Impacts of excessive dietary phosphorus on zebra mussels
- PDF / 319,457 Bytes
- 8 Pages / 547.087 x 737.008 pts Page_size
- 64 Downloads / 178 Views
PRIMARY RESEARCH PAPER
Impacts of excessive dietary phosphorus on zebra mussels Reid L. Morehouse • Andrew R. Dzialowski Punidan D. Jeyasingh
•
Received: 2 August 2012 / Revised: 19 October 2012 / Accepted: 24 November 2012 / Published online: 8 December 2012 Ó Springer Science+Business Media Dordrecht 2012
Abstract Stoichiometric theory predicts that organisms should experience dietary imbalances not only when nutrients (e.g., phosphorus, P) are limiting relative to carbon (C), but also when nutrients are in excess (i.e., well above somatic demand). Nevertheless, few experiments have elucidated the response of consumers in such low C:P conditions. We assessed the growth, tissue stoichiometry, and nutrient excretion of the invasive primary consumer, zebra mussel (ZM), Dreissena polymorpha, under three dietary C:P conditions (C:P = 20, 45, 380) in the laboratory. The two low C:P conditions represent increasingly common eutrophic systems, while the high C:P treatment is representative of oligotrophic systems. Growth rates and condition were lower when ZMs were fed a low C:P (20 and 45) diet, compared to the C:P = 380 treatment, wherein ZMs grew rapidly and exhibited lower somatic C:P. Furthermore, ZMs in the C:P = 20 and C:P = 45 treatments excreted more ammonia indicative of protein catabolism. These results clearly show that hypereutrophic conditions invoke significant shifts in physiology, growth, and condition of
Handling editor: John Havel R. L. Morehouse (&) A. R. Dzialowski P. D. Jeyasingh Department of Zoology, Oklahoma State University, 501 Life Sciences West, Stillwater, OK 74078, USA e-mail: [email protected]
ZMs. Together, these results are consistent with stoichiometric theory that predicts costs associated with the intake of excess dietary P. Keywords Eutrophication Ecological stoichiometry Excessive nutrients Hypereutrophic Invasive species
Introduction Elemental imbalances occur when consumers obtain food items that contain essential elements in proportions that are different from the proportions required for growth, reproduction, and maintenance (Sterner & Elser, 2002). Such stoichiometric imbalances between consumers and their food resources are common in most ecosystems, and influence the performance and distribution of species (Sterner & Elser, 2002). Imbalances are particularly strong at the base of foodwebs where the stoichiometry of primary producers is often different from primary consumers (Elser et al., 2000), leading to stoichiometric constraints on consumer growth and performance, despite constant food (energy) supply. Primary consumers grow optimally when the elemental composition of the food resource is balanced with respect to the consumer’s dietary requirements (Sterner & Hessen, 1994). In many ecosystems, carbon is often in surplus while nutrients are limiting (Hessen & Anderson, 2008). Thus, foods with high carbon (C, energy) content and low nutrient content
123
74
are regarded as low quality, while higher concentrations of mineral nutrients indicate hig
Data Loading...
