Secondary Food Source Research Articles

\u2018Stray appetites\u2019: a socio-ecological analysis of free-ranging dogs living alongside human communities in Bangalore, India

Across the developing world, humans and free-ranging domestic dogs share common spaces. The relationship between these dogs and humans can range from one of dependence, to apathy, to conflict. Given the high number of humans attacked by dogs every year in India, and the lack of an effective population control strategy, we seek to provide insights into the conflict and propose alternative population management options based on reducing the carrying capacity of the environment. We used a mixed methods approach to understand both ecological and sociological underpinnings of free-ranging dog-human relationships in Bangalore, India. We conducted a photographic capture-recapture survey of free-ranging dogs to estimate population size and linked it to the availability of potential food sources. We also conducted a qualitative survey to assess attitudes of residents towards the dog population. We found that dog population varied from 192 to 1888 per square kilometre across a gradient of housing densities. The density of houses, bakeries and garbage piles were significant predictors of dog population size. Crucially, as low as 10 to 18% of houses supported the large population of dogs, highlighting the need for residents to act responsibly towards the dogs. Further, we found that garbage, although significant, is a secondary food source to household-maintained dogs. Since on the whole, respondents expressed the desire for a reduction in dog population, we suggest decreasing the carrying capacity of the environment by targeting these three food sources.

The Evolutionary Ecology of Metamorphosis.

Almost all animal species undergo metamorphosis, even though empirical data show that this life-history strategy evolved only a few times. Why is metamorphosis so widespread, and why has it evolved? Here we study the evolution of metamorphosis by using a fully size-structured population model in conjunction with the adaptive-dynamics approach. We assume that individuals compete for two food sources; one of these, the primary food source, is available to individuals of all sizes. The secondary food source is available only to large individuals. Without metamorphosis, unresolvable tensions arise for species faced with the opportunity of specializing on such a secondary food source. We show that metamorphosis can evolve as a way to resolve these tensions, such that small individuals specialize on the primary food source while large individuals specialize on the secondary food source. We find, however, that metamorphosis evolves only when the supply rate of the secondary food source exceeds a high threshold. Individuals postpone metamorphosis when the ecological conditions under which metamorphosis originally evolved deteriorate but will often not abandon this life-history strategy, even if it causes population extinction through evolutionary trapping. In summary, our results show that metamorphosis is not easy to evolve but that, once evolved, it is hard to lose. These findings can explain the widespread occurrence of metamorphosis in the animal kingdom despite its few evolutionary origins.

Tissue-specific δ13C in ancient and modern tropical seabirds and flying fish in the Xisha Islands, South China Sea

ABSTRACTWe analyzed 13C characteristics in samples of bird bones, feathers, eggshell carbonate and membrane from modern specimens of red-footed booby (Sula sula) as well as fish muscle, scales, and bones from its predominant food source, flying fish (Exocoetus volitans), and muscle from its secondary food source squid (Loligo chinensis), as well as in ancient sub-fossil samples of seabird and flying fish at the Xisha Islands, South China Sea. δ13C is tissue-specific in both seabirds and flying fish due to the variance in turn-over among the tissues and differences in the type and content of amino acids across a diverse range of tissues. The δ13C discrimination factors also differed significantly among the various tissues between tropical seabirds and their prey. A Suess effect, caused by fossil fuel combustion and the emission of carbon with fewer 13C isotopes, was observed in the bird and fish tissue from ancient to modern time. Our study provides a multiple variability index for δ13C in organisms along a food chain, and verifies that tissue-specific 13C analysis is essential to identify diet and species and thus is a valuable tool for research on tropical seabird ecology.

Functional roles of an engineer species for coastal benthic invertebrates and demersal fish.

