Direct evidence of imbalanced seagrass (Posidonia oceanica) shoot population dynamics in the Spanish Mediterranean

Marbà, Núria; Duarte, Carlos M.; Díaz-Almela, Elena; Terrados, Jorge; Álvarez, Elvira; Martı́nez, Regino; Santiago, Rocío; Gacia, Esperança; Grau, Antoni

doi:10.1007/bf02732753

Cited by 88 publications

(55 citation statements)

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“…Additionally, the shoot density of permanent P. oceanica plots situated at depths of 10 m or less off Cabrera Island (Marbà and Duarte, 2010) The available evidence for the Balearic Islands (Ál-varez et al, 2009; this study) suggests that shoot density of Posidonia oceanica meadows was either stable or increasing during the 2003-2008 period, which contrasts with results from other studies that found a net reduction in shoot density on permanent plots where P. oceanica shoots are tagged and counted yearly (Marbà and Duarte, 2010). Annual monitoring of shoot density may not be sensitive enough to detect shoot density changes unless a large number of replicated counts are done (Marbà et al, 2005), but by averaging shoot density values from a large meadow surface the results might better reflect net shoot balances at the meadow scale. The intensive labour required by a yearly shoot (Marbà et al, 2005) and because plagiotropic, horizontally-growing rhizomes produce many more new shoots than orthotropic, vertically-growing rhizomes (González-Correa et al, 2007), census data might reflect actual net shoot balances at the meadow scale only if the permanent plots used to obtain them sample the density of plagiotropic rhizomes in the meadow accurately.…”

Section: Discussioncontrasting

confidence: 77%

“…Annual monitoring of shoot density may not be sensitive enough to detect shoot density changes unless a large number of replicated counts are done (Marbà et al, 2005), but by averaging shoot density values from a large meadow surface the results might better reflect net shoot balances at the meadow scale. The intensive labour required by a yearly shoot (Marbà et al, 2005) and because plagiotropic, horizontally-growing rhizomes produce many more new shoots than orthotropic, vertically-growing rhizomes (González-Correa et al, 2007), census data might reflect actual net shoot balances at the meadow scale only if the permanent plots used to obtain them sample the density of plagiotropic rhizomes in the meadow accurately. Although further research should be done to resolve this contradiction, the extremely warm summer of 2003 seems to have increased the mortality rate of P. oceanica shoots (Marbà and Duarte, 2010 The disparity of the inter-annual trends detected by different studies (Table 3) suggests that local conditions and processes may have a large influence on the inter-annual variability of shoot density.…”

Section: Discussionmentioning

confidence: 99%

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Inter-annual variation of shoot density and biomass, nitrogen and phosphorus content of the leaves, and epiphyte load of the seagrass <i>Posidonia oceanica</i> (L.) Delile off Mallorca, western Mediterranean

Terrados¹,

Medina-Pons²

2010

Sci. Mar.

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SUMMARY:The epiphyte load, the ash content of the epiphytes, the leaf biomass, the nitrogen and phosphorus content of the leaves, and the density of shoots of the Mediterranean seagrass Posidonia oceanica (L.) Delile were monitored yearly from 2003 to 2008 in two shallow meadows off Mallorca (western Mediterranean) with the aim of identifying the responses of P. oceanica meadows to mid-term environmental variability. Inter-annual variability of P. oceanica meadows was significant for most of the descriptors examined: shoot biomass, epiphyte load, nitrogen and phosphorus content of the leaves, and shoot density. Shoot density increased by a factor of 2 and epiphyte load by a factor of 4 from 2003 to 2008. P. oceanica descriptors were generally not correlated with each other or with the average sea surface temperature during August. Long-term data series of descriptors of P. oceanica status are essential to improve understanding about the response of this important Mediterranean coastal ecosystem to natural and anthropogenic disturbances and to assess the effects of rapid global environmental change.Keywords: inter-annual variation, seagrass, epiphyte load, nitrogen, phosphorus, Posidonia oceanica, Western Mediterranean. RESUMEN: Variación interanual de la densidad de haces, biomasa foliar del haz, concentración de nitróge-no y fósforo en las hojas y de la carga de epífitos de la angiosperma marina Posidonia oceanica (L.) Delile en Mallorca, Mediterráneo occidental. -La carga de epífitos, el contenido en cenizas de los mismos, la biomasa foliar, el contenido en nitrógeno y fósforo de las hojas y la densidad de haces de la angiosperma marina Posidonia oceanica (L.) Delile se midieron anualmente desde 2003 a 2008 en dos praderas someras en Mallorca (Mediterráneo occidental) para identificar la respuesta de las praderas de P. oceanica a la variabilidad ambiental a medio plazo. Las praderas de P. oceanica presentan una gran variabilidad interanual pues la mayoría de los descriptores examinados (densidad de haces, biomasa foliar del haz, concentración de nitrógeno y fósforo en las hojas y carga de epífitos) cambiaron durante el periodo [2003][2004][2005][2006][2007][2008]. La densidad de haces se multiplicó por dos mientras que la carga de epífitos lo hizo por cuatro. No se encontró correlación entre la mayoría de los descriptores de P. oceanica ni tampoco con la temperatura del agua superficial del mar en agosto. La obtención de series temporales a largo plazo sobre descriptores del estado de las praderas de P. oceanica es necesaria para mejorar la comprensión de las respuestas de este importante ecosistema costero del Mediterráneo a perturbaciones naturales y antropogénicas y para evaluar los efectos del cambio global.Palabras clave: variación interanual, angiospermas marinas, epífitos, nitrógeno, fósforo, Posidonia oceanica, Mediterráneo occidental.

