double oblique patterns for 15 min. Nine stations were sampled on 

 20 March and nine on 10 April (Table 3-3, Fig. 1-2). All samples 

 were preserved in buffered 4°7o formaldehyde except for the 20 

 March 0.333 mm mesh samples from stations 13, 14, 15, and 17. 

 These were split: one-half was frozen for hydrocarbon analyses and 

 one-half preserved in formaldehyde. The 0.333 mm net was lost 

 after four stations and the frame was refitted with a 0.505 mm net. 

 Thereafter at stations 3, 5, 6, and 8 one 0.505 mm sample was split 

 and the other was preserved whole. 



On 10 April three 0.333 mm samples (stations 1, 11, 14) were 

 split. One-half of each of these was frozen for hydrocarbon 

 analyses and one-half was preserved. The 0.505 mm samples and 

 the remaining 0.333 mm samples were preserved. 



Table 3-3. — Summary of plankton samples collected on RV Strider cruises 78-01 

 and 78-02 in the area of the Ocean 250 grounding. Zero indicates duplicate 0.505 

 mm mesh samples and no 0.333 mm mesh samples; x indicates 0.333 mm and 0.505 

 mm mesh samples. 







Plankton 





Station 



RV Strider cruise 



78-01 



RV Strider cruise 78-02 



number 



20 March 1978 (day 4) 



10 April 1978 (day 21) 



1 







X 



3 









X 



5 









X 



6 









X 



8 











9 







X 



10 







X 



12 



x' 







13 



X 





X 



14 



X 





X 



15 



X 







16 







X 



17 



X 







Total 



9 





9 



'0.333 mm mesh net lost; no sample— replaced with 0.505 mm mesh net. 



Laboratory procedure. — All fish eggs and larvae were re- 

 moved from the 20 March and 10 April 0.333 mm and 0.505 mm 

 samples. They were identified, counted, and then sent to Arlene 

 Longwell of the NMFS Laboratory at Milford, Conn., for 

 cytogenetic studies (Hughes and Longwell, see section 3.4). 



Each plankton sample was subsampled with a Folsom splitter 

 until the total number of animals in the subsample was reduced to 

 between 500 and 1,000. The zooplankton were identified and 

 counted, and the number of animals per sample was calculated. 



Results and discussion. — The species composition is typical of 

 a coastal community with estuarine, coastal, and offshore species. 

 Oikopleura sp. was the dominant organism in March following the 

 spill, but was absent in April samples. Balanus balanoides nauplii, 

 Pseudocalanus minutus, Tortanus discaudatus, Temore longi- 

 comis, and Acartia clausi characterized both sampling periods. Like 

 Oikopleura sp., Sagitta elegans numbers varied between the two 

 cruises, but S. elegans has been observed to have distinctly patchy 

 distribution. These findings are summarized in Table 3-4 where 

 relative abundance, dominance indices, and elementary statisitics 

 were calculated for the plankton samples from each cruise follow- 

 ing the method of Fager and McGowan (1963). For this analysis all 

 plankton samples from each cruise were grouped by mesh size to 

 rninimize sampling bias. 



The plankton community showed little change during the 

 postspill period. Damage or alteration to the community was not 

 evident. Species composition and abundance at the time just fol- 

 lowing the spill and 3 wk later remained fairly constant. The only 

 major change in population composition observed was the large 

 number of Oikopleura sp. which dominated the plankton samples 

 immediately after the spill, but which was entirely absent in the 

 samples from the follow-up cruise. This is probably attributable to 

 a population bloom and the patchy nature of plankton rather than 

 to an effect of gasoline contamination. 



No visual evidence of external hydrocarbon contamination 

 was observed during the identification process. 



Acknowledgments. — The authors extend their gratitude to 

 Thomas McKenney (NMFS, Narragansett Laboratory) for his help 

 in the collection of the samples and to Janet Murphy (NMFS, 

 Woods Hole Laboratory) and Joseph Kane (NMFS, Narragansett 

 Laboratory) for analyzing the plankton samples from RV Strider 

 cruises 78-01 and 78-02, respectively. We are particularly grateful to 

 Thomas Plichta (NMFS, Narragansett Laboratory) for running the 

 Fager statistical program. 



3.4 Cytologkal-Cytogenetic Analyses of Fourbeard Rock- 

 ling and Yellowtail Flounder Eggs from Plankton at 

 Ocean 250 Gasoline Spill 



This section was prepared by J. B. Hughes" and A. Crosby 

 Longwell." 



Methods. — All fish eggs were picked out of the plankton col- 

 lections and identified as to species. Eggs were those of the 

 fourbeard rockling and yellowtail flounder. Both species have 

 buoyant eggs which float near the water surface (Bigelow and 

 Welsh 1924). Fourbeard rockling eggs were common at more 

 stations throughout the sampling period. As many as 31 1 fourbeard 

 rockling eggs and only 16 yellowtail flounder eggs were collected. 

 All eggs were used in the following studies. 



Eggs were preserved, along with other plankton, in a 1:10 

 dilution of neutralized formaldehyde. A few of the fourbeard 

 rockling eggs were dehydrated and goldplated for scanning electron 

 microscopy. 



To examine the eggs and their chorions in the ordinary light 

 microscope, the chorion was dissected off the egg, the yolk re- 

 moved and discarded. The embryo and chorion were stained and 

 squashed separately. The stain used was 2% orcein in 45% acetic 

 acid mixed 19:1 with proprionic acid (Longwell and Hughes 1980). 

 Eggs were first sorted as to development stage, and their gross 

 morphology was examined. 



Results and discussion. 



Condition of chorion, outer egg membrane, of fourbeard 

 rockling eggs. — The outer egg membranes of three fourbeard rock- 

 ling eggs taken 4 d after the gasoline spill, 20 March, examined with 

 the 100 x objective of the light microscope, showed areas of gross 

 deterioration. Other portions of the same chorions still showed 

 normal structure with pinhole pores. See Figures 3-4 to 3-7. The 

 poor condition of the egg chorion in this small sample of eggs may 



"Northeast Fisheries Center Milford Laboratory, National Marine Fisheries 

 Service, NOAA, Milford, CT 05460. 



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