Interactions of fish, algae, and abiotic factors in a shallow, tropical pond
- PDF / 736,597 Bytes
- 16 Pages / 547.087 x 737.008 pts Page_size
- 58 Downloads / 207 Views
(0123456789().,-volV) ( 01234567 89().,-volV)
TROPICAL LAKES
Interactions of fish, algae, and abiotic factors in a shallow, tropical pond Tim Mayer
Received: 15 July 2019 / Revised: 30 June 2020 / Accepted: 2 August 2020 Ó This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply 2020
Abstract Protecting and restoring shallow tropical lakes and wetlands requires a knowledge of what shapes and controls algal dynamics and primary productivity in these systems. Algal community structure and composition can be regulated either through biotic or abiotic controls. Large-scale changes in fish populations can affect algal communities by altering food web dynamics and the physical and chemical properties of the aquatic environment. A reduction in fish biomass can lead to a reduction in algal biomass because of increased grazing by zooplankton and reduced availablity of nutrients. However, the omnivorous fish common in tropical systems often consume algae, and their reduction can increase algal biomass. There is a need for more information on the effect of fish removals/reductions in tropical systems. In a five-year study of a shallow, tropical pond in Hawaii, I investigated the water quality effects of tilapia removal following the occurrence of two natural fish die-offs. I describe the concurrent impacts of water-level fluctuations and the fish die-offs on the physical and chemical conditions
Guest editors: Alonso Ramı´rez, Checo Colon-Gaud, Margarita Caballero & Gabriela Va´zquez / Recent Advances in Tropical Lake Research T. Mayer (&) US Fish and Wildlife Service, 911 NE 11th Ave, Portland, OR, USA e-mail: [email protected]
of the pond and the subsequent changes in the algal community. Overall, nutrients, suspended sediment, organic matter, and algal biomass were significantly reduced and light availability significantly increased in the absence of tilapia. Keywords Trophic cascades, Fish die-offs, Mozambique tilapia Tropical lake restoration Eutrophication Phytoplankton dynamics Nutrient dynamics
Introduction Protecting and restoring shallow tropical lakes and wetlands requires a knowledge of what shapes and controls algal dynamics and primary productivity in these systems. Algal community structure and composition can be regulated either through ‘‘top-down,’’ biotic controls, such as consumption of algae by zooplankton or fish, or ‘‘bottom-up,’’ abiotic controls, such as a nutrient or light deficiency (Kitchell & Carpenter, 1993; Reynolds, 2006; Menezes et al., 2010). Nutrient limitation is implicated as the primary control of algae in many systems and P is usually the limiting nutrient, at least in freshwater temperate systems (Wetzel, 2001). But algae are also commonly constrained by physical properties of the aquatic environment, such as light availability, mixing and
123
Hydrobiologia
flushing rates, and water-level fluctuations (Ozen et al., 2010; Zohary et al., 2010; Brasil et al., 2016). Tropical shallow lakes are reported to be e
Data Loading...
