Long-term exposure to acidification disrupts reproduction in a marine invertebrate

Abstract

Climate change research is advancing to more complex and more comprehensive studies that include long-term experiments, multiple life-history stages, multi-population, and multi-trait approaches. We used a population of the barnacle Balanus improvisus known to be sensitive to short-term acidification to determine its potential for long-term acclimation to acidification. We reared laboratory-bred individuals (as singles or pairs), and field-collected assemblages of barnacles, at pH 8.1 and 7.5 (≈ 400 and 1600 μatm pCO2 respectively) for up to 16 months. Acidification caused strong mortality and reduced growth rates. Acidification suppressed respiration rates and induced a higher feeding activity of barnacles after 6 months, but this suppression of respiration rate was absent after 15 months. Laboratory-bred barnacles developed mature gonads only when they were held in pairs, but nonetheless failed to produce fertilized embryos. Field-collected barnacles reared in the laboratory for 8 months at the same pH’s developed mature gonads, but only those in pH 8.1 produced viable embryos and larvae. Because survivors of long-term acidification were not capable of reproducing, this demonstrates that B. improvisus can only partially acclimate to long-term acidification. This represents a clear and significant bottleneck in the ontogeny of this barnacle population that may limit its potential to persist in a future ocean.

Invariant Gametogenic Response of Dominant Infaunal Bivalves From the Arctic Under Ambient and Near-Future Climate Change Conditions

“…It is tempting to conclude that our findings indicate resilience of the reproductive stage examined to near-term climatic forcing, but our observations of the successful progression of gametogenesis took place under standard laboratory conditions which, following accepted protocols (e.g., Pansch et al, 2018), include a constant supply of food. This may have inadvertently provided a sufficient supply of energy to overcome the metabolic costs of environmental stress (Cominassi et al, 2020) and mitigated the impact on gametogenesis.…”

Mapping the correlations and gaps in studies of complex life histories

“…While planktotrophic species may be more difficult to study compared to lecithotrophs, there are excellent candidates for individual longitudinal studies that are in our dataset. For example, planktotrophic crustacean larvae, particularly decapods, are large, robust and have been cultured individually to the juvenile and/or adults stages in the laboratory (Oliphant et al, 2013 ; Oliphant & Thatje, 2013 ; Pansch et al 2018 ; van Alstyne et al, 2014 ), and in the field (Lathlean & Minchinton, 2012 ). Our map suggests that rather than selecting species conducive to studying correlations between stages, we have prioritized studying a few model species that have small, less‐resilient larvae, and are not ideal for individual longitudinal studies (e.g., echinoderms; Figure 5 ).…”

Causes and consequences of acidification in the Baltic Sea: implications for monitoring and management

“…Adult barnacles from habitats with high pCO 2 fluctuations have been shown to be more tolerant to high pCO 2 levels than barnacles from habitats with comparatively stable pCO 2 levels 58 . The more sensitive populations have further been shown to be less capable to adapt to long-term elevated pCO 2 , which significantly effects reproduction 59 . Growth of the seagrass Zostera marina appears to be weakly positively influenced by increasing pCO 2 60 , whereas responses of the macroalgae Fucus vesiculosus differ between studies—from negative to weakly positive 60 , 61 .…”

“…It should be noted that information on species’ responses to acidification is sometimes based on relatively short-term experiments, and there are major knowledge gaps both regarding effects of long-term exposure 59 and the capacity of species and ecosystems to adapt 64 . Recent studies have emphasized the need to account for effects of multiple stressors (e.g.…”