Sediment samples were collected as part of the macrobenthic 

 survey and on some of the submersible dives. The distribution of 

 Pennatula was compared to sediment types and found to occur over 

 a broad range of grain sizes. It was most abundant in silts and 

 clays but on occasion was found in gravelly areas. 



The microscale distribution of sea pens is shown in 

 relation to the course of the Johnson Sea Link submersible dive 

 #1414 in Figure 3. This dive was conducted in Georges Basin 

 (42°28.18'N 67°20.06'W), at a depth of 1060 feet, and represents 

 the highest density of sea pens observed in the Gulf of Maine. 

 The photo frame numbers represent 200 random photographs taken 

 during the dive transect. The density of sea pens varied 

 substantially during the course of the dive with several clusters 

 of sea pens being evident, as well as a reduction in density 

 along the dive transect. Another way of examining this data is 

 to plot the numbers of photographs containing the different 

 numbers of sea pens (Figure 4). From this plot, it is evident 

 that up to 55 sea pens occurred in a single frame. Chi-square 

 analysis of these data was utilized to compare the actual 

 distribution with that of a calculated Poisson distribution. The 

 data did not fit the Poisson or random distribution. 

 Subsequently, a negative binomial, which is often successfully 

 used to describe contagious invertebrate distributions (Elliot, 

 1983), was fit to the data. Again, no significant fit was found 

 between the observed and expected values. No other mathematical 

 models have been fit to the dataset since, as described below, 

 the actual observed microscale distribution may be modified by 

 individual sea pen behavior which, in turn, may negate simple 

 mathematical modelling of the population's distribution. 



Bearing in mind that sea pens can, and do, occasionally 

 retract completely into the sediment, the observed numbers of sea 

 pens per photograph represent an average density for dive #1414 

 of 2.5 m"2 with values ranging from to over 8 m~^ per 

 individual photo frame. In another area of Georges Basin average 

 density dropped to 0.19 m"^ while in other regions of the Gulf, 

 such as Truxton Swell and Jeffreys Bank, density averaged 0.2 m~^ 

 and 1.4 m~ , respectively. 



Sea pen behavior was observed in and around four lm2 

 quadrats at a station on Jeffreys Bank in 1986. A total of 17 

 sea pens were monitored over one entire 24 hour period ( 9 inside 

 the quadrats and 8 outside) to evaluate their extension and 

 contraction behavior. Only two sea pens were observed to 

 contract completely; they were no longer present during the final 

 dive. One other sea pen was noted to appear from a fully 

 contracted position between the second and third dive. This was 

 also one of the two sea pens that contracted completely, again, 

 during the last dive. All other sea pens maintained a fully 

 extended posture over the course of the experiment. 



In the laboratory, animals collected from Jeffreys Bank, 

 established themselves in burrows and exhibited extension and 



125 



