DOCSLIB.ORG

RATES of METAZOAN MEIOFAUNAL MICROBIVORY : a REVIEW Paul Montagna

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
RATES of METAZOAN MEIOFAUNAL MICROBIVORY : a REVIEW Paul Montagna RATES OF METAZOAN MEIOFAUNAL MICROBIVORY : A REVIEW Paul Montagna To cite this version: Paul Montagna. RATES OF METAZOAN MEIOFAUNAL MICROBIVORY : A REVIEW. Vie et Milieu / Life & Environment, Observatoire Océanologique - Laboratoire Arago, 1995, pp.1-9. hal- 03051016 HAL Id: hal-03051016 https://hal.sorbonne-universite.fr/hal-03051016 Submitted on 10 Dec 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. VIE MILIEU, 1995, 45 (1): 1-9 RATES OF METAZOAN MEIOFAUNAL MICROBIVORY : A REVIEW PAUL A. MONTAGNA The University of Texas at Austin, Marine Science Institute, P.O. Box 1267, Port Aransas, Texas 78373 U.S.A. BACTERIES RÉSUMÉ - La méiofaune consomme des Bactéries, des microalgues, des Proto- MICROALGUES zoaires, du matériel détritique et d'autres méiobenthontes. Elle peut également ab- NUTRITION sorber de la matière organique dissoute. L'objet de cet article de synthèse concerne RÉPONSE FONCTIONNELLE la méiofaune microphage, et en particulier la prédation sur les Bactéries et les microalgues par les Nématodes et les Harpacticoïdes. La plupart des études utilisent les techniques radioisotopiques. Elles se divisent en deux catégories : celles qui envisagent d'élucider la biologie de la nutrition de la méiofaune, et celles qui cherchent à évaluer l'impact de l'importance de la méiofaune dans le recyclage du carbone. La méiofaune broute (sélectionne) les petites particules de la biomasse microbienne. Le taux de broutage de la méiofaune augmente lorsque l'abondance de la nourriture bactérienne disponible s'accroit. C'est une réponse fonctionnelle que les modèles d'optimisation prédisent. La méiofaune présente également des taux de consommation différents selon les sources de nourriture. Il existe des dif- férences ontogénétiques du taux de broutage et de sélection. Ces différences in- tragénériques sont faibles. Les modes de nutrition varient avec les diverses phases du cycle de vie. En dépis d'une forte variabilité d'un point à l'autre du globe, le taux moyen de broutage de la méiofaune est de 0,01 • h1, ce qui représente 1% par heure de la biomasse des hétérotrophes et des autotrophes. Ainsi, la méiofaune a un impact global significatif sur tous les processus faisant intervenir des micro- bionthes. BACTERIA ABSTRACT - Metazoan meiofauna eat bacteria, microalgae, protozoans, détritus, MICROALGAE and other meiofauna. They also have the ability to absorb dissolved organic matter. FEEDING The focus of this review is on meiofaunal microbivory, particularly the use of FUNCTIONAL RESPONSES bacteria and microalgae by nématodes and harpacticoids. Most of the studies utilize radioisotope techniques. The studies fall into two catégories : those done to elu- cidate meiofaunal feeding biology, and those done to assess the impact and im- portance of meiofauna in carbon cycling. Meiofauna graze on (i.e., select) small particles of microbial biomass. Meiofaunal grazing rates increase when offered increased abundances of microbial food. This is a functional response predicted by optimization models. Meiofauna also have différent grazing rates on différent species of food. Ontogenetic grazing rate and sélection différences exist. The évi- dence for intrageneric différences in grazing rates is weak. Différences of feeding modes exist with différent life history stages. There is much variability from site to site Worldwide, but on average meiofauna graze at a rate of 0.01 h ', or 1% of the standing stock of both heterotrophs and autotrophs per hour. Therefore, meiofauna have a significant global impact on microbially mediated processes. INTRODUCTION solid feeders that either eat or clean whole parti- cles (Marcotte, B.M. 1977, Ph.D. Thesis, Dalhousie University, 212 pp., described in Hicks During the 1970's, little was known about how, and Coull, 1983). There are also four nematode what, and how much meiofauna consumed feeding groups : deposit feeders, epistrate feeders, (Fenchel, 1978; Coull and Bell, 1979). A lot has scavengers and predators (Jensen, 1987). Al- changed. The kinematics of meiofaunal feeding though some nématodes (as well as meiofaunal has been defined. There are four