CALORIC VALUES OF SOME 

 NORTH ATLANTIC CALANOID COPEPODS 



Evaluation of the dynamics of energy exchange of 

 a marine ecosystem necessitates a knowledge of 

 the caloric equivalents of its living constituents. 

 This information, in combination with informa- 

 tion on growth, metabolism, and assimilation 

 rates can lead to predictions of energy conver- 

 sion between trophic levels and estimates of pro- 

 duction. 



Researchers have accumulated a considerable 

 quantity of data concerning the caloric value of 

 marine organisms (Cummins 1967; Thayer et al. 

 1973; Tyler 1973); however, values recorded for 

 marine, planktonic copepod species have been few 

 (Slobodkin and Richman 1961; Comita et al. 1966; 

 Cummins 1967). My research reports the caloric 

 values for seven species of marine copepods, six of 

 which apparently have not been previously re- 

 corded. These studies are part of an overall inves- 

 tigation of the bioenergetics of the early life stages 

 of some North Atlantic fish species. 



Materials and Methods 



Plankton samples were collected in July and 

 August 1972 off Narragansett Bay, R.I. except for 

 samples of Pseudocalanus minutus which were 

 collected in April 1971 off the coast of Delaware. 

 All samples were preserved in 5% Formalin^ and 

 were prepared and combusted in July and August 

 1972. Laboratory preparation included rinsing the 

 samples in distilled water for 1 h, sieving through 

 a coarse mesh screen to remove large detritus, and 

 hand sorting adults of the various copepod species 

 under a dissecting microscope. Pure copepod 

 species samples were dried for 24 h at 90°C and 

 desiccated in a silica gel desiccator after which 

 they were made into pellets for combustion. All 

 combustion was done in a Parr 1241 automatic, 

 adiabatic calorimeter adapted for a microbomb. 

 Combustion samples for each copepod species were 

 done in triplicate. Percent ash for each copepod 

 species was determined by ashing uncombusted 

 pellets in triplicate at 500°C for 4 h in a muffle 

 furnace. 



Results 



Mean values for the caloric determinations of 



the seven species of copepods (Table 1) were as 

 follows: 5,251.9 cal/g dry weight, 5,626.3 cal/g 

 ash-free dry weight, and 6.70% ash. Statistical 

 analysis of the means of caloric values for each 

 species (Duncan's New Multiple Range Test, Steel 

 and Torrie 1960) indicated that Calanus ftninar- 

 chicus had significantly higher values of both 

 calories per gram dry weight and calories per 

 gram ash-free dry weight than all other species, 

 that Temora longicornis had significantly lower 

 values for calories per gram ash-free dry weight 

 than all species except Centropages hamatus, and 

 that the differences between Acartia tonsa, Tor- 

 tanus discaudatus, P. minutus, Centropages 

 typicus, and C. hamatus were minimal (Table 1). 

 Temora longicornis had the highest percent ash. 

 Acartia tonsa and P. minutus also had relatively 

 high ash values in comparison with the other 

 species, while Calanus finmarchicus was inter- 

 mediate and higher than the three remaining 

 species (Table 1). 



Table l. — Caloric and ash values for some North Atlantic 

 copepods. Species are recorded in order from largest to smallest 

 mean value under each category. Those species side-scored have 

 similar means (Duncan's New Multiple Range Test, P = 0.05). 



Standard 

 Species Mean deviation 



cal/g dry weight 

 {Calanus finmarchicus 6,425.1 ±187.0 



Centropages typicus 

 Tortanus discaudatus 

 Centropages hamatus 



4.70 

 4.32 

 4.10 



tO.28 

 b0.07 

 t0.13 



^Reference to trade names does not imply endorsement by 

 National Marine Fisheries Service, NOAA. 



Discussion 



Since the species in this study were preserved in 

 Formalin for short periods of time and rinsed in 

 distilled water to remove the Formalin before pro- 

 cessing, the estimates of caloric and ash content 



218 



