DOCSLIB.ORG

Freshwater Biology, in Press

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Freshwater Biology, in Press Freshwater Biology (2008) 53, 1291–1302 doi:10.1111/j.1365-2427.2008.01962.x Stoichiometric relationships in vernal pond plankton communities CARLA E. CA´ CERES*,ALANJ.TESSIER†, ANDRI ANDREOU* AND MEGHAN A. DUFFY‡ *School of Integrative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, U.S.A. †Division of Environmental Biology, National Science Foundation, Arlington, VA, U.S.A. ‡School of Biology, Georgia Institute of Technology, Atlanta, GA, U.S.A. SUMMARY 1. The light-nutrient hypothesis (LNH) predicts that changes in light supply can alter the balance of nutrient and energy limitation in primary producers. We tested this prediction by examining temporal changes in vernal forest ponds, which are highly dynamic systems with respect to seasonal change in light and nutrient supply. In three vernal ponds that differ in productivity, we measured changes in light, total and seston nitrogen and phosphorus, and seston carbon and chlorophyll during the spring, before and after tree leaf-out. We also quantified changes in the population dynamics of the major zooplankton grazers in these systems. 2. In each pond, nutrient levels increased and light levels declined, creating a temporal shift in light-nutrient supply to the plankton. Results generally supported predictions of stoichiometric theory and the LNH, but there were notable exceptions. 3. Seston C : N : P ratios rapidly changed in response to dramatic increases in N and P supply rates. However, seston N : P was typically lower than values for total N : P in the water. Furthermore, as predicted, we observed a decline in seston C : P as the light : nutrient ratio declined, but seston C : N simultaneously increased. These results suggest an unexpected shift towards potential nitrogen limitation. Alternatively, this change in nutrient ratios may be driven by a seasonal change in phytoplankton composition or nutritional mode. 4. Seston carbon concentrations remained stable despite seasonal changes in grazing intensity associated with the phenology of large-bodied Daphnia grazers. However, chlorophyll concentrations declined dramatically as the season progressed, resulting in a simultaneous decline in the C : Chlorophyll ratio of seston. Both pond shading and increased grazing probably contributed to the decline in chlorophyll. Keywords: carbon, Daphnia, light-nutrient hypothesis, nitrogen, phosphorus questions of energy versus nutrient limitation can be Introduction addressed at multiple trophic levels (Hassett et al., Ecological stoichiometry, the balance of nutrients and 1997; Elser et al., 2000; Hall et al., 2006). The elemental energy in ecological interactions, provides a valuable composition of primary producers fluctuates in framework for investigating trophic interactions response to external changes in nutrient supply (Sterner & Elser, 2002). By tracking supply rates of whereas that of grazers is more constant (Andersen elements such as carbon, nitrogen and phosphorus & Hessen, 1991; Hessen & Faafeng, 2000). Hence, through the primary producers and into grazers, stoichiometric theory predicts thresholds of change where, depending upon the nutrient supply ratios, it Correspondence: Carla E. Ca´ceres, 515 Morrill Hall, Urbana, IL is expected that grazers can become limited by 61801, U.S.A. Email: [email protected] nutrients (food quality) rather than energy (food Ó 2008 The Authors, Journal compilation Ó 2008 Blackwell Publishing Ltd 1291 1292 C. E. Ca´ceres et al. quantity). Such transitions impact energy flow and reasons. First, these systems tend to exhibit dramatic nutrient recycling within ecosystems, can shift com- temporal changes in light and nutrient supply levels petitive relationships among species, and shape the (Colburn, 2004). In forested ponds, tree leaves pre- evolution of organism physiology and life history dictably open out over the course of a few weeks, (Andersen, 1997; Sterner & Elser, 2002). decreasing light levels dramatically. In addition, The stoichiometric framework considers more than vernal ponds form from nutrient-dilute snowmelt just the supply of elemental nutrients. Light is also and rain, but should experience a large increase in important, as is the interaction between light and nutrient supply due to decomposition from forest nutrients. In their light-nutrient hypothesis (LNH), floor litter (Wilbur, 1997). Second, temporary ponds