Southern California Bight 2003 Regional Monitoring Program: IV. Demersal Fishes and Megabenthic Invertebrates
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- Figure VII-1. Total parasite prevalence for all host fish species collected at depths of 22-198 m in the Southern California Bight, July through October 2003, host fishes in phylogenetic order.
- Figure VII-2. Total parasite mean intensity for all host fish species collected at depths of 22-198 m in the Southern California Bight, July through October 2003, host fishes in phylogenetic order.
Table VII-16. Frequency of occurrence of parasites on host fishes collected at depths of 22-198 m in the Southern California Bight, July through October 2003, hosts and parasites in phylogenetic order. For complete host and parasite scientific names refer to Tables 59 and 61, respectively. 
Figure VII-1. Total parasite prevalence for all host fish species collected at depths of 22-198 m in the Southern California Bight, July through October 2003, host fishes in phylogenetic order. 
Figure VII-2. Total parasite mean intensity for all host fish species collected at depths of 22-198 m in the Southern California Bight, July through October 2003, host fishes in phylogenetic order. 
Figure VII-3. Individual parasite prevalence for California scorpionfish (Scorpaena guttata) collected at depths of 22-198 m in the Southern California Bight, July through October 2003, parasites in phylogenetic order. 
Figure VII-4. Individual parasite mean intensity for California scorpionfish (Scorpaena guttata) collected at depths of 22-198 m in the Southern California Bight, July through October 2003, parasites in phylogenetic order. 
Figure VII-5. Total parasite mean intensity for all host fish species collected at depths of 22-198 m in the Southern California Bight, July through October 2003, host fishes in order of increasing maximum standard length (mm). Historically the LA Large-Outfall area has had a large influx of contaminants, such as DDT and PCBs, most of which still remain in the sediment (Stull 1995, Schiff 2000). Schiff and Allen (1996) found high levels of total DDT and total PCB in livers of three species of flatfish, Pacific sanddab, longfin sanddab, and Dover sole, collected on the Palos Verdes Shelf near the outfall. They attributed the accumulation to the niche of each of these fish species, an intimate association with the sediment, historical contamination on the Palos Verdes Shelf, and feeding upon resident infaunal invertebrates. In contrast, the prevalence of the piscicolid leech Austrobdella spp. 1 parasitic on California scorpionfish was significantly higher at OC (48.5 %) compared to HY (5.7 %), LA (0%), and SD (0%; p=0.0194; Appendix E-E9). This is a new species of leech, thus little is known of its life history and geographical range. It is possible that the range of this leech is restricted to the San Pedro Shelf and Santa Monica Bay. In addition, the lernaeopodid copepod N. scorpaenae, also parasitic on California scorpionfish, had a significantly higher mean intensity at HY and OC (79.8 and 89.1) than at LA and SD (32.0 and 15.7; p=0.0335; Appendix E-E10). The HY and OC areas are distant, separated by the LA area (Figures VII-3 through VII-5). Love et al. (1987) found California scorpionfish formed large offshore spawning aggregations in waters deeper than their off-season habitat. Tagging results indicated that fish return to the same spawning area annually. However, little is known of the alongshore movements of California scorpionfish in the SCB. Because both HY and OC areas have large, broad continental shelves, it is possible that when the fish move back onshore, they go to either shelf. Therefore, it is possible the similar prevalence and mean intensity of California scorpionfish at HY and OC is because the same population, thus the same assemblage of parasites, was sampled from these two areas. Kabata (1963) was among the first to demonstrate that parasites could be used to delineate fish stocks for management purposes and was instrumental in pioneering the use of parasites as biological tags for fisheries management. Since then, various parasites have been used as potential biological tags for fish stock and habitat identification (Leaman and Kabata 1987, Stanley et al. 1992, Oliva et al. 2004). Thus, the use of ectoparasites of California scorpionfish as biomarkers could potentially give some insight to the movement patterns of this host. It is interesting to note, even with the numerous studies and monitoring of benthic fishes in southern California, three new species of leeches, one new species of copepod, and 56 new host records were found in this study. This is likely due to the nature of marine monitoring sampling in the SCB. The protocol of many studies and monitoring programs does not include inspection for small parasitic organisms occurring on the sampled fishes, and only the larger parasites, such as the eye copepod (Phrixocephalus cincinnatus) and the gill isopod Pacific fish louse(E. vulgaris) are reported (Allen et al. 1998, Allen et al. 2002a, CSDMWWD 2004, CLAEMD 2005, CSDLAC 2005, OCSD 2006). It is recommended that if these programs plan to continue to include sampling of ectoparasites, the routine monitoring methods should be modified. For example, a subsample of target host species from outfall and nonoutfall areas, such as California scorpionfish, speckled sanddab, bigmouth sole, and hornyhead turbot, could be frozen and brought back to the laboratory for a thorough inspection and identification of ectoparasites. The presence/absence and prevalence of the various ectoparasites could then be determined and used as a monitoring tool. In conclusion, this study may serve not only as a basis of the species composition of the host-parasite fauna in the SCB, but also as an indication that certain host species and their ectoparasites can be a useful tool for identifying different areas subjected to environmental stress, such as effluent and sediment contamination. This study was the first of its kind attempted throughout the SCB. The outcome of the study suggests a reduction of the number of potential species of demersal fishes and their corresponding ectoparasites as bioindicators, from 34 species down to three. Results indicate that the prevalence of the copepod Holobomolochus prolixus on speckled sanddab, and total parasitization on bigmouth sole and hornyhead turbot, can be used as bioindicators of environmental stress in the SCB. In addition, the mean intensity of the parasitic larval stage chalimus on bigmouth sole and both the copepod Acanthochondria fraseri and the gnathiid praniza larvae on hornyhead turbot, also can be used as an indication of environmental stress. Many of the fishes that were evaluated in this study are of commercial importance (e.g., California scorpionfish and California halibut) and thus information about the parasite infestations on these hosts may be important to consumers and fisheries managers. Furthermore, the parasite-host relationships of California scorpionfish are complex and should be investigated further. The prevalence of the leech Austrobdella spp. 1 on California scorpionfish at OC was higher than at the other three Large-Outfall areas, indicating a narrow parasite range. In addition, the median mean intensity of the copepod Naobranchia scorpaenae on California scorpionfish was high at HY and OC, two areas distant from each other, implying host movement. Although the sample sizes of this study were large and covered a widespread geographical area, the results from this study are from a single survey within one year. Routine sampling of ectoparasites is needed to see if these trends persist. It is apparent that additional information on both taxonomic and ecological aspects of fish parasites in the SCB are greatly needed. 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