harpacticoid sized annelids) are deposit feeders, most metazoan feeding groups : point feeders that are sélective meiofauna behavior is adapted to pick spécifie mi- epistrate pickers, line feeders that scrape edges of crobial food items, e.g., microalgae, bacteria, and particles, plane sweepers that sweep food into protozoans. Some workers have referred to this their mouths from two-dimensional surfaces, and feeding habit as «grazing,» and have measured 2 P.A. MONTAGNA how much microbial biomass is consumed by algae (Deco, 1988), and one study used fluores- meiofauna (Montagna, 1984; Decho, 1988; Blan- cence-labeled bacteria to measure grazing on bac- chard, 1991). Whereas macrofaunal (and pre- teria (Epstein and Shiaris, 1992). Both of thèse sumably meiofaunal) deposit feeders have fluorescence techniques are very powerful and adaptations to acquire food by ingesting large have advantages for studies spécifie to bacteria or volumes of sédiment (Lopez and Levinton, 1987), microalgae. The radioisotope approach has prob- meiofaunal grazers have adaptations to pick out lème, but it is currently the only way to measure spécifie microbial particles (Marcotte, 1977 in grazing on both bacteria and microalgae. There- Hicks and Coull, 1983; Jensen, 1987). fore, this review will mostly cover radioisotope One of the most successful areas of study tracer studies. There are two techniques for em- during the 1980's was to measure how much ploying radioactive tracers to measure the inverte- meiofauna eat in the field. It was found that meio- brate feeding via grazing. Microbial food is either fauna can vary their ingestion rates of microbes pre-labeled (Haney, 1971) or labeled while it is in response to changes in food quality or quantity being grazed (Daro, 1978). Both techniques have (Deco, 1988; Montagna and Yoon, 1991). Thèse advantages and disadvantages that limit their use results suggest that meiofaunal grazing rates are to either laboratory or field studies. The pre-label- a functional response to changes in the environ- ing technique requires growing microbes with a ment. I use this term in the same way that Taghon radioactive tracer, introducing the labeled microbe and Green (1990) defined functional response : to the existing microbial community and knowing «how any animal changes its feeding rate in re- the spécifie activity of the food source. Such con- sponse to changes in abundance of its food. » ditions are best achieved in laboratory studies. Meiofauna, particularly harpacticoids, can ex- The synoptic labeling technique is more amenable ponentially increase feeding rates as a function of to in situ studies, because only the radioactive increased microphytobenthos (Montagna, et al, tracer is introduced and microbial uptake of the 1995). More information is needed on how to tracer and meiofaunal grazing can be measured at apply models to meiofauna feeding, but we need the same time. a reliable and easy way to obtain feeding rate It is difficult to review the literature and dé- measurements. The current radioisotope tech- termine the comparative quantitative différences niques are neither well understood, nor easy to in meiofaunal microbivory, because of différences use (Montagna, 1993). in approach to measuring feeding rates and diffé- Together nématodes and harpacticoids usually rences in reporting the rates measured. In large make up 90-98 % of the meiofaunal community part, the différences exist because différent end- (Mclntyre, 1969; Coull and Bell, 1979; Dye and points are desired. Studies on carbon flow might Furstenburg, 1981; Platt, 1981). This paper fo- report rates on a biomass spécifie basis (e.g., |Xg 1 cuses on nématodes and harpacticoids because C • ind • h" ), whereas studies on the impact of they dominate the community. So, when I refer meiofauna grazing on microbial populations might 1 to metazoan meiofauna, I am referring to mainly report the flow rate (e.g., h )- The focus of this nématodes and harpacticoids and exclude benthic review is on assessing the latter issue, therefore microfauna (flagellâtes, ciliates and foraminifera). I have reported flow rates. This requires that the There is no doubt that microfauna are important, amount of food (e.g., carbon, chlorophyll, or num- but they may have différent behavior and meta- ber of cells) offered or available for eating is bolism than metazoan meiofauna (Rivkin and De known and reported. In this case it is simple to Laca, 1990). Meiofauna can utilize organic matter calculate the flow rate, i.e., the percent grazed per in diverse forms, but this review is focusing on unit time. An advantage to reporting the flow rate the utilization of the microflora : bacteria and mi- is that the inverse is the turnover time required crophytobenthos. The main purpose of this paper for the microbial population to maintain itself is to review the current literature on meiofaunal under the grazing pressure of meiofauna. Turnover