Sterner et al. (1997) make several predictions regard- are often dominated by mixotrophic algae (Colburn, ing how nutrient use efficiency should vary across 2004). As the season progresses, this ability to change systems experiencing different light to nutrient ratios. nutritional mode as light and nutrient supply ratios The general concept is that as light becomes more are altered, coupled with overall changes in species limiting to primary producers, their elemental com- composition, may contribute to variance in the stoi- position should become enriched in nutrients such as chometric ratios of the seston. Third, the influence of nitrogen and phosphorus relative to carbon, resulting top-down factors on seston stoichiometry can fluctu- in increased food quality for grazers and higher ate just as dramatically as the bottom-up factors of trophic transfer efficiency. Of course, low light condi- light and nutrients (DeMott & Tessier, 2002). Hall tions will also reduce overall primary productivity, et al. (2007) showed evidence that grazers may play a decreasing food quantity for grazers. However, the key role in explaining field patterns of variation in evidence available from lakes suggests that limitation seston stoichiometry. In particular, top-down effects via food quality (including stoichiometry, phyto- of grazers increase turnover rate of the producers and plankton assemblage, fatty acid composition, etc.) is recycling rates of elements, both of which are often more important than is limitation by food expected to influence the stoichiometry of producers. quantity (Sterner & Schulz, 1998). Large-bodied daphniid species, which are a hallmark Several predictions of the LNH have been con- of temporary ponds (Schneider & Frost, 1996; firmed by focusing on comparisons among lakes that Colburn, 2004), hatch from diapausing eggs and can differ in mixing depth (mean light conditions for the quickly attain high biomass. Just as quickly, these phytoplankton), transparency and productivity either populations can disappear from the water entirely, as by using short-term manipulations such as mesocosm the result of producing diapausing rather than imme- experiments or broad-scale comparative studies (e.g. diately hatching eggs and increased predation. This Urabe & Sterner, 1996; Sterner et al., 1997; Hessen, creates a highly dynamic system with respect to Færøvig & Andersen, 2002; Diehl, Berger & Wohrl, grazer-imposed mortality rates on the primary pro- 2005; Schade et al., 2005; Dickman, Vanni & Horgan, ducers. 2006). Hall et al. (2007) extended the LNH to include In this study, we ask how temporal changes in light ponds that differ in light caused by tree shading, but and nutrient supply coupled with seasonal changes in still considered only spatial variation among commu- grazer abundance relate to seston stoichiometry in nities. However, light limitation has long been viewed three temporary ponds located in southwestern MI, as central in explaining temporal variation in primary U.S.A. Specifically, we addressed the following ques- productivity in most temperate ecosystems, and is tions (1) Are the patterns of temporal changes in pivotal to our understanding of seasonal succession in seston stoichiometry similar across ponds that differ the plankton (Sommer et al., 1986). The LNH predicts in trophic state (nutrient supply)? (2) Are these that an annual reduction in light level may cause a temporal changes related to the reduction in light shift in the balance of nutrient and light limitation in supply caused by tree leaf-out? In addition, we the phytoplankton. However, this prediction has discuss how seasonal changes in grazer abundance received limited testing (Chrzanowski & Grover, may influence, or be influenced by, seston stoichiom- 2001). etry. Our study was motivated by the premise that Vernal ponds are intriguing systems in which to temporal shifts in elemental ratios, including light, address these stoichiometric concepts for a number of may be particularly important in forested temporary Ó 2008 The Authors, Journal compilation Ó 2008 Blackwell Publishing Ltd, Freshwater Biology, 53, 1291–1302 Stoichiometry in temporary ponds 1293 ponds, where canopy closure, temporal variation in <15 lm and <3 lm) were also filtered onto GF ⁄F glass- supply rates and variable grazing pressure can create fibre filters, extracted in cold 95% ethanol and mea- substantial seasonal changes. sured by use of narrow band fluorometry (Welsch- meyer, 1994). To sample the zooplankton assemblage, we col- Methods lected three replicate zooplankton samples (12–21 L We studied three natural, vernal forest ponds that each) on each date by pooling 4–7 (depending on differ in productivity as reflected by nutrient concen- pond size) grab samples, taken with a 3-L pitcher. trations of nitrogen and phosphorus (Roughwood, The grab samples were taken while walking a Woodfrog and West Gull). The ponds, located in transect through the middle of each pond, taking Kalamazoo County, MI, U.S.A., fill with snowmelt care not to resample previously disturbed areas and rainwater in early spring (March–early April), at (Dudycha, 2004). Two of the samples
