24
b-have restricted tolerance range that is controlled by water temperature
and salinity.
13-fish species that live in estuaries :
a-grow more slowly because of a high predation pressure.
b-grow rapidly because of a lack of predation.
14-the biological productivity of organisms that live in estuaries :
a-is high, because of high nutrients levels and reduced predation levels.
b-is low, because of changes in salinity and temperature.
15-lagoons are : a-isolated bodies of water that do not receive input of
freshwater.
b-are semi-enclosed bodies of water where fresh water and salt water
intermingle.
16-lagoons can be vegetated : a-by seaweeds, seagrasses……..etc
or
have bottom that are barren.
b-can not support any plant or animal plant.
17-lagoons waters are biologically productive
and support local and
commercial fisheries :
a-but human activities reduced aquatic life in lagoons by polluting the
water and using them as dumping sites.
b-but changes in salinity because of river inflow render their water too
stressful for marine organisms.
Exercise : answer the following questions :
1-what is an estuary and how does it differ from a lagoon ?
2-why do estuaries have low species diversity ,but exceptionally high
biological productivity ?
3-what are the different f actors that affect the chemical composition of
water in estuaries ?
4-why do fish species that live in estuaries grow more rapidly ?