Effects of land-based fish farm effluent on the morphology and growth of Ascophyllum nodosum (Fucales, Phaeophyceae) in southwestern Nova Scotia

doi:2011.26.3.253

Algae > Volume 26(3); 2011 > Article

Algae 2011;26(3): 253-263. doi: https://doi.org/10.4490/algae.2011.26.3.253

Katelyn L. White¹, Jang Kyun Kim² and David J. Garbary¹^,*

¹Department of Biology, St. Francis Xavier University, Antigonish, NS B2G 2W5, Canada
²Department of Plant and Animal Sciences, Nova Scotia Agricultural College, Truro, NS B2N 5E3, Canada

*Corresponding Author

Email: dgarbary@gmail.com

ABSTRACT

Phenotypic plasticity was examined in the economically and ecologically important brown alga Ascophyllum nodosum in southwestern Nova Scotia, considering specifically how nutrient loading affected its vegetative and reproductive features. To determine this, we examined morphometric changes in A. nodosum from two sites receiving direct effluent impacts from a land-based finfish aquaculture facility and from two control sites, approximately 2 km away from the aquaculture facility in opposite directions. Fronds from test sites were significantly younger than from control sites (5 y vs. 8 y); however, fronds from farm sites were significantly larger (219 g vs. 90 g) because of their higher growth rates. Thalli from farm sites had greater reproductive potential, as shown by numbers of receptacle initials (797 initials vs. 281 initials). These results suggest limited nutrient inflows from land-based aquaculture may positively affect adjacent Ascophyllum populations by inducing higher growth rates. We conclude that the coordination of effluent management from land-based aquaculture with natural resource harvesting of A. nodosum may be beneficial. Further study is necessary to determine the limits of nutrient loading for this potentially beneficial outcome.

Key words: aquaculture; Ascophyllum nodosum; morphology; nutrient enrichment; plasticity; tidal heights; wave exposure