2 Reef Environments
2.1 Hydrodynamics and Thermohaline Features
of Reef Waters
Among the most important hydrophysical factors interacting with the reef
biota and influencing reef growth and its morphometry are currents, wave
stress, tides, internal waves, thermohaline structure of the water column.
These factors themselves, and also their influence upon the reef biota, have
been so far insufficiently studied because of their extremely complex and
variable nature. Each individual reef is unique in its morphology, and thus
has its own peculiar relationship with the physical environments, which are
moreover very variable in different regions of the tropical zone. The
currents interfering with reefs form a multitude of reciprocally directed
eddies. The first attempts to clear up the complex nature of hydrodynamics
in the reef areas and to investigate the interference of currents with their
geomorphological structures had been made by American hydrologists on
some atolls of the Marshall Islands during the nuclear tests in 1947 -1950
(Von Arx 1948; Munk and Sargent 1948). Later, investigations of the same
kind were made at the Caribbean reefs (Shinn 1963; Kuhlmann 1974, 1975;
Roberts 1974, 1977; Roberts et al. 1975). Studies on the tide currents and
measurements of the residence time of water in lagoons were accomplished
at the Fanning atoll (Gallagher et al. 1971), the Takapoto atoll (Sournia and
Ricard 1976a), the Canton atoll (Roberts 1974), and the Tarawa atoll
(Kimmerer and Walsh 1981). Studies on the hydrology of the GBR had
been started in the late 1920s by Orr (1933). Later, extensive studies were
carried out by French Research Insitution ORSTOM (Brandon 1973) and by
the Australian Institute of Marine Science (AIMS). Hydrologists from
AIMS gained fundamental insight into reef hydrodynamics (Pickard et al.
1977; Andrews 1983b; Andrews and Gentien 1982; Wolanski and Pickard
1985, 1986). Circulation in the lagoon of the barrier reef off New Caledonia
was studied by Rougerie (1985).
These investigations showed that among the most important factors of the
hydrodynamic stress in coral reef areas are the tides (Church et al. 1985).
They induce regular and powerful tidal currents, which have a great impact
upon the formation of reef constructions, as well as on zonal distribution of
2.1 Hydrodynamics and Thermohaline Features
of Reef Waters
Among the most important hydrophysical factors interacting with the reef
biota and influencing reef growth and its morphometry are currents, wave
stress, tides, internal waves, thermohaline structure of the water column.
These factors themselves, and also their influence upon the reef biota, have
been so far insufficiently studied because of their extremely complex and
variable nature. Each individual reef is unique in its morphology, and thus
has its own peculiar relationship with the physical environments, which are
moreover very variable in different regions of the tropical zone. The
currents interfering with reefs form a multitude of reciprocally directed
eddies. The first attempts to clear up the complex nature of hydrodynamics
in the reef areas and to investigate the interference of currents with their
geomorphological structures had been made by American hydrologists on
some atolls of the Marshall Islands during the nuclear tests in 1947 -1950
(Von Arx 1948; Munk and Sargent 1948). Later, investigations of the same
kind were made at the Caribbean reefs (Shinn 1963; Kuhlmann 1974, 1975;
Roberts 1974, 1977; Roberts et al. 1975). Studies on the tide currents and
measurements of the residence time of water in lagoons were accomplished
at the Fanning atoll (Gallagher et al. 1971), the Takapoto atoll (Sournia and
Ricard 1976a), the Canton atoll (Roberts 1974), and the Tarawa atoll
(Kimmerer and Walsh 1981). Studies on the hydrology of the GBR had
been started in the late 1920s by Orr (1933). Later, extensive studies were
carried out by French Research Insitution ORSTOM (Brandon 1973) and by
the Australian Institute of Marine Science (AIMS). Hydrologists from
AIMS gained fundamental insight into reef hydrodynamics (Pickard et al.
1977; Andrews 1983b; Andrews and Gentien 1982; Wolanski and Pickard
1985, 1986). Circulation in the lagoon of the barrier reef off New Caledonia
was studied by Rougerie (1985).
These investigations showed that among the most important factors of the
hydrodynamic stress in coral reef areas are the tides (Church et al. 1985).
They induce regular and powerful tidal currents, which have a great impact
upon the formation of reef constructions, as well as on zonal distribution of