Your article: Robust quantification of fish early life CO2 sensitivities via serial experimentation, Biology Letters, 2018 (DOI: 10.3410/f.734523360.793553721), has been recommended in F1000Prime as being of special significance in its field by F1000 Faculty Member Philip Munday.
28 November 2018. Hannes, Emma, and Chris are happy to announce that Biology Letters just published our latest study, a meta-analysis of 20 standard CO2 exposure experiments conducted on Atlantic silverside offspring between 2012-2017. All these years of sustained experimental work resulted in the most robustly constrained estimates of overall CO2 effect sizes for a marine organism to date.
The study demonstrated:
A general tolerance of Atlantic silverside early life stages to pCO2 levels of ~2,000 µatm
A significant overall CO2 induced reduction of embryo and overall survival by -9% and -13%, respectively
The seasonal change in early life CO2 sensitivity in this species
The value of serial experimentation to detect and robustly estimate CO2 effects in marine organisms
This figure shows the summary of early life responses to high CO2 conditions in Atlantic silversides across all experiments conducted between 2012-2017. Effect size was estimated using the log-transformed response ratio (A-D). Error bars are 95% confidence intervals. The responses are considered significant if the confidence interval does not include zero. Panels E-F: seasonal decomposition of response ratios, showing that silverside early life stages are most sensitive to high CO2 at the beginning and end of their spawning season.
20 July 2018. We are happy to announce that Diversity just published Chris Murray’s paper on complex CO2 x temperature effects in Atlantic silverside offspring. The paper synthesizes 5 large multistressor experiments conducted since 2014, finding evidence for the large CO2 tolerance in this species across a large temperature range.
M. menidia. Offspring responses to control (blue), high (red), and extreme (green) CO2 conditions at four temperatures across five CO2 × temperature factorial experiments. Traits include embryo survival (A–E), hatch length (F–I), larval survival (J–N) and larval growth rate (O–R). Individual replicates are represented by small faded circles. Treatment means (±SD) are depicted by large, bold circles and connected by dotted lines. Note: different scales used for hatch length measurements due to differences in sample timing; panels F and G use 1dph length Y axis (left) while panels H and I use hatch length Y axis (right).
31 March 2018. We’re happy to announce that Marine Biology just published our latest study examining the starvation tolerance of silverside larvae and juveniles at contrasting CO2 conditions. We compiled observations from five separate experiments spanning different years, laboratories, temperatures, life stages, and CO2 levels. Contrary to expectation, we found that starvation rates were largely independent of the CO2 environment in this fish species.
One major set of data was produced by Elle Parks as part of her Research Experience for Undergraduates (NSF-REU) in summer 2017. Well done, everybody!
Baumann, H., Parks, E.M.*, and Murray, C.S.* (2018)
Hannes shows Elle Parks (REU 2017), how individual screen with enumerated embryos are suspended into the replicate rearing containers. (Photo: Peter Morenus, UConn)
On 9 June, Elle and Julie strip-spawn Atlantic silverside females into spawning dishes covered in window screen for eggs to attach. (Photo: Peter Morenus, UConn)
M. menidia. (A) Relative cumulative starvation mortalities of early juveniles reared under ambient (grey line, diamonds) vs. high CO2 conditions (black line, circles). Symbols depict individual replicates, lines represent treatment means. (B) Total length of juveniles perishing during the experiment at ambient (grey diamonds) vs. high CO2 conditions (black circles). Lines represent the median(solid lines), 5th and 95th percentiles (dashed lines) of TL estimated with locally weighted, non-parametric density estimators. The initial TL distribution at the beginning of the experiment is depicted on day 0 as the median (white circle), 5th/95th percentiles (whiskers) and the minimum and maximum (white stars).
Congratulations to Emma Cross to her new publication in Global Change Biology today!
The common brachiopod Calloria inconspicua (pink shells) in their natural environment in New Zealand. Photo credit: Dr Liz Harper.
Her study that was part of her PhD-research concludes that the brachiopod Calloria inconspicua, a common seafloor dwelling marine invertebrate from New Zealand, is more resilient to environmental change than expected.
This research feature makes the case for multistressor research to a broad general audience and introduces our NSF project and its participants. Download the feature by clicking on the pictures or the link below.
28 November 2017. The Journal of Experimental Marine Biology and Ecology just published the latest study by our group looking at differences in the CO2 sensitivity of Atlantic silverside offspring stemming from different mothers. Congratulations to Jacob Snyder for his first peer-reviewed publication.
Among the highlights of the study:
Offspring produced by different females varied in their sensitivity to high CO2 conditions.
Specific fatty acids in eggs were correlated to the log-transformed CO2 response ratio of embryo survival and hatch length.
Maternal provisioning might be an additional determinant of CO2 sensitivity in fish early life stages.
M. menidia. Responses to high CO2 conditions among replicates within and among females: (A) embryo and larval survival; (B) overall survival; (C) SL at hatch; and (D) final SL (16 dph). Patterns of larval growth were nearly identical to panel D and are therefore omitted. Ambient and high CO2 treatments are denoted by red and blue colors, respectively. Small symbols depict replicate survival (A,B) or replicate average size (C,D), while large symbols depict CO2 treatment averages for each female. Black lines connect average response for each female. Asterisks represent significant differences (P < 0.05) between CO2 levels within offspring of each female (Bonferroni adjusted t-test). Letters denote to females A to E.
