Vecchione: Paralarval ecology of Lolliguncula brevis 



519 



only 30 were collected in 9 estuarine samples (2%; 

 Table 1). The greatest abundance (270/100 m 3 ) calcu- 

 lated during this study from either estuarine or coastal 

 waters came from an epibenthic pullsled sample taken 

 at station E3 in May 1981; all pullsled samples from 

 that location and time included large numbers of 

 paralarvae (Table 1). Also, paralarvae from estuarine 

 waters were significantly larger (mean DML 2.5mm) 

 than those from coastal waters (2.0mm; /-test, P< 

 0.05). Paralarvae were collected in the estuary only 

 during May, July, and August. Although the estuarine 

 sampling included waters that varied greatly in salin- 

 ity, L. brevis were found there only in waters with 

 salinities >27 x 10" 3 . 



Paralarval feeding 



Fifty paralarval digestive tracts were examined. Of 

 these, 33 paralarvae were <2mm DML, 12 were 

 2-3 mm DML, and 5 were >3mm DML; the largest was 

 9.3mm DML. The largest specimen had pieces of 

 crustacean exoskeleton in the stomach and intestine 

 but only fluid in the caecum. Of the other specimens 

 >3mm DML, one had nondescript solid chunks in its 

 stomach, caecum, and intestine, one had fluid and ink 

 in the stomach and caecum, and the digestive tracts 

 of the other two were empty. In the 2-3 mm size-class, 

 two contained solid chunks of unrecognizable food, four 



had liquid and semiliquid mush in their digestive tracts, 

 and six were empty. Of the smallest size-class, one con- 

 tained crustacean appendages, four had amorphous 

 chunks of food (usually in the combined stomach/ 

 caecum, although one specimen had a chunk of food 

 in the esophagus), fifteen had one or more of the 

 digestive organs inflated with fluid, and thirteen were 

 empty. Therefore, of the total sample 18% of the 

 paralarvae had solid food material in the digestive 

 system. 



Discussion 



Distribution 



Paralarval L. brevis do not seem to be as euryhaline 

 as the adults. Trawl-caught L. brevis are osmocon- 

 formers that are known to tolerate salinities as low as 

 17.5 x 10~ 3 (Hendrix et al. 1981) and have been re- 

 ported from estuarine waters with much lower salin- 

 ities (<10xl0 -3 , Laughlin and Livingston 1982). 

 Paralarvae, however, were not found at salinities 

 <22 x 10 " 3 , and were most abundant at higher salin- 

 ities. This may in part explain why the paralarvae were 

 rare in the estuary as well as why they were most abun- 

 dant in nearbottom samples where the salinity is higher 

 than near the surface in both coastal and estuarine 

 waters of Louisiana (Vecchione et al. 1983). The 

 estuarine paralarvae were larger, and presumably 

 older, than those of coastal waters. Thus, although 

 estuarine paralarvae were not found in low-salinity 

 waters, it appears that the distribution of this species 

 shifts toward the estuary with growth, perhaps because 

 of the onshore set of the nearbottom currents. Eury- 

 halinity may develop ontogenetically late during para- 

 larval development. 



The spawning location for this species in Louisiana 

 waters is not known. Whereas L. brevis eggs have been 

 reported in trawl studies from Tampa Bay, Florida 

 (Hall 1970) and from bay and coastal waters off Texas 

 (Hixon 1980), extensive trawling (Vecchione In press 

 b) at the same coastal and estuarine stations as the 

 zooplankton projects reported here failed to collect any 

 squid eggs throughout the same time period as this 

 study. In Galveston Harbor, Texas, L. brevis attaches 

 its egg capsules to hard surfaces, sometimes covering 

 crab traps so thickly as to make them useless for their 

 designed purpose (A. Landry, Texas A&M Univ., 

 Galveston, pers. commun., 1984). The Louisiana trawl- 

 ing study avoided areas of hard substrate and thus 

 probably missed local spawning areas. Hixon (1980) 

 reported that L. brevis egg capsules were collected off 

 Galveston from March through December in depths of 

 2-18m with salinities of 21-35 x 10 -3 and tempera- 