Load more

Recommended publications
  • Dung Beetle Richness, Abundance, and Biomass Meghan Gabrielle Radtke Louisiana State University and Agricultural and Mechanical College, [email protected]
    Louisiana State University LSU Digital Commons LSU Doctoral Dissertations Graduate School 2006 Tropical Pyramids: Dung Beetle Richness, Abundance, and Biomass Meghan Gabrielle Radtke Louisiana State University and Agricultural and Mechanical College, [email protected] Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_dissertations Recommended Citation Radtke, Meghan Gabrielle, "Tropical Pyramids: Dung Beetle Richness, Abundance, and Biomass" (2006). LSU Doctoral Dissertations. 364. https://digitalcommons.lsu.edu/gradschool_dissertations/364 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Doctoral Dissertations by an authorized graduate school editor of LSU Digital Commons. For more information, please [email protected]. TROPICAL PYRAMIDS: DUNG BEETLE RICHNESS, ABUNDANCE, AND BIOMASS A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Biological Sciences by Meghan Gabrielle Radtke B.S., Arizona State University, 2001 May 2007 ACKNOWLEDGEMENTS I would like to thank my advisor, Dr. G. Bruce Williamson, and my committee members, Dr. Chris Carlton, Dr. Jay Geaghan, Dr. Kyle Harms, and Dr. Dorothy Prowell for their help and guidance in my research project. Dr. Claudio Ruy opened his laboratory to me during my stay in Brazil and collaborated with me on my project. Thanks go to my field assistants, Joshua Dyke, Christena Gazave, Jeremy Gerald, Gabriela Lopez, and Fernando Pinto, and to Alejandro Lopera for assisting me with Ecuadorian specimen identifications. I am grateful to Victoria Mosely-Bayless and the Louisiana State Arthropod Museum for allowing me work space and access to specimens.
    [Show full text]
  • "Species Richness: Small Scale". In: Encyclopedia of Life Sciences (ELS)
    Species Richness: Small Advanced article Scale Article Contents . Introduction Rebecca L Brown, Eastern Washington University, Cheney, Washington, USA . Factors that Affect Species Richness . Factors Affected by Species Richness Lee Anne Jacobs, University of North Carolina, Chapel Hill, North Carolina, USA . Conclusion Robert K Peet, University of North Carolina, Chapel Hill, North Carolina, USA doi: 10.1002/9780470015902.a0020488 Species richness, defined as the number of species per unit area, is perhaps the simplest measure of biodiversity. Understanding the factors that affect and are affected by small- scale species richness is fundamental to community ecology. Introduction diversity indices of Simpson and Shannon incorporate species abundances in addition to species richness and are The ability to measure biodiversity is critically important, intended to reflect the likelihood that two individuals taken given the soaring rates of species extinction and human at random are of the same species. However, they tend to alteration of natural habitats. Perhaps the simplest and de-emphasize uncommon species. most frequently used measure of biological diversity is Species richness measures are typically separated into species richness, the number of species per unit area. A vast measures of a, b and g diversity (Whittaker, 1972). a Di- amount of ecological research has been undertaken using versity (also referred to as local or site diversity) is nearly species richness as a measure to understand what affects, synonymous with small-scale species richness; it is meas- and what is affected by, biodiversity. At the small scale, ured at the local scale and consists of a count of species species richness is generally used as a measure of diversity within a relatively homogeneous area.
