A•r some time during the annual cycle, most vertebrates restrict their activities to a definite area which may be termed the home range. If all or part of the home range is defended against other individuals of the same species, the guarded area is called a territory, according to current usage. Territoriality is an important mechanism which reduces intraspecific competition; it is especially pronounced in nest-building animals (birds, certain fish, insects, etc.) which have complicated behavior patterns requiring highly co6rdinated actions during reproductive periods. Establishment of territories and home ranges produces characteristic intrapopulation distribution patterns which have important bearing on the choice of census methods (See Odum, 1953, Chap. 6). Examination of the voluminous literature on territorialism in birds April] 195.51 ODU•I •ND KUI•NZLI•R, Measurement of Territory Size 129

No abstract

Modiolus demissus Dillwyn was studied near Sapelo Island, Georgia. The size distribution of the mussels was bimodal with maximum numbers in the dry weight (body) classes 0–24 mg and 400–599 mg. The total weight of mussels smaller than 200 mg was less than 2% of the total population weight. Random samples gave an estimated population density of 7.8/m2 for the entire inhabited marsh; the estimated organic biomass was 11.5 gm/m2, one third of which was body and two thirds was shell conchiolin. The population was most dense near the heads of small creeks, averaging 32 mussels/m2. The mussels, however, were not only more abundant in some types of marsh than in others, they were also clumped within areas of uniform marsh. Shell growth occurred throughout the year, especially in small and medium‐sized individuals, but it was more rapid during the warm months. The height‐to‐weight ratio changed with the seasons, the mussels being heaviest prior to spawning. Growth and mortality of mussels in flower pots in the marsh indicated a net annual population growth of 445 mg/m2 (dry body weight) and a net annual mortality loss of 1200 mg/m2. Allowance for bias would place the steady state growth‐mortality rate necessary to just maintain the population somewhere between these two estimates. Population growth and gamete production accounted for an energy flux of about 13.9 and 2.8 kg‐cal/m2/yr, respectively. Respiration by the population accounted for approximately 39 kg‐cal/m2/yr, over two thirds of which took place in air during ebb tide. Total assimilation amounted to 56 kg‐cal/m2/yr.

Export of organic carbon per unit runoff from five small, eastern North Carolina watersheds with considerable swamp drainage was severalfold higher than the export rates from upland watersheds reported in the literature. This reflects the higher concentrations of organic carbon, especially dissolved forms, in swamp waters and is probably attributable to increased contact time between water and organic debris as well as to concentration effects of high evapotranspiration in swamps.

The phosphorus budget of a Modiolus demissus population in a Georgia intertidal salt marsh was studied. Percentage phosphorus in mussel bodies decreased from loJ0 of the dry weight in small individuals to 0.6% in adults. There was also a seasonal variation in phosphorus content of adults; the maximum occurred during spawning early in September, the minimum in November.The standing crop of phosphorus in the population was 37.2 mg P/m2, the body fraction comprising 67%, the shell 3O%, and the liquor 3%. Prorated losses and elimination rates (pg P/m2 day) of the population were: mortality 21; gametes 11; dissolved organic 23; phosphate 260; and feces 460. Quantities of phosphorus present in natural marsh water (mg P/m2) were: particulate 14; phosphate 19; and dissolved organic 6. The mussel population removed 5.4 mg P/m2 of particulate phosphorus and 0.07 mg P/m2 of phosphate daily, of which 0.78 mg P/m2 was required as food and 4.7 mg P/m2 was deposited as pseudofeces.The turnover time of phosphorus in the population was 115 days. The major effect of the population on the ecosystem was the removal of particulate matter from sea water; the turnover time of the particulate phosphorus in the water was 2.6 days under the supposition that the mussel population was the only agent involved.Mussels are more important as biogeochemical agents than as energy consumers. Determination of the participatory turnover time of a substance via any route in a system sets the maximum turnover time of that system. Determination of the turnover time of a substance for an entire system fixes the maximum flux rate via any one route in the system,