545 



he farm the sea. This contrast between developing 

 technology and the inadequacies of cultural and legal 

 frameworks for regulation is a characteristic of 

 'revolution'. 



The Marine Revolution is, to my mind, quite as 

 important a development as the previous Agricultural 

 and Industrial Revolutions. It is no more obvious on 

 a day-to-day basis than the Agricultural and Industrial 

 Revolutions were in their time. Future Man will clearly 

 see this Revolution as his inner-space logistics and 

 utilization increase. 



ECOSYSTEMS AND HOMEOSTASIS 



The ecosystem is the fundamental functional unit of 

 the natural world. It is comprised of all the hving and 

 non-living components of an environment and the 

 totahty of their interrelationships. An ecosystem has 

 properties of self-sustainment. Solar energy must be 

 added, but nutrients and other materials are recycled. 

 Examples are a lake, a forest, an estuary, and a coral 

 reef. 



Carrying Capacity, Limiting Factors, and Synergisms. 

 Carrying capacity may be defined as the number of indi- 

 viduals of a species within a particular ecosystem 

 beyond which no major increase in numbers may occur. 

 It fluctuates about an equilibrium level and may change 

 seasonally or even daily. It is regulated according to 

 Liebig's 'law' of the minimum and Shelford's 'law' of 

 tolerance, which together state that the presence or abun- 

 dance of an organism locally is determined by the 

 amounts of critical materials available or by the local 

 levels of environmental factors such as salinity or 

 temperature. 



It is typical of ecology that 'laws' are easy to state 

 but difficult to prove. A major reason for this is 

 synergism; that is, environmental factors often act 

 together to produce effects which are different quanti- 

 tatively or qualitatively from the effects expected 

 separately or additively. Carrying capacity and limiting 

 factors apply to all living things. The foolish assump- 

 tion is that technology may negate them for Man. 

 Technology cannot alter ecological laws, though it 

 can redirect utilization in limited ways. 



Productivity. Productivity is determined by turnover 

 rate. The standing crop or biomass is a poor indicator 

 of this, as it tells little about how often materials are 

 recycled. Plants absorb about one per cent of solar 

 energy for photosynthesis. An examination of trophic 

 levels from these producers to primary, secondary, or 

 tertiary consumers, reveals that each step involves 

 about a 90 per cent loss of energy. Thus, food-chains 



are usually short and each trophic level shows much 

 lower productivity than its predecessor. 



Nutrients, unhke energy, are recycled. The biogeo- 

 chemical cycles of gases, salts, and minerals, are most 

 efficient in complex ecosystems. Man can occasionally 

 increase productivity through the addition of sub- 

 stances which once were limiting. More often, his 

 'making the desert bloom' fails in the long run through 

 failure to recognize the interrelationships of these 

 cycles. 



Primary productivity varies widely. Deserts and the 

 waters of the deep oceans, which together cover most 

 of the Earth, produce less than one gram of dry organic 

 matter per square metre per day. Grasslands, waters 

 over the continental shelf, and marginal agriculture 

 produce 0-5 to 3 gm; moist forests and agriculture 

 produce 3 to 10 gm; estuaries, inshore seas, and inten- 

 sive agriculture produce 10 to 25 gm (Odum, 1959). 



Owing to their large total productive area and 

 volume, the seas contain more living material than the 

 land supports. However, Man's utilization is at a 

 higher trophic level in the sea : land = sun -^ grass — » 

 cow ; sea = sun ->■ phytoplankton -> zooplankton -> 

 primary carnivore (e.g. herring) -► secondary carni- 

 vore (e.g. tunny). The seas contain a much greater total 

 diversity of hfe in terms of classes of animals than does 

 the land, but owing to the lower oxygen content of 

 water than air, the seas are dominated by animals of 

 lower metabolic rate, but higher ecological efficiency 

 than birds and mammals. Lastly, the sea provides a more 

 stable environment than the land; in it, the 'weather' 

 is mild and the productive season is long. For all 

 these reasons, marine productivity is not equivalent 

 to that of land. 



Homeostasis, Simplification, and Pollution. Homeo- 

 statis defines the 'balance of nature'. All ecosystems 

 depend upon recycling for sustainment and upon 

 complexity for stabiUty. These involve intricate 

 mechanisms analogous to (but more complex than) 

 the heat-producing, dissipating, and conserving mec- 

 hanisms which regulate human body temperature. 

 Ecosystems are never perfectly balanced, but homeo- 

 static mechanisms give them recuperative power which, 

 when exceeded, leads to breakdown ; the eutrophication 

 of Lake Erie is a classic example of such excess. 



A major part of homeostasis lies in complexity 

 which insures both productivity and stability, and also 

 has aesthetic value for Man (Elton, 1958; Dasmann, 

 1968). Man is a simplifier of ecosystems and thus 

 reduces their recuperative power. The many forms of 

 pollution are the most serious stresses in this regard. 

 Historically, Man has depended upon maximum 

 homeostatic capacities of the environment to endure 

 pollution; but in simplifying and polluting at the 

 same time, he attacks with a two-edged sword. 



