Effect of large- and small- bodied zooplankton on phytoplankton in a eutrophic oxbow

Macrozooplankton and microzooplankton effects on the phytoplankton were measured in situ in a eutrophic lake. Indigenous phytoplankton were incubated for 5 days in 301 mesocosms with either the macro- and microzooplankton (complete), microzooplankton only (micro) or no zooplankton (none). Changes in phytoplankton biovolume were investigated. Rotifer densities became significantly higher in the 'micro' treatment than in the 'complete' and 'none' treatments. Total algal biovolume changed little in the 'complete' and 'none' treatments, but increased significantly in the 'micro' treatment. The results suggest that macrozooplankton (Daphnia magna) suppressed it and microzooplankton (Keratella cochlearis) enhanced it. They had opposite net effects on the phytoplankton. Suppression of microzooplankton by Daphnia probably had an indirect negative effect on the phytoplankton

Report of the 2005 Workshop on Ocean Ecodynamics Comparison in the Subarctic Pacific

I. Scientific Issues Posed by OECOS II. Participant Contributions to the OECOS Workshop A. ASPECTS OF PHYTOPLANKTON ECOLOGY IN THE SUBARCTIC PACIFIC Microbial community compositions by Karen E. Selph Subarctic Pacific lower trophic interactions: Production-based grazing rates and grazing-corrected production rates by Nicholas Welschmeyer Phytoplankton bloom dynamics and their physiological status in the western subarctic Pacific by Ken Furuya Temporal and spatial variability of phytoplankton biomass and productivity in the northwestern Pacific by Sei-ichi Saitoh, Suguru Okamoto, Hiroki Takemura and Kosei Sasaoka The use of molecular indicators of phytoplankton iron limitation by Deana Erdner B. IRON CONCENTRATION AND CHEMICAL SPECIATION Iron measurements during OECOS by Zanna Chase and Jay Cullen 25 The measurement of iron, nutrients and other chemical components in the northwestern North Pacific Ocean by Kenshi Kuma The measurement of iron, nutrients and other chemical components in the northwestern North Pacific Ocean by Kenshi Kuma C. PHYSICAL OCEANOGRAPHY, FINE-SCALE DISTRIBUTION PATTERNS AND AUTONOMOUS DRIFTERS The use of drifters in Lagrangian experiments: Positives, negatives and what can really be measured by Peter Strutton The interaction between plankton distribution patterns and vertical and horizontal physical processes in the eastern subarctic North Pacific by Timothy J. Cowles D. MICROZOOPLANKTON Microzooplankton processes in oceanic waters of the eastern subarctic Pacific: Project OECOS by Suzanne Strom Functional role of microzooplankton in the pelagic marine ecosystem during phytoplankton blooms in the western subarctic Pacific by Takashi Ota and Akiyoshi Shinada E. MESOZOOPLANKTON Vertical zonation of mesozooplankton, and its variability in response to food availability, density stratification, and turbulence by David L. Mackas and Moira Galbraith Marine ecosystem characteristics and seasonal abundance of dominant calanoid copepods in the Oyashio region by Atsushi Yamaguchi, Tsutomu Ikeda and Naonobu Shiga OECOS: Proposed mesozooplankton research in the Oyashio region, western subarctic Pacific by Tsutomu Ikeda Some background on Neocalanus feeding by Michael Dagg Size and growth of interzonally migrating copepods by Charles B. Miller Growth of large interzonal migrating copepods by Toru Kobari F. MODELING Ecosystem and population dynamics modeling by Harold P. Batchelder III. Reports from Workshop Breakout Groups A. PHYSICAL AND CHEMICAL ASPECTS WITH EMPHASIS ON IRON AND IRON SPECIATION B. PHYTOPLANKTON/MICROZOOPLANKTON STUDIES C. MESOZOOPLANKTON STUDIES IV. Issues arising during the workshop A. PHYTOPLANKTON STOCK VARIATIONS IN HNLC SYSTEMS AND TROPHIC CASCADES IN THE NANO AND MICRO REGIMES B. DIFFERENCES BETWEEN EAST AND WEST IN SITE SELECTION FOR OECOS TIME SERIES C. TIMING OF OECOS EXPEDITIONS D. CHARACTERIZATION OF PHYSICAL OCEANOGRAPHY V. Concluding Remarks VI. References (109 page document

