skip to main content


Title: Temperature-dependent effects on fecundity in a serial broadcast spawning fish after whole-life high CO2 exposure
Abstract Experiments examining fish sensitivities to future oceanic CO2 levels have greatly expanded over past decades and identified many potentially affected traits. Curiously, data on reproductive trait responses to high CO2 are still scarce, despite their strong link to Darwinian fitness and thus to population vulnerability to ocean acidification. We conducted two rearing experiments on the first broadcast-spawning marine fish model (Atlantic silverside, Menidia menidia) to examine how long-term and novel whole life-cycle exposures to predicted future CO2 levels (∼2,000 µatm) affect laboratory spawning, temperature-specific reproductive investment, fecundity, and size distributions of maturing oocytes. At low temperatures (17°C), female body size and therefore potential fecundity (FPot, oocytes/female) slightly increased with CO2, while relative fecundity (FRel, oocytes/g female) remained unaffected. At high temperatures (24°C), high CO2 substantially reduced both FPot (−19%) and FRel (−28%) relative to control treatments. Irrespective of CO2, females at 24°C grew larger and heavier than those at 17°C, and although larger females produced larger oocytes at some developmental stages, they also had lower gonadosomatic indices and lower FRel. Our findings contrast with most previous studies and thus highlight the need to investigate reproductive impacts of increasing CO2 on multiple fish species with contrasting life history strategies.  more » « less
Award ID(s):
1756751
NSF-PAR ID:
10319866
Author(s) / Creator(s):
; ; ; ; ; ;
Editor(s):
Browman, Howard
Date Published:
Journal Name:
ICES Journal of Marine Science
Volume:
78
Issue:
10
ISSN:
1054-3139
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. null (Ed.)
    Concurrent ocean warming and acidification demand experimental approaches that assess biological sensitivities to combined effects of these potential stressors. Here, we summarize five CO2 × temperature experiments on wild Atlantic silverside, Menidia menidia, offspring that were reared under factorial combinations of CO2 (nominal: 400, 2200, 4000, and 6000 µatm) and temperature (17, 20, 24, and 28 °C) to quantify the temperature-dependence of CO2 effects in early life growth and survival. Across experiments and temperature treatments, we found few significant CO2 effects on response traits. Survival effects were limited to a single experiment, where elevated CO2 exposure reduced embryo survival at 17 and 24 °C. Hatch length displayed CO2 × temperature interactions due largely to reduced hatch size at 24 °C in one experiment but increased length at 28 °C in another. We found no overall influence of CO2 on larval growth or survival to 9, 10, 15 and 13–22 days post-hatch, at 28, 24, 20, and 17 °C, respectively. Importantly, exposure to cooler (17 °C) and warmer (28 °C) than optimal rearing temperatures (24 °C) in this species did not appear to increase CO2 sensitivity. Repeated experimentation documented substantial inter- and intra-experiment variability, highlighting the need for experimental replication to more robustly constrain inherently variable responses. Taken together, these results demonstrate that the early life stages of this ecologically important forage fish appear largely tolerate to even extreme levels of CO2 across a broad thermal regime. 
    more » « less
  2. Ocean acidification is occurring in conjunction with warming and deoxygenation as a result of anthropogenic greenhouse gas emissions. Multistressor experiments are critically needed to better understand the sensitivity of marine organisms to these concurrent changes. Growth and survival responses to acidification have been documented for many marine species, but studies that explore underlying physiological mechanisms of carbon dioxide (CO2) sensitivity are less common. We investigated oxygen consumption rates as proxies for metabolic responses in embryos and newly hatched larvae of an estuarine forage fish (Atlantic silverside, Menidia menidia) to factorial combinations of CO2×temperature or CO2×oxygen. Metabolic rates of embryos and larvae significantly increased with temperature, but partial pressure of CO2 (PCO2) alone did not affect metabolic rates in any experiment. However, there was a significant interaction between PCO2 and partial pressure of oxygen (PO2) in embryos, because metabolic rates were unaffected by PO2 level at ambient PCO2, but decreased with declining PO2 under elevated PCO2. For larvae, however, PCO2 and PO2 had no significant effect on metabolic rates. Our findings suggest high individual variability in metabolic responses to high PCO2, perhaps owing to parental effects and time of spawning. We conclude that early life metabolism is largely resilient to elevated PCO2 in this species, but that acidification likely influences energetic responses and thus vulnerability to hypoxia. 
