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Effects of initial enrichment of nitrogen and phosphorus on Bostrychia and Caloglossa (Ceramiales, Rhodophyta) growth using digital imaging
Author(s) -
Ryder Kelly,
West John,
Nicholls David
Publication year - 1999
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 - 10.1046/j.1440-1835.1999.00150.x
Subject(s) - ceramiales , biology , phosphorus , nitrogen , botany , algae , materials science , physics , quantum mechanics , metallurgy
SUMMARY Growth experiments measured the effects of an initial starvation period followed by a single nutrient pulse. Nutrient pulses were conducted at four different N‐levels (65, 1514, 2900, and 6080 μg N L ‐1 ) and four different P‐levels (84, 281, 639, and 849 μg P L ‐1 ) using isolates of Bostrychia moritziana (Sonder ex Kutzing) J.Agardh and Caloglossa leprieurii (Mon‐tagne) G.Martens. Specific growth rates (% day ‐1 ) in primary axis length (6. moritziana only) and surface area were measured using digital imaging. Results showed that the specific growth rates of both algae were highly dependent on the N‐levels of the seawater ( P < 0.001–0.05). Specific growth rates for the B. moritziana were approximately 3.5% day ‐1 at t = 7 days declining to approximately 1.0–1.5% day ‐1 at t = 49 days for the primary axis length, and approximately 8–9% day ‐1 declining to approximately 2–3% day ‐1 for surface area. The specific growth rate declined more rapidly with decreasing N initially added to the medium. In C. leprieurii , the specific growth rates for all four conditions at t = 8 days were approximately 11–13% day ‐1 , but N/O declined to approximately 3% day‐ 1 whereas the others declined to only approximately 7–8% day ‐1 by t = 49 days. The effects of initial P‐levels on growth varied, but generally indicated a direct relationship with specific growth rate. In C. leprieurii , the number of nodes and blades per plant was also measured via digital imaging and were found to increase with increasing N‐levels, whereas P‐levels had no influence. It was concluded that B. moritziana and C. leprieurii are prone to N‐limitation, but P‐limitation is less prone. Using digital imaging to measure the specific growth rate in total surface area and primary axis length provided a significantly more accurate depiction of the rate of growth than some of the more conventional means of measuring growth rate.