568 



BROAD ECOLOGICAL STUDIES 



Scope of ecological studies 



Broad ecological studies are needed to integrate all of the factors 

 acting to shape the nature of the estuarine zone. We need to expand 

 the baseline research on estuarine systems to include studies on nutrient 

 and thermal additions, circulation and transfer of substances and 

 energy, productivity, species interaction, effects of pollution, biological 

 indicators of environmental change, and ecosystem analysis. The broad 

 impact of economic poisons,^ must be identified and quantified. What 

 are the sources, effects, and fate of the various pesticides and herbi- 

 cides, and how may these effects be mitigated? What are the details 

 of the life histories and environmental requirements of estuarine- 

 associated and estuarine-dependent species? Studies should be con- 

 ducted to determine the dependence of marine species on estuarine 

 nursery areas, to measure the impact of inland development on the 

 estuarine ecosystem, and to determine the quality and quantity of fish 

 and wildlife habitat areas necessary to maintain present population 

 levels and to satisfy predicted future use. Studies should be imple- 

 mented on rare and endangered species of fish and shellfish. One of 

 the most important gaps remaining is our lack of knowledge of the 

 dynamics of food chains, the relationships between phytoplankton on 

 one end of the food chain and fish at the other, especially quantitative 

 data on biomass and replacement rates of both benthic and pelagic 

 invertebrates which are not of economic value themselves but are im- 

 portant parts of the food chain or, in some cases, are antagonistic to 

 economically important species. 



Energy flow in food webs 



Much study is required to determine the absolute and relative con- 

 tributions of phytoplankton, spermatophytes such as turtle grass and 

 Spartina, and organic detritus to the energy used in these food chains. 

 This concept of energy transfer is one of the most important aspects 

 to understand in order to efficiently manage complex estuarine environ- 

 ments, for it is a fundamental property of the system and provides an 

 extremely valuable approach to evaluation of the effects of pollution 

 and change. It is essential to be able to quantitatively describe the 

 energy transfer for individual species, for trophic levels, and for 

 communities. Constructive manipulations of the sequential nature of 

 energy transfer and utilization can be achieved by the application of 

 system models for studies on movements and rates of transfer of se- 

 lected pollutants within the system, such as insecticides and heavy 

 metals. Such programs are dependent upon the availability of raw data 

 on 'input to the ecosystem, bioconcentration, sedimentation, and output 

 from the ecosystem. One of the early requirements in any manage- 

 ment program should include an energy budget analysis. 



Ecosystem rehabilitation 



Research is needed on the recovery of an area during the course 

 of cleaning it up. How long does it take, what indications do we have 

 along the way, and how will cleaner water affect the area ; for exam- 



* Pesticides, herbicides, defoliants, rodenticldes, etc. 



