(ii) To estimate growth of periphyton, microscope slides were supported just below the water level in a specially constructed float. Slides were collected each month, the cells were scraped off, extracted with acetone, and the chlorophyll estimated as in (i).
c) Observations on plants
The bunds surrounding the kei wais and the islands carry a fairly dense growth of plants. In both cases, the main species are Kandelia candel (L.) Druce, Phragmites karka (Retz.) Trin., Acanthus ilicifolius L., and the fern Acrostichum aureum L. The first three species grow around the margins of the bunds and islands and thus overhang the water.
Throughout the experimental period, observations were made on the stages of growth of Kandelia and Phragmites. Litter fall from Kandelia was estimated by surrounding the lower half of two bushes with a funnel-shaped structure of fine nylon netting; the litter was collected from the net each month, and the quantity expressed on a dry weight basis. Probable litter production by Phragmites was estimated in August 1978 when the plants were becoming senescent: the stems and leaves within 4 × 1 m2 quadrats were harvested separately and oven-dried.
d) Decomposition of submerged Kandelia leaves
Matched sets of senescent leaves were immersed in the kei wai either in plastic mesh bags (1 × 1 mm mesh) or in plastic vials with 2 mm holes punched through them. Individual bags and vials were collected at weekly intervals. Leaves from the bags were used to study the progress of fragmentation and were analysed by the Kjeldahl method to determine their nitrogen content and thus their approximate protein content. Leaves from the vials were used to follow changes in dry weight and content of hot water.
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tion. Chlorophyll was extracted by grinding the MgCO, with acetone, and measuring the extinction coefficients at 663 and 750 nm. Some elements of the phytoplankton were identified by microscopic examination.
(ii) To estimate growth of periphyton microscope slides were supported just below water level in a specially construct- ed float. Slides were collected each month, the cells were scrapped off, extracted with acetone, and the chlorophyll estimated as in (i).
c) Observations on plants
The bunds surrounding the kei wais, and the islands, carry a fairly dense growth of plants. In both cases the main species are Kandelia candel (L.) Druce, Phragmites karka (Ritz.) Trin., Acan- thus ilicifolius L. and the fern Acrostichum aureum L. The first three species grow around the margins of the bunds and islands, and thus over-hang the water.
Throughout the experimental period, observations were made on the stages of growth of Kandelia and Phragmites. Litter fall from Kandelia was estimated by surrounding the lower half of two bushes with a funnel-shaped structure of fine nylon netting; the litter was collected from the net each month and the quantity expressed on a dry/weight basis. Probable litter production by Phragmites was estimated in August 1978 when the plants were becoming senescent: the stems and leaves within 4 × 1 m2 quad- rats were harvested separately and oven dried.
d) Decomposition of submerged Kandelia leaves
Matched sets of senescent leaves were immersed in the kei wai either in plastic mesh bags (1 × 1 mm. mesh) or in plastic vials with 2 mm holes punched through them. Individual bags and vials were collected at weekly intervals. Leaves from the bags were used to study the progress of fragmentation, and were analysed by the Kjeldahl method to determine their nitrogen content and thus their approximate protein content. Leaves from the vials were used to follow changes in dry weight and content of hotwater
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