254
HILARY B. MOORE
K. Phases of water
In various publications (e.g. 1965) Drost-Hansen has brought
together data suggesting that there are changes in the properties of
water in the neighborhood of 15", 30' and 46°C. Some of the examples
indicate a rather abrupt change at these temperatures in the wellbeing of organisms as expressed in such aspects as their growth rates.
Several of the curves we have shown in the various sections indicate
optimal conditions between 16" and 2OoC, so it was of interest to see
whether this could be accounted for by these apparent structural changes
in water. We failed to account for our optima in terms of relative time
spent in two of the phases assuming various degrees of well being in
each. It would seem that the effects which can be demonstrated at
controlled temperatures in the laboratory are not to be expected in the
sea, at Ieast in shallow waters, where organisms have to be adapted to
such widely, often rapidly varying temperatures.
V. DISUUS~ION
In the introduction we emphasized that we were concerned with
finding general trends, but that there would be many individual
species or localities whose characteristics would diverge from the
general pattern. In the same way particular sections of the evidence
presented with regard to high stress in the tropics may be open to
alternative explanation, but we must consider whether the whole array
of evidence, taken together, is convincing.
Of the environmental factors which are likely to affect stress,
temperature is considered first. From polar to tropical waters there
is a range from about 0 ' to about 3OoC, and in shallow water there is a
general correlation of temperature with latitude, although this varies
considerably on different coasts. The seasonal range of temperature
also shows a clear cut relation to latitude, being greatest in midlatitudes and low in polar and tropical seas. This range is important in
connection with triggering spawning. Temperature fluctuation may
also be advantageous to the well-being of an organism as indicated by
Allee et al. (1949).
Salinities tend to be considerably lower in high than in midlatitudes, and somewhat lower in tropical waters. Seasonal salinity
ranges are somewhat greater in the tropics than in temperate waters.
To the extent that food supply is ultimately dependent on primary
production, this is more uniform throughout the year in the tropics, and
more seasonal with increasing latitude.
Tidal ranges are greatest in mid-latitudes, decreasing polewards
HILARY B. MOORE
K. Phases of water
In various publications (e.g. 1965) Drost-Hansen has brought
together data suggesting that there are changes in the properties of
water in the neighborhood of 15", 30' and 46°C. Some of the examples
indicate a rather abrupt change at these temperatures in the wellbeing of organisms as expressed in such aspects as their growth rates.
Several of the curves we have shown in the various sections indicate
optimal conditions between 16" and 2OoC, so it was of interest to see
whether this could be accounted for by these apparent structural changes
in water. We failed to account for our optima in terms of relative time
spent in two of the phases assuming various degrees of well being in
each. It would seem that the effects which can be demonstrated at
controlled temperatures in the laboratory are not to be expected in the
sea, at Ieast in shallow waters, where organisms have to be adapted to
such widely, often rapidly varying temperatures.
V. DISUUS~ION
In the introduction we emphasized that we were concerned with
finding general trends, but that there would be many individual
species or localities whose characteristics would diverge from the
general pattern. In the same way particular sections of the evidence
presented with regard to high stress in the tropics may be open to
alternative explanation, but we must consider whether the whole array
of evidence, taken together, is convincing.
Of the environmental factors which are likely to affect stress,
temperature is considered first. From polar to tropical waters there
is a range from about 0 ' to about 3OoC, and in shallow water there is a
general correlation of temperature with latitude, although this varies
considerably on different coasts. The seasonal range of temperature
also shows a clear cut relation to latitude, being greatest in midlatitudes and low in polar and tropical seas. This range is important in
connection with triggering spawning. Temperature fluctuation may
also be advantageous to the well-being of an organism as indicated by
Allee et al. (1949).
Salinities tend to be considerably lower in high than in midlatitudes, and somewhat lower in tropical waters. Seasonal salinity
ranges are somewhat greater in the tropics than in temperate waters.
To the extent that food supply is ultimately dependent on primary
production, this is more uniform throughout the year in the tropics, and
more seasonal with increasing latitude.
Tidal ranges are greatest in mid-latitudes, decreasing polewards