title: Ocean Acidification Affects Hemocyte Physiology in the Tanner Crab (Chionoecetes bairdi).
abstract: We used flow cytometry to determine if there would be a difference in hematology, selected immune functions, and hemocyte pH (pHi), under two different, future ocean acidification scenarios (pH = 7.50, 7.80) compared to current conditions (pH = 8.09) for Chionoecetes bairdi, Tanner crab. Hemocytes were analyzed after adult Tanner crabs were held for two years under continuous exposure to acidified ocean water. Total counts of hemocytes did not vary among control and experimental treatments; however, there were significantly greater number of dead, circulating hemocytes in crabs held at the lowest pH treatment. Phagocytosis of fluorescent microbeads by hemocytes was greatest at the lowest pH treatment. These results suggest that hemocytes were dying, likely by apoptosis, at a rate faster than upregulated phagocytosis was able to remove moribund cells from circulation at the lowest pH. Crab hemolymph pH (pHe) averaged 8.09 and did not vary among pH treatments. There was no significant difference in internal pH (pHi) within hyalinocytes among pH treatments and the mean pHi (7.26) was lower than the mean pHe. In contrast, there were significant differences among treatments in pHi of the semi-granular+granular cells. Control crabs had the highest mean semi-granular+granular pHi compared to the lowest pH treatment. As physiological hemocyte functions changed from ambient conditions, interactions with the number of eggs in the second clutch, percentage of viable eggs, and calcium concentration in the adult crab shell was observed. This suggested that the energetic costs of responding to ocean acidification and maintaining defense mechanisms in Tanner crab may divert energy from other physiological processes, such as reproduction.
authors: National Ocean and Atmospheric Administration, National Marine Fisheries Services, Northeaster Fisheries Science Center, Milford, Connecticut, United States of America.
authors: Shannon L
authors: SL
authors: Meseck
authors: National Ocean and Atmospheric Administration, National Marine Fisheries Services, Northeaster Fisheries Science Center, Milford, Connecticut, United States of America.
authors: Jennifer H
authors: JH
authors: Alix
authors: Kodiak Laboratory, Resource Assessment and Conservation Engineering Division, Alaska Fisheries Science Center, National Marine Fisheries Service, NOAA, Kodiak, Alaska, United States of America.
authors: Katherine M
authors: KM
authors: Swiney
authors: Kodiak Laboratory, Resource Assessment and Conservation Engineering Division, Alaska Fisheries Science Center, National Marine Fisheries Service, NOAA, Kodiak, Alaska, United States of America.
authors: W Christopher
authors: WC
authors: Long
authors: National Ocean and Atmospheric Administration, National Marine Fisheries Services, Northeaster Fisheries Science Center, Milford, Connecticut, United States of America.
authors: Gary H
authors: GH
authors: Wikfors
authors: Kodiak Laboratory, Resource Assessment and Conservation Engineering Division, Alaska Fisheries Science Center, National Marine Fisheries Service, NOAA, Kodiak, Alaska, United States of America.
authors: Robert J
authors: RJ
authors: Foy
mesh_terms: D000818:Animals; D003386:Brachyura / Q000187:drug effects / Q000276:immunology*; D006434:Hemocytes / Q000737:chemistry / Q000166:cytology / Q000187:drug effects / Q000276:immunology*; D042541:Intracellular Space / Q000187:drug effects; D010586:Phagocytes / Q000187:drug effects; D012623:Seawater / Q000737:chemistry*; D013997:Time Factors