Through their tissues or activities, engineer species create, modify, or maintain habitats and alter the distribution and abundance of many plants and animals. This study investigates key ecological functions performed by an engineer species that colonizes coastal ecosystems. The gregarious tubiculous amphipod Haploops nirae is used as a biological model. According to previous studies, the habitat engineered by H. nirae (i.e., Haploops habitat) could provide food and natural shelter for several benthic species such as benthic diatoms belonging to the gender Navicula, the micrograzer Geitodoris planata, or the bivalve Polititapes virgineus. Using data from scientific surveys conducted in two bays, this study explored whether (1) the Haploops sandy‐mud community modifies invertebrate and ichthyologic community structure (diversity and biomass); (2) H. nirae creates a preferential feeding ground; and (3) this habitat serves as a refuge for juvenile fish. Available Benthic Energy Coefficients, coupled with more traditional diversity indices, indicated higher energy available in Haploops habitat than in two nearby habitats (i.e., Sternaspis scutata and Amphiura filiformis/Owenia fusiformis habitats). The use of isotopic functional indices (IFIs) indicated (1) a higher functional richness in the Haploops habitat, related to greater diversity in food sources and longer food chains; and (2) a higher functional divergence, associated with greater consumption of a secondary food source. At the invertebrate‐prey level, IFIs indicated little specialization and little trophic redundancy in the engineered habitat, as expected for homogenous habitats. Our results partly support empirical knowledge about engineered versus nonengineered habitats and also add new perspectives on habitat use by fish and invertebrate species. Our analyses validated the refuge‐area hypothesis for a few fish species. Although unique benthic prey assemblages are associated with Haploops habitat, the hypothesis that it is a preferential feeding area was not verified. However, specialist feeding behavior was observed for predators, which calls for further investigation.

Diet composition of the golden jackal and the sympatric red fox in an agricultural area (Hungary)

In order to better understand the ecology of the golden jackal (Canis aureus) and interspecific relationships among carnivores, we studied its dietary pattern and the diet of its main competitor, the red fox (Vulpes vulpes) over a three-year period. The study was carried out in an agricultural area in SW Hungary and was based on scat analysis (jackal n = 373, fox n = 268 samples). The jackal primarily consumed small mammals in all seasons (mean biomass consumed: 72 %). The secondary food sources were wild ungulates (in winter and spring; mainly wild boar Sus scrofa, including piglets) and plants (in summer and autumn; mainly wild fruits). The consumption of cervids in winter and in spring was only detected in low proportions. The fox also primarily consumed small mammals (50.3 % of trophic niche breadth, B), but their consumption dropped in summer and autumn. Two-thirds of the summer and autumn diet consisted of plants, while the bird consumption was higher in spring and summer. The diet compositions of both predators were similar. However, compared with jackal, the fox consumed significantly higher proportions of birds. The standardized trophic niche breadth (BA) of these canids was very narrow (0.09), and the food overlapped in high proportions (69.8 %). The study confirmed the partial partitioning of food resources and opportunistic feeding of both canids.

Distribution and microhabitat associations of the juveniles of a high-value sea cucumber, Stichopus cf. horrens, in northern Philippines

There is considerable global interest in rebuilding depleted populations of sea cucumbers (Echinodermata, Holothuroidea) to address conservation and economic goals. For the vast majority of holothurian species, the habitat and food requirements of the juvenile stage are poorly understood. We investigated the distribution and microhabitat associations of juveniles of a commercially important sea cucumber, Stichopus cf. horrens, in the shallow, shoreward side of a coral reef (or backreef) in northern Philippines (16°21′38.7″N, 119°59′47.9″E). Relationships between juvenile density and the physical, chemical and biological characteristics of their habitat were examined. Potential food sources of the juveniles were also investigated using elemental and stable isotope analysis. Results showed that juveniles are more abundant in seagrass areas and the transition zone between seagrass and the rubble-dominated reef flat. A non-metric multidimensional scaling (MDS) plot indicated that juvenile density was most positively associated with coarser sand and rubble (>0.5 mm) and seagrass (Thalassia hemprichii) abundance (2D stress = 0.11). Juvenile density was also positively associated with sediment organic matter from plant detritus to a lesser extent. Elemental and isotope analysis of one site indicated that epiphytes were the primary food source of juveniles, while sediment detritus from microalgae and seagrass was a secondary food source. This study corroborates anecdotal evidence regarding the importance of seagrass to S. cf. horrens as potential refugia and source of high-quality food for its juveniles. These findings underscore the need to protect the nursery habitats of wild juveniles and provide critical information for the selection of suitable natural habitats for releasing cultured juveniles of this important species.

