Estimates of fish egg moribundity based on cytological- 

 cytogenetic study of the embryos.— Embryo cells and mitoses of all 

 available eggs were examined. Cellular state was determined, and 

 the mitotic index and incidences of abnormal telophases scored over 

 the entire embryo. From these observations estimates of moribun- 

 dity were made. The fourbeard rockling and yellowtail flounder 

 embryos were categorized as moribund if the embryos showed one 

 or more of the following: cell lysis or nuclear pyknosis; anomalous, 

 disorderly mitoses over the entire embryo (pertinent to stage II 

 only); more than 50% abnormal telophases (pertinent to stage II 

 only); absence of any mitotic telophases whatsoever. Tables 3-5 to 

 3-8 provide the details of moribundity by developmental stage for 

 each station at which eggs were collected. 



Paucity of eggs at several stations did not allow meaningful 

 station-to-station comparisons of moribundity levels. Also, we 

 could not preclude from the station distribution or from the 

 analytical chemical analyses done on plankton, benthos, and fish as 

 reported in this volume, that eggs from any station were not expos- 

 ed to the gasoline, either by maternal uptake prior to spawning or 

 by direct exposure after spawning. Data are accordingly interpreted 

 and discussed in terms of moribundity for day sampled. 



Postspill day 2, 18 March. — (a) Fourbeard rockling. 

 Fourbeard rockling eggs collected 2 d after the spill were, un- 

 fortunately, few in number. This, however, may have been the 

 result of egg loss as the most severely affected eggs settle out of the 



water column, and temporary cessation of much spawning in the 

 affected area in the immediate aftermath of the spill. Total number 

 of eggs in t'te plankton was 12, and 3 of these were used for scan- 

 ning electron microscopy, as noted above. 



All nine eggs remaining for cytological study of embryo cells 

 and mitoses were moribund (Table 3-5). Eggs were collected at 

 three sample stations only, 1 12, 115, and 1 17 (Fig. 3-14). They were 

 all in very early development stages, II and III, i.e., at the morula 

 and blastula stages. The average number of mitotic telophases per 

 embryo, an indicator of developmental rate, was 16.4 even though 

 embryos showed cell lysis and other signs of impending mortality. It 

 is more common to find such moribund embryos with few, or no 

 mitoses at all. It would seem as if the fourbeard rockling eggs were 



Table 3-5. — Cytological-cytogenetic estimates of fourbeard rockling 

 egg moribundity 2 d after the Ocean 250 gasoline spill. See Figure 3-14 

 (map) for explanation of system for designating same sample station 

 on consecutive cruises. 



Sample 

 station 



Development stage II-III (morula-blastula) 



Total no. 



No. moribund 



112 



115 

 117 



18° 



NAPATREE PT 



WATCH HILL PT 



205 



SUGAR REEF 



CATUUB • 

 ROCKS 



3 # 



203 



206* 



/ IfcWATCH HILL REEF 



17 • 



117 



217 



•214 



? . ■• : 



• 8 



208 



•io 



210 



"• 



2 • 



202 



•l 

 201 



•12 

 112 

 212 



I3» 

 213 





1 



1 



1 



18* 



54 e 



52" 



50" 



Figure 3-14.— Survey area and station locations for RV Stricter cruise 78-01. Asterisk marks the location of grounding of barge Ocean 250 on Watch HID Reef. The 100 series 

 numbers refer to postspfl) day 2 samples; the 200 series, to postspill day 4 samples. Numbers 1-18 refer to postspill day 25 samples. Only stations at which fish eggs were sampled 

 are indicated. 



27 



