152 



NOAA Technical Report NMFS 140 



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GEOGRAPHIC AREA 



Figure 149 

 Density and biomass of Cirripedia in each <>f th 



geographic areas. 



creased with increasing depth (to 0.1 g/m 2 at 100-199 

 m) (Table 13; Fig. 150). An exception to this trend 

 occurred in the 200-499 m depth class. In this deepvvater 

 zone the density was low but the biomass was much 

 larger (2.5 gm 2 ) than the general trend would have 

 indicated. This relatively large value may have been due 

 to the presence of Balanus hameri in this depth class. 

 This species is exceptionally large and occurs in moder- 

 ately deep water. 



Barnacles occurred in only a small proportion of the 

 samples, but they were much more common (139! ) in 

 the shallow depth class (0-24 m) than in the other 

 classes (3 to 4%). None were present in depths greater 

 than 500 m (Table 15). 



Relation to Sediments 



Barnacles were found in all sediment types of the New 

 England region that were sampled. Their average den- 

 sity was, surprisingly, highest (56 individuals/m 2 ) in 



sand-silt sediments (Table 16; Fig. 151 ). Moderate den- 

 sities (29 and 16 individuals/m ) occurred on gravel 

 and sand bottoms. The other sediment types yielded 

 low (<5/m ) densities. 



The biomass of barnacles was largest (11 g/m 2 ) on 

 gravel bottoms and was moderate (4.4 and 2.4 g/m L ) in 

 sand-silt and sand. Low quantities (<0.5 g/m 2 ) pre- 

 vailed in the other sediments (Table 18; Fig. 151). 



The unexpectedly high density of cirripedes in sand- 

 silt bottoms resulted from high concentrations of small 

 specimens (average weight <0.1 g) in a small propor- 

 tion (3%) of the samples. Small barnacles densely colo- 

 nize occasional mollusk shells and other firm substrates, 

 often of biogenic origin, but rarely are they able to 

 attain large size in these habitats. Conversely, on gravel 

 bottoms the average size of individual barnacles was 0.3 

 to 0.4 g. 



Frequency of occurrence of barnacles was low in all 

 types of bottom sediments. Shell and gravel ranked 