Load more

Recommended publications
  • Freshwater Ecosystems and Biodiversity
    Network of Conservation Educators & Practitioners Freshwater Ecosystems and Biodiversity Author(s): Nathaniel P. Hitt, Lisa K. Bonneau, Kunjuraman V. Jayachandran, and Michael P. Marchetti Source: Lessons in Conservation, Vol. 5, pp. 5-16 Published by: Network of Conservation Educators and Practitioners, Center for Biodiversity and Conservation, American Museum of Natural History Stable URL: ncep.amnh.org/linc/ This article is featured in Lessons in Conservation, the official journal of the Network of Conservation Educators and Practitioners (NCEP). NCEP is a collaborative project of the American Museum of Natural History’s Center for Biodiversity and Conservation (CBC) and a number of institutions and individuals around the world. Lessons in Conservation is designed to introduce NCEP teaching and learning resources (or “modules”) to a broad audience. NCEP modules are designed for undergraduate and professional level education. These modules—and many more on a variety of conservation topics—are available for free download at our website, ncep.amnh.org. To learn more about NCEP, visit our website: ncep.amnh.org. All reproduction or distribution must provide full citation of the original work and provide a copyright notice as follows: “Copyright 2015, by the authors of the material and the Center for Biodiversity and Conservation of the American Museum of Natural History. All rights reserved.” Illustrations obtained from the American Museum of Natural History’s library: images.library.amnh.org/digital/ SYNTHESIS 5 Freshwater Ecosystems and Biodiversity Nathaniel P. Hitt1, Lisa K. Bonneau2, Kunjuraman V. Jayachandran3, and Michael P. Marchetti4 1U.S. Geological Survey, Leetown Science Center, USA, 2Metropolitan Community College-Blue River, USA, 3Kerala Agricultural University, India, 4School of Science, St.
    [Show full text]
  • Sediment Fe:PO4 Ratio As a Diagnostic and Prognostic Tool for the Restoration of Macrophyte Biodiversity in Fen Waters
    Freshwater Biology (2008) 53, 2101–2116 doi:10.1111/j.1365-2427.2008.02038.x APPLIED ISSUES Sediment Fe:PO4 ratio as a diagnostic and prognostic tool for the restoration of macrophyte biodiversity in fen waters JEROEN J. M. GEURTS*,†,ALFONSJ.P.SMOLDERS*,†, JOS T. A. VERHOEVEN‡,JANG.M. ROELOFS* AND LEON P. M. LAMERS* *Aquatic Ecology and Environmental Biology, Institute for Wetland and Water Research, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands †B-WARE Research Centre, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands ‡Landscape Ecology, Institute of Environmental Biology, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands SUMMARY 1. Globally, freshwater wetlands, including fen waters, are suffering from biodiversity loss due to eutrophication, water shortage and toxic substances, and to mitigate these pressures numerous restoration projects have been launched. Water quality data are generally used to evaluate the chances of reestablishment of aquatic vegetation in fen waters and shallow peat lakes. Here we investigated whether sediment characteristics, which are less prone to fluctuate in time, would result in more reliable predictions. 2. To test if sediment characteristics can indeed be used not only for an easy and early diagnosis of nutrient availability and water quality changes in fen waters, but also for the prognosis of biodiversity response, we recorded the aquatic vegetation and collected surface water, sediment pore water and sediment samples in 145 fen waters in the Netherlands, Ireland and Poland. 3. Endangered macrophyte species were more closely related to surface water chemis- try than common species in terms of occurrence and abundance.
    [Show full text]
  • Marine, Estuarine and Freshwater Biology Major (B.S.)
