Long-term and trans-life-cycle effects of exposure to ocean acidification in the green sea urchin Strongylocentrotus droebachiensis

Anthropogenic CO2 emissions are acidifying the world’s oceans. A growing body of evidence demonstrates that ocean acidification can impact survival, growth, development and physiology of marine invertebrates. Here, we tested the impact of long-term (up to 16 months) and trans-life-cycle (adult, embryo/larvae and juvenile) exposure to elevated pCO2 (1,200 μatm, compared to control 400 μatm) on the green sea urchin Strongylocentrotus droebachiensis. Female fecundity was decreased 4.5-fold when acclimated to elevated pCO2 for 4 months during reproductive conditioning, while no difference was observed in females acclimated for 16 months. Moreover, adult pre-exposure for 4 months to elevated pCO2 had a direct negative impact on subsequent larval settlement success. Five to nine times fewer offspring reached the juvenile stage in cultures using gametes collected from adults previously acclimated to high pCO2 for 4 months. However, no difference in larval survival was observed when adults were pre-exposed for 16 months to elevated pCO2. pCO2 had no direct negative impact on juvenile survival except when both larvae and juveniles were raised in elevated pCO2. These negative effects on settlement success and juvenile survival can be attributed to carry-over effects from adults to larvae and from larvae to juveniles. Our results support the contention that adult sea urchins can acclimate to moderately elevated pCO2 in a matter of a few months and that carry-over effects can exacerbate the negative impact of ocean acidification on larvae and juveniles

Coprolites as evidence for plant–animal interaction in Siluro–Devonian terrestrial ecosystems

A FEW remarkable finds document the colonization of land by animals and plants in the mid-Palaeozoic1–3, but much rarer is unequivocal evidence for plant–animal interaction4,5. Here we announce the discovery of coprolites (fossil faeces) in Upper Silurian (412 Myr) and Lower Devonian (390 Myr) rocks from the Welsh Borderland that pre-date examples of similar composition in the Carboniferous by about 90 million years6,7. The majority consist predominantly of undigested land-plant spores with varying proportions of cuticles, tubes and less readily identifiable (presumably plant) material. Because coeval animal fossils of suitable size are carnivores8, direct evidence for the coprolite producers is lacking, but we speculate that they could have been spore eaters (and hence the earliest example of herbivory of higher plants) or detritivores similar to modern millipedes. In either case, they demonstrate the cycling of primary productivity in early terrestrial ecosystems