A study of the reproducibility of water conditions between small enclosures and a tropical waterbody

Supervising Scientist, 1989

Technical Memorandum 28
Noller BN, McBride TP, Hunt CW and Hart BT
ISSN 0810-9532
ISBN 0 644 09135 5

About the report

Limnological enclosures of 100 L volume were placed in a tropical waterbody for five weeks. Measurements were made regularly of the main physical water quality variables (temperature, pH, concentrations of seston [total, inorganic and organic] and dissolved oxygen) and two biological indicators (chlorophyll a and diatom assemblage composition) in the enclosures and in the surrounding waterbody. Good replication was obtained between identical enclosures containing water without sediment, but not between these enclosures and an enclosure containing water and sediment. The representativeness of the enclosures (ability to imitate the response of the waterbody to applied changes) was poor. Significant changes in the chlorophyll a /seston in the waterbody following rainfall were not detected in the enclosures. The inclusion of sediment in an enclosure significantly affected most of the variables measured, but did not improve the representativeness of the enclosure.