1922] Allen: Studies on Marine Phytoplanktoii at La Jolla 34.3 



CONCLUSION 



Since the work of 1920 and 1021 has been a direct extension and 

 expansion of the work in 1919 it is scarcely desirable or appropriate 

 to attempt to state very much in the way of general conclusions in this 

 immediate connection. Such a statement can be more satisfactorily 

 attempted after study of the records for one or more years. 



Meanwhile, however, one or two points may be noted to advantage : 

 First, the measured water method seems to be by far the best for 

 a standard method and the surface level the best for a standard level 

 of collecting. At the time of this writing. May 26. 1921. we have 

 given a continuous trial to this plan of procedure over a period of 

 twenty-one months at our pier and fifteen months at another. In 

 addition we have used it on various boats and now have it in operation 

 at three other piers. From such experience we are convinced that 

 it is the only method affording an adequate basis for expansive 

 quantitative work on the phytoplankton as distinguished from the 

 elementary, superficial work permitted by any tow or haul net method. 

 Second, it appears probable that water currents have very pro- 

 nounced influence on phytoplankton production. 



Third, when conditions for production are highly favorable in our 

 area, there is evident response by large numbers of phytoplankton 

 organisms frequently of both dinoflagellates and diatoms. 



Fourth, conditions of occurrence suggest the probability that cer- 

 tain common forms of wide distribution, such as Nitzschia seriata CI. 

 and Prorocentrum micans Ehr., may serve well as indicators of certain 

 general conditions of the ecologic complex while some less abundant 

 forms, such as Asterionella japoniea CI. and Dinoph'ysis homunculus 

 Stein, may prove to be excellent indicators of more specific conditions 

 in the ecologic complex. 



Lastly, it is evident that the problems of the ecologic complex of 

 the sea are fascinating as well as intricate and baffling; e.g., was the 

 big diatom pulse in September due merely to the transfer into our 

 area of a seed bed of diatoms which had developed farther north .' 

 ( >r was it due to removal of predatory eopepods by the small fish 

 which the mackerel chased in? Or was it due to the high increase in 

 carbon dioxide and nitrogenous materials resulting from the presence 

 and activity of unusual quantities of fish? Or was it due to a com- 

 bination of all these, with a thousand other influences, the resultant 

 of all of which was good? 



