzed 631 P. bimaculatus individuals. The species consumed mainly terrestrial insects, but presented an herbivorous trend in some sites. A generalist trophic behavior was presented in the wet season and a specialist behavior in the dry season occupying different trophic levels and presenting variable trophic width. This flexible feeding strategy enables P. bimaculatus to exploit resources from different trophic levels. The high consumption (%RII > 50) of terrestrial insects could indicate that P. bimaculatus may transport allochthonous energy into the river. Furthermore, the high invasive potential of the species represents a risk for the freshwater ecosystems of central Mexico, a region that has been recognized as a hotspot for freshwater fish conservation.

Shining new lights on chytrid cell biology: quantitative live cell imaging of rhizoid development in an early-diverging fungus

Chytridiomycota (Chytrids) are the most basal lineage within the true fungi, however they have largely remained in the dark in terms of their fundamental cell biology. In aquatic ecosystems, chytrids can dominate ‘dark matter’ surveys and are important saprotrophs of recalcitrant organic carbon. They therefore play an integral biogeochemical role in carbon cycling. Unlike ‘higher’ dikaryan fungi that feed via multicellular hyphae, chytrids are unicellular and develop an anucleate rhizoid system that acts as the trophic interface of the cell. Understanding the functions of the rhizoid has the potential to shed light on the trophic biology of ‘dark matter’ chytrids. We applied 3D and 4D live-cell confocal microscopy to morphometrically quantify rhizoid development in the model saprotrophic chytrid Rhizoclosmatium globosum under different nutrient treatments. Rhizoid branching was highest under carbon-rich conditions, whereas under carbon-starved treatments, rhizoids grew significantly longer and were less branched, in what we interpret to be a ‘search strategy’ for nutrient sources. F-actin and the cell wall were identified throughout the rhizoid system. Chemical inhibition of actin and cell wall glucan synthesis induced the development of hyperbranched paramorphs, suggesting that these components underpin rhizoid branching and organising cell polarity at the rhizoid tip. Previous studies have shown that inhibition of these components induces an identical phenotype in dikaryan fungi. These findings represent an important step in understanding the trophic biology of a biogeochemically important microbe and unveil striking similarities in cell development between early-diverging and ‘higher’ dikaryan fungi.

New insight into the trophic biology of age-0 Atlantic bluefin tuna in the western Mediterranean using stomach content and stable isotope analyses

The trophic biology of age-0 Thunnus thynnus (ABFT) was investigated at two locations off the Iberian Mediterranean coast (Cambrils and Valencia) between 2012 and 2014 using stomach content analysis (SCA), and stable isotope analyses of bulk-tissue (BSIA) and individual amino acids (AA-CSIA). Interannual and geographic differences were observed in diet and isotopic compositions. Although the diet was diverse, the major food resources were by far anchovy (%W = 77.04 and 47.76 for Cambrils and Valencia, respectively) and clupeids (%W = 18.97 and 25.31, respectively). SCA and BSIA results suggested a wider trophic niche for ABFT from Valencia, where the proportions of prey items were more homogeneous. Beside differences in diet composition, bulk and amino acid (AA) isotopic spatial and temporal variations may also reflect shifts in the isotopic baselines. δ13C values of essential AAs may be good tracers of carbon sources, though clear patterns relative to primary consumers were not found. Patterns of δ15N values of trophic relative to source AAs reflected differential fractionation rates, underpinning their usefulness as trophic position (TP) indicators. TPs estimated from the three analyses lay about 4. TP values calculated from muscle samples collected in 2013 using the AA pair glutamic acid and phenylalanine (3.63 and 4.03 for Cambrils and Valencia, respectively) were close to, though lower than, TP estimates derived from SCA (4 and 4.05, respectively) and BSIA (4.39 and 4.63, respectively).

Patterns and dynamics of neutral lipid fatty acids in ants \u2013 implications for ecological studies