Food Policy: Urban Farming as a Supplemental Food Source

Food policy has a unique role for public, nonprofit, private, and academic stakeholders. Growing food in the city is a challenge worldwide. Food systems can be destroyed by external (weather extremes) and internal (zoning regulations) forces. This study explores urban farms as a secondary food source and their common themes across four sectors. A Northeastern U.S. city was the case study to examine how it implemented its formal urban agriculture program. The positive social change implications of urban farms include greater food visibility and food access in low-income areas and more consumer awareness about growing fresh food. This study contributes a realistic view of urban farms: They are a secondary food source, but local food alone cannot feed large populations.

Landscape effects on jay foraging behavior decrease acorn dispersal services in dehesas

Dehesas are savanna-like, oak woodlands with a high conservation value that are threatened by chronic regeneration failure. Acorn dispersal by Eurasian jays (Garrulus glandarius) is vital for oak recruitment although jay preference for continuous forests may condition this mutualism in dehesas. In this study, we evaluated whether the acorn dispersal services provided by jays to oaks differed between both habitats and assessed factors that could potentially drive such differences. We (1) monitored acorn removal rates at feeders located close to focal trees in a holm oak (Quercus ilex) forest and in a nearby dehesa over a 6-year period; (2) measured the spatial traits of focal trees and their acorn production; and (3) monitored dispersal distances and microhabitat selection for acorn caching during 2012.Our results indicated that jays were able to exploit dehesas located close to forest habitats, but did so infrequently and as a secondary food source (acorn removal rates were six times lower in dehesa than in nearby forests). This likely occurred because dehesas did not offer new or more abundant food sources on a landscape scale. In forests, tree choice was driven by crop traits while in dehesas it was driven by spatial location. Jays preferentially foraged at dehesa trees near forest patches and aggregated to other trees, regardless of crop traits. Acorns were mobilized four times closer in dehesas, and seeds were preferentially cached in unsuitable microhabitats for seedling establishment. Our results suggest that (i) distance to forest habitats and tree isolation effects on jay foraging behavior reduces their dispersal services in dehesas as compared to nearby forests, and (ii) practices designed to enhance acorn dispersal by jays in this habitat should focus on the maintenance or creation of forest patches interspersed within dehesa areas.

Investigating isotopic functional indices to reveal changes in the structure and functioning of benthic communities

Summary With the use of stable isotopes, new concepts have emerged based on the idea that the ecological niche can be approximated by the isotopic niche defined as a δ‐space area with isotopic δ values as coordinates. This study aims to (i) redefine functional indices originally based on quantitative biological traits of species and demonstrate the ecological significance of newly defined isotopic functional indices (IFI) in a δ‐isotopic space, (ii) compare IFI using biomass data with existing unweighted isotopic indices using only isotopic compositions. Using a community‐wide approach, we tested IFI using isotopic compositions of a large set of associated species from two marine benthic communities widely reported in coastal shallow waters: the common Amphiura filiformis muddy‐sand community and the engineered Haploops nirae sandy‐mud community. Biomass and isotopic composition (13C and 15N) of all species were measured during four seasons. IFI were calculated in the isotopic space defined by the two communities, and variations were analysed: (i) isotopic functional richness indices measure the overall extent of the community trophic niche. They are higher in the Haploops community due to a higher diversity in food sources but also to longer food chains. (ii) isotopic functional evenness indices quantify the regularity in species distribution and the density in species packing. They showed that the biomass is concentrated at the edges of the food web in the Haploops community, outside the isotopic range of the main food source. (iii) isotopic functional divergence indices quantify the degree to which species distribution maximizes the divergence. They showed a larger utilization of secondary food sources in the Haploops community. The IFI variations responded according to expectations overall, based on the extensive knowledge of those communities. Results highlighted that IFI weighted with species biomass provide new insights into how the structure of energy accumulation as biomass between species is likely to underpin community structure and the interplay between structural components of richness, diversity and evenness of biomass distribution.