    more » « less
  3. null (Ed.)
    Despite the remarkable expansion of laboratory studies, robust estimates of single species CO 2 sensitivities remain largely elusive. We conducted a meta-analysis of 20 CO 2 exposure experiments conducted over 6 years on offspring of wild Atlantic silversides ( Menidia menidia ) to robustly constrain CO 2 effects on early life survival and growth. We conclude that early stages of this species are generally tolerant to CO 2 levels of approximately 2000 µatm, likely because they already experience these conditions on diel to seasonal timescales. Still, high CO 2 conditions measurably reduced fitness in this species by significantly decreasing average embryo survival (−9%) and embryo+larval survival (−13%). Survival traits had much larger coefficients of variation (greater than 30%) than larval length or growth (3–11%). CO 2 sensitivities varied seasonally and were highest at the beginning and end of the species' spawning season (April–July), likely due to the combined effects of transgenerational plasticity and maternal provisioning. Our analyses suggest that serial experimentation is a powerful, yet underused tool for robustly estimating small but true CO 2 effects in fish early life stages. 
    more » « less
  4. Browman, Howard (Ed.)
    Ocean acidification may impact the fitness of marine fish, however, studies reporting neutral to moderate effects have mostly performed short-term exposures to elevated CO2, whereas longer-term studies across life stages are still scarce. We performed a CO2 exposure experiment, in which a large number (n > 2200) of Atlantic silverside Menidia menidia offspring from wild spawners were reared for 135 days through their embryonic, larval, and juvenile stages under control (500 µatm) and high CO2 conditions (2300 µatm). Although survival was high across treatments, subtle but significant differences in length, weight, condition factor and fatty acid (FA) composition were observed. On average, fish from the acidified treatment were 4% shorter and weighed 6% less, but expressed a higher condition factor than control juveniles. In addition, the metrics of length and weight distributions differed significantly, with juveniles from the high CO2 treatment occupying more extreme size classes and the length distribution shifting to a positive kurtosis. Six of twenty-seven FAs differed significantly between treatments. Our results suggest that high CO2 conditions alter long-term growth in M. menidia, particularly in the absence of excess food. It remains to be shown whether and how these differences will impact fish populations in the wild facing size-selective predation and seasonally varying prey abundance. 
    more » « less
  5. ABSTRACT

    Ocean acidification (OA) resulting from anthropogenic CO2 emissions is impairing the reproduction of marine organisms. While parental exposure to OA can protect offspring via carryover effects, this phenomenon is poorly understood in many marine invertebrate taxa. Here, we examined how parental exposure to acidified (pH 7.40) versus ambient (pH 7.72) seawater influenced reproduction and offspring performance across six gametogenic cycles (13 weeks) in the estuarine sea anemone Nematostella vectensis. Females exhibited reproductive plasticity under acidic conditions, releasing significantly fewer but larger eggs compared to ambient females after 4 weeks of exposure, and larger eggs in two of the four following spawning cycles despite recovering fecundity, indicating long-term acclimatization and greater investment in eggs. Males showed no changes in fecundity under acidic conditions but produced a greater percentage of sperm with high mitochondrial membrane potential (MMP; a proxy for elevated motility), which corresponded with higher fertilization rates relative to ambient males. Finally, parental exposure to acidic conditions did not significantly influence offspring development rates, respiration rates, or heat tolerance. Overall, this study demonstrates that parental exposure to acidic conditions impacts gamete production and physiology but not offspring performance in N. vectensis, suggesting that increased investment in individual gametes may promote fitness.

     
    more » « less