BackgroundTrophic interactions are a fundamental aspect of ecosystem functioning, but often difficult to observe directly. Several indirect techniques, such as fatty acid analysis, were developed to assess these interactions. Fatty acid profiles may indicate dietary differences, while individual fatty acids can be used as biomarkers. Ants are among the most important terrestrial animal groups, but little is known about their lipid metabolism, and no study so far used fatty acids to study their trophic ecology. We set up a feeding experiment with high- and low-fat food to elucidate patterns and dynamics of neutral lipid fatty acids (NLFAs) assimilation in ants. We asked whether dietary fatty acids are assimilated through direct trophic transfer, how diet influences NLFA total amounts and patterns over time, and whether these assimilation processes are similar across species and life stages.ResultsAnts fed with high-fat food quickly accumulated specific dietary fatty acids (C18:2n6, C18:3n3 and C18:3n6), compared to ants fed with low-fat food. Dietary fat content did not affect total body fat of workers or amounts of fatty acids extensively biosynthesized by animals (C16:0, C18:0, C18:1n9). Larval development had a strong effect on the composition and amounts of C16:0, C18:0 and C18:1n9. NLFA compositions reflected dietary differences, which became more pronounced over time. Assimilation of specific dietary NLFAs was similar regardless of species or life stage, but these factors affected dynamics of other NLFAs, composition and total fat.ConclusionsWe showed that ants accumulated certain dietary fatty acids via direct trophic transfer. Fat content of the diet had no effect on lipids stored by ants, which were able to synthesize high amounts of NLFAs from a sugar-based diet. Nevertheless, dietary NLFAs had a strong effect on metabolic dynamics and profiles. Fatty acids are a useful tool to study trophic biology of ants, and could be applied in an ecological context, although factors that affect NLFA patterns should be taken into account. Further studies should address which NLFAs can be used as biomarkers in natural ant communities, and how factors other than diet affect fatty acid dynamics and composition of species with distinct life histories.

The trace element contents in tissues of Dolly Varden Salvelinus malma Walbaum, 1792 sympatric morphs from Lake Kronotskoe (Kamchatka)

The liver, gonads, gills, and muscles of five trophically distant charr morphs from Lake Kronotskoe, as well as silty sediments of the lake, were tested for trace-element contents. Concentrations of Mn, Fe, Ni, Cu, Zn, Rb, Sr, As, and Se were detectable in the fish tissues, while the xenobiotics Hg, Cd, and Pb were not determined. The current data indicate a strong correlation between trace-element content and the ecology of each morph and no relationship to the fish length. In the majority, the Ni, Cu, and Zn levels were strongly dependent on trophic biology. The contents of Rb, Mn, and Se were dependent on the distribution of the charr morphs along the depth gradient and correlated with the accumulation of these elements in the bottom sediments.

Effect of marine protected areas (MPAs) on consumer diet: MPA fish feed higher in the food chain.

Marine Protected Areas (MPAs) are often established to mitigate the effects of overfishing and other human disturbances. In Fiji these are locally managed and, where enforced, have significantly higher coral cover, higher fish biomass, and lower seaweed cover than in the adjacent, unprotected reefs (non-MPAs). We investigated how the isotopic signatures of a common, mid-level consumer, Epinephelus merra, differed among three small (0.5- 0.8km2) MPAs versus adjacent, unprotected reefs. Isotopic ratios suggested that the fish in the MPAs fed higher in the food chain than those in the adjacent non-MPAs, despite being slightly smaller in size. Calculations using a brown alga as representative of the basal level of the food chain estimate this difference to be about half a trophic level. Thus, the isotopic ratio of a mid-level consumer can be noticeably altered over scales of only a few hundred meters. This may result from more complete food webs and hence greater prey choice and availability in the MPAs and implies that MPAs affect not only species' abundance and diversity, but also diet composition and trophic biology of member individuals. Our findings suggest E. merra exhibits considerable site fidelity in its feeding biology and thus provides a localized isotopic signal of its reef of residence. If the isotopic signal of this mid-level carnivore is reflective of the composition of the food web beneath it, the signal might provide an easily obtained indication of reef conditions in that area.

Better late than never? Interannual and seasonal variability in breeding chronology of gentoo penguins at Stranger Point, Antarctica

Rapid climate change recorded in the western Antarctic Peninsula confronts species with less predictable conditions in the marine and terrestrial environments. We analysed the breeding chronology and nesting site selection of gentoo penguins (Pygoscelis papua) at King George Island (Isla 25 de Mayo), Antarctica, during four seasons in which differences in snow presence and persistence on the ground were observed. We recorded an overall delay as well as seasonal asynchrony at the beginning of reproduction for those years with higher snow deposition. A redistribution of breeding groups was also observed. Nevertheless, the population breeding success and chicks’ weight at fledging remained relatively constant, despite the delay in breeding chronology, the increased duration of foraging trips during the guard stage and the decreased weight of stomach contents during the crèche stage. We suggest that the plasticity of their trophic biology, along with the flexibility of their breeding phenology and relocation of breeding groups, may be complementary reasons why gentoo penguin populations in the region have remained stable in spite of the changing conditions currently registered.Keywords: Antarctica; breeding delay; breeding phenology; snow; Pygoscelis papua; Euphausia superba (Published: 13 May 2013)Citation: Polar Research 2013, 32, 18448, http://dx.doi.org/10.3402/polar.v32i0.18448

