Session Title

Session S-09A: Harmful Algal Blooms, Climate, Shellfish, and Public Health - Emerging Issues in a Changing World

Conference Track

Harmful Algal Blooms and Shellfish

Conference Name

Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Start Date

2-5-2014 10:30 AM

End Date

2-5-2014 12:00 PM

Abstract

As a large, island rich, estuary, the Salish Sea is strongly influenced by a diversity of ocean water intrusions and by direct and indirect human activities. The consequences of these processes provide multiple stressors on incumbent species, such as the potentially economically damaging blooms of the fish-killing flagellate Heterosigma akashiwo. Here we present laboratory findings on the combination of increased ocean acidification (pH) and modified nutrient supply (N:P) on the toxicity of a Puget Sound isolate from the Salish Sea. The toxicity and growth responses of batch cultures, conducted at a range of initial concentrations of nitrate and phosphate (N:P ratios from 1:1 to 48:1) and two pH levels (8.1 & 7.4), were examined throughout the exponential and stationary phases of growth . A modified fish gill cell bioassay was used to quantify the ecotoxicological response, generally associated with the fish-killing potential. The toxicity of the H. akashiwo cultures varied strongly with culture conditions in two general ways. First, cells grown under lower pH conditions (pH 7.4) were less toxic than the cells grown at pH 8.1. Second, cells at the lower pH were more toxic during the exponential / early stationary growth phase compared with the cells grown at normal pH levels where levels of toxicity were greatest in the stationary phase. Similarly, modification of the initial N:P conditions of the growth medium had a significant influence on observed toxicity, with the greatest toxicity occurring at 12:1 and 15:1 during the late exponential growth phase. These laboratory results demonstrate the importance of understanding how multiple stressors potentially influence the toxicity of natural fish-killing blooms of H. akashiwo in the Salish Sea.

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Language

English

Format

application/pdf

Type

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May 2nd, 10:30 AM May 2nd, 12:00 PM

Multiple stressors on the potential toxicity of Heterosigma akashiwo, a fish-killing flagellate in the Salish Sea.

Room 615-616-617

As a large, island rich, estuary, the Salish Sea is strongly influenced by a diversity of ocean water intrusions and by direct and indirect human activities. The consequences of these processes provide multiple stressors on incumbent species, such as the potentially economically damaging blooms of the fish-killing flagellate Heterosigma akashiwo. Here we present laboratory findings on the combination of increased ocean acidification (pH) and modified nutrient supply (N:P) on the toxicity of a Puget Sound isolate from the Salish Sea. The toxicity and growth responses of batch cultures, conducted at a range of initial concentrations of nitrate and phosphate (N:P ratios from 1:1 to 48:1) and two pH levels (8.1 & 7.4), were examined throughout the exponential and stationary phases of growth . A modified fish gill cell bioassay was used to quantify the ecotoxicological response, generally associated with the fish-killing potential. The toxicity of the H. akashiwo cultures varied strongly with culture conditions in two general ways. First, cells grown under lower pH conditions (pH 7.4) were less toxic than the cells grown at pH 8.1. Second, cells at the lower pH were more toxic during the exponential / early stationary growth phase compared with the cells grown at normal pH levels where levels of toxicity were greatest in the stationary phase. Similarly, modification of the initial N:P conditions of the growth medium had a significant influence on observed toxicity, with the greatest toxicity occurring at 12:1 and 15:1 during the late exponential growth phase. These laboratory results demonstrate the importance of understanding how multiple stressors potentially influence the toxicity of natural fish-killing blooms of H. akashiwo in the Salish Sea.