Prey preference of the common vampire bat (Desmodus rotundus, Chiroptera) using molecular analysis

Morphological identification of prey fragments in vampire bat feces is impossible because of an exclusively blood-based diet. Therefore, studies of their foraging ecology require innovative approaches. We investigated the diet of Desmodus rotundus using a PCR–restriction fragment length polymorphism (RFLP) molecular method by amplifying the cytochrome b mitochondrial gene (380bp) from DNA fecal samples collected from captive bats fed with blood from chickens, cattle, pigs, dogs, and humans—the 5 most frequently attacked prey species in rural areas of the Brazilian Amazonia. The prey preference of the vampire bat was investigated in 18 riverine villages, where the availability of domestic animals to bats was quantified. Prey DNA amplified from fecal samples exhibited no visible signals of vampire bat DNA. A PCR–RFLP flowchart and a combination of 2 DNA restriction enzymes allowed the direct identification of prey to species level. The enzymes’ restriction profile did not overlap with those of vampire bats or wild mammal and avian species. Chickens were the most attacked prey species (61.4% of the identifications, n = 27), but pigs were highly preferred in relation to prey availability. This suggests a preference for mammalian blood in D. rotundus diet, with chickens exploited as a secondary food source. No wild vertebrate species was identified in the fecal samples, indicating that vampire bats are selectively feeding on the blood of domesticated animals, probably because they are more predictable and easily accessed resources.

SELDI-TOF MS를 활용한 혈당강하 수수 종자의 펩타이드 프로파일링 및 특이 발현 펩타이드 선발

혈당 강하를 목적으로 선발된 수수계통의 종자 유래 펩타이드의 양적, 질적 형질을 특성화하고 혈당 강하 수수에서 특이적으로 발현 펩타이드를 선발하기 위하여, 혈당 강하수수 7계통과 비 혈당 강하 수수 5계통에 대한 종자 펩타이드 프로파일링을 SELDI-TOF MS 기법을 활용하여 분석하였다. 1. 분자량의 범위가 2~20 kDa에서 검출된 수수 12계통 종자의 펩타이드는 CM10 (weak cation exchanger)에서 104개와 Q10 (strong anion exchanger)에서 95개였으며, 펩타이드 양적발현에서 12계통 간 유의성(p < 0.01)을 보인 펩타이드는 CM10에서 99개와 Q10에서 93개였다. 2. 12계통 간 양적 발현에 유의적(p < 0.01) 펩타이드를 이용한 heat map 분석에서 수수 각 계통 종자의 고유한 펩타이드 프로파일과 특이적으로 발현하는 펩타이드를 제시하고 있다. 3. 수수 12계통간의 근연거리를 이용한 군집분석에서 혈당 강하 수수 7계통과 비 혈당 강하 수수 5계통이 서로 다른 2개의 군집을 형성하였다. 4. 혈당 강하 계통에서 유의성(p < 0.00001)이 있게 발현되는 펩타이드를 29개 선정하였으며, 이중에서 혈당강하 계통에서만 공통적으로 높게 발현된 10개의 펩타이드(분자량이 2231.6, 2845.4, 2907.9, 3063.5, 3132.6, 3520.8, 4078.8, 5066.2, 5296.5, 5375.5 Da)를 선발하였다. Sorghum seed is traditionally used as secondary food sources in addition to rice in Korea. While the hypoglycemia regulating phytochemicals have been found in sorghum seed, peptides related with hypoglycemia never been studied before. To obtain the peptide characteristics and the specifically high-expressed peptides in hypoglycemic sorghum seed, peptide profiles of seven hypoglycemic and five non-hypoglycemic sorghum lines bred in RDA were determined using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS). The twelve sorghum lines exhibited 104 peptides on CM10 protein chip array (weak cation exchange) and 95 peptides on Q10 (weak cation exchange) in the molecular mass range from 2,000 to 20,000 Da. Heat map via supervised hierarchical clustering of the significantly different peptides (p < 0.01) in peak intensity among the 12 lines effectively revealed the specifically upregulated peptides in each line and distinguished between 7 hypoglycemic and 5 non-hypoglycemic lines. Through the comparison with hypoglycemic and non-hypoglycemic lines, 10 peptides including 2231.6, 2845.4, 2907.9, 3063.5, 3132.6, 3520.8, 4078.8, 5066.2, 5296.5, 5375.5 Da were specifically high-expressed in hypoglycemic lines at p < 0.00001. This study characterized seed peptides of 12 sorghums and found ten peptides highly expressed for hypoglycemic sorghum lines, which could be used as peptide biomarkers for identification of hypoglycemic sorghum.

