A one-century suite of seagrass bed maps: can we trust ancient maps?

Leriche, Agathe; Boudouresque, Charles–François; Bernard, Guillaume; Bonhomme, Patrick; Denis, Jacques

doi:10.1016/j.ecss.2003.09.007

Cited by 51 publications

(47 citation statements)

References 14 publications

(12 reference statements)

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“…The number of leaves per shoot was not different between stations, a finding which is consistent with previous studies (Capiomont et al 2000. A decline in shoot density, leaf area index, leaf surface and leaf length at disturbed stations compared with control sites has been found by several authors (Leriche et al 2004, Ben Brahim et al 2010). These results cannot be assigned only to nutrient enrichment; several factors may also explain this decline: first, the decrease in water transparency at the disturbed station (Table 1) involves the reduction of light intensity necessary for photosynthesis.…”

Section: Discussionsupporting

confidence: 80%

Variability in the structure of epiphytic microalgae assemblages on the leaves of <em>Posidonia oceanica</em> in relation to human disturbance in a meadow off Tunisia

et al. 2014

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Summary:We investigated the impact of sewage discharge on Posidonia oceanica meadows in Mahdia, eastern Tunisia. We specifically addressed changes in biometric plant parameters and epiphytic microalgae composition on leaves caused by this anthropogenic interference. A hierarchical sampling design was used to compare epiphytic microalgae structure between one disturbed and two control stations. Samples were collected by SCUBA diving at 8 m depth in August 2009. A total of 58 microalgae taxa were identified on leaves. At the disturbed station, leaf length, leaf surface area and the leaf area index decreased, whereas epiphytic dinoflagellate abundances increased compared with the control stations, with more Prorocentrales, Protoperidiniales and potentially toxic species on leaves of the disturbed station. Moderate nutrient enrichment (mainly Si(OH) 4 and NH 4 + ) and low water transparency at the disturbed station were associated with the increased abundances of some dinoflagellate species.Keywords: epiphytic microalgae; sewage disturbance; spatial variability; Posidonia oceanica.Variabilidad en la estructura de las comunidades de microalgas epífitas en las hojas de Posidonia oceanica en respuesta a las perturbaciones humanas en una pradera de Túnez Resumen: Se ha investigado el impacto de los vertidos de aguas residuales en praderas de Posidonia oceanica situadas en Mahdia (Este de Túnez). Se han estudiado los cambios en los parámetros biométricos de la planta y la composición de las microalgas epífitas en las hojas causadas por esta interferencia antrópica. Se ha utilizado un diseño de muestreo jerárquico para comparar las microalgas epífitas entre la estación perturbada y dos estaciones control. Las muestras se recolectaron en buceo autónomo a 8 m de profundidad en Agosto de 2009. La longitud, el área y el índice de área de las hojas era inferior en la estación perturbada mientras que las abundancias de los dinoflagelados epífitos eran mayores en las estaciones control, con más Prorocentrales, Protoperidiniales y otras especies tóxicas potenciales en las hojas de la estación perturbada. Un ligero aumento de nutrientes en la estación perturbada (sobre todo Si(OH) 4 y NH 4 + ) y una menor transparencia del agua iba asociada a un aumento en la abundancia de algunas especies de dinoflageladas.

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Section: Discussionsupporting

confidence: 80%

Variability in the structure of epiphytic microalgae assemblages on the leaves of <em>Posidonia oceanica</em> in relation to human disturbance in a meadow off Tunisia

et al. 2014

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“…Indeed, this study is based on transect diving and samples gathered thanks to a dredge, two techniques that give a great part to interpolation. Thus, Pergent-Martini et al (1995) and Leriche et al (2004) showed, in the Marseille region, that the large differences in the distribution of P. oceanica meadows, are explained more by errors and inaccuracies in the old maps used as reference than by a real change in their distribution (Montefalcone et al, 2013). This last hypothesis seems to be confirmed by the fact that on maps made with more recent and comparable methods (Pasqualini, 1997), the total area of seagrass would have only decreased by 2% during the last sixteen http://epublishing.ekt.gr | e-Publisher: EKT | Downloaded at 11/05/2018 17:31:07 | Medit.…”

Section: Discussionmentioning

confidence: 99%

Is Posidonia oceanica regression a general feature in the Mediterranean Sea?

et al. 2013

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Over the last few years, a widespread regression of Posidonia oceanica meadows has been noticed in the Mediterranean Sea. However, the magnitude of this decline is still debated. The objectives of this study are (i) to assess the spatio-temporal evolution of Posidonia oceanica around Cap Corse (Corsica) over time comparing available ancient maps (from 1960) with a new (2011) detailed map realized combining different techniques (aerial photographs, SSS, ROV, scuba diving); (ii) evaluate the reliability of ancient maps; (iii) discuss observed regression of the meadows in relation to human pressure along the 110 km of coast. Thus, comparison with previous data shows that, apart from sites clearly identified with the actual evolution, surfaces occupied by the seagrass Posidonia oceanica are relatively stable. The recorded differences seem more related to changes in mapping techniques. These results confirm that in areas characterized by moderate anthropogenic impact, Posidonia oceanica meadows are not subject to significant regression and that the changes due to the evolution of mapping techniques are not negligible. However, others facts should be taken into account before extrapolating to the Mediterranean Sea (e.g. currently mapped surfaces) and assessing the amplitude of actual regression.

