III. DETRITUS IN THE FOOD CHAIN 

 A. Theoretical Perspectives 



III-A-1 



Melchiorri-Santolini, U., and J.W. Hopton, eds. 1972. Detritus and its 



role in aquatic ecosystems. Memorie dell ' Institute italiano di idrobiologia, 



29 Suppl. 540 pp. 



The purpose of the IBP UNESCO Symposium on Detritus and its 

 role in aquatic ecosystems was to present to investigators interested 

 in aquatic environments an up-to-date review of the diversity of work 

 that is being undertaken to clarify the role of detritus and to in- 

 dicate the variety of information that has been obtained. 



Forty-five scientists from twelve countries met in Pallanja, 

 Italy, from May 23-27, 1972, to explore this topic. Twenty-four 

 papers were presented and discussed on the subject of detritus 

 in aquatic ecosystems. A wide area was covered, ranging from specific 

 problems such as the attachment of bacteria to detrital particles, 

 to very expanded problems such as carbon flow in whole ecosystems 

 and detrital participation in the flow. Abstracts for two of these 

 papers are presented elsewhere, (See III-A-2 and III-A-3.) (H.D.) 



Keywords: detritus, aquatic ecosystems 



III-A-2 



Mann, K.H. 1972. Macrophyte production and detritus food chains in 



coastal waters. Pages 353-383 vn_^' Melchiorri-Santolini and J.W. Hopton, 

 eds., Detritus and its role in aquatic ecosystems. Memorie dell ' Institute 

 italiano di idrobiologia, 29 Suppl. 



This paper reviews the distribution, productivity, and detritus- 

 forming activities of marine macrophytes (including marsh plants) on 

 a global scale. In reviewing previous productivity studies, the author 

 points out that an annual production of 500 to 1,000 g C/m^ is typical 

 of coastal macrophytes (kelps, sea grasses, rock weeds, marsh grasses, 

 and mangroves). These may be compared with world averages for phyto- 

 plankton production: 50 g C/m^ per year for the open ocean and 

 100 g C/m^ per year for the coastal zone. The macrophyte fringe of 

 the oceans has an intensity of production which may be up to 40 times 

 the intensity of production in the open ocean. Previous studies 

 suggested that the productivity of Spartina alterni flora marshes 

 decreased regularly with latitude; however, in his own research on 

 the Petpeswick Inlet in Nova Scotia, the author found that annual 

 production averages about 290 g C/m^, one of the highest figures re- 

 corded north of Georgia. 



Among the marine fishes of the world, the use of detritus as a 

 major source of food is not common. The available evidence suggests 



89 



