direct correlation of river flow and 

 detritus in the system. By the fall, 

 there is still no significant rela- 

 tionship although there are occasion- 

 al influxes of detritus with minor 

 peaks in the river flow. By winter, 

 however, there is a strong direct re- 

 lationship between microdetrital 

 loading and river flow peaks. How- 

 ever, the winter regression differs 

 from that of the spring detrital 

 loading which, though significantly 

 associated with river flow levels, 

 requires higher river levels for com- 

 parable concentrations and loading of 

 detritus. This analysis indicates 

 that the degree and timing of river 

 flooding on a seasonal basis affects 

 the level of detrital loading to the 

 estuary. 



The key to the biological sig- 

 nificance of the detrital flux into 

 the estuary lies in the spatial/ 

 temporal response of the estuarine 

 biota. Such a response is not easily 

 determined because of the natural 

 variability of the system. Livings- 

 ton (1978) and White et al. (1979) 

 have described the experimental basis 

 for the detrital-based energy system 

 in the Apalachicola estuary whereby 

 organic particulate matter and dis- 

 solved nutrients are transformed into 

 microbial biomass. Such energy is 

 then utilized by a diverse macro- 

 fauna. Sheridan and Livingston 

 (1979) and Laughlin and Livingston 

 (in review) have detailed some key 

 components of the food web structure 

 in the Apalachicola estuary. The 

 detrital input is an important part 

 of the system. The timed reaction of 

 the biological components to climato- 

 logical features such as rainfall and 

 river flow have also been established 

 (Livingston et al. 1977; Livingston 

 and Loucks, 1979). There are various 

 indications that seasonal and annual 

 variation of river input is an 

 important factor in the estuarine 

 response. The results of this study 



indicate that the qualitative and 

 quantitative aspects of detrital in- 

 put into the estuary are dependent on 

 a number of factors that vary 

 throughout a given season, and from 

 year to year. While the important 

 detrital food web is closely asso- 

 ciated with the timing and degree of 

 river flooding, functional relation- 

 ships remain undetermined and are 

 currently under study. However, it 

 is clear that, while the river is 

 important with regard to bay produc- 

 tivity, such relationships depend to 

 considerable degree on climatological 

 conditions, trophic response, and the 

 natural history of various estuarine 

 species . 



The data presented here are 

 preliminary in that the biological 

 response of the estuary remains de- 

 pendent on various features of the 

 estuarine habitat. Experimental 

 studies are currently being carried 

 out to determine the relationship 

 of the estuarine food webs and com- 

 munity structure with potential bio- 

 logical-controlling features such as 

 predation and competition. However, 

 the results of this study indicate 

 the importance of the specific 

 timing (seasonal, annual) of clima- 

 tological events relative to the 

 quality and quantity of input of 

 allochthonous detritus which moves 

 into the estuary. Periodic (pulsed) 

 movement of detritus is only one part 

 of the biologically important fea- 

 tures of habitat organization. A 

 knowledge of the details of biologi- 

 cal response to such environmental 

 variables will be necessary if we 

 are to understand the impact of 

 anthropogenic alteration of the tim- 

 ing and extent of river flow on 

 receiving estuarine systems. 



LITERATURE CITED 



de la Cruz, A. A. Production and 

 transport of detritus in wet- 



327 



