Methods for the measurement of seagrass abundance and depth distribution

Duarte, Carlos M.; Kirkman, Hugh

doi:10.1016/b978-044450891-1/50008-6

Cited by 58 publications

(58 citation statements)

References 9 publications

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“…The high annual precipitation in the tropical areas causes water clarity lower than that of northern and southern latitudes. Similar studies had been conducted in clear coastal waters and documented in [15,16], that were mostly in clear waters (Case-1) of Australia. Less efforts are required to obtain good STAGB results from the analysis of the images acquired during low spring tides, and as when seagrass leaves are exposed.…”

Section: Introductionmentioning

confidence: 78%

Change Detection of Submerged Seagrass Biomass in Shallow Coastal Water

Misbari

Hashim

2016

Remote Sensing

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Satellite remote sensing is an advanced tool used to characterize seagrass biomass and monitor changes in clear to less-turbid waters by analyzing multi-temporal satellite images. Seagrass information was extracted from the multi-temporal satellite datasets following a two-step procedure: (i) retrieval of substrate-leaving radiances; and (ii) estimation of seagrass total aboveground biomass (STAGB). Firstly, the substrate leaving radiances is determined by compensating the water column correction of the pre-processed data because of the inherent errors associated with the geometric and radiometric fidelities including atmospheric perturbations. Secondly, the seagrass leaving radiances were correlated to the corresponding in situ STAGB to predict seagrass biomass. The relationship between STAGB and cover percentage was then established for seagrass meadows occurring in Merambong, Straits of Johor, Malaysia. By applying the above-mentioned approach on Landsat Thematic Mapper (TM) acquired in 2009 and Operational Land Imager (OLI) data acquired in 2013, the resulting maps indicated that submerged STAGB in less clear water can be successfully quantified empirically from Landsat data, and can be utilized in STAGB change detection over time. Data validation showed a good agreement between in situ STAGB and Landsat TM (R 2 = 0.977, p < 0.001) and OLI (R 2 = 0.975, p < 0.001) derived water leaving radiances for the studied seagrass meadows. The STAGB was estimated as 803˘0.47 kg in 2009, while it was 752.3˘0.34 kg in 2013, suggesting a decrease of 50.7 kg within the four-year interval. This could be mainly due to land reclamation in the intertidal mudflat areas performed, with a view to increase port facilities and coastal landscape development. Statistics on dugong sightings also supports changes in STAGB.

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Section: Introductionmentioning

confidence: 78%

Change Detection of Submerged Seagrass Biomass in Shallow Coastal Water

Misbari

Hashim

2016

Remote Sensing

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“…The number of samples was determined after the elaboration of a performance curve for the macrofauna groups from a previous sampling. The subsequent samplings took into account the size of the small seagrass meadow studied here, as recommended by Duarte & Kirkman (2001), using a sampling design based on Burdick & Kendrick (2001) for patched meadows. Each core was sectioned in belowground and aboveground, the former of which included a thin upper layer (smaller than 0.5 cm) of the sediment.…”

Section: Methodsmentioning

confidence: 99%

Seasonal variation of the crustacean fauna in the belowground and aboveground strata in a Halodule wrightii meadow of northeastern Brazil

Barros

Souza‐Filho

Paiva

et al. 2017

Iheringia, Sér. Zool.