    [Show full text]
  • Diverse Allochthonous Resource Quality Effects on Headwater Stream Communities Through Insect-Microbe Interactions
    DIVERSE ALLOCHTHONOUS RESOURCE QUALITY EFFECTS ON HEADWATER STREAM COMMUNITIES THROUGH INSECT-MICROBE INTERACTIONS By Courtney Larson A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of Entomology—Doctor of Philosophy Ecology, Evolutionary Biology and Behavior—Dual Major 2020 ABSTRACT DIVERSE ALLOCHTHONOUS RESOURCE QUALITY EFFECTS ON HEADWATER STREAM COMMUNITIES THROUGH INSECT-MICROBE INTERACTIONS By Courtney Larson Freshwater resources are vital to environmental sustainability and human health; yet, they are inundated by multiple stressors, leaving aquatic communities to face unknown consequences. Headwater streams are highly reliant on allochthonous sources of energy. Riparian trees shade the stream, limiting primary production, causing macroinvertebrates to consume an alternative food source. Traditionally, leaf litter fallen from riparian trees is the primary allochthonous resource, but other sources, such as salmon carrion associated with annual salmon runs, may also be important. An alteration in the quantity or quality of these sources may have far reaching effects not only on the organisms that directly consume the allochthonous resource (shredders), but also on other functional feeding groups. Allochthonous resources directly and indirectly change stream microbial communities, which are used by consumers with potential changes to their life histories and behavior traits. The objective of my research was to determine the influence allochthonous resources have on stream
    [Show full text]
  • Regras Entre Assembléias De Espécies: Relação Entre Biodiversidade E Funcionamento Do Ecossistema
    Santos, G.A.P. dos UNIVERSIDADE FEDERAL DE PERNAMBUCO Chapter: Open letter. DOUTORADO EM CIÊNCIAS BIOLÓGICAS REGRAS ENTRE ASSEMBLÉIAS DE ESPÉCIES: RELAÇÃO ENTRE BIODIVERSIDADE E FUNCIONAMENTO DO ECOSSISTEMA. GIOVANNI AMADEU PAIVA DOS SANTOS I TÍTULO: Species assembly rules and the biodiversity-ecosystem functioning relationship CCB, Recife-PE, 2007. Santos, G.A.P. dos UNIVERSIDADE FEDERAL DE PERNAMBUCO Chapter: Sub-Cover. DOUTORADO EM CIÊNCIAS BIOLÓGICAS Universidade Federal de Pernambuco Doutorado em Ciências Biológicas Centro de Ciências Biológicas Regras entre assembléias de espécies: Relação entre biodiversidade e funcionamento do ecossistema. Species assembly rules and the biodiversity- ecosystem functioning relationship. Giovanni Amadeu Paiva dos Santos Tese apresentada ao Doutorado de Ciências Biológicas da UFPE, como requisito necessário para o recebimento do título de Doutor em Ciências Biológicas. RECIFE, JULHO DE 2007. II TÍTULO: Species assembly rules and the biodiversity-ecosystem functioning relationship CCB, Recife-PE, 2007. 1.1.1 1.1.2 1.1.3 Santos, Giovanni Amadeu Paiva dos Regras entre assembléias de espécies: relação entre biodiversidade e funcionamento do ecossistema / Giovanni Amadeu Paiva dos Santos. – Recife: O Autor, 2009. 263 folhas: fig., tab. Tese (doutorado) – Universidade Federal de Pernambuco. CCB. Departamento de Ciências Biológicas, 2009. 1.1.3.1.1.1 Inclui bibliografia. 1. Biodiversidade 2. Funcionamento dos ecossistemas I Título. 574 CDU (2.ed.) UFPE 1.2 577 CDD (22.ed.) CCB – 2009- 043 COMISSAO EXAMINADORA "Regras entre assemblfHas de especies: rela~ao entre biodiversidade e funcionamento do ecossistema" TITULARES ,Ore c'~~ l .l;/'>1i( Ji /',- C'"'-~" -- ia Tereza dos Santos Correia (OrientadorIlJFPE) /~-/z:; , ~ Prof. L Ricardo Coutinho - (IEAPM/RJ) om Gilbert Willem Moens (Ghent UniversityIBelgica) SUPLENTES , " ' '/l{ ) c::< \, /,_k".
