9. ) Eurytemora herdmani 



Bigelow (1926) found E^. herdmani to be scarce in the Gulf of Maine and 

 suggested that this species did not breed successfully seaward of the outer 

 headlands. However, Sherman (1970) found that it was generally present all 

 year in coastal Gulf of Maine waters and in the late summer-early fall in 

 Boothbay Harbor (Sherman 1976) . This species is also one of the most 

 abundant copepods in Passamaquoddy Bay (Fish and Johnson 1937). In Penobscot 

 Bay, numbers of E^. herdmani decrease towards the outer bay, which indicates 

 the importance of the estuary as a source of production for this species 

 (Bertrand 1977). Three generations (late spring, mid-summer and fall) appear 

 to be present in the upper bay (Bertrand 1977). This population is increased 

 by immigrants which may have more than four generations a year and are 

 carried to the bay by river discharge (Bertrand 1977) • Evidently E^. herdmani 

 thrives best in brackish waters of estuaries. 



10.) Cirripeds 



Cirriped, immature (nauplii and cyprid) stages include several species 

 of barnacles of the genus Balanus, especially during the summer. During the 

 winter-spring months, the population in coastal Maine waters is probably 

 dominated by Balanus balanoides . There appear to be two peaks of abundance 

 which occur in spring (March and April or April and May) in Penobscot Bay 

 (Bertrand 1977). In Boothbay Harbor, there appears to be only one major 

 peak of cirriped larvae, in spring, with possibly a minor peak in reproduc- 

 tion in May (Sherman 1976) . It is unknown whether these peaks represent 

 the spawning activities of different species. The interaction of temperature 

 along with food supply accounts for the reproductive peaks in barnacles 

 (Vernberg and Vernberg 1970) . 



11.) Cladocerans 



Two species of cladocerans dominate the zooplankton of Penobscot Bay; 

 Podon leuckarti and Evadne nordmani from April through October (Bertrand 1977) 

 Seasonal occurrence for P. leuckarti and E^. nordmani were almost exactly the 

 same; however, maximal abundances occurred slightly earlier for E^. nordmani 

 (Bertrand 1977). Densities were highest in mid-July with a second, though 

 smaller, peak in late August or early September. In the Gulf of Maine and 

 Boothbay Harbor the same pattern and time of greatest abundance of the 

 cladocerans were noted (Bigelow 1926; Sherman 1976). Gieskes (1971) found 

 that seasonal surface temperature was an important factor governing both 

 the presence and abundance of P^. leuckarti and E^. nordmani in the North 

 Atlantic. The temperature at which these cladocerans first appeared 

 was about 43 to 45°F (6 to 7°C) and the optimal temperature for highest 

 numbers i£ around 55°F (13°C). Both these species of cladocerans increase 

 in numbers toward the outer Penobscot Bay (Bertrand 1977). Bertrand (1977) 

 suggests that higher numbers of E^. nordmani in the upper bay indicate that 

 this species can compete more successfully in a variable environment. E^. 

 nordmani reproduces parthenogenetically through the summer from cysts that 

 overwinter on the bottom (Bigelow 1926; Bainbridge 1958). Possibly £. 

 leuckarti has the same mode of reproduction. 



(Continued) 



4-F-5 



10-80 