Spatial and Semantic Validation of Secondary Food Source Data

Governmental and commercial lists of food retailers are often used to measure food environments and foodscapes for health and nutritional research. Information about the validity of such secondary food source data is relevant to understanding the potential and limitations of its application. This study assesses the validity of two government lists of food retailer locations and types by comparing them to direct field observations, including an assessment of whether pre-classification of the directories can reduce the need for field observation. Lists of food retailers were obtained from the Central Business Register (CVR) and the Smiley directory. For each directory, the positive prediction value (PPV) and sensitivity were calculated as measures of completeness and thematic accuracy, respectively. Standard deviation was calculated as a measure of geographic accuracy. The effect of the pre-classification was measured through the calculation of PPV, sensitivity and negative prediction value (NPV). The application of either CVR or Smiley as a measure of the food environment would result in a misrepresentation. The pre-classification based on the food retailer names was found to be a valid method for identifying approximately 80% of the food retailers and limiting the need for field observation.

Benefits of aggregation in woodlice: a factor in the terrestrialization process?

In the animal kingdom, living in group is driven by a tradeoff between the costs and the benefits of this way of life. This review focuses especially on the benefits of aggregation and crowding in woodlice (Crustacea: Isopoda: Oniscidea). Indeed, woodlice are well known to live in groups. Their aggregation behavior, as described in the early works of Allee, is regarded as a mechanism to prevent desiccation to which woodlice are extremely sensitive. However, it is now clear that there are additional benefits to aggregation in woodlice. Hence, this review addresses not only the limitation of water loss as the main factor explaining aggregation patterns, but also alternative explanations as reduction of oxygen consumption, increase in body growth, biotic stimuli for reproduction, better access to mates, possible shared defenses against predators, promotion of coprophagy as a secondary food source, sheltering behavior and the acquisition of internal symbionts. In addition, we place woodlice in the context of a terrestrialization process and propose that woodlice—the only suborder of Crustacea almost entirely composed of strictly terrestrial species—are a model taxon for studying the evolution of sociality through the transition from water to land. Further, we discuss other ultimate causes of aggregation preserved in terrestrial isopods in light of those explained in aquatic isopods and under the concept of exaptation. This knowledge could help understand, in this and other taxa, how the spatial closeness between conspecifics may promote the colonization of new environments and nonphysiological responses to climatic constraints.

Tooth Root Morphology in the Early Pliocene African Bear Agriotherium africanum (Mammalia, Carnivora, Ursidae) and its Implications for Feeding Ecology

