Influence of light intensity and nutrient source on δ13C and δ15N signatures in Ulva pertusa

Dudley, Bruce; Barr, Neill; Shima, Jeffrey S.

doi:10.3354/ab00241

Cited by 37 publications

(21 citation statements)

References 40 publications

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“…It should also be noted that the “AI” is likely to overestimate the contribution of autotrophs to epilithon in shaded ponds, given that algae in lower light tend to increase chlorophyll stores relative to biomass (Dudley et al. ). This suggests increased contributions of the heterotrophic component of epilithon in ponds with endemic canopy.…”

Section: Discussionmentioning

confidence: 99%

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Effects of invasion at two trophic levels on diet, body condition, and population size structure of Hawaiian red shrimp

Dudley

MacKenzie

Sakihara³

et al. 2017

Ecosphere

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Abstract. We examined the degree to which invasion by non-native, nitrogen (N)-fixing riparian trees and poeciliid fish alters diet of a common grazer/detritivore in brackish ponds on the dry coast of Hawai‛i Island. Because this shrimp, Halocaridina rubra (ʻ opaeʻula), displays a preference for autotrophic components of epilithon, we hypothesized that tree canopy would reduce their body condition and abundance, but that this would be moderated by nutrient quality of leaf litter (high-quality, non-native, nitrogen-fixing tree vs. low-quality, endemic non-nitrogen-fixing tree). We hypothesized that poeciliid invasion would reduce population size and body condition of H. rubra by direct predation and by inducing reductions in feeding rate. Analysis of stable isotopes (dD, d13 C, and d 15 N) showed that direct consumption of leaf litter detritus supplemented H. rubra diet in ponds with canopy cover. In addition, epilithon in ponds with canopy cover was isotopically more similar to leaf litter than epilithon in ponds without canopy cover, and our evidence suggests this may be due to contributions of allochthonous nutrient sources to epilithon assemblages. However, canopy cover, whether native or invasive, did not decrease epilithon growth rates and had little effect on shrimp body condition or population size. In contrast, poeciliid invasion reduced daylight grazing on the benthos, and caused a reduction in body condition among larger shrimp. Our results indicate that primary succession by invasive trees may shift food web linkages in these ponds from autotrophic to heterotrophic support, without negative impacts on native grazer/detritivore communities. We suggest that poeciliid invasions have sub-lethal effects on H. rubra as well as their direct predation effects, with potential long-term implications for the ecosystem function of anchialine ponds and other coastal systems.

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Section: Discussionmentioning

confidence: 99%

“…, Dudley et al. ). Increasing the number of isotope tracers that can be used in food web studies has the potential to improve reliability of mixing models (Fry , , Soto et al.…”

Section: Introductionmentioning

confidence: 99%

Effects of invasion at two trophic levels on diet, body condition, and population size structure of Hawaiian red shrimp

Dudley

MacKenzie

Sakihara³

et al. 2017

Ecosphere

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“…The main intrinsic factors affecting variability of macroalgal δ 15 N are the preferential mobilization of light isotopes (isotopic fractionation) during uptake, excretion and metabolic reactions (Teichberg et al, 2008) and intra-frond variability (Carballeira et al, 2014;Raimonet et al, 2013;Savage and Elmgren, 2004;Viana et al, in review). External factors are littoral position (Kim et al, 2013) or light (Dudley et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Variability in δ 15 N of intertidal brown algae along a salinity gradient: Differential impact of nitrogen sources

Viana

Bode

2015

Science of The Total Environment

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“…) enhancement of growth rates when supplied with ammonium, no benefit of ammonium over nitrate (e.g., Gracilaria tenuistipitata , Haglund and Pedersen and Ulva pertusa , Dudley et al. ) and even significantly lower growth rates when supplied with ammonium (e.g., Solieria chordalis , Brown ). This variation in response likely stems from the wide range of light, temperature and nutrient concentrations used in these experiments (e.g., ambient light levels [200–700 μmol photons · m −2 · s −1 ] or consistent 12:12 [light:dark] cycles at 55 μmol photons · m −2 · s −1 , see Buschmann et al.…”

Section: Discussionmentioning

confidence: 99%

Restricted use of nitrate and a strong preference for ammonium reflects the nitrogen ecophysiology of a light‐limited red alga

Pritchard

Hurd

Beardall

et al. 2015

Journal of Phycology

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Ammonium and nitrate are important sources of inorganic nitrogen for coastal primary producers. Nitrate has higher energy requirement for uptake and assimilation, compared with ammonium, suggesting that it might be a more efficient nitrogen source for slow-growing, light-limited macroalgae. To address this hypothesis, we examined the nitrogen ecophysiology of Anotrichium crinitum, a rhodophyte macroalgae common in low-light habitats in New Zealand. We measured seasonal changes in seawater nitrate and ammonium concentrations and the concentration of nitrate and ammonium stored internally by A. crinitum. We determined the maximal uptake rates of nitrate and ammonium seasonally and grew A. crinitum in the laboratory with these nitrogen sources under two ecologically relevant saturating light levels. Our results show that field-harvested A. crinitum has a high affinity for ammonium and although it will grow when supplied exclusively with nitrate, internal nitrate pools are low and it is unable to take up nitrate without several days of acclimation to saturating light. Our data predict that A. crinitum would be able to sustain growth with ammonium as the sole source of nitrogen, a strategy that would help it survive under low-light conditions that prevail in the field.

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Influence of light intensity and nutrient source on δ13C and δ15N signatures in Ulva pertusa

Cited by 37 publications

References 40 publications

Effects of invasion at two trophic levels on diet, body condition, and population size structure of Hawaiian red shrimp

Effects of invasion at two trophic levels on diet, body condition, and population size structure of Hawaiian red shrimp

Variability in δ 15 N of intertidal brown algae along a salinity gradient: Differential impact of nitrogen sources

Restricted use of nitrate and a strong preference for ammonium reflects the nitrogen ecophysiology of a light‐limited red alga

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