October, 2nd, 2017: Happy to announce that Estuaries and Coasts just published (online) our article that looked at unifying principles of pH and DO fluctuations across many US nearshore habitats. The datasets belongs to the US Nearshore Estuaries Research Reserves System (NERRS) and is one of the most extensive monitoring datasets in coastal aquatic habitats. In this case, we used 15 years of continuous monitoring data (> 5 million data points) from 16 different reserves across the US Atlantic, Caribbean, Gulf of Mexico, and Pacific coasts and analyzed short- to long-term variability in pH and DO fluctuations. Among the highlights:
Our analyses confirmed that large, metabolically driven fluctuations of pH and DO are a unifying feature of nearshore habitats. Even more so, we were able to show that across habitats, one can predict mean pH or mean diel pH fluctuations simply based on salinity and oxygen levels/fluctuations. This provided strong empirical evidence that common metabolic principles drive diel to seasonal pH/DO variations within as well as across a diversity of estuarine environments.
As expected, there were no interannual, monotonic trends in nearshore pH conditions; instead interannual fluctuations were of similar magnitude than the pH decrease predicted for the average surface ocean over the next three centuries.
By correlating weekly anomalies of pH, oxygen, and temperature, we found strong empirical support for the notion that coastal acidification — in addition to being driven by eutrophication and atmospheric CO2 increases — is exacerbated simply by warming, likely via increasing community respiration.
Among many other aspects, the paper analyzed interannual trends in temperature (red bars), dissolved oxygen (%, blue bars), and pH (green bars) at 16 US Nearshore Ecological Research Reserves (NERRS), shown as yearly anomalies derived from averaging monthly anomalies for each variable, site, and year. Black trend lines were derived by LOESS smoothing.
October 10th 2016 was a special day for our still young lab here at the University of Connecticut, Today, the ICES Journal of Marine Science published the paper of Chris Murray et al., which is the first of hopefully many publications of our experimental findings originating out of our new laboratory facility here at UConn Avery Point.
Chris and his co-authors report on a large-scale, quantitative rearing experiment on Atlantic silversides eggs, larvae and juveniles under contrasting CO2 conditions that took place between May – September 2015. This novel experiment was designed to address three critical issues lacking in previous ocean acidification research on fish. First, the study spanned several ontogenetic stages. Second, it used very large numbers of individuals to robustly characterize not just potential shifts in mean responses, but also changes in the distribution of length, weight, and condition factor. Third, it provided food at standardized, non-excess levels to prevent that potential metabolic costs of high CO2 exposure could be compensated by survivors simply by eating more food.
Overall the study demonstrated seemingly small but significant growth reductions due to high CO2 and identified a small number of fatty acids that were of significantly different concentrations in high vs. control juveniles.
Distributions of condition factor per 2mm TL interval for juvenile M.menidia reared for 122dph at control (a) and high CO2 conditions (b). Thick and thin black lines correspond to the 10th/90th and 25th/75th percentiles, respectively, while the red line depicts the median. Data below the 10th and above the 90th percentiles are depicted by black dots. Underlying grey bars show relative frequencies for each 2 mm TL class. Black and grey numbers correspond to numbers of individuals measured for both TL and wW, or for TL only, respectively.
Cumulative frequency distributions of (a) total length (TL) and (b) wet weight (wW), in juvenile M. menidia reared for 122 dph at control and high CO2 conditions.
Gobler & Baumann’s review provides a good overview over the nascent field of multi-stressor acidification and hypoxia work. A first part firmly establishes that virtually all hypoxic zones in the ocean are also acidified, given that metabolic processes (i.e., respiration) consume oxygen and release CO2 into the environment. In a second part, the sparse emerging evidence for multistressor effects of low pH (high CO2) and low oxygen are reviewed, showing that while the majority of effects are additively negative, every study so far has also found synergistically negative effects of combined stressors in at least one trait.
Examples for synergistic negative effects of low DO and low pH (high CO2) on different traits and marine taxa. (a) Synergistic decrease in respiration rate in small and big sea urchins [27]; (b) growth rate of juvenile quahog was unaffected by low DO or low pH individually, but decreased under combined stressor conditions [23]; (c) survival of Atlantic silverside larvae to 10 dph. Survival was robust against low pH and sensitive to low DO, but decreased synergistically under combined stressors (green arrow, [22]); (d) representation of Po ̈rtners [25] ‘Oxygen- and capacity-limited thermal tolerance’ framework, adapted to the multiple stressor scenario of acidification and hypoxia.
Abstract
There is increasing recognition that low dissolved oxygen (DO) and low pH conditions co-occur in many coastal and open ocean environments. Within temperate ecosystems, these conditions not only develop seasonally as temperatures rise and metabolic rates accelerate, but can also display strong diurnal variability, especially in shallow systems where photosynthetic rates ameliorate hypoxia and acidification by day. Despite the widespread, global co-occurrence of low pH and low DO and the likelihood that these conditions may negatively impact marine life, very few studies have actually assessed the extent to which the combination of both stressors elicits additive, synergistic or antagonistic effects in marine organisms. We review the evidence from published factorial experiments that used static and/or fluctuating pH and DO levels to examine different traits (e.g. survival, growth, metabolism), life stages and species across a broad taxonomic spectrum. Additive negative effects of combined low pH and low DO appear to be most common; however, synergistic negative effects have also been observed. Neither the occurrence nor the strength of these synergistic impacts is currently predictable, and there- fore, the true threat of concurrent acidification and hypoxia to marine food webs and fisheries is still not fully understood. Addressing this knowledge gap will require an expansion of multi-stressor approaches in experimental and field studies, and the development of a predictive framework. In consider- ation of marine policy, we note that DO criteria in coastal waters have been developed without consideration of concurrent pH levels. Given the per- sistence of concurrent low pH–low DO conditions in estuaries and the increased mortality experienced by fish and bivalves under concurrent acidifi- cation and hypoxia compared with hypoxia alone, we conclude that such DO criteria may leave coastal fisheries more vulnerable to population reductions than previously anticipated.