Tooth root surface areas serve as proxies for bite force potentials, and by extension, dietary specialization in extant carnivorans. Here, we investigate the feeding ecology of the extinct large-bodied ursid Agriotherium africanum, by comparing its root surface areas (reconstructed with the aid of computed tomography and three-dimensional image processing) and bite force estimates, with those of extant carnivorans. Results show that in absolute terms, canine and carnassial bite forces, as well as root surface areas were highest in A. africanum. However, when adjusted for skull size, A. africanum’s canine roots were smaller than those of extant solitary predators. With teeth being the limiting factor in the masticatory system, low canine root surface areas suggest that A. africanum would have struggled to bring down large vertebrate prey. Its adjusted carnassial root sizes were found to be smaller than those of extant hard object feeders and the most carnivorous tough object feeders, but larger than those of extant omnivorous ursids and Ursus maritimus. This and the fact that it displayed its highest postcanine root surface areas in the carnassial region (rather than the most distal tooth in the tooth row) suggest that A. africanum consumed more vertebrate tissue than extant omnivorous ursids. With an apparent inability to routinely bring down large prey or to consume mechanically demanding skeletal elements, its focus was most likely on tough tissue, which it acquired by actively scavenging the carcasses of freshly dead/freshly killed animals. Mechanically less demanding skeletal elements would have been a secondary food source, ingested and processed mainly in association with muscle and connective tissue.

Ethno-Edible Mushroom of Pleurotus sp., Clytocybe nebularis and Auricularia auricula in Ranupani Village, East Java

This paper documented the knowledge about the wild edible fungal flora of Ranupani Village of East Java Indonesia that used by indigenous Tenggerese tribes. Study was conducted by using semi-structured interview and purposive sampling. Data were analyzed quantitatively descriptive. Index of Cultural Significance (ICS) was used to evaluate the importance of non-wood forest yields for local people. Identification of edible mushrooms was based on Guidelines of Flora Diversity Data Collection. This study was focus on the three edible mushrooms which are eaten mostly by the villagers, i.e. Pleurotus sp., Clytocybe nebularis and Auricularia auricula. The result is the Ranupani residents perception of edible mushrooms and its potential as an alternative source of food based on local knowledge and local wisdom of Tenggerese. Pleurotus sp. has the highest preference and intensity to be consumed with 3,2 ICS. It means culturally, this edible mushroom were not too important but intensively used as a secondary food sources such as soup (added or sauted), chips (dried) and fried. Ranupani Villagers always consumed edible mushrooms in rainy season. The ability of residents to distinguish edible mushrooms are equal to the searching ability to find edible mushroom substrate. The residents will recognized the substrate of edible mushrooms on dead trunks of Pasang Tree ( Lithocarpus sundaicus ), Danglu ( Engelhardia spicata ), Kemlandingan ( Albizia Montana ), Casuarina ( Casuarina junghuhniana ) and acacia ( Acacia decurens ). Residents who do not have the ability to distinguish and searching were consumer, get the edible mushrooms by buying from the searcher or distributor in packs. The characteristics of an edible mushrooms are a discrete soft flesh of the fruit body, dark color, no ring on the stipe, the presence of insects (e.g. moths) in the lamellae) and the type of mushroom substrate. There were also assisted growths of wild mushrooms by the residents’ raw chop the dead tree trunk as a substrate deliberately. Respondents who knew the time of harvesting edible mushroom were 58.3%. Pasang mushrooms (natural & assisted growth) can be found throughout the rainy season, with an interval of 12 days for subsequent retrieval. While Barat and Kuping mushrooms are found throughout the rainy season, but randomly distributed in the forest. There were unwritten but spoken hereditary local wisdom for the sustainable of the edible mushrooms in Tengger. Only Tenggerese allowed collecting and selling the edible mushrooms in Tengger area to the Tenggerese themselves and tourist (local or foreign). This wisdom is supported by TNBTS regulation that the edible mushroom were not allowed exported out of TNBTS area. This wisdom expectedly makes sure that the edible mushrooms should be sustained in the forest. Keywords: Ethno-edible mushrooms, Ranupani

High site fidelity and low site connectivity in temperate salt marsh fish populations: a stable isotope approach

