Effects of temperature and salinity on mortality and metabolism of Ophiopholis mirabilis

Abstract

Specimens of the ophiuroid Ophiopholis mirabilis were acclimated at 15°C and 30 PSU and then assessed for temperature and salinity tolerance as these parameters were increased or decreased by 1 unit per day. Oxygen consumption, ammonia excretion, and moisture content were measured at different temperatures (5, 10, 15, 20 and 25°C) and salinities (25, 30 and 35 PSU). Ophiopholis mirabilis could tolerate temperatures of 0–24°C in the experimental situation, and mortality was 0% in the salinity range of 22 to 48 PSU at 15°C. Two-way ANOVA showed that the oxygen consumption, ammonia excretion and Q₁₀ (used to describe the temperature sensitivity of respiration) were significantly affected by temperature and salinity and the interactions between the two factors were significant. The interaction for moisture content was not significant. Respiration of O. mirabilis was most sensitive at 10–15°C. Stepwise multiple regression analysis revealed a significant positive relationship between oxygen consumption, temperature and salinity. Ammonia excretion and moisture content of the brittle stars showed an inverse relationship with salinity but a positive relationship with temperature. The results suggested that the temperature and salinity tolerance of O. mirabilis is determined by a range of values present in its habitat (i.e. 30–32 PSU and −1 to 22°C). The main cause of mortality of ophiuroids in the present study might be a change in tissue moisture beyond their regulatory capacity.

Key words:

• Ammonia excretion
• Ophiopholis mirabilis
• oxygen consumption
• salinity
• temperature
• tolerance

Funding

This study was supported by the National Basic Research Program of China (Grant no. 2011CB409805); the National Science & Technology Pillar Program (Grant no. 2011BAD13B06); the Special Fund for the Basic R & D Program in the Central Non-profit Research Institutes (20603022013042); and the National Science and Technology Planning Project of China (Grant no. 2011BAD13B05).

Editorial responsibility: Eric Thompson

Additional information

Funding

Funding: This study was supported by the National Basic Research Program of China (Grant no. 2011CB409805); the National Science & Technology Pillar Program (Grant no. 2011BAD13B06); the Special Fund for the Basic R & D Program in the Central Non-profit Research Institutes (20603022013042); and the National Science and Technology Planning Project of China (Grant no. 2011BAD13B05).