Production cycles in aquatic microcosms

Technical Report · Tue Feb 08 04:00:00 EST 1977

DOI:https://doi.org/10.2172/7309730· OSTI ID:7309730

Jassby, A; Dudzik, M; Rees, J; Lapan, E; Levy, D; Harte, J

Four 700-liter cylindrical containers were filled with demineralized water, enriched with nutrients, and inoculated with 3.5-liter lakewater samples. The microcosms were maintained at a temperature of 18/sup 0/C under a 12:12 L:D cycle for 6 months and several manipulations of their trophic structure were carried out, including addition of snails (Physa sp.), mosquitofish (Gambusia affinis), and catfish (Placostomas placostomas). Temporal variation of the phytoplankton resembled the bimodal patterns of certain natural systems. Further analysis demonstrated a close analogy with the predator-prey oscillations of temperate marine waters: an initial bloom is terminated by zooplankton grazing; the resulting low phytoplankton levels lead to gradual starvation of the zooplankton; and a second bloom follows the final dieoff of zooplankton. Both decreasing the concentration of initial nutrients and stocking the microcosms with Gambusia decreases the time between the spring and fall blooms. The problem of heavy periphyton growth in microcosms was not solved with the introduction of either Physa or Placostomas. Possible solutions to this and to other problems peculiar to microcosm research are discussed, and modifications are suggested for increasing the ability of microcosms to simulate natural systems.

• Research Organization: California Univ., Berkeley (USA). Lawrence Berkeley Lab.
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 7309730
• Report Number(s): LBL-5965
• Country of Publication: United States
• Language: English

Related Subjects

520100* -- Environment
Aquatic-- Basic Studies-- (-1989)
54 ENVIRONMENTAL SCIENCES
550500 -- Metabolism
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
AQUATIC ECOSYSTEMS
AQUATIC ORGANISMS
BIOMASS
CELL CONSTITUENTS
CHEMICAL REACTIONS
DIFFUSION
ECOSYSTEMS
ENERGY SOURCES
FISHES
FOOD
GROWTH
INVERTEBRATES
MOLLUSCS
NUTRIENTS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PHYTOPLANKTON
PLANKTON
RENEWABLE ENERGY SOURCES
SEASONAL VARIATIONS
SNAILS
STIMULATION
SURVIVAL TIME
SYNTHESIS
VARIATIONS
VERTEBRATES
ZOOPLANKTON