Fish embryo vulnerability to combined acidification and warming coincides with low capacity for homeostatic regulation

The vulnerability of fish embryos and larvae to environmental factors is often attributed to a lack of adult-like organ systems (gills) and thus insufficient homeostatic capacity. However, experimental data supporting this hypothesis are scarce. Here, by using Atlantic cod (Gadus morhua) as a model,...

Full description

Saved in:
Bibliographic Details
Published inJournal of experimental biology
Main Authors Dahlke, Flemming, Lucassen, Magnus, Bickmeyer, Ulf, Wohlrab, Sylke, Puvanendran, Velmurugu, Mortensen, Atle, Chierici, Melissa, Pörtner, Hans-Otto, Storch, Daniela
Format Journal Article
LanguageEnglish
Published England 01.01.2020
Subjects
Early-life history
Gastrulation
Atlantic cod
Energy allocation
Ion regulation
Critical period
Ocean acidification
Online AccessGet full text

Cover

More Information
Summary:The vulnerability of fish embryos and larvae to environmental factors is often attributed to a lack of adult-like organ systems (gills) and thus insufficient homeostatic capacity. However, experimental data supporting this hypothesis are scarce. Here, by using Atlantic cod (Gadus morhua) as a model, the relationship between embryo vulnerability (to projected ocean acidification and warming) and homeostatic capacity was explored through parallel analyses of stage-specific mortality and in vitro activity and expression of major ion pumps (ATP-Synthase, Na+/K+-ATPase, H+-ATPase) and co-transporters (NBC1, NKCC1). Immunolocalization of these transporters was used to study ionocyte morphology in newly-hatched larvae. Treatment-related embryo mortality until hatch (+20% due to acidification and warming) occurred primarily during an early period (gastrulation) characterized by extremely low ion transport capacities. Thereafter, embryo mortality decreased in parallel with an exponential increase in activity and expression of all investigated ion transporters. Significant changes in transporter activity and expression in response to acidification (+15% activity) and warming (-30% expression) indicate some potential for short-term acclimatization, although likely associated with energetic trade-offs. Interestingly, whole-larvae enzyme capacities (supported by abundant epidermal ionocytes) reached levels similar to those previously measured in gill tissue of adult cod, suggesting that early-life stages without functional gills are better equipped in terms of ion homeostasis than previously thought. This study implies that the gastrulation period represents a critical transition from inherited (maternal) defenses to active homeostatic regulation, which facilitates enhanced resilience of later stages to environmental factors.
ISSN:1477-9145