Effects of multiple stressors on the impact of ocean acidification on marine biota

Author(s)

Marilia Nagata Ragagnin

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto Oceanográfico (IO/DIDC)
• Defense date: 2017-05-24

Examining board members

Alexander Turra; Gustavo Muniz Dias; Paulo Antunes Horta Junior

• Advisor: Alexander Turra; Wellington Silva Fernandez

Abstract

Multiple stressors due to anthropogenic activities may cause combined impacts in marine organisms. Effects of ocean acidification associated with other anthropogenic impacts are poorly understood, especially in coastal regions. In these areas, shading caused by infrastructure development, such as harbor construction, may potentially interact with CO2-induced pH reduction and affect invertebrate populations. Here we evaluated reduced pH and shading effects on mortality, growth, calcification and displacement behavior to live predator (danger signal) and dead gastropod (resource availability signal) odors using juveniles of the hermit crab Pagurus criniticornis collected in Araçá Bay (São Paulo state, SE Brazil). After a 98 days experiment period, both stressors had a significant interaction on mortality and an additive effect on total growth. No difference in calcification was recorded among treatments, indicating that individuals were able to maintain calcification under reduced pH. When exposed to odor of live predators, crabs\' responses were affected only by shading. However, an interactive effect between both stressors was observed in response to gastropod odor, leading to reduced displacement behavior. This study shows how local disturbance impacts may enhance effects of global environmental changes on intertidal crustacean populations. (AU)

• FAPESP's process: 15/02727-0 - Effects of ocean acidification and shading on growth, exoskeleton calcification and behavior of hermit crabs
• Grantee: Marilia Nagata Ragagnin
• Support Opportunities: Scholarships in Brazil - Master