Publisher :
Place of publication :
Publication year : 2009
Thematic : Environmental Education
Language : English
Note
Anthropogenic climate change poses a serious threat to biodiversity.
In marine environments, multiple climate variables, including
temperature and CO2 concentration ([CO2]), are changing simultaneously.
Although temperature has well-documented ecological
effects, and many heavily calcified marine organisms experience
reduced growth with increased [CO2], little is known about the
combined effects of temperature and [CO2], particularly on species
that are less dependent on calcified shells or skeletons. We manipulated
water temperature and [CO2] to determine the effects on
the sea star Pisaster ochraceus, a keystone predator.Wefound that
sea star growth and feeding rates increased with water temperature
from 5 °C to 21 °C. A doubling of current [CO2] also increased
growth rates both with and without a concurrent temperature
increase from 12 °C to 15 °C. Increased [CO2] also had a positive but
nonsignificant effect on sea star feeding rates, suggesting [CO2]
may be acting directly at the physiological level to increase growth
rates. As in past studies of other marine invertebrates, increased
[CO2] reduced the relative calcified mass in sea stars, although this
effect was observed only at the lower experimental temperature.
The positive relationship between growth and [CO2] found here
contrasts with previous studies, most of which have shown negative
effects of [CO2] on marine species, particularly those that are
more heavily calcified than P. ochraceus. Our findings demonstrate
that increased [CO2] will not have direct negative effects on all
marine invertebrates, suggesting that predictions of biotic responses
to climate change should consider how different types of
organisms will respond to changing climatic variables.
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Keywords : Sphenomorphus luzonense
Encoded by : Pauline Carmel Joy Eje