    University of New Hampshire 1 MEFB 401 Marine Estuarine and Freshwater Biology: 1 MARINE, ESTUARINE AND Freshmen Seminar MEFB 503 Introduction to Marine Biology 4 FRESHWATER BIOLOGY MEFB 525 Introduction to Aquatic Botany 4 MAJOR (B.S.) MEFB 527 Aquatic Animal Diversity 4 Choose one Freshwater course: 4 http://colsa.unh.edu/dbs/mefb/marine-estuarine-and-freshwater-biology- MEFB 717 Lake Ecology bs or MEFB 719Field Studies in Lake Ecology Choose one Physiology/Function course: 4-5 Description ZOOL 625 Principles of Animal Physiology & ZOOL 626 and Animal Physiology Laboratory The Major in Marine, Estuarine and Freshwater Biology is intended to or ZOOL 773 Physiology of Fish give students interested in the fields of marine and freshwater biology Choose one Marine or Estuarine course: 4 the background to pursue careers, including potential advanced study, in MEFB 725 Marine Ecology this area of biology. The major builds on a broad set of basic scientific or ZOOL 750 Biological Oceanography courses represented by a core curriculum in math, chemistry, physics and biology. The background in basic science is combined with a series of MEFB Electives: Choose 3 required and elective courses in the aquatic sciences from watershed Evolution, Systematics and Biodiversity to ocean. The goal is to provide a solid foundation of knowledge in BIOL 566 Systematic Botany 4 freshwater, estuarine and marine biology while having the flexibility to GEN 713 Microbial Ecology and Evolution 4 focus on particular areas of scientific interest from molecular biology to MEFB 625 Introduction to Marine Botany 4 ecosystem studies. Students will have the opportunity to specialize in areas of their own interest, such as aquaculture and fisheries or animal MEFB 722 Marine Phycology 4 behavior.
    [Show full text]
  • Can Results from Simple Aquatic Mesocosm Experiments Be Applied Across Broad Spatial Scales?
    Freshwater Biology (2010) doi:10.1111/j.1365-2427.2010.02495.x Moving on up: can results from simple aquatic mesocosm experiments be applied across broad spatial scales? AMANDA C. SPIVAK, MICHAEL J. VANNI AND ELIZABETH M. METTE Zoology Department, Miami University, Oxford, OH, U.S.A. SUMMARY 1. Aquatic ecologists use mesocosm experiments to understand mechanisms driving ecological processes. Comparisons across experiments, and extrapolations to larger scales, are complicated by the use of mesocosms with varying dimensions. We conducted a mesocosm experiment over a volumetric scale spanning five orders of magnitude (from 4 L to whole ponds) to determine the generality of algal responses to nutrient enrichment. Recognising that mesocosm dimensions may affect algal growth, we also manipulated the ratio of mesocosm surface area to volume (SA : V) over two levels (high versus low). We used mesocosm tanks of similar size and construction to those commonly used in aquatic experiments to increase the generality of our results. 2. Volume was generally a stronger determinant of algal responses than mesocosm shape (i.e. SA : V). However, the effects of both volume and shape on algae were weak and explained a small portion of the variance in response variables. In addition, there was no consistent, directional relationship (positive or neutral) between mesocosm volume and algal abundance (estimated by chlorophyll concentration). Combined, our findings suggest that results from small-scale experiments, examining the direct response of algae to nutrient enrichment, can probably be ‘moved on up’ and applied to larger, more natural aquatic systems. 3. Algal response to nutrient enrichment (e.g.
    [Show full text]
  • Freshwater Fish Biogeography in the Bering Glacier Region, Alaska
    Freshwater Fish Biogeography In The Bering Glacier Region, Alaska Item Type Thesis Authors Weigner, Heidi L. Download date 06/10/2021 09:41:47 Link to Item http://hdl.handle.net/11122/9162 FRESHWATER FISH BIOGEOGRAPHY IN THE BERING GLACIER REGION, ALASKA A DISSERTATION Presented to the Faculty of the University of Alaska Fairbanks in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY By Heidi L. Weigner, B.S. Fairbanks, Alaska December 2012 UMI Number: 3537845 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. UMI 3537845 Published by ProQuest LLC 2013. Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code. ProQuest LLC 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106-1346 FRESHWATER FISH BIOGEOGRAPHY IN THE BERING GLACIER REGION, ALASKA By Heidi L. Weigner RECOMMENDED: Chair, Dgpartment of Biology and Wildlife APPROVED: Abstract Bering Glacier, Alaska, is Earth’s largest surging glacier, with surges occurring approximately every 20-30 years since 1900. Surges and subsequent retreats lead to a dynamic environment for aquatic communities, as glacial ice over-rides landscapes and new habitats form during glacial retreat. Lands around Bering Glacier are administered by the State of Alaska and the U.S.
