UC Merced Undergraduate Research Journal

Symbiotic relationships are fundamental to ecological systems, shaping species interactions andinfluencing survival, reproduction, and evolutionary pathways. One well-studied example of a mutualistic symbiotic relationship occurs between the Hawaiian bobtail squid (Euprymnascolopes) and the gram-negative bacterium Vibrio fischeri. This partnership enhances the survivability of both organisms through a specialized form of camouflage known as counterillumination. In this process, V. fischeri utilizes quorum sensing to regulate bioluminescence, producing light that matches the surrounding environment and conceals the squid’s silhouette from predators below. In return, the squid maintains a specialized light organ that provides rich nutrients, creating a stable environment for the bacteria to proliferate. While notably efficient and stable, the effectiveness of this relationship can be influenced by external environmental factors. Conditions such as temperature, pH, and salinity play crucial roles in determining the success of bacterial colonization, bioluminescence efficiency, and host-symbiontinteractions. Since E. scolopes and V. fischeri are highly sensitive to environmental changes, they serve as valuable bioindicators for assessing the broader impacts of climate change on oceanic symbioses. Climate change impacts, such as ocean acidification and increasing temperature, have been demonstrated to be detrimental to this intricate mutualism. This review paper will examine the effects of climate change factors on the symbiotic relationship and the surrounding environment, and analyze how each factor can promote or prevent the growth of the microbe V.fischeri. The possible implications and adaptations made by these organisms in the face of progressing environmental stressors will also be discussed and analyzed throughout the review.