Biology Reference
In-Depth Information
Chapter 21
Bottom-Up Versus Top-Down Control
of Macroalgal Blooms
Mirta Teichberg, Paulina Martinetto, and Sophia E. Fox
21.1
Introduction
Macroalgal blooms are increasing worldwide and have many detrimental effects on
ecosystems, including more frequent occurrences of anoxia, and loss of seagrasses,
coral cover, and ecologically and commercially important species. The increased
occurrences of macroalgal blooms have been attributed primarily to increases in the
supply of the limiting nutrients, referred to as “bottom-up” control, and decreased
grazer abundance due to overfishing and habitat degradation, referred to as
“top-down” control. This chapter begins with an overview of the occurrence of
macroalgal blooms worldwide and their ecological consequences. It discusses
the role of coastal eutrophication and overfishing as the two main global drivers of
bloom formations. The relative role of bottom-up versus top-down control in struc-
turing ecological communities is controversial and has been heavily debated within
the scientific community. This chapter will provide an overview of the main
arguments of this debate in marine coastal waters. Specifically, scientific evidence
supporting bottom-up versus top-down controls in shallow estuaries and coastal bays,
coral reefs, and intertidal or subtidal rocky shores will be reviewed to understand how
systems differ in response to these controls. We will provide an outlook on the future
M. Teichberg (
*
)
Leibniz-Center for Tropical Marine Ecology, Bremen, Germany
e-mail:
mirta.teichberg@zmt-bremen.de
P. Martinetto
Laboratorio de Ecolog´a, Departamento de Biolog´a, Facultad de Ciencias Exactas y Naturales,
Universidad Nacional de Mar del Plata, Instituto de Investigaciones Marinas y Costeras (IIMyC),
CONICET-UNMDP, Mar del Plata, Argentina
e-mail:
pmartin@mdp.edu.ar
S.E. Fox
Cape Cod National Seashore, National Park Service, Wellfleet, MA, USA
e-mail:
Sophia_Fox@nps.gov