Catch Rate, Distribution, Trophic and Reproductive Biology of the African Carp Labeo coubie in the Agbokim Waterfalls, Nigeria

The catch rate, diet, size, and reproduction of 565 specimen of Labeo coubie were studied over 24 months (January 2005–January 2007) in three reaches [upstream, midstream (waterfalls region) and downstream] along the 6817.7 m length of Agbokim waterfalls during wet and dry seasons. Data were processed using fecundity (F), allometric coefficient (b), Fultons condition factor, and diet breadth. Fecundity values were 10411.0 ± 121, 15102.0 ± 303.5 and 24143.3 ± 662 eggs for fish from upstream, midstream, and downstream, respectively, with overall mean value of 19811.3 ± 223 eggs. The relationships of fecundity with total weight, ovary weight, ovary length, body breadth were positively linear. Mean allometric coefficient (b) of the length–weight relationship of fish in the three reaches were 2.662 ± 0.291 (upstream), 2.592 ± 0.368 (midstream), and 2.622 ± 0.315 (downstream) and all showed significant departure from cubic value (negative allometry). Detritus, phytoplanktons and plant materials were the dominant food items in the diet, contributing 36.8%, 32.1%, and 17.2% of stomach content, respectively. Food Richness of 7 and Gut Repletion Index, 100% were recorded. The low mean diet breadth exhibited by fish from the three sampling sites showed that the species has low trophic flexibility and cannot easily change feeding habit. Mean condition factor varied from 0.442 ± 0.127 upstream to 0.648 ± 0.146 downstream. Downstream therefore provided better spawning conditions for Labeo coubie in the tropical waterfalls ecosystems.

On the Diets of Neotropical Treeboas (Squamata: Boidae:Corallus)1

Nine species of the Neotropical boid genus Corallus are distributed from southeastern Guatemala to southeastern Brazil. Based largely on previously published papers, we accumulated 271 prey records for all species combined, and they comprised 2 frogs, 69 lizards (mostly Anolis), 1 snake, 65 birds, and 134 mammals (marsupials, rodents, bats). There is a conspicuous difference in diet between the two West Indian species (C. cookii and C. grenadensis) and species occurring on the mainland: juvenile and subadult boas from the West Indies prey almost entirely on anoles, whereas on the mainland (with the notable exceptions of C. batesii and C. caninus), those age classes prey largely on birds and bats. Four species (C. cookii, C. grenadensis, C. hortulanus, and C. ruschenbergerii) are vertebrate generalists and exhibit both active and ambush foraging modes. Adult C. batesii and C. caninus (and, perhaps, C. cropanii) are specialists on mammalian prey, may only utilize an ambush foraging mode, and were the only species for which we had at least three prey records that did not include avian prey. Although more common than the critically endangered C. cropanii, both C. annulatus and C. blombergii seem genuinely rare and it is premature to make any generalizations regarding their trophic biology.

An insight into the feeding ecology of deep-sea canyon nematodes — Results from field observations and the first in-situ13C feeding experiment in the Nazaré Canyon

Submarine canyon systems provide a heterogeneous habitat for deep-sea benthos in terms of topography, hydrography, and the quality and quantity of organic matter present. Enhanced meiofauna densities as found in organically enriched canyon sediments suggest that nematodes, as the dominant metazoan meiobenthic taxon, may play an important role in the benthic food web of these sediments. Very little is known about the natural diets and trophic biology of deep-sea nematodes, but enrichment experiments can shed light on nematode feeding selectivity and trophic position. An in-situ pulse-chase experiment (Feedex) was performed in the Nazaré Canyon on the Portuguese margin in summer 2007 to study nematode feeding behaviour. 13C-labelled diatoms and bacteria were added to sediment cores which were then sampled over a 14-day period. There was differential uptake by the nematode community of the food sources provided, indicating selective feeding processes. 13C isotope results revealed that selective feeding was less pronounced at the surface, compared to the sediment subsurface. This was supported by a higher trophic diversity in surface sediments (Θ−1=3.50±0.2) compared to the subsurface (2.78±0.6), implying that more food items may be used by the nematode community at the sediment surface. Predatory and scavenging nematodes contributed relatively more to biomass than other feeding types and can be seen as key contributors to the nematode food web at the canyon site. Non-selective deposit feeding nematodes were the dominant trophic group in terms of abundance and contributed substantially to total nematode biomass. The high levels of ‘fresh’ (bioavailable) organic matter input and moderate hydrodynamic disturbance of the canyon environment lead to a more complex trophic structure in canyon nematode communities than that found on the open continental slope, and favours predator/scavengers and non-selective deposit feeders.

