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Effects of nutrient enrichment and herbivory on morphology, reproduction and chemical content of T urbinaria conoides ( P haeophyceae)
Author(s) -
Mayakun Jaruwan,
Kim Jeong Ha,
Lapointe Brian E.,
Prathep Anchana
Publication year - 2013
Publication title -
phycological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.438
H-Index - 44
eISSN - 1440-1835
pISSN - 1322-0829
DOI - 10.1111/pre.12023
Subject(s) - nutrient , stipe (mycology) , biology , holdfast , herbivore , fucales , botany , algae , frond , brown algae , ecology
Summary The effects of nutrient enrichment and herbivory on resource allocation patterns among morphology, reproduction, and chemical content of the brown alga, T urbinaria conoides ( J . A gardh) K ützing were tested in the shallow subtidal zone of the G ulf of T hailand. The field experimental design comprised 36 plots (50 × 50 cm 2 ) with and without herbivores, and two nutrient levels. Cages (uncaged and fully caged plots) were used to exclude herbivorous fishes and two nutrients levels were achieved by experimental enrichment above ambient nutrient concentrations. For morphology of T urbinaria , the maximum length (holdfast to frond apex), the width of the base of the stipe, number of blades, holdfast and stipe diameter were measured. Biomass, reproductive output, and tissue nutrient (carbon: nitrogen: phosphorus) content of T . conoides were examined. Phlorotannin concentrations were examined using a modified F olin‐ C iocalteu method. The results showed that herbivory had no effect on morphology, reproduction, or phlorotannin concentrations. This could be due to the structural and morphological deterrents of alga, which might minimize grazing effects from herbivorous fishes. Nutrient enrichment had no effect on morphology and reproduction of T . conoides , possibly due to low nutrient demand in T urbinaria . However, nutrient enrichment did affect phlorotannin concentrations, as phlorotannins in the enriched plots were lower than the ambient plots. These results support, in part, the carbon–nutrient balance hypothesis that states algae will allocate fewer resources to production of anti‐herbivore chemical compounds when enriched with potential growth‐limiting nutrients.