Assessing physiological tipping point of sea urchin larvae exposed to a broad range of pH

• Our ability to project the impact of global change on marine ecosystem is limited by our poor understanding on how to predict species sensitivity. For example, the impact of ocean acidification is highly species-specific, even in closely related taxa. The aim of this study was to test the hypothesis that the tolerance range of a given species to decreased pH corresponds to their natural range of exposure. Larvae of the green sea urchin Strongylocentrotus droebachiensis were cultured from fertilization to metamorphic competence (29days) under a wide range of pH (from pH(T)=8.0/pCO(2)approximate to 480atm to pH(T)=6.5/pCO(2)approximate to 20000atm) covering present (from pH(T) 8.7 to 7.6), projected near-future variability (from pH(T) 8.3 to 7.2) and beyond. Decreasing pH impacted all tested parameters (mortality, symmetry, growth, morphometry and respiration). Development of normal, although showing morphological plasticity, swimming larvae was possible as low as pH(T)7.0. Within that range, decreasing pH increased mortality and asymmetry and decreased body length (BL) growth rate. Larvae raised at lowered pH and with similar BL had shorter arms and a wider body. Relative to a given BL, respiration rates and stomach volume both increased with decreasing pH suggesting changes in energy budget. At the lowest pHs (pH(T)6.5), all the tested parameters were strongly negatively affected and no larva survived past 13days post fertilization. In conclusion, sea urchin larvae appeared to be highly plastic when exposed to decreased pH until a physiological tipping point at pH(T)=7.0. However, this plasticity was associated with direct (increased mortality) and indirect (decreased growth) consequences for fitness.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Environmental Sciences (hsv//eng)

Nyckelord

development

morphometric

ocean acidification

physiology

Strongylocentrotus droebachiensis

INDUCED SEAWATER ACIDIFICATION

OCEAN-ACIDIFICATION

STRONGYLOCENTROTUS-DROEBACHIENSIS

INTRACELLULAR-PH

MYTILUS-EDULIS

CARBONIC-ACID

CO2

GROWTH

CALCIFICATION

EMBRYOS

ATES OF AMERICA

V109

P18192

RATHMANN R

1978

JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY

V34

P23

ARR M

1992

MARINE ECOLOGY PROGRESS SERIES

V79

P275

RISTEN R

1982

JOURNAL OF BIOLOGICAL CHEMISTRY

V257

P4881

ARR M

1990

SCIENCE

V247

P1071

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