Skidaway Institute of Oceanography

SkIO is a multidisciplinary research institution within the University System of Georgia and is located on a 700 acre campus on Skidaway Island, 16 miles southeast of Savannah. The Institute sits on the banks of the Skidaway River, with access to a diverse range of estuarine and coastal habitats. Site features a wealth of information regarding SkIO's research and education programs. Data, figures, and more are available in the Research section. Educational levels: Graduate or professional, Undergraduate lower division, Undergraduate upper division

Integrating functional diversity, food web processes, and biogeochemical carbon fluxes into a conceptual approach for modeling the upper ocean in a high-CO2 world

Marine food webs influence climate by channeling carbon below the permanent pycnocline, where it can be sequestered. Because most of the organic matter exported from the euphotic zone is remineralized within the "upper ocean" (i.e., the water column above the depth of sequestration), the resulting CO2 would potentially return to the atmosphere on decadal timescales. Thus ocean-climate models must consider the cycling of carbon within and from the upper ocean down to the depth of sequestration, instead of only to the base of the euphotic zone. Climate-related changes in the upper ocean will influence the diversity and functioning of plankton functional types. In order to predict the interactions between the changing climate and the ocean's biology, relevant models must take into account the roles of functional biodiversity and pelagic ecosystem functioning in determining the biogeochemical fluxes of carbon. We propose the development of a class of models that consider the interactions, in the upper ocean, of functional types of plankton organisms (e.g., phytoplankton, heterotrophic bacteria, microzooplankton, large zooplankton, and microphagous macrozooplankton), food web processes that affect organic matter (e.g., synthesis, transformation, and remineralization), and biogeochemical carbon fluxes (e.g., photosynthesis, calcification, respiration, and deep transfer). Herein we develop a framework for this class of models, and we use it to make preliminary predictions for the upper ocean in a high-CO2 world, without and with iron fertilization. Finally, we suggest a general approach for implementing our proposed class of models

Report of the 2004 Workshop on In Situ Iron Enrichment Experiments in the Eastern and Western Subarctic Pacific

Foreword 1. BACKGROUND AND OBJECTIVES (pdf, 0.1 Mb) 2. 2004 WORKSHOP SUMMARY (pdf, < 0.1 Mb) 2.1. What have we learned from the enrichment experiments? 2.2 What are the outstanding questions? 2.3 Recommendations for SEEDS-II 3. EXTENDED ABSTRACTS OF THE 2004 WORKSHOP 3.1 Synthesis of the Iron Enrichment Experiments: SEEDS and SERIES (pdf, 0.5 Mb) Iron fertilization experiment in the western subarctic Pacific (SEEDS) by Atsushi Tsuda The response of N and Si to iron enrichment in the Northeast Pacific Ocean: Results from SERIES by David Timothy, C.S. Wong, Yukihiro Nojiri, Frank A. Whitney, W. Keith Johnson and Janet Barwell-Clarke 3.2 Biological and Physiological Responses (pdf, 0.2 Mb) Zooplankton responses during SEEDS by Hiroaki Saito Phytoplankton community response to iron and temperature gradient in the NW and NE subarctic Pacific Ocean by Isao Kudo, Yoshifumi Noiri, Jun Nishioka, Hiroshi Kiyosawa and Atsushi Tsuda SERIES: Copepod grazing on diatoms by Frank A. Whitney, Moira Galbraith, Janet Barwell-Clarke and Akash Sastri The Southern Ocean Iron Enrichment Experiment: The nitrogen uptake response by William P. Cochlan and Raphael M. Kudela 3.3 Biogeochemical Responses (pdf, 0.5 Mb) What have we learned regarding iron biogeochemistry from iron enrichment experiments? by Jun Nishioka, Shigenobu Takeda and W. Keith Johnson Iron dynamics and temporal changes of iron speciation in SERIES by W. Keith Johnson, C.S. Wong, Nes Sutherland and Jun Nishioka Dissolved organic matter dynamics during SEEDS and SERIES experiments by Takeshi Yoshimura and Hiroshi Ogawa Formation of transparent exopolymer particles during the in-situ iron enrichment experiment in the western subarctic Pacific (SEEDS) by Shigenobu Takeda, Neelam Ramaiah, Ken Furuya and Takeshi Yoshimura Atmospheric measurement by Mitsuo Uematsu 3.4 Prediction from Models (pdf, 0.3 Mb) Modelling iron limitation in the North Pacific by Kenneth L. Denman and M. Angelica Peña A proposed model of the SERIES iron fertilization patch by Debby Ianson, Christoph Voelker and Kenneth L. Denman 4. LIST OF PARTICIPANTS FOR THE 2004 WORKSHOP (pdf, < 0.1 Mb) APPENDIX 1 Report of the 2000 Planning Workshop on Designing the Iron Fertilization Experiment in the Subarctic Pacific (pdf, 1 Mb) APPENDIX 2 Terms of Reference for the Advisory Panel on Iron fertilization experiment in the subarctic Pacific Ocean (pdf, < 0.1 Mb) APPENDIX 3 Historical List of Advisory Panel Members on Iron fertilization experiment in the subarctic Pacific Ocean (pdf, < 0.1 Mb) APPENDIX 4 IFEP-AP Annual Reports (pdf, 0.1 Mb) APPENDIX 5 PICES Press Articles (pdf, 0.6 Mb) (194 page document

