KAPLAN, WELKER, and KRAUS: EFFECTS OF DREDGING 



Salsola kali and other plants growing on patches 

 of shghtly higher ground. The dominant animal 

 is Modiolus demissus which was abundant on all 

 four major islands, averaging 19.58 specimens per 

 m^. Colonies of fiddler crabs, predominantly Uca 

 pugnax, were found on islands I and II. 



The islands are little more than hassocks of 

 Spartina. At low tide they project 0.7 m to 1 m 

 above the water surface; at high tide they are vir- 

 tually inundated. The largest of the islands, 

 island II, was 115.59 m x 42.39 m. 



The islands represent the most unspoiled aspect 

 of the Goose Creek marsh. For that reason, they 

 were chosen as the site for estimating the 

 productivity of the Spartina alterniflora marsh 

 along the periphery of Goose Creek. The result- 

 ing figure will be higher than other productivity 

 estimates because it does not represent the 

 Spartina patens and Phragmites communis 

 marshes which are both transitory and strongly 

 affected by man in the Goose Creek area. 



Island II, the most southeasterly of the islands, 

 was sampled by means of seven stations arranged 

 at 15 m intervals and staggered so that both 

 edges and the center of the islands were sampled 

 at least twice (Figure 13). 



A 1.83 m X 1.83 m frame was placed on the area 

 to be sampled so that 3.34 m^ were delimited. A 

 team of four collectors was stationed, one collector 

 on each of the sides of the sample area, to prevent 

 motile forms from escaping. All surface-dwelling 

 animals were removed by hand. The area was then 

 spaded to a depth of 20 cm to remove burrowing 

 forms. The total area sampled was 23.4 m^. 



Table 20 represents the animal biomass of the 

 stations on island II. Animals making up the 

 species mix were: 104 Uca pugnax, 6 Uca pugi- 

 lator, 442 Modiolus demissus, 28 Sesarma reticu- 

 latum, 1 Carcinus maenus, 3 Littorina littorea, 

 and one unidentified Nereid. 



The total wet weight of the macrofauna taken 

 from the seven stations is 2,327.01 g, or 90.94 

 g/m^. The corresponding calculation for dry 

 weight is 20.21 g/m^. The ratio of dry weight to 

 wet weight is 1:4.9. 



The computations for estimating primary pro- 

 ductivity of the marsh were taken from Udell et 

 al. (1969) from their study of the Hempstead, 

 Long Island, salt marsh. They calculated a total 

 minimal estimate (harvest method) of annual 

 production of 3.68 tons per acre of tall Spartina 



Figure 13. — The distribution of stations on island II. 



Table 20.— Biomass of animals found on island II, Goose Creek. 



alterniflora and 2.55 tons per acre of the mixed 

 species comprising the typical Long Island marsh 

 (tall and short .S. alterniflora, S. patens, Distichlis 

 spicata, etc.). These weights corresponded to a 

 mean dry weight of 827.2 g/m^ for tall S. alterni- 

 flora and (by extrapolation) 578 g/m^ for the mixed 

 species. Animal production taken from our mid- 

 August study is 20.21 g/m^, dry weight. Sanders 

 (1956) suggests that standing crop figures for 

 infauna are a function of productivity by a 

 ratio of 2.1-5:1. Since the organisms predomi- 

 nating in our samples are predominantly "long- 

 lived," Sanders' factor of 2.1 was applied. Animal 

 productivity of the marsh comes to 42.4 g/m^/yr, 

 by this calculation. This is roughly 5% of the tall 

 S. alterniflora productivity figure or 7% of the 

 overall estimate. The total animal and plant pro- 

 ductivity of the tall S. alterniflora marsh as repre- 

 sented by island II, is 869.64 g/m^/yr. Thus, if the 

 dredged channel had passed through island II 

 instead of skirting it, its 4,900 m^ of marsh or 

 4,261.2 kg (dry weight) of animal and plant 

 productivity would have been permanently 

 obliterated. 



The portion of the Goose Creek marsh inun- 

 dated as spoil areas has been estimated at 108,712 

 m^. Using Udell's estimate of 2.55 tons/acre 

 (4,553.57 kg/ha), the total primary productivity 

 of the marsh which became the spoil areas would 



469 



