Grosell Martin, Marek Bret, Walls Sarah, Pope Carolyn, Sam Cameron, Heuer Rachael M, Oehlert Amanda M
Department of Marine Biology and Ecology, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149-1098, USA.
Department of Marine Geosciences, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149-1098, USA.
J Exp Biol. 2025 Jul 15;228(14). doi: 10.1242/jeb.249834. Epub 2025 Jul 18.
Marine fish are likely one of the top producers of biogenic carbonate in the oceans. However, nothing is known about the production rate and composition of intestinal carbonate (ichthyocarbonate) excreted by mesopelagic fishes, which are small, fragile and account for up to 94% of global fish biomass. To address this knowledge gap, and associated uncertainty of global ichthyocarbonate production, we identified a model species residing at 350-430 m, depths relevant for mesopelagic fishes. The blackbelly rosefish (Helicolenus dactylopterus) lacks swim bladders and survives capture and transfer to the lab. Freshly collected blackbelly rosefish, maintained at 6°C, contained high amounts of intestinal ichthyocarbonate (0.4 g kg-1) and excreted ∼5 mg kg-1 h-1 ichthyocarbonate, in agreement with expectations based on allometric and thermal relationships for other species. Despite longer intestinal residence time, intestinal and excreted ichthyocarbonates are similar in crystallite morphology, composition and sinking rate, but have a higher dissolution rate than that produced by shallow water species at higher temperatures, ruling out strong effects of pressure and low temperatures on ichthyocarbonate formation and excretion. Considering allometric and thermal relationships, the metabolic rate of blackbelly rosefish is lower than that of other marine fish in general, and mesopelagic fishes in particular. Our observations support assumptions of ichthyocarbonate excretion by mesopelagic fishes, and suggest that thermal and allometric relationships for ichthyocarbonate excretion determined from shallow water species extend to fish populations at depth.
海洋鱼类可能是海洋中生物源碳酸盐的主要生产者之一。然而，对于生活在中层水域的鱼类（它们体型小、身体脆弱，占全球鱼类生物量的94%）所排泄的肠道碳酸盐（鱼源碳酸盐）的产生速率和组成，我们却一无所知。为了填补这一知识空白，并解决全球鱼源碳酸盐产量的相关不确定性问题，我们确定了一种生活在350 - 430米深度（与中层水域鱼类相关的深度）的模式物种。黑腹玫瑰鱼（Helicolenus dactylopterus）没有鱼鳔，能够在被捕捞并转移到实验室后存活下来。刚采集的黑腹玫瑰鱼在6°C的环境下饲养，体内含有大量的肠道鱼源碳酸盐（0.4克/千克），并且每小时排泄约5毫克/千克的鱼源碳酸盐，这与基于其他物种的异速生长和热关系所做的预期相符。尽管肠道停留时间更长，但肠道和排泄出的鱼源碳酸盐在微晶形态、组成和沉降速率方面相似，但溶解速率比高温环境下浅水物种产生的鱼源碳酸盐更高，这排除了压力和低温对鱼源碳酸盐形成和排泄的强烈影响。考虑到异速生长和热关系，黑腹玫瑰鱼的代谢率总体上低于其他海洋鱼类，尤其是中层水域鱼类。我们的观察结果支持了中层水域鱼类排泄鱼源碳酸盐的假设，并表明从浅水物种确定的鱼源碳酸盐排泄的热关系和异速生长关系可扩展到深海鱼类种群。
