Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 8575
Title: Impaired development of krill larvae (Euphausia pacifica) reared at pCO2 levels currently observed in the Northeast Pacific
Author: Anna K. McLaskey, Julie E. Keister, Paul McElhany, M. B. Olson, D. S. Busch, M. Maher, Amanda K. Winans
Publication Year: 2016
Journal: Marine Ecology Progress Series
Keywords: Ocean acidification,Krill,pH

Despite the critical importance of euphausiids inmarine food webs, little ocean acidification
(OA) research has focused on them. Euphausia pacifica is a dominant and trophically important
species of euphausiid throughout the North Pacific and the California Current Ecosystem,
where low pH conditions are occurring in advance of those in the global ocean. We assessed the
impact of reduced pH on the hatching and larval development of E. pacifica in the laboratory and
characterized the pH to which E. pacifica eggs and larvae are currently exposed in Puget Sound,
Washington (USA), a large estuary connected to the California Current. In 2 independent sets of
laboratory experiments that lasted 6 to 22 d and which involved broods from 110 different females,
we found that hatching is robust to a wide range of pH levels, but larval development and survival
are reduced at pH levels that are currently observed within their habitat. Survival from 3 d post
hatch to the calyptopis 2 stage was reduced by an average of 20%at pH 7.69 compared to pH 7.96.
Even though this population experiences a range ofpHconditions on seasonal and daily timescales,
it may be living near the limits of its pH tolerance. Continued OA may push these organisms past
their threshold, which could have cascading negative consequences for higher trophic levels.

Theme: Ecosystem approach to improve management of marine resources
Foci: Understand how climate influences ecosystem variability.