    [Show full text]
  • Bacterivory of a Mudflat Nematode Community Under Different Environmental Conditions
    Bacterivory of a mudflat nematode community under different environmental conditions Pierre-Yves Pascal, Christine Dupuy, Pierre Richard, Jadwiga Rzeznik-Orignac, Nathalie Niquil To cite this version: Pierre-Yves Pascal, Christine Dupuy, Pierre Richard, Jadwiga Rzeznik-Orignac, Nathalie Niquil. Bac- terivory of a mudflat nematode community under different environmental conditions. Marine Biology, Springer Verlag, 2008, pp.671-682. 10.1007/s00227-008-0960-9. hal-00293542 HAL Id: hal-00293542 https://hal.archives-ouvertes.fr/hal-00293542 Submitted on 4 Jul 2008 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. 1 1 Bacterivory of a mudflat nematode community under different 2 environmental conditions 3 Pierre-Yves Pascal *1, Christine Dupuy 1, Pierre Richard 1, Jadwiga Rzeznik-Orignac 2, 4 Nathalie Niquil 1 5 1Littoral, Environnement et Sociétés (LIENSS) UMR 6250 CNRS-Université de La 6 Rochelle, 2 Rue Olympe de Gouges, 17042 La Rochelle cedex, France 7 2Biologie des organismes marins et écosystèmes (BOME) UMR-CNRS 5178–USM 0401– 8 MNHN, 61 Rue Buffon, 75231 Paris, France 9 *Corresponding author: [email protected]; Tel. 33 (0)5-46-45-83-88 10 Abstract 11 The fate of the benthic bacterial biomass is a topic of major importance in understanding 12 how soft-bottom environments function.
    [Show full text]
  • Rhizophagy Cycle: an Oxidative Process in Plants for Nutrient Extraction from Symbiotic Microbes
    microorganisms Review Rhizophagy Cycle: An Oxidative Process in Plants for Nutrient Extraction from Symbiotic Microbes James F. White 1,* , Kathryn L. Kingsley 1, Satish K. Verma 2 and Kurt P. Kowalski 3 1 Department of Plant Biology, Rutgers University, New Brunswick, NJ 08901, USA; [email protected] 2 Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi, UP 221005, India; [email protected] 3 U.S. Geological Survey, Great Lakes Science Center, 1451 Green Road, Ann Arbor, MI 48105-2807, USA; [email protected] * Correspondence: [email protected]; Tel.: +1-848-932-6286 Received: 22 August 2018; Accepted: 5 September 2018; Published: 17 September 2018 Abstract: In this paper, we describe a mechanism for the transfer of nutrients from symbiotic microbes (bacteria and fungi) to host plant roots that we term the ‘rhizophagy cycle.’ In the rhizophagy cycle, microbes alternate between a root intracellular endophytic phase and a free-living soil phase. Microbes acquire soil nutrients in the free-living soil phase; nutrients are extracted through exposure to host-produced reactive oxygen in the intracellular endophytic phase. We conducted experiments on several seed-vectored microbes in several host species. We found that initially the symbiotic microbes grow on the rhizoplane in the exudate zone adjacent the root meristem. Microbes enter root tip meristem cells—locating within the periplasmic spaces between cell wall and plasma membrane. In the periplasmic spaces of root cells, microbes convert to wall-less protoplast forms. As root cells mature, microbes continue to be subjected to reactive oxygen (superoxide) produced by NADPH oxidases (NOX) on the root cell plasma membranes.
    [Show full text]
  • Community Diversity
    Community Diversity Topics What is biodiversity and why is it important? What are the major drivers of species richness? Habitat heterogeneity Disturbance Species energy theory Metobolic energy theory Dynamic equilibrium hypothesis (interactions among disturbance and energy) Resource ratio theory How does biodiversity influence ecosystem function? Biodiversity and ecosystem function hypothesis Integration of biodiversity theory How might the drivers of species richness and hence levels of species richness differ among biomes? Community Diversity Defined Biodiversity Merriam-Webster - the existence of many different kinds of plants and animals in an environment. Wikipedia - the degree of variation of life forms within a given species, ecosystem, biome, or an entire planet. U.S. Congress Office of Technology Assessment - the variety and variability among living organisms and the ecological complexes in which they occur. Diversity can be defined as the number of different items and their relative frequency. For biological diversity, these items are organized at many levels, ranging from complete ecosystems to the chemical structures that are the molecular basis of heredity. Thus, the term encompasses different ecosystems, species, genes, and their relative abundance." Community Diversity Defined Species richness - Species evenness - Species diversity - Community Diversity Defined Species richness - number of species present in the community (without regard for their abundance). Species evenness - relative abundance of the species that are
    [Show full text]
  • Are Fauna the Next Frontier in Soil Biogeochemical Models?
