PROJECT REPORT PR-2008-10
Necropsy and Liver Histopathology for Fish Sampled in the Vicinity of the Barbers Point Ocean Outfall and the Maunalua Bay Reference Station, O’ahu, Hawai’i, January-March 2008
Thierry M. Work
May 2008, viii + 16 pp.
Fish-liver histopathology is an important biological tool used to assess fish for exposure to pollution because fish collected from polluted environments may have neoplasms in the liver.
In 2008 gross necropsy and fish-liver histopathology was done on 10 specimens each of Lutjanus kasmira, Myripristis berndti, and Selar crumenophthalmus collected live near the terminus of the Barbers Point Ocean Outfall. An additional cohort of 10 specimens each of L. kasmira, M. berndti, and S. crumenophthalmus were collected live at the Maunalua Bay Reference Station FR2.
Compared to S. crumenophthalmus from the reference station, those from Barbers Point had less lymphoid infiltrates and vacuolation and no necrosis nor atrophy. However fish from Barbers Point had more hemorrhage, coccidia, and melanized macrophages. Necrosis and atrophy were seen only at the reference station whereas metazoa were seen only in fish from Barbers Point.
M. berndti from Barbers Point had less melanized macrophage centers and vacuolation but more lymphoid infiltrates and necrosis compared to the reference station. Hemorrhage was seen with equal frequency from both areas, and atrophy was seen only at Barbers Point whereas chronic inflammation was seen only at the reference station.
L. kasmira from the Barbers Point outfall had more atrophy, vacuolation, and melanized macrophage centers but less lymphoid infiltrates. Hemorrhage, necrosis, and emphysema were seen only at the reference station.
Lymphoid infiltrates are nonspecific and could be caused by a variety of etiologies including infectious, toxic, or other types of agents which can injure the tissue. The vacuolation seen in all fish had a diffuse pattern and this type of change could indicate physiologic storage of lipid or glycogen or, in extreme cases, metabolic or toxic anomalies that can lead to damage to cytoplasmic organelles.
Low levels of coccidia are expected in the liver of Selar crumenophthalmus and were not related to outfalls. Wild fish have many parasites (Microsporidia, nematodes, cestodes), some of which migrate through the liver and most of which are species specific in their life cycles.
The emphysema and hemorrhage and acute necrosis were rapid changes most likely due to decompression trauma the fish received during capture. Neoplastic changes were not seen in any fish.