Abstract
We investigated the potential for cross-generational plasticity to influence how offspring respond to hypoxia and ocean acidification (hereafter HypOA) in the coastal forage fish Atlantic silverside (Menidia menidia). Mature wild silversides were treated with a control [dissolved oxygen (DO):100% air saturation (a.s.) / pCO2: 650 µatm] or HypOA conditions [DO: 40% a.s. / pCO2: 2300 µatm] for 10 days prior to spawning. Their offspring were reared under both treatments in factorial experimental design. Parental acclimation to HypOA altered several offspring traits, including increased embryo survival under HypOA and an overall reduction in post-hatch growth rate. Offspring from HypOA-treated parents that were reared under control conditions had larger eyes across the developmental period. When compared against the overall control group, larvae directly exposed to HypOA exhibited 2,416 differentially expressed transcripts (DETs). Although most of these DETs were specific to individual parental treatments, the most enriched Gene Ontology terms were conserved across parental treatments, including terms related to neurotransmitter secretion, nervous system development, axon pathfinding, calcium channel activity, proteolysis, and extracellular matrix organization. Larvae from HypOA-treated parents that were reared under control conditions exhibited a shift in constitutive gene expression similar to that seen in larvae directly exposed to HypOA. This highly consistent finding indicates that parental acclimation before fertilization promotes the transcriptional frontloading of genes in offspring. This effect may have primed regulatory functions in offspring that sense and respond to low DO and elevated pCO2 conditions. Though, our results suggest that this altered developmental phenotype may have some negative fitness consequences for offspring.
Competing Interest Statement
The authors have declared no competing interest.
List of Symbols and Abbreviations
- a.s.
- air saturation
- AT
- total alkalinity
- ANOVA
- analysis of variance
- BP
- biological process term (Gene Ontology)
- CC
- Control-treated parents and control-reared offspring
- CH
- Control-treated parents and HypOA-reared offspring
- CPM
- counts per million
- ESL
- Environmental Systems Laboratory
- DET
- differentially expressed transcript
- DIC
- dissolved inorganic carbon
- DO
- dissolved oxygen
- dpf
- days post-fertilization
- dph
- days post-hatch
- FC
- fold change
- FDR
- false discovery rate
- GABA
- gamma-aminobutyric acid
- GO
- Gene Ontology
- HC
- HypOA-treated parents and control-reared offspring
- HH
- HypOA-treated parents and HypOA-reared offspring
- Hif
- hypoxia induced factor
- HypOA
- concurrent hypoxia and acidification
- IVF
- in vitro fertilization
- MF
- molecular function term (Gene Ontology)
- pCO2
- partial pressure of CO2
- pHT
- pH on the total scale
- WHOI
- Woods Hole Oceanographic Institution