Brown Tide Symposium and Workshop : 15-16 July 1991

The 'brown tide' bloom of an aberrant Chrysophyte sp. phytoplankter occurred for more than 18 months and extended into both upper (cover map) and lower Laguna Madre, Texas. Great concern for the Laguna Madre ecosystem was shown during the brown tide event by local, state and regional groups, but little previous knowledge was available about this unusual phytoplankton bloom. Since field data had been collected by an ongoing UTMSI field program in the Laguna, it was felt that a workshop format meeting should be convened with national and international experts to discuss the data and results on brown tide and other unusual phytoplankton blooms. A relatively quick response was needed as planning for the workshop started in May 1991 for a meeting date in July, with support supplied by the Gulf of Mexico Program of U.S. Environmental Protection Agency (Grant No. X 006242-01-0), The Resource Protection Division of the Texas Parks and Wildlife Department and The University of Texas Marine Science Institute. This report includes the agenda, abstracts of presentations and summary of findings by the workshop participants. The participants also strongly agreed that long term research support was necessary to further understand the brown tide bloom and its effects. To that end, a resolution was drafted and unanimously approved by all the workshop participants.September 1991Marine Scienc

Ocean odours

The ocean's distinctive smell is caused by a single chemical released by plankton and other marine life, dimethyl sulphide (DMS). A study by a group of investigators from the University of Groningen used a technique called laser-sheet particle image velocimetry to monitor the water flows produced by aquatic animals. The investigators looked closely at how DMS affects copepods. Their tests showed that when DMS hit a copepod, the test animal reacted with a search behaviour. This demonstrates that copepods can smell the DMS and suggests that this and possibly other compounds released by phytoplankton and microzooplankton may help copepods in finding their prey

Coupling the PLANKTOM5.0 marine ecosystem model to the OCCAM 1º ocean general circulation model for investigation of the sensitivity of global biogeochemical cycles to variations in ecosystem complexity and physical environment

The earliest marine ecosystem models consisted of a simple representation of the main features of marine ecosystems, including, typically, variables for phytoplankton, zooplankton, nutrient and detritus (NPZD models). These have been incorporated into ocean general circulation models to give a basic representation of ecosystem function, providing predictions of bulk quantities such as global primary production, export and biomass which can be compared with available observations. A recent trend has been to increase the number of phytoplankton and zooplankton groups modelled, as analogues of different plankton groups observed to exist in the ocean, for example diatoms and cocolithophores (the so-called plankton functional type or PFT approach). It is usually assumed that the increase in complexity of the model will result in simulated ecosystems which more faithfully reproduce observations than NPZD models, but this has not been demonstrated systematically. The robustness of the PFT models to changes in model parameters and to changes to the physical environment in which it is embedded, have not been investigated. As a first step towards these goals, we incorporate a state-of-the-art PFT model, PLANKTOM5.0 into the OCCAM ocean general circulation model. A 6 year simulation is performed, covering the years 1989-1994 with identical parameter choices to an existing run of PLANKTOM5.0 coupled to the OPA general circulation model. This document describes the development of the coupled model and the 6 year simulation. Comparison with the OPA model and sensitivity of the solution to parameter choices will be described in a forthcoming journal paper