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“…A bibliographic database plays a major role in the study of habitat distribution and its changes over time. In some Mediterranean regions, information on coralligenous distribution is available in the literature but its reliability must be estimated (Leriche et al 2001). Acoustic technologies are increasingly being used for monitoring benthic habitats (Zapata-Ramirez et al 2013), and those used for mapping coralligenous communities normally include side-scan sonars and multibeam sonars (Bonacorsi et al 2012, Gordini et al 2012.…”

Section: Introductionmentioning

confidence: 99%

Combining literature review, acoustic mapping and in situ observations: an overview of coralligenous assemblages in Liguria (NW Mediterranean Sea)

Molina¹,

Montefalcone²,

Vassallo³

et al. 2011

Sci. Mar.

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Summary:A review and update of the existing knowledge on the coralligenous assemblages of Liguria (NW Italy) was conducted as an essential step towards management measures for their conservation according to the EU Marine Strategy Framework Directive. By combining a literature review, acoustic mapping and in situ observations on a geographic information systems platform, we were able to assess the distribution and heterogeneity of coralligenous assemblages and the main pressures affecting them. The reliability of the literature was previously estimated using a dependability index. The coralligenous assemblages cover an area of 130.9 ha and range from 10 to 113 m depth. Twelve different biological facies (five of them not included in the EUNIS list) were identified and four main geomorphotypes (plungingcliffs, paleocliffs, rockfalls and shoals) were recognized. Incident light values influenced the distribution of four facies in Portofino promontory. Pressures were found on 33% of the coralligenous assemblages investigated, mainly due to fishing activities, mass mortality events, invasive species and occasional mucilaginous events. Our results showed a high spatial, geomorphological and biological heterogeneity of coralligenous assemblages in Liguria.Keywords: mapping; literature review; heterogeneity; coralligenous assemblages; NW Mediterranean Sea.Combinando revisión bibliográfica, mapas acústicos y observaciones in situ: sinopsis de las formaciones coralígenas en Liguria (NO del mar Mediterráneo) Resumen: Una revisión y actualización del conocimiento existente sobre las formaciones coralígenas en Liguria (NO de Italia) ha sido implementado como paso esencial con vistas a las medidas de gestión para su conservación de acuerdo con la Directiva Marco sobre la Estrategia Marina. Combinando en plataforma SIG revisión bibliográfica, mapas acústicos y observaciones in situ hemos sido capaces de determinar la distribución de las formaciones coralígenas, su heterogeneidad y sus principales presiones. La fiabilidad de la bibliografía fue estimada a través del índice de confianza (DI). Las formaciones coralígenas cubren un área de 130.9 ha en un rango de profundidad que va desde los 10 m a los 113 m. 12 facies biológicas diferentes (5 de ellas no incluidas en la lista EUNIS) fueron identificadas y 4 geomorfotipos principales (acantilado actual, paleoacantilado, cúmulo de rocas y bajos) fueron reconocidos. Los valores de luz incidente influenciaron la distribución de 4 facies en el promontorio de Portofino. Fueron encontradas presiones en el 33% de las formaciones coralígenas investigadas, principalmente debidas a actividades de pesca, episodios de muerte masiva, especies invasoras y proliferación de algas mucilaginosas. Nuestros resultados mostraron una elevada heterogeneidad espacial, geomorfológica y biológica de las formaciones coralígenas en Liguria.

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A one-century suite of seagrass bed maps: can we trust ancient maps?

Cited by 51 publications

References 14 publications

Variability in the structure of epiphytic microalgae assemblages on the leaves of <em>Posidonia oceanica</em> in relation to human disturbance in a meadow off Tunisia

Variability in the structure of epiphytic microalgae assemblages on the leaves of <em>Posidonia oceanica</em> in relation to human disturbance in a meadow off Tunisia

Is Posidonia oceanica regression a general feature in the Mediterranean Sea?

Combining literature review, acoustic mapping and in situ observations: an overview of coralligenous assemblages in Liguria (NW Mediterranean Sea)

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