Adult and juvenile fish utilise salt marshes for food and shelter at high tide, moving into adjacent sublittoral regions during low tide. Understanding whether there are high levels of site fidelity for different species of coastal fish has important implications for habitat conservation and the design of marine protected areas. We hypothesised that common salt marsh fish species would demonstrate a high site fidelity, resulting in minimal inter-marsh connectivity. Carbon ((13)C) and nitrogen ((15)N) stable isotope ratios of larvae and juveniles of five common salt marsh fish (Atherina presbyter, Chelon labrosus, Clupea harengus, Dicentrarchus labrax, Pomatoschistus microps), seven types of primary producer and seven secondary consumer food sources were sampled in five salt marshes within two estuary complexes along the coast of south-east England. Significant differences in (13)C and (15)N signatures between salt marshes indicated distinct sub-populations utilising the area of estuary around each salt marsh, and limited connectivity, even within the same estuary complex. (15)N ratios were responsible for the majority of inter-marsh differences for each species and showed similar site-specific patterns in ratios in primary producers, secondary consumers and fish. Fish diets (derived from isotope mixing models) varied between species but were mostly consistent between marsh sites, indicating that dietary shifts were not the source of variability of the inter-marsh isotopic signatures within species. These results demonstrate that for some common coastal fish species, high levels of site fidelity result in individual salt marshes operating as discrete habitats for fish assemblages.

Comparing agroforestry systems’ ex ante adoption potential and ex post adoption: on-farm participatory research from southern Malawi

Agroforestry (AF) systems have been the focus of numerous research and development projects in southern Africa, yet their adoption rate generally remains low. Employing on-farm, participatory research techniques in southern Malawi, we compared the suitability of three AF-based systems that relay crop the dominant staple, maize (Zea mays), with the perennial legumes Sesbania sesban, Tephrosia vogelii, and Cajanus cajan (pigeonpea). Our secondary objective was to compare two methodologies employed to investigate AF adoption: farming systems based ex ante adoption potential and ex post adoption analysis. Nineteen percent of farmers preferred S. sesban, 26% T. vogelii, and 55% pigeonpea. Between 2001 and 2003, S. sesban adoption ranged from 3 to 6%, T. vogelii from 16 to 20%, and pigeonpea from 76 to 100%. Pigeonpea and T. vogelii were primarily preferred and adopted for their immediate livelihood benefits—a secondary food source in the case of pigeonpea and a fish poison in the case of T. vogelii. Though S. sesban was the most promising in terms of biophysical impacts, many farmers found it labor intensive and its lack of immediate livelihood benefits was a deterrent to adoption. With food insecurity a pervasive hardship in the region, farmers will likely continue to focus on satisfying immediate livelihood needs before prioritizing longer-term soil-quality improvement techniques. Both ex ante adoption potential and ex post adoption analysis contributed distinct and valuable data, and relying on either exclusively would have limited our understanding of the AF systems.

Food web of a SW Atlantic shallow coastal lagoon: spatial environmental variability does not impose substantial changes in the trophic structure

