of large detrital fragments. This action provided cavities that were 

 heavily invaded by pennate diatoms and particles that became suspended 

 in the water column and populated by bacteria. 



Nutrient analyses indicated that the shrimp were excreting large 

 quantities of ammonia, phosphate, nitrate and nitrite, which, together 

 with the dissolved organic material (DOM) release, is presumably 

 responsible for the heavy growth of microflora and increased protein 

 fraction in both feces and large and small uneaten detrital fragments. 



Palaemonetes pugio , while supporting its own trophic requirements, 

 accelerates the breakdown of detritus, preventing blockages or bottlenecks 

 that might occur from the pulses of emergent grass and macroalgal detritus 

 that occur in the embayment. This repackaging into feces, heterogeneous 

 fragments, DOM and shrimp biomass makes detrital energy available at a 

 variety of trophic levels, smoothing out the organic pulses over time and 

 space, and raising the efficiency of transfer to the food web. By milling 

 and fertilizing the detrital substrate, P_. pugio enhances microbial settle- 

 ment on the detritus, which further raises its nutritional value. The 

 special adaptation of £_. pugio to decomposer systems limits predation and 

 competition, allowing the shrimp to develop the large populations necessary 

 to carry out its role effectively. (A. A. -modified) 



Keywords: salt marsh ecosystem, nutrient values, grass shrimp 



III-E-14 



Odum, W.E. 1971. Pathways of energy flow in a south Florida estuary. 

 University of Miami Sea Grant Technical Bulletin No. 7. 162 pp. 



The feeding habits of more than eighty species of animals were monitored 

 from stomach content examinations of over 7,000 individuals made over 

 a period of 10 months. From a consideration of these feeding habits 

 on an annual basis, the organisms were classified as herbivores, omnivores, 

 primary carnivores, middle carnivores, and higher carnivores. The 

 principal source of food for the aquatic animal community of the Everglades 

 mangrove belt, is vascular plant detritus originating principally from 

 red mangrove leaves. During the process of decay and microbial coloni- 

 zation, the detritus particles increase in relative protein content 

 and in caloric value. There are at least four pathways by which freshly 

 fallen mangrove leaves are utilized by heterotrophs: (A) dissolved 

 organic substances to microorganisms to higher consumers, (B) dissolved 

 organic substances to sorption on sediment and aged detritus particles 

 to higher consumers, (C) leaf material to higher consumers, (D) leaf 

 material to bacteria and fungi to higher consumers. The last pathway 

 is believed to be the most important. There exists a key group of 

 omnivorous estuarine organisms which ingest quantities of vascular 

 plant detritus. In the North River estuary, this key group of detritus 

 consumers includes amphipods, mysids, cumaceans, ostracods, chironomid 

 midge larvae, harpacticoid and planktonic copepods, snapping shrimp, 



130 