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ABSTRACT. The diff erent microhabitats provided by seagrasses and the habit of the species determinate the vertical distribution of crustaceans. This study verifi ed the infl uence of the seasonality on the spatial distribution of the crustacean community associated with a Halodule wrightii meadow. From April 2006 to July 2007, we performed fi fteen samplings in Goiabeiras Beach, Ceará State, each with fi ve sectioned replicates in belowground and aboveground. Cumaceans and the amphipod Hyale media (Dana, 1853) had a higher frequency, density, and dominance than the other taxa, in both strata. The community exhibited gradual changes along the study, in both the belowground and aboveground strata, but the seagrass structure was not suffi cient to explain the vertical distribution of the crustacean fauna along the time.KEYWORDS. Seagrass, shoal grass, benthic communities. RESUMO. Variação sazonal da fauna de crustáceos nos estratos subterrâneo e aéreo em uma pradaria de Halodule wrightii do nordeste do Brasil.Os diferentes microhabitats proporcionados pelas pradarias marinhas e o habito das espécies determinam a distribuição vertical de espécies de crustáceos. Este estudo verifi cou a infl uência da sazonalidade sobre a distribuição espacial da comunidade de crustáceos associada a uma pradaria de Halodule wrightii. De abril de 2006 a julho de 2007, foram realizadas 15 amostragens na praia das Goiabeiras, estado do Ceará, em cada uma com cinco amostras seccionadas em partes aérea e subterrânea. Cumáceos e o anfípode Hyale media (Dana, 1853) tiveram a maior frequência, densidade e dominância em relação a outros táxons, em ambos os estratos. A comunidade exibiu mudanças graduais ao longo do estudo, em ambos os estratos aéreo e subterrâneo, mas a estrutura da pradaria não foi sufi ciente para explicar a distribuição vertical da fauna de crustáceos ao longo do tempo.PALAVRAS-CHAVE. Pradarias marinhas, capim marinho, comunidades bentônicas.

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“…One permanent 0.04 m 2 quadrat was established in the centre of each experimental plot at the commencement of the study. Stem density, percentage cover and maximum and average canopy heights (cm) were measured non-destructively in the permanent quadrats, as per Duarte & Kirkman (2001). Above-ground biomass was measured destructively in a 20 × 20 cm quadrat placed randomly in the sampling area of each plot.…”

Section: Methodsmentioning

confidence: 99%

“…All stems in the quadrat were cut off at sediment level and placed immediately in a bag. Later, the above-ground material was separated into leaf, stem and epiphyte components for every 10 cm layer of the canopy (as per Carruthers & Walker 1997) to determine leaf, stem and epiphyte biomass, and leaf and leaf cluster density, as per Duarte & Kirkman (2001). These components were counted and dried at 60°C for 48 h. To minimise destructive sampling of the plot area, a single core sample (0.01 m 2 , 20 cm deep) was collected from inside the above-ground biomass quadrat to quantify below-ground biomass.…”

Section: Methodsmentioning

confidence: 99%

Effects of experimental reduction of light availability on the seagrass Amphibolis griffithii

Mackey¹,

Collier²,

Lavery³

2007

Mar. Ecol. Prog. Ser.

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The response of the meadow-forming seagrass Amphibolis griffithii (Black) den Hartog to light reduction was examined over a 3 mo period and a subsequent 1 mo recovery period. Morphological and physiological variables were measured in meadows subjected to an average reduction in photosynthetic photon flux density (PPFD) of 88% relative to unshaded controls. Leaf biomass, leaf cluster density and the number of leaves per cluster all declined in shaded plots, and after 3 mo were about 30, 50 and 60% of the controls, respectively. Leaf extension was one-third that of the control plots. Epiphyte biomass in shaded plots was 44% of the controls after 6 wk of shading and 18% after 3 mo of shading. Leaf chlorophyll concentration was affected by shading, but only in the upper canopy: shaded leaves had 55% more chlorophyll than control leaves. Shading reduced the carbohydrate stored in the rhizomes of shaded plants: sugars declined rapidly and continuously and, after 3 mo, were < 20% of the control values; a decline in starch concentrations lagged behind that of sugars. All variables showed a significant shift towards the values in control plots 42 d after removal of shading, indicating a capacity for recovery, though in many cases these variables remained significantly lower than those in the controls. A. griffithii and its epiphytes respond rapidly to severe, shortterm reductions in light availability, but responses at the scale of shoots and whole meadows also allow the plants to respond rapidly to improved light conditions.

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Methods for the measurement of seagrass abundance and depth distribution

Cited by 58 publications

References 9 publications

Change Detection of Submerged Seagrass Biomass in Shallow Coastal Water

Change Detection of Submerged Seagrass Biomass in Shallow Coastal Water

Seasonal variation of the crustacean fauna in the belowground and aboveground strata in a Halodule wrightii meadow of northeastern Brazil

Effects of experimental reduction of light availability on the seagrass Amphibolis griffithii

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