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 362:69-83 (2008) - DOI: https://doi.org/10.3354/meps07401 Food web of a SW Atlantic shallow coastal lagoon: spatial environmental variability does not impose substantial changes in the trophic structure Laura Rodríguez-Graña1,6,*, Danilo Calliari2,6, Daniel Conde1, Javier Sellanes3,4, Roberto Urrutia5 1Sección Limnología, and 2Sección Oceanología, Facultad de Ciencias, Universidad de la República, Iguá 4225, CP 11400 Montevideo, Uruguay 3Departamento de Biología Marina, Universidad Católica del Norte, Larrondo 1281, Coquimbo, Chile 4Centro de Investigación Oceanográfica en el Pacífico Sur-Oriental (COPAS), and 5Centro EULA, Universidad de Concepción, Casilla 160-C, Concepción, Chile 6Present address: Department of Marine Ecology, Göteborgs University, Kristineberg 566, 450 34 Fiskebäckskil, Sweden *Emails: laurod@fcien.edu.uy and laura.rodriguez@marecol.gu.se ABSTRACT: We performed a detailed analysis of the food web structure of Laguna de Rocha, a temporally open coastal lagoon in the Southwest Atlantic, characterised by spatial gradients in salinity, nutrient levels and trophic status. Carbon and nitrogen stable isotopes of main producers, invertebrate and vertebrate consumers, and stomach contents of ichthyofauna were analysed seasonally at freshwater (north) and marine-influenced (south) sites to determine whether environmental differences induced changes in food web structure. Contribution of primary and secondary food sources and trophic linkages were assessed with the multisource-partitioning model IsoSource and an index that quantifies the contribution of each organism as food for the ecosystem. Isotopic analyses were performed for 10 primary organic matter sources (OM), 13 invertebrates and 9 fish species. Suspended and sediment OM constituted the most important primary sources, while direct consumption of macrophytes and macroalgae was marginal. The small invertebrates Neomysis americana, Nephtys fluviatilis, Pseudodiaptomus richardii and an amphipod were the most important intermediate consumers at both sites (except P. richardii, which was present only in the north). Top predators were the fish species Micropogonias furnieri, Paralichthys orbygnianus and Hoplias malabaricus, and the maximum estimated trophic level (between 3.4 and 4.8) varied seasonally, but not between sites. Fish stomach content analyses largely confirmed results from the IsoSource mixing model. Overall results indicated that, despite environmental differences between sites, the structure of the biological assemblages and general trophic patterns were similar at both sites. KEY WORDS: Food web structure · Coastal lagoon · Estuaries · Benthic–pelagic coupling · Isotopic mixing models Full text in pdf format Supplementary appendix PreviousNextCite this article as: Rodríguez-Graña L, Calliari D, Conde D, Sellanes J, Urrutia R (2008) Food web of a SW Atlantic shallow coastal lagoon: spatial environmental variability does not impose substantial changes in the trophic structure. Mar Ecol Prog Ser 362:69-83. https://doi.org/10.3354/meps07401Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 362. Online publication date: June 30, 2008 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2008 Inter-Research.

Vickers Focus Subsistence: Continuity through the Seasons

The Vickers focus is an archaeological group found in south-central and southwestern Manitoba. After a brief occupation of the Tiger Hills region where these people were believed to have practiced horticulture, they moved west into the Lauder Sandhills of Manitoba and became intensive bison hunters. The faunal assemblages from two Vickers focus occupations in the Lauder Sandhills are examined to determine activity areas and the subsistence strategies of each site. The Jackson site contains a small bison kill and associated processing area while the nearby Vera site was mainly used for processing. Seasonality of each site is also inferred from faunal remains with Jackson being occupied during the colder months and Vera inhabited during a warmer season. One assumes that seasonality would be a significant factor in subsistence strategies as indicated by the ethnographic record. The predominance of bison exploitation with only a limited use of secondary food sources at the Vera and Jackson sites suggest that seasonality was not a deciding factor of their subsistence strategies.

Use of lipids to study the trophic ecology of deep-sea xenophyophores

Xenophyophores, widespread giant deep-sea protists, dominate the megafaunal organ- isms visible on the seafloor in some areas. Owing to the extreme fragility of their tests (external part), little is known about them, and their diet is largely a matter of speculation. The extensive accumula- tion of fecal pellets (stercomes) within their tests attests to the degree to which xenophyophores feed on particulate matter. During the EUMELI 2 cruise, xenophyophores were recovered intact at the sur- face of box-cores from an abyssal mesotrophic site in the northeastern Atlantic. They were identified as Syringammina corbicula. In our study, we compare the lipid composition of xenophyophores col- lected at the top of cores with sediment from the same mesotrophic environment devoid of these pro- tists. The distribution of lipid classes was obtained by the use of the Iatroscan (TLC-FID) technique, and the molecular composition of several lipid classes containing fatty acids and sterols was investi- gated. Of special interest are the triacylglycerols of xenophyophores, energy storage lipids in ani- mals, resulting in part from fatty acids found in their diet. They contained a higher level of bacterial fatty acids than those in the reference sediment. It would seem that, in addition to particle trapping, xenophyophores also feed on microbes. Our study points to the occurrence of a specialized bacterial flora, probably growing on the stercomes, which might serve as a secondary food source different from the microflora found in the control sediment.