184 Y.H. CHEUNG, K.Y. TAI, S.W. TSAO AND L.B. THROWER
chains. The grazing food chain begins with microscopic floating algae (phytoplankton) and algae which are attached to surfaces. These plants are eaten by various animals which exploit part of the energy and nutrients they contain. By a sequence of “eating and being eaten” the energy and nutrients pass eventually to the animals that constitute the produce of the kei wai and support their growth and reproduction. Thus the grazing food chain exploits solar energy and the nutrients present in the water. It should be remembered that the waters of the estuary are comparatively rich in nutrients.
A second basis for production is the detritus food chain. In this context, "detritus" is the dead material in the kei wai: the remains of plants and animals that lived there, and any organic materials that may enter the water. The origin and fate of these materials are described in Part II. Broadly, however, they are colonized by bacteria and fungi which decompose and change them. Fragments of detritus, including the bacteria and fungi, are eaten by small animals and the energy they contain eventually passes to the larger animals that are the produce of the kei wai. Thus, any organic material added to the kei wai is a "supplement" of energy and nutrients that is exploited via the detritus food chain. One such supplement is the leaves of mangroves and associated plants that fall into the water. Moreover, the importance of such materials was recognised in the traditional practice (described to us by an elderly kei wai operator from China) of depositing soft, easily decomposed leaves (eg. Solanum nigrum) into the kei wai.
Harvesting
There are essentially two kinds of harvesting procedure, which may be called the "shrimp harvest” and the "fish harvest”; both depend on tidal movement. Shrimp harvests are carried out ten times per lunar month on days 1-5 and 16-20 (the days of the highest tides) from the third to eleventh month inclusive, so that there are 90 such harvests per year. Fish harvests are carried out once in each of the ninth and tenth lunar months.
If possible, the shrimp harvest is begun in the evening. In the following description, the times are by way of example. At about
184 Y.H. CHEUNG, K.Y. TAI, S.W. TSAO AND L.B. THROWER
chains. The grazing food chain begins with microscopic floating algae (phytoplankton) and algae which are attached to surfaces. These plants are eaten by various animals which exploit part of the energy and nutrients they contain. By a sequence of “eating and being eaten❞ the energy and nutrients pass eventually to the ani- mals that constitute the produce of the kei wai and support their growth and reproduction. Thus the grazing food chain exploits solar energy and the nutrients present in the water. It should be remembered that the waters of the estuary are comparatively rich in nutrients.
A second basis for production is the detritus food chain. In this context, "detritus" is the dead material in the kei wai: the remains of plants and animals that lived there, and any organic materials that may enter the water. The origin and fate of these materials are described in Part II. Broadly, however, they are colonized by bac- teria and fungi which decompose and change them. Fragments of detritus, including the bacteria and fungi, are eaten by small ani- mals and the energy they contain eventually passes to the larger animals that are the produce of the kei wai. Thus, any organic material added to the kei wai is a "supplement" of energy and nutrients that is exploited via the detritus food chain. One such supplement is the leaves of mangroves and associated plants that fall into the water. Moreover, the importance of such materials was recognised in the traditional practice (described to us by an elderly kei wai operator from China) of depositing soft, easily decomposed leaves (eg. Solanum nigrum) into the kei wai.
Harvesting
There are essentially two kinds of harvesting procedure, which may be called the "shrimp harvest” and the "fish harvest”; both depend on tidal movement. Shrimp harvests are carried out ten times per lunar month on days 1-5 and 16-20 (the days of the highest tides) from the third to eleventh month inclusive, so that there are 90 such harvests per year. Fish harvests are carried out once in each of the ninth and tenth lunar months.
If possible, the shrimp harvest is begun in the evening. In the following description, the times are by way of example. At about
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