Surf smelt accelerate usage of endogenous energy reserves under climate change

RESEARCH ARTICLE Surf smelt accelerate usage of endogenous energy reserves under climate change Megan RussellID1*, M. Brady Olson1, Brooke A. Love2 1 Department of Biology, College of Science and Engineering, Western Washington University, Bellingham, WA, United States of America, 2 Department of Environmental Sciences, College of the Environment, Western Washington University, Bellingham, WA, United States of America * meg83@hawaii.edu Abstract Surf smelt (Hypomesus pretiosus) are ecologically critical forage fish in the North Pacific ecosystem. As obligate beach spawners, surf smelt embryos are exposed to wide-ranging marine and terrestrial environmental conditions. Despite this fact, very few studies have assessed surf smelt tolerance to climate stressors. The purpose of this study was to exam- ine the interactive effects of climate co-stressors ocean warming and acidification on the energy demands of embryonic and larval surf smelt. Surf smelt embryos and larvae were collected from spawning beaches and placed into treatment basins under three temperature treatments (13˚C, 15˚C, and 18˚C) and two pCO2 treatments (i.e. ocean acidification) of approximately 900 and 1900 μatm. Increased temperature significantly decreased yolk size in surf smelt embryos and larvae. Embryo yolk sacs in high temperature treatments were on average 7.3% smaller than embryo yolk sacs from ambient temperature water. Larval yolk and oil globules mirrored this trend. Larval yolk sacs in the high temperature treatment were

45.8% smaller and oil globules 31.9% smaller compared to larvae in ambient temperature. There was also a significant positive effect of acidification on embryo yolk size, indicating embryos used less maternally-provisioned energy under acidification scenarios. There was no significant effect of either temperature or acidification on embryo heartrates. These results indicate that near-future climate change scenarios may impact the energy demands of developing surf smelt, leading to potential effects on surf smelt fitness and contributing to variability in adult recruitment. Introduction Surf smelt (Hypomesus pretiosus; Girard 1854 [1]) are small, schooling forage fish that provide a critical link in the marine food web by facilitating energy transfer from primary producers to higher trophic levels, including numerous species of sea birds, marine mammals, and other commercially important fish [2–5]. Surf smelt range extends from Prince William Sound, Alaska, to southern California [6], and they interact closely with the nearshore environment, especially during spawning events and juvenile development. Like other forage fish (e.g. her- ring, sand lance), surf smelt require unaltered shoreline to thrive [7, 8], making them PLOS ONE PLOS ONE | https://doi.org/10.1371/journal.pone.0270491 June 27, 2022 1 / 14 a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS Citation: Russell M, Olson MB, Love BA (2022) Surf smelt accelerate usage of endogenous energy reserves under climate change. PLoS ONE 17(6): e0270491. https://doi.org/10.1371/journal. pone.0270491

Editor: Erik V. Thuesen, Evergreen State College, UNITED STATES Received: August 27, 2021 Accepted: June 10, 2022 Published: June 27, 2022 Peer Review History: PLOS recognizes the benefits of transparency in the peer review process; therefore, we enable the publication of all of the content of peer review and author responses alongside final, published articles. The editorial history of this article is available here: https://doi.org/10.1371/journal.pone.0270491 Copyright: © 2022 Russell et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All data files will be available from the SEANOE database: Russell Megan (2018). Surf Smelt Embryo and Larvae Data. SEANOE. https://doi.org/10.17882/85830.