    [Show full text]
  • Freshwater Biology ----�------�----�------�--- (2010) 1205-1218 Doi:1O.1111/J.1365-2427.2009.02344.X Freshwater Biology 55
    Freshwater Biology ----�----------------�----�----- ---------�--- (2010) 1205-1218 dOi:1O.1111/j.1365-2427.2009.02344.x Freshwater Biology 55, Ecoregion and land-use influence invertebrate and detritus transport from headwater streams t CHRISTOPHER A. BINCKLEY*, MARK S. WIPFLI , R. BRUCE MEDHURST*, KARL POLIVKA�, PAUL HESSBURG�, R. BRION SALTER� AND JOSHUA Y. KILL� *Alaska Cooperative Fish and Wildlife Research Unit, Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, U.S.A. t us Geological Survey, Alaska Cooperative Fish and Wildlife Research Unit, Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, U.S.A. � Pacific Northwest Research Station, US Forest Service, 1133 N. Western Ave, Wenatchee, WA, U.S.A. SUMMARY 1. Habitats are often connected by fluxes of energy and nutrients across their boundaries. For example, headwater streams are linked to surrounding riparian vegetation through invertebrate and leaf litter inputs, and there is evidence that consumers in downstream habitats are subsidised by resources flowing from headwater systems. However, the strength of these linkages and the manner in which potential headwater subsidies vary along climatic and disturbance gradients are unknown. 2. We quantified the downstream transport of invertebrates, organic matter and inorganic sediment from 60 fishless headwater streams in the Wenatchee River Basin located on the eastern slope of the Cascade Range in Washington, U.s.A. Streams were classified into four groups (each n = 15) based on their position within two ecological subregions (wet and dry) and the extent of past timber harvest and road development (logged and unlogged). 3. Time and ecoregion were significant for all response variables as transport varied across sampling periods, and dry ecoregion streams displayed significantly higher mean values.
    [Show full text]
  • Development of a Zooplankton Biotic Index for Trophic State Prediction in Tropical Reservoirs
    Limnetica, 38(1): 303-316 (2019). DOI: 10.23818/limn.38.21 © Asociación Ibérica de Limnología, Madrid. Spain. ISSN: 0213-8409 Development of a zooplankton biotic index for trophic state prediction in tropical reservoirs Bruno Paes De-Carli1,2,*, Adriano Bressane3, Regina Márcia Longo3, Agatha Manzi-Decarli2, Viviane Moschini-Carlos1 and Marcelo Luiz Martins Pompêo4 1 São Paulo State University (UNESP), Institute of Science and Technology, Environmental Sciences Graduate Program, Campus at Sorocaba city, 03 March Avenue, 511, Brazil. 2 Paulista University (UNIP), Institute of Health, Campus at Santos city, Francisco Manoel Avenue, unnum- bered, Brazil. 3 Pontifical Catholic University of Campinas (PUCCAMP), Faculty of Environmental engineering, Dom Pedro I Highway (SP-065), Brazil. 4 Department of Ecology (IB-USP), University of São Paulo, São Paulo, Brazil. * Corresponding author: [email protected] Received: 31/07/18 Accepted: 26/11/18 ABSTRACT Development of a zooplankton biotic index for trophic state prediction in tropical reservoirs Reservoirs are built mainly for public supply and power generation. However, water quality is almost always compromised by discharge of domestic and industrial sewage, as well as by agricultural residues. Several ecological indices are currently used to analyze different impacts in this environment. The aim of this study was to develop a zooplankton index for tropical reservoirs. Limnological data were obtained from seven Brazilian reservoirs (Atibainha, Broa, Barra Bonita, Salto Grande, Rio Grande, Itupararanga, and Igaratá). Weighted values of ecological optimum were obtained through species response analysis (unimodal distribution) related to chlorophyll a concentration. The results obtained using the zooplankton index (ZBI) proposed had significant correlations with eutrophication indicators.
    [Show full text]
  • How Important Are Terrestrial Organic Carbon Inputs for Secondary Production in Freshwater Ecosystems?
