When oil is incorporated into the feces of zooplankton the specific 

 gravity of the combined pellet (oil and feces) is greater than the oil before 

 ingestion, and it therefore sinks in the water column (Parker et al., 1970). 

 Ingestion by plankton animals acts as a precipitation mechanism for otherwise 

 buoyant oil particles. The contaminated fecal pellets may then either become 

 covered by sediment or ingested by detritus feeders. 



The impact of oil on zooplankton is not clear. The observed oil con- 

 tamination could affect feeding and reproduction. Sensitive chemoreceptive 

 pores are located along the dorsal exoskeleton of copepods. The pores are 

 used for positioning during reproduction. If they were to become impacted 

 with oil, the individual probably would not be able to reproduce success- 

 fully. 



Mandibular contamination shown in copepods in Figure 4-3 may interfere 

 with the handling and ingesting of desired food particles. The toxicity of 

 ingested oil is poorly understood. The degree of toxicity depends on the 

 presence of volatile, aromatic compounds that are released through time as 

 the oil "ages." Additional studies are planned by NMFS to assess the effects 

 of petroleum hydrocarbons on zooplankton. 



4.1.2 Ichthyoplankton Studies 



Ichthyoplankton studies were contributed by W. Smith, D. Busch, L. 

 Sullivan, and K. Sherman of NEFC laboratories at Sandy Hook and Narragan- 

 sett and are based on samples collected during the first cruise of the Dela- 

 ware II (DE 76-13) . Fish eggs and larvae were collected with paired bongo 

 samplers and a surface neuston net at Stations 4 through 9 on the first 

 Delaware II cruise (DE 76-13) using standard Marine Resources Monitoring, 

 Assessment, and Prediction Program (MARMAP) sampling procedures (Figure 4-1). 

 Stations 7 and 8 were within the area of oil pancakes. Station 9 was at the 

 boundary between "clean" and oil-contaminated surface water, while Stations 

 4, 5, and 6 were outside the southern periphery of the oiled area. The 

 neuston nets towed on Stations 7 and 8 were saturated with oil (Figure 4-5) . 



Only two species of eggs were in the samples: cod and pollock. Pollock 

 eggs were most numerous within and adjacent to the spill zone, at Stations 7, 

 8, and 9, while cod eggs were concentrated around the periphery of the spill, 

 at Stations 4, 5, and 6 (Figure 4-6). 



At Station 9 adjacent to the spill area, oil globules were found adher- 

 ing to the surface membrance (chorion) of 93% of the pollock eggs. Of these 

 eggs, later examined by A. Longwell at the NMFS Milford Laboratory, 98% were 

 dead or moribund as determined through cytogenetic examination. In contrast, 

 only 64% of the cod eggs showed evidence of oil contamination. At Stations 

 4, 5, and 6 outside the spill area, more of the eggs were viable. 



Six species of fish larvae were in the collections: sand launce, cod, 

 pollock, rockling, hake, and herring. Of these species, only sand launce was 

 abundant. Other larvae were rare (Table VII-16 in Appendix VII). The abun- 

 dancede of sand launce decreased sharply at the two sampling stations within 



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