The abundance of nauplii in the samples were generally less than other 

 later developmental stages (Bertrand 1977) . This does not reflect the true 

 population structure and perhaps indicates that the Oithona population in 

 Penobscot Bay is recruited from offshore populations, where temperatures 

 are lower and salinity higher than in the estuary (Bertrand 1977) . The 

 presence of nauplii at all stations sampled in Penobscot Bay indicates that 

 there is a locally produced generation (Bertrand 1977) . 



In the western Gulf of Maine, Fish (1936) reported this species as 

 breeding from March to September, and noted that it was a very "fecund" 

 organism with high mortality in the early developmental stages. Three major 

 generations could be recognized there from January to August. Females with 

 eggs were recorded from March through June in Block Island Sound (Deevey 

 1952) . Thus the reproductive periods of this species seem to be associated 

 with the cooler portions of the season. 



8.) Acartia sp. 



Two species of Acartia , A. longiremis and A. clausi (also known as 

 A. hudsonica ; Bradford 1976), are characteristically present in the coastal 

 marine waters of Maine. A third Acartia species, A. tonsa may be present 

 in low abundances in some areas . 



A. tonsa was not recorded by Sherman (1976) from the Boothbay Harbor 

 region. The higher salinity of this area probably accounts for the absence 

 of this copepod. However, in upper Penobscot Bay, Bertrand (1977) found 

 this species in low abundance from June through October but copepodites 

 (i.e., young copepods) were not found and it was presumed that propogation 

 took place in the Penobscot River estuary where temperatures are higher and 

 salinity lower. 



In Boothbay Harbor A. clausi is the dominant copepod in the summer with 

 a major peak of abundance in July and August, while the less abundant A. 

 longiremis had a July-August peak followed by a comparable peak in November 

 (Sherman 1976) . This pattern seems to reflect the Acartia population in 

 the coastal Gulf of Maine waters (Bigelow 1926). In Penobscot Bay, popula- 

 tions of A. clausi followed those described for Boothbay Harbor; however, 

 A. longiremis was only found in the Bay in autumn and early winter 

 (Bertrand 1977). Since no copepod stages were found, Bertrand (1977) suggests 

 that individuals from the automn population peak in the Gulf of Maine 

 immigrate into the Bay. 



In the Gulf of Maine, Bigelow (1926) suggested two breeding seasons for 

 A. longiremis ; early spring and late summer. Sherman (1968) found a seasonal 

 maximum of A. longiremis in summer in the central coastal area of the Gulf 

 of Maine. In Penobscot Bay, Bertrand (1977) found that there were probably 

 three to four broods of A. clausi per year. Bertrand (1977) states that 

 there are apparently four generations in the upper bay and three in the 

 lower bay. He feels that occurrence of a fourth generation in the upper 

 bay in the summer may be due to the higher temperatures and more food 

 available to developmental stages in this area. 



(Continued) 



4-F-4 