Trophic biology of Stylophora pistillata larvae: evidence from stable isotope analysis

The successful recruitment of planktonic larvae to coral reefs is essential for the contin- ued existence of these highly diverse ecosystems. Feeding strategies may affect recruitment success and potentially determine species distribution by controlling the dispersal range of the larvae. Our aim here was to ascertain the feeding strategies of planula larvae of the coral Stylophora pistillata by using stable isotopes. Planula larvae, fragments of parental colonies, and 3 potential food types were analyzed for carbon and nitrogen stable isotope compositions and C/N ratios. We found that planu- lae were depleted in 13 C when compared to parental tissues, whereas their C/N ratios were 2-fold higher. Following lipid extraction, there were no significant differences in δ 13 C values and C/N ratios between lipid-free planulae and parental colonies. This indicates that the differences in δ 13 C origi- nate in the lipid content of the planulae and not from any isotopic fractionation that may occur dur- ing embryological development. Controlled feeding experiments were conducted using phytoplank- ton, zooplankton, and bacteria. Despite the presence of an oral opening, the planulae did not show any feeding behavior, and the stable isotope data corroborated the observations of no feeding. Moreover, following 2 wk of starvation in the dark, planulae started to utilize their lipid and protein reservoirs. These results stress the importance of the photosynthates translocated from the algal symbionts to these planulae as an energy source.

Nutritional ecology of marine herbivorous fishes: ten years on

Summary 1. Marine herbivorous fishes are considered to be of critical importance in determining the biological structure of shallow reef environments, and by implication have key roles in carbon flux in reef ecosystems. Despite this, the nutritional processes that underpin these critical ecological roles have received comparatively little attention. 2. Here we give an overview of recent progress in the nutritional ecology of marine herbivorous fishes, and then examine two recent paradigms that we consider important in the development of the field: (i) the role of temperature in latitudinal gradients of diversity and abundance, and (ii) the impact of these fishes on coral reefs. Our aim is to illustrate how an integrative nutritional ecology approach can enrich insights gained from studies of fish herbivory, and to emphasize the distinctive differences between herbivory in marine and terrestrial systems. 3. We argue that much of the work on trophic biology in marine herbivorous fishes has focused on the ecological impacts of fishes on reefs, the deterrent properties of marine algae, and the morphological and mechanical aspects of ingestion. This has come at the expense of two of the elements necessary for an integrative understanding of feeding ecology, that is, food composition and the physiological processes involved in nutrient extraction and utilization. Together, these factors have hindered the development of the nutritional framework for analysing food resources, feeding patterns and evolutionary trends that has proved successful for terrestrial vertebrate herbivores. 4. The reef grazing and algal secondary metabolite paradigms, while both extremely productive, have failed to develop the clear predictive framework for diet choice required in broader contexts such as reef management and understanding the evolution of herbivory. The lack of a focus on nutritional factors has led to premature conclusions on the influence of temperature on algal digestion, both at the level of digestive processes and the biogeography of marine faunas. 5. Some marine herbivorous fishes appear to be bending the ‘rules’ of hindgut fermentation, especially with respect to temperature and fermentation substrates, and so the study of nutritional ecology in these animals has potential to generate novel insights for the field of vertebrate nutrition

Spurious and functional correlates of the isotopic composition of a generalist across a tropical rainforest landscape

