Trophic niche shifts driven by phytoplankton in sandy beach ecosystems. (5th October 2016)

• Record Type: Journal Article
• Authors: Bergamino, Leandro; Martínez, Ana; Han, Eunah; Lercari, Diego; Defeo, Omar
• Is Part Of: Estuarine, coastal and shelf science. Volume 180(2016)
• Page Start: 33
• Page End: 40
• Publication Date: 2016-10-05
• Subjects: Stable isotopes -- Food webs -- Diatoms -- Asterionellopsis guyunusae -- sandy beaches -- Uruguay; Estuarine oceanography -- Periodicals; Coasts -- Periodicals; Estuarine biology -- Periodicals; Seashore biology -- Periodicals; Coasts; Estuarine biology; Estuarine oceanography; Seashore biology; Periodicals; 551.461805
• DOI: 10.1016/j.ecss.2016.06.023
• Languages: English
• ISSNs: 0272-7714

Abstract

Abstract: Stable isotopes (δ 13 C and δ 15 N) together with chlorophyll a and densities of surf diatoms were used to analyze changes in trophic niches of species in two sandy beaches of Uruguay with contrasting morphodynamics (i.e. dissipative vs. reflective). Consumers and food sources were collected over four seasons, including sediment organic matter (SOM), suspended particulate organic matter (POM) and the surf zone diatom Asterionellopsis guyunusae . Circular statistics and a Bayesian isotope mixing model were used to quantify food web differences between beaches. Consumers changed their trophic niche between beaches in the same direction of the food web space towards higher reliance on surf diatoms in the dissipative beach. Mixing models indicated that A. guyunusae was the primary nutrition source for suspension feeders in the dissipative beach, explaining their change in dietary niche compared to the reflective beach where the proportional contribution of surf diatoms was low. The high C/N ratios in A. guyunusae indicated its high nutritional value and N content, and may help to explain the high assimilation by suspension feeders at the dissipative beach. Furthermore, density of A. guyunusae was higher in the dissipative than in the reflective beach, and cell density was positively correlated with chlorophyll a only in the dissipative beach. Therefore, surf diatoms are important drivers in the dynamics of sandy beach food webs, determining the trophic niche space and productivity. Our study provides valuable insights on shifting foraging behavior by beach fauna in response to changes in resource availability. Highlights: Food web structure of sandy beaches was assessed by isotopic analysis. δ 13 C and δ 15 N values in consumers showed niche variation between beaches. Consumers shifted the isotopic trophic niche space between beaches. Higher reliance of surf diatoms in the dissipative beach induced isotopic shifts. The surf diatom Asterionellopsis guyunusae determine food web differences in beaches.