Copper tolerance and distribution of epibiotic bacteria associated with giant kelp Macrocystis pyrifera in southern California.

Julia Busch,Elizabeth Dinsdale,Juliana Ribeiro Nascimento,Bas E Dutilh,Ana Carolina Rubem Magalhães

doi:10.1007/s10646-015-1460-6

Abstract

Kelp forests in southern California are important ecosystems that provide habitat and nutrition to a multitude of species. Macrocystis pyrifera and other brown algae that dominate kelp forests, produce negatively charged polysaccharides on the cell surface, which have the ability to accumulate transition metals such as copper. Kelp forests near areas with high levels of boating and other industrial activities are exposed to increased amounts of these metals, leading to increased concentrations on the algal surface. The increased concentration of transition metals creates a harsh environment for colonizing microbes altering community structure. The impact of altered bacterial populations in the kelp forest have unknown consequences that could be harmful to the health of the ecosystem. In this study we describe the community of microorganisms associated with M. pyrifera, using a culture based approach, and their increasing tolerance to the transition metal, copper, across a gradient of human activity in southern California. The results support the hypothesis that M. pyrifera forms a distinct marine microhabitat and selects for species of bacteria that are rarer in the water column, and that copper-resistant isolates are selected for in locations with elevated exposure to transition metals associated with human activity.

Highlights

IntroductionFound in shallow temperate coastal waters as well as deeper tropical waters, kelp forests are dominated by brown algae from the genus Laminaria (Santelices 2007), such as Macrocystis pyrifera (giant kelp) and their high productivity provide habitats and nutrients to an entire ecosystem (Egan et al 2008; Goecke et al 2010)
Kelp forests are one of the most widespread and productive ecosystems
While the algal surface is desirable for colonization, in locations where the amount of transition metals is increased by human activity, the bioaccumulation of metals by the kelp may create a stressful environment for bacteria

Summary

Introduction

Found in shallow temperate coastal waters as well as deeper tropical waters, kelp forests are dominated by brown algae from the genus Laminaria (Santelices 2007), such as Macrocystis pyrifera (giant kelp) and their high productivity provide habitats and nutrients to an entire ecosystem (Egan et al 2008; Goecke et al 2010). The nutrient-rich surface of the macroalgae provides a desirable location for epibiotic colonization resulting in higher abundance and diversity of microbial populations (Egan et al 2008; Blight and Thompson 2008; Armstrong et al 2001; Lachnit et al 2011). While the algal surface is desirable for colonization, in locations where the amount of transition metals is increased by human activity, the bioaccumulation of metals by the kelp may create a stressful environment for bacteria.

Methods

Results

Conclusion