BackgroundThe isotopic composition of generalist consumers may be expected to vary in space as a consequence of spatial heterogeneity in isotope ratios, the abundance of resources, and competition. We aim to account for the spatial variation in the carbon and nitrogen isotopic composition of a generalized predatory species across a 500 ha. tropical rain forest landscape. We test competing models to account for relative influence of resources and competitors to the carbon and nitrogen isotopic enrichment of gypsy ants (Aphaenogaster araneoides), taking into account site-specific differences in baseline isotope ratios.ResultsWe found that 75% of the variance in the fraction of 15N in the tissue of A. araneoides was accounted by one environmental parameter, the concentration of soil phosphorus. After taking into account landscape-scale variation in baseline resources, the most parsimonious model indicated that colony growth and leaf litter biomass accounted for nearly all of the variance in the δ15N discrimination factor, whereas the δ13C discrimination factor was most parsimoniously associated with colony size and the rate of leaf litter decomposition. There was no indication that competitor density or diversity accounted for spatial differences in the isotopic composition of gypsy ants.ConclusionAcross a 500 ha. landscape, soil phosphorus accounted for spatial variation in baseline nitrogen isotope ratios. The δ15N discrimination factor of a higher order consumer in this food web was structured by bottom-up influences - the quantity and decomposition rate of leaf litter. Stable isotope studies on the trophic biology of consumers may benefit from explicit spatial design to account for edaphic properties that alter the baseline at fine spatial grains.

Lipid, sterols and fatty acids of abyssal polychaetes, crustaceans, and a cnidarian from the northeast Pacific Ocean: food web implications

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 372:157-167 (2008) - DOI: https://doi.org/10.3354/meps07707 Lipid, sterols and fatty acids of abyssal polychaetes, crustaceans, and a cnidarian from the northeast Pacific Ocean: food web implications Jeffrey C. Drazen1,*, Charles F. Phleger2,3, Michaela A. Guest4, Peter D. Nichols2,3 1University of Hawaii, Department of Oceanography, 1000 Pope Road, Honolulu, Hawaii 96822, USA 2CSIRO, Marine and Atmospheric Research, Food Futures Flagship, Hobart, Tasmania 7000, Australia 3Antarctic and Climate Ecosystems CRC, Hobart, Tasmania 7001, Australia 4Tasmanian Aquaculture and Fisheries Institute, Taroona, Nubeena Crescent, Tasmania 7053, Australia *Email: jdrazen@hawaii.edu ABSTRACT: The lipid, sterol, and fatty acid compositions of the abyssal anemone Bathyphellia australis, the 3 polychaetes Laetmonice sp., Paradiopatra sp. and Travisia sp., 3 crustaceans (Munidopsis sp. and 2 lysianassid amphipods), and an unidentified caridean shrimp were determined from a site in the northeast Pacific Ocean. Lipid composition was dominated by phospholipids in most species. However, energy storage lipids (triacylglycerols and wax esters) contributed >50% to the total lipids in the lysianassid amphipods and the unidentified caridean shrimp, and lipids made up 19 and 45% of amphipod and 14% of shrimp dry mass, suggesting sporadic feeding and the need for energy storage. The dominant sterol was cholesterol. The presence of phytosterols in the anemone, the polychaetes and Munidopsis sp. suggested consumption of phytodetritus, but none of the specimens had levels suggesting that phytodetritus was their main food resource. The levels of essential photosynthetically derived polyunsaturated fatty acids (PUFA) corroborated the sterol results. The ratio of 18:1ω9/18:1ω7 further suggested carnivory as the predominant mode of foraging in the abyssal animals, although to varying degrees. Some distinct differences in the fatty acid (FA) composition of these animals allowed for their separation, confirming that FA profiles will be useful in future biomarker approaches to deep-sea food web studies. KEY WORDS: Polychaeta · Cnidaria · Crustacea · Deep sea · Trophic biology · Lipid composition · Sterols · Fatty acid biomarkers Full text in pdf format PreviousNextCite this article as: Drazen JC, Phleger CF, Guest MA, Nichols PD (2008) Lipid, sterols and fatty acids of abyssal polychaetes, crustaceans, and a cnidarian from the northeast Pacific Ocean: food web implications. Mar Ecol Prog Ser 372:157-167. https://doi.org/10.3354/meps07707 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 372. Online publication date: December 09, 2008 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2008 Inter-Research.

Biología trófica de los juveniles del género Liza (Pisces: Mugilidae) en la laguna costera del Mar Menor (SE Península Ibérica)

Trophic biology of juvenile stages of Liza species (Pisces: Mugilidae) in the Mar Menor coastal lagoon (SE Iberian Peninsula) In this work data is presented concerning the food and feeding habits of three species of mullet juveniles that are present in the Mar Menor coastal lagoon: Liza saliens (Risso, 1810), L. aurata (Risso, 1810) and L. ramado (Risso, 1810). Diet of of the three species was omnivorous; they fed on numerous prey items, both animal and vegetal preys. Interspecific differences on diet composition were found, as well as intraspecific differences from sampling periods. Moreover, size-related differences in their feeding habits were found, suggesting the existence of ontogenic changes in the diet of the studied species.