    Accepted: 19 January 2017 DOI: 10.1111/fwb.12909 REVIEW How important are terrestrial organic carbon inputs for secondary production in freshwater ecosystems? Michael T. Brett1 | Stuart E. Bunn2 | Sudeep Chandra3 | Aaron W. E. Galloway4 | Fen Guo2 | Martin J. Kainz5 | Paula Kankaala6 | Danny C. P. Lau7 | Timothy P. Moulton8 | Mary E. Power9 | Joseph B. Rasmussen10 | Sami J. Taipale11 | James H. Thorp12,13 | John D. Wehr14 1 Department of Civil & Environmental Engineering, University of Washington, Seattle, WA, U.S.A. 2 Australian Rivers Institute, Griffith University, Brisbane, QLD, Australia 3 Global Water Center and Biology Department, University of Nevada, Reno, NV, U.S.A. 4 Oregon Institute of Marine Biology, University of Oregon, Charleston, OR, U.S.A. 5 WasserCluster Lunz-Biological Station, Donau-Universit€at Krems, Lunz am See, Austria 6 Department of Environmental and Biological Sciences, University of Eastern Finland, Joensuu, Finland 7 Department of Ecology and Environmental Science, Umea University, Umea, Sweden 8 Departamento de Ecologia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil 9 Department of Integrative Biology, University of California Berkeley, Berkeley, CA, U.S.A. 10 Department of Biological Sciences, University of Lethbridge, Lethbridge, AB, Canada. 11 Department of Biological and Environmental Science, University of Jyv€askyla,€ Jyv€askyla,€ Finland 12 Kansas Biological Survey, Lawrence, KS, U.S.A. 13 Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, U.S.A. 14 Louis Calder Center – Biological Field Station, Fordham University, Armonk, NY, U.S.A. Correspondence Michael T. Brett, Department of Civil and Abstract Environmental Engineering, University of 1.
    [Show full text]
  • Relative Importance of Phosphorus, Invasive Mussels and Climate for Patterns in Chlorophyll a and Primary Production in Lakes Michigan and Huron David M
    University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln USGS Staff -- ubP lished Research US Geological Survey 2015 Relative importance of phosphorus, invasive mussels and climate for patterns in chlorophyll a and primary production in Lakes Michigan and Huron David M. Warner USGS Great Lakes Science Center, Ann Arbor, MI Barry M. Lesht University of Illinois at Chicago Follow this and additional works at: http://digitalcommons.unl.edu/usgsstaffpub Warner, David M. and Lesht, Barry M., "Relative importance of phosphorus, invasive mussels and climate for patterns in chlorophyll a and primary production in Lakes Michigan and Huron" (2015). USGS Staff -- Published Research. 866. http://digitalcommons.unl.edu/usgsstaffpub/866 This Article is brought to you for free and open access by the US Geological Survey at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in USGS Staff -- ubP lished Research by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Freshwater Biology (2015) 60, 1029–1043 doi:10.1111/fwb.12569 Relative importance of phosphorus, invasive mussels and climate for patterns in chlorophyll a and primary production in Lakes Michigan and Huron † DAVID M. WARNER* AND BARRY M. LESHT *USGS Great Lakes Science Center, Ann Arbor, MI, U.S.A. † Department of Earth and Environmental Sciences, University of Illinois at Chicago, Chicago, IL, U.S.A. SUMMARY 1. Lakes Michigan and Huron, which are undergoing oligotrophication after reduction of phosphorus loading, invasion by dreissenid mussels and variation in climate, provide an opportunity to conduct large-scale evaluation of the relative importance of these changes for lake productivity.
    [Show full text]
  • Predation on Seabirds by Pacific Cod Gadus Macrocephalus Near the Aleutian Islands, Alaska
    Ulman et al.: Pacific Cod predation on seabirds 231 PREDATION ON SEABIRDS BY PACIFIC COD GADUS MACROCEPHALUS NEAR THE ALEUTIAN ISLANDS, ALASKA SADIE E.G. ULMAN1, TUULA HOLLMÉN2, REID BREWER3 & ANNE H. BEAUDREAU4 1Alaska SeaLife Center, Seward, Alaska 99664 ([email protected]) 2Alaska SeaLife Center and School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Seward, Alaska 99664 3University of Alaska Southeast, Sitka, Alaska 99835 4School of Fisheries and Ocean Sciences, Fisheries Division, University of Alaska Fairbanks, Juneau, Alaska 99801 Received 15 July 2015, accepted 28 July 2015 SUMMARY ULMAN, S.E.G., HOLLMÉN, T., BREWER, R. & BEAUDREAU, A.H. 2015. Predation on seabirds by Pacific cod Gadus microcephalus near the Aleutian Islands, Alaska. Marine Ornithology 43: 231–233. In marine systems, most seabirds are considered upper trophic level consumers, yet they may be vulnerable to predation by other marine animals. There are varying accounts of large fish eating birds, but little is known about whether predation by demersal fish predators is an important source of mortality for seabirds. Fish processors in Dutch Harbor, Alaska, have observed seabird remains in Pacific Cod Gadus macrocephalus stomachs. We analyzed seabird remains from Pacific Cod caught off Cape Sarichef in Unimak Pass from mid-January through early April 2011. Of 74 different seabird remains examined, five avian genera were identified. These results provide documentation that Pacific Cod consume seabirds; either by predation or scavenging. Overall, the significance of seabird predation by fish is not well known, but may be episodically important. Key words: Pacific cod, predation, diet, Crested Auklet Aethia cristatella Seabirds by and large exhibit decreasing populations, and current bird species that were recovered from stomachs of commercially major threats include pollution and commercial fisheries at sea, and harvested cod and discuss potential mechanisms for this interaction.