    Soil Biology & Biochemistry 102 (2016) 40e44 Contents lists available at ScienceDirect Soil Biology & Biochemistry journal homepage: www.elsevier.com/locate/soilbio Beyond microbes: Are fauna the next frontier in soil biogeochemical models? * A. Stuart Grandy a, , William R. Wieder b, c, Kyle Wickings d, Emily Kyker-Snowman a a Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH 03824, USA b Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, Boulder, CO 80307, USA c Institute for Arctic and Alpine Research, University of Colorado, Boulder, CO 80309, USA d Department of Entomology, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456, USA article info abstract Article history: The explicit representation of microbial communities in soil biogeochemical models is improving their Received 2 March 2016 projections, promoting new interdisciplinary research, and stimulating novel theoretical developments. Received in revised form However, microbes are the foundation of complicated soil food webs, with highly intricate and non- 3 August 2016 linear interactions among trophic groups regulating soil biogeochemical cycles. This food web includes Accepted 9 August 2016 fauna, which influence litter decomposition and the structure and activity of the microbial community. Available online 25 August 2016 Given the early success of microbial-explicit models, should we also consider explicitly representing faunal activity and physiology in soil biogeochemistry models? Here we explore this question, arguing Keywords: Microbes that the direct effects of fauna on litter decomposition are stronger than on soil organic matter dynamics, fl Fauna and that fauna can have strong indirect effects on soil biogeochemical cycles by in uencing microbial Earth systems models population dynamics, but the direction and magnitude of these effects remains too unpredictable for Food web interactions models used to predict global biogeochemical patterns.
    [Show full text]
  • Microbes Are Trophic Analogs of Animals
    Microbes are trophic analogs of animals Shawn A. Steffana,b,1, Yoshito Chikaraishic, Cameron R. Curried, Heidi Hornd, Hannah R. Gaines-Daya, Jonathan N. Paulie, Juan E. Zalapab, and Naohiko Ohkouchic aDepartment of Entomology, University of Wisconsin, Madison, WI 53706; bUS Department of Agriculture-Agricultural Research Service, University of Wisconsin, Madison, WI 53706; cDepartment of Biogeochemistry, Japan Agency for Marine-Earth Science and Technology, Yokosuka 237-0061, Japan; dDepartment of Bacteriology, University of Wisconsin, Madison, WI 53706; and eDepartment of Forest & Wildlife Ecology, University of Wisconsin, Madison, WI 53706 Edited by James M. Tiedje, Michigan State University, East Lansing, MI, and approved October 15, 2015 (received for review May 5, 2015) In most ecosystems, microbes are the dominant consumers, com- These organisms commandeer most of the heterotrophic biomass mandeering much of the heterotrophic biomass circulating through circulating through the food web (13). Indeed, in terrestrial systems, food webs. Characterizing functional diversity within the micro- the vast majority of primary production is not captured by herbi- biome, therefore, is critical to understanding ecosystem functioning, vores; rather, it falls to the ground and is consumed by microbes and particularly in an era of global biodiversity loss. Using isotopic fin- small invertebrate detritivores (7, 12, 14). Higher-order carnivores gerprinting, we investigated the trophic positions of a broad di- consume the detritivores, conjoining the upward flow of detritivore versity of heterotrophic organisms. Specifically, we examined the and herbivore biomass (9, 11, 15, 16), but if the trophic positions in naturally occurring stable isotopes of nitrogen (15N:14N) within amino the basal layers of the food web cannot be accurately measured, the acids extracted from proteobacteria, actinomycetes, ascomycetes, entire food web rests on a poorly known, tenuous platform (9).
