Estimation of net primary productivity of intertidal seaweeds — limitations and latent problems

Murthy, M. S. R.; Ramakrishna, T.; Babu, G V Sarat; Rao, Y. N.

doi:10.1016/0304-3770(86)90086-0

Cited by 16 publications

(11 citation statements)

References 13 publications

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“…Ash content remained fairly constant during the sampling period (20% DW). Net production was estimated from biomass data, using two different methods described by Murthy et al (1986). Method 1 is based on the sum of the positive biomass variations, assuming that a negative variation in a period between two samplings, corresponds to a biomass loss that was not produced within the considered period.…”

Section: Field Workmentioning

confidence: 99%

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Modelling growth of Ruppia cirrhosa

Calado

Duarte

2000

Aquatic Botany

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The main objectives of this work were to synthesise information on the autoecology of Ruppia cirrhosa Petagna (Grande) in a mathematical model and to use the model to simulate its growth, production and harvest. Model parameters were allowed to vary as a result of acclimation, following experimental data reported in the literature. Biomass data from Santo André lagoon (SW Portugal) were used to calibrate the model. Validation was carried out with independent data sets from Santo André lagoon and from Tancada lagoon (NE Spain). Model simulations show a reasonable agreement with observed data with a similar biomass temporal dynamics and peaks. Self-shading appears to be an important self-regulating mechanism of biomass growth and production. The results obtained predict an annual net primary production of 361 g DW m −2 well within the estimates based on harvesting techniques (295-589 g DW m −2 ). Model results suggest that controlled harvesting of macrophyte biomass may be carried out without affecting macrophyte real net production, through the reduction of light limitation under the plant canopy.

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Section: Field Workmentioning

confidence: 99%

“…The former, based on biomass differences, are a function of time and have important errors proportional to the time lag between two consecutive samplings (Murthy et al, 1986). These methods allow only the estimation of net production.…”

Section: Introductionmentioning

confidence: 99%

Modelling growth of Ruppia cirrhosa

Calado

Duarte

2000

Aquatic Botany

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“…Daily mortality, calculated as the decline rate of tagged fronds per day, as a function of average daily wave power. Wiegert & Evans (1964), as adapted by Murthy et al (1986) was used. Another approach for NPP evaluation was based on the sum of biomass differences with mortality (computed from the loss rates of tagged plants).…”

Section: Model Simulationsmentioning

confidence: 99%

“…Harvesting techniques are beset with a number of problems, namely the usually high variability of biomass standing stocks and the difficulties to quantify precisely the dead and decaying parts, as these fractions often do not accumulate in situ (Murthy et al, 1986). One of the possible ways to quantify mortality losses is through tagging of algal fronds.…”

Section: Introductionmentioning

confidence: 99%

A methodology for parameter estimation in seaweed productivity modelling

Duarte

Ferreira

1993

Fourteenth International Seaweed Symposium

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This paper presents a combined approach for parameter estimation in models of primary production. The focus is on gross primary production and nutrient assimilation by seaweeds.A database of productivity determinations, biomass and mortality measurements and nutrient uptake rates obtained over one year for Gelidium sesquipedale in the Atlantic Ocean off Portugal has been used. Annual productivity was estimated by harvesting methods, and empirical relationships using mortality/ wave energy and respiration rates have been derived to correct for losses and to convert the estimates to gross production.In situ determinations of productivity have been combined with data on the light climate (radiation periods, intensity, mean turbidity) to give daily and annual productivity estimates. The theoretical nutrient uptake calculated using a 'Redfield ratio' approach and determinations of in situ N and P consumption by the algae during incubation periods have also been compared.The results of the biomass difference and incubation approaches are discussed in order to assess the utility of coefficients determined in situ for parameter estimation in seaweed production models.

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“…He concluded that the technically simple harvest method (converting seasonal biomass estimates to energy equivalents) was as sound as other, more technically sophisticated techniques . Murthy et al (1986) adapted and then compared the three most commonly used harvest methods to marine macroalgae . They concluded that a standard procedure for determining NPP in seaweeds might be nearly impossible for the following reasons : production losses due to frond detachment and grazing are difficult to standardize ; there is a large interspecies variation in both life cycles and morphology ; and there is a large between habitat diversity .…”

Section: Introductionmentioning

confidence: 99%

Annual net primary production calculated from eastern Canadian Irish moss fishery data

1990

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Western Prince Edward Island Irish moss (Chondrus crispus) has been intensively dragraked since 1966 . As well, most unattached fronds removed by wave surge, ice, etc . are brought to shore by waves and currents, where they are harvested eagerly . Accurate annual fishing yields were recorded between 1966 and 1981 inclusive . Given that herbivore densities are reduced, likely due to the intensive raking, and that mean annual bycatch (non-Irish moss seaweeds) (23 .4 %) and commercial bed sizes (873 ha) were known, the fishing yields thus were considered a unique database from which to calculate net primary production (NPP) . Factors used to convert from wet to dry wt (DW), and from dry wt to carbon were 0 .22 an 0 .31, respectively . Calculated mean annual NPP values were as follows : 2 .101 ± 0 .654 t (DW) ha -1 y -1 ; 210 .1 g DW m-2 yr -1 and 63 .0 g CM-2 yr -1 . These values are much lower than those calculated for northwest Atlantic kelp and rockweed but similar to that determined for northeast Atlantic Gracilaria verrucosa . The interannual variability pattern for NPP was similar for both the wild Irish moss harvest and that of experimental Chondrus crispus outplants placed in one of the 14 commercial beds .

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Estimation of net primary productivity of intertidal seaweeds — limitations and latent problems

Cited by 16 publications

References 13 publications

Modelling growth of Ruppia cirrhosa

Modelling growth of Ruppia cirrhosa

A methodology for parameter estimation in seaweed productivity modelling

Annual net primary production calculated from eastern Canadian Irish moss fishery data

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