    [Show full text]
  • Freshwater Biology and Water Supply in Britain
    Freshwater biology and water supply in Britain Item Type book Authors Pearsall, W.H.; Gardiner, A.C.; Greenshields, F. Publisher Freshwater Biological Association Download date 09/10/2021 18:01:49 Link to Item http://hdl.handle.net/1834/22850 FRESHWATER BIOLOGICAL ASSOCIATION OF THE BRITISH EMPIRE Scientific Publication No. 11 FRESHWATER BIOLOGY AND WATER SUPPLY IN BRITAIN by W. H. PEARSALL, D.Sc. F.R.S. A. C. GARDINER, M.A. F. GREENSHIELDS, Ph.D. Price to non-members 4s. 0d. 1946 FRESHWATER BIOLOGICAL ASSOCIATION. Wray Castle, Ambleside, Westmorland. PUBLICATIONS. Scientific Publications (Nos. 1 to 6 and No. 8 post free 1s. 7d. each. Nos. 7, 9, 10 post free 2s. 7d., and No. 11 post free 4s. 1d.) No. 1. A key to the British Species of Corixidae (Hemiptera- Heteroptera) with notes on their distribution, by T. T. Macan. No. 2. A key to the British Species of Plecoptera (Stoneflies) with notes on their ecology, by H. B. N. Hynes. No. 3. The Food of Coarse Fish, by P. H. T. Hartley. No. 4. A key to the British Water Bugs (Hemiptera-Heteroptera excluding Corixidae) with notes on their ecology, by T. T. Macan. No. 5. A key to the British Species of Freshwater Cladocera, with notes on their ecology, by D. J. Scourfield and J. P. Harding, No. 6. The Production of Freshwater Fish for Food, by T. T. Macan, C. H. Mortimer and E. B. Worthington. No. 7. Keys to the British Species of Ephemeroptera, with keys to the genera of the nymphs, by D. E.
    [Show full text]
  • Marine & Freshwater Biology
    Bachelor of Science Marine & Freshwater Biology ABOUT THE PROGRAM The Marine and Freshwater Biology co-op major provides a broad perspective on aquatic environments based on the physical as well as the biological sciences. Students build upon core courses in ecology, evolution, genetics, and physiology of aquatic biota as you study freshwater and marine environments and work with aquatic organisms experimentally in the field and in the lab. You will have the opportunity to perform independent research projects under a variety of field and laboratory conditions to enhance your learning experience and participate in co-op work terms to gain knowledge and skills in a workplace setting. The Marine and Freshwater Biology major capitalizes on Guelph's recognized excellence in aquatic research. The state-of-the-art Hagen Aqualab on campus allows researchers and students to simulate global aquatic environments and maintain a wide variety of marine and freshwater flora and fauna in Guelph. This program prepares students for post-graduate work in the aquatic sciences, and provides a sound scientific background for students pursuing careers in biology, management and conservation, aquaculture, biotechnology, education, and research in either government or private sectors. WHY CO-OP? As a co-op student, you will gain relevant work experience, build professional networks, and develop essential interpersonal skills needed to succeed in the workplace, all while getting paid and earning your university degree. Guelph’s co-op program is unique due to the exceptional level of support provided, including a co-op preparatory course, a personal connection with a Co-op Coordinator to assist you during the employment process, and access to senior student mentors.
    [Show full text]