    [Show full text]
  • Burning Reduces Nematode Abundance in Reconstructed Prairies
    Burning reduces nematode abundance in reconstructed prairies EVIE KENEPP Biology Department, Grinnell College, PO Box 805, Grinnell, IA 50112, USA Introduction community upon death (Freckman and Baldwin, 1990). Their effect on Nematodes are one of the most plant production is less numerous and diverse groups of conclusive and depends highly on organisms. They have an intricate the interaction between specific relationship with the soil plant and nematode species: some ecosystem (Freckman & Baldwin, plants are resistant to nematode 1990; Ingham, 1994). Nematodes are invasion, while others are microscopic worms that vary in tolerant of high numbers of size, but most are less than 4 mm nematodes feeding in or on their in length (Freckman and Baldwin, roots (Freckman and Baldwin, 1990). There are six 1990). classifications of nematodes, It is important to know the based on their feeding habits: impact of nematodes on prairie endoparasites, ectoparasites, ecosystems so they can be properly microbivores, and fungivores, managed. Smolick (1974) estimated omnivores and predators, which that root-feeding nematodes play a unique role in soil food consumed as much plant material as webs (Freckman and Virginia, 1997; cattle in a Colorado grassland Ingham, 1994). Plant-feeding ecosystem (as cited in Freckman nematodes affect primary plant and Virginia, 1989). Ingham and production by feeding on roots and Detling (1984) found that in seed heads. Other types of grassland ecosystems, nematode nematodes affect nutrient cycling herbivory decreased plant and decomposition by feeding on production from 6-13% (as cited in fungi, bacteria and microfauna. Freckman and Virginia, 1989). A (Freckman & Baldwin, 1990; high population of root-feeding Freckman & Virginia, 1997).
    [Show full text]
  • Arboreal Arthropod Predation on Early Instar Douglas-Fir Tussock Moth Redacted for Privacy
    AN ABSTRACT OF THE THESIS OF Becky L. Fichter for the degree of Doctor of Philosophy in Entomologypresented onApril 23, 1984. Title: Arboreal Arthropod Predation on Early Instar Douglas-fir Tussock Moth Redacted for privacy Abstract approved: William P. StOphen Loss of early instar Douglas-fir tussock moth( Orgyia pseudotsugata McDunnough) (DFTM) has been found to constitute 66-92% of intra-generation mortality and to be a key factor in inter-generation population change. This death has been attributed to dispersal and to arthropod predation, two factors previously judged more important to an endemic than an outbreak population. Polyphagous arthropod predators are abundant in the forest canopy but their predaceous habits are difficult to document or quantify. The purpose of the study was to develop and test a serological assay, ELISA or enzyme-linked immunosorbent assay, for use as an indirect test of predation. Development of this assay involved production of an antiserum reactive with DFTM but not reactive with material from any coexisting lepidopteran larvae. Two-dimensional immunoelectrophoresis was used to select a minimally cross-reactive fraction of DFTM hemolymph as the antigen source so that a positive response from a field-collected predator would correlate unambiguously with predation on DFTM. Feeding trials using Podisus maculiventris Say (Hemiptera, Pentatomidae) and representative arboreal spiders established the rate of degredation of DFTM antigens ingested by these predators. An arbitrary threshold for deciding which specimens would be considered positive was established as the 95% confidence interval above the mean of controls. Half of the Podisus retained 0 reactivity for 3 days at a constant 24 C.
    [Show full text]
  • Food Webs, Body Size, and Species Abundance in Ecological Community Description
    Food Webs, Body Size, and Species Abundance in Ecological Community Description TOMAS JONSSON, JOEL E. COHEN, AND STEPHEN R. CARPENTER I. Summary ............................................... 2 A. Trivariate Relationships................................ 2 B. Bivariate Relationships ................................ 3 C. Univariate Relationships . ............................ 4 D. EVect of Food Web Perturbation ........................ 4 II. Introduction . ........................................... 4 A. Definitions .......................................... 7 III. Theory: Integrating the Food Web and the Distributions of Body Size and Abundance . ................................... 9 A. Predicting Community Patterns.......................... 10 B. The Distribution of Body Sizes .......................... 13 C. Rank-Abundance and Food Web Geometry . ............. 15 D. Linking the Food Web to the Relationship Between Body Size and Numerical Abundance . ............................ 16 E. Trophic Pyramids and the Relationship Between Consumer and Resource Abundance Across Trophic Levels ............ 18 IV. Data: Tuesday Lake . ................................... 20 A. The Manipulation . ................................... 21 B. The Data ........................................... 22 V. Results: Patterns and Relationships in the Pelagic Community of Tuesday Lake ........................................... 25 A. Trivariate Distributions: Food Web, Body Size, and Abundance 25 B. Bivariate Distributions. ................................ 29 C.
    [Show full text]