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Section: Discussioncontrasting

confidence: 77%

Section: Discussionmentioning

confidence: 99%

Inter-annual variation of shoot density and biomass, nitrogen and phosphorus content of the leaves, and epiphyte load of the seagrass <i>Posidonia oceanica</i> (L.) Delile off Mallorca, western Mediterranean

Terrados¹,

Medina-Pons²

2010

Sci. Mar.

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“…The global loss rate of threatened coastal ecosystems is estimated at 4-9% year −1 for corals (Gardner et al 2003, Bellwood et al 2004), a minimum of 1-2% year −1 for saltmarshes (Adam 2002;Lotze et al 2006), 1-3% year −1 for mangroves (Valiela et al 2001) and 2-5% year −1 for seagrass meadows Wyllie-Echeverria 1998, Duarte 2002;Marbà et al 2005;Orth et al 2006; Fig. 1), all of which are more rapid than the global loss rate of tropical forests, estimated at 0.5% year −1 (Achard et al 2002).…”

Section: Valuable Coastal Ecosystems Are In Declinementioning

confidence: 99%

The Charisma of Coastal Ecosystems: Addressing the Imbalance

Duarte

Dennison

Orth

et al. 2008

Estuaries and Coasts: J CERF

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434

132

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Coastal ecosystems including coral reefs, mangrove forests, seagrass meadows, and salt marshes are being lost at alarming rates, and increased scientific understanding of causes has failed to stem these losses. Coastal habitats receive contrasting research effort, with 60% of all of the published research carried out on coral reefs, compared to 11-14% of the records for each of salt marshes, mangrove forests, and seagrass meadows. In addition, these highly connected and interdependent coastal ecosystems receive widely contrasting media attention that is disproportional to their scientific attention. Seagrass ecosystems receive the least attention in the media (1.3% of the media reports) with greater attention on salt marshes (6.5%), considerably more attention on mangroves (20%), and a dominant focus on coral reefs, which are the subject of three in every four media reports on coastal ecosystems (72.5%). There are approximately tenfold lower reports on seagrass meadows in the media for every scientific paper published (ten), than the 130-150 media reports per scientific paper for mangroves and coral reefs. The lack of public awareness of losses of less charismatic ecosystems results in the continuation of detrimental practices and therefore contributes to continued declines of coastal ecosystems. More effective communication of scientific knowledge about these uncharismatic but ecologically important coastal habitats is required. Effective use of formal (e.g., school curricula, media) and informal (e.g., web) education avenues and an effective partnership between scientists and media communicators are essential to raise public awareness of issues, concerns, and solutions within coastal ecosystems. Only increased public understanding can ultimately inform and motivate effective management of these ecologically important coastal ecosystems.

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“…Mediterranean seagrass meadows, particularly those of the endemic species Posidonia oceanica, are experiencing widespread decline (Marba et al 1996(Marba et al , 2005Peirano et al 2005) due to a combination of direct anthropogenic pressure and climate change (Sánchez-Jerez and Ramos Esplá 1996; Balestri et al 2004;Pergent-Martini et al 2006). This decline is offering scope for opportunistic and exotic species to invade these habitats.…”

Section: Introductionmentioning

confidence: 99%

Effects of seagrasses and algae of the Caulerpa family on hydrodynamics and particle-trapping rates

et al. 2009

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The widespread decline of seagrass beds within the Mediterranean often results in the replacement of seagrasses by opportunistic green algae of the Caulerpa family. Because Caulerpa beds have a different height, stiffness and density compared to seagrasses, these changes in habitat type modify the interaction of the seafloor with hydrodynamics, influencing key processes such as sediment resuspension and particle trapping. Here, we compare the effects on hydrodynamics and particle trapping of Caulerpa taxifolia, C. racemosa, and C. prolifera with the Mediterranean seagrasses Cymodocea nodosa and Posidonia oceanica. All macrophyte canopies reduced near-bed volumetric flow rates compared to bare sediment, vertical profiles of turbulent kinetic energy revealed peak values around the top of the canopies, and maximum values of Reynolds stress increased by a factor of between 1.4 (C. nodosa) and 324

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Direct evidence of imbalanced seagrass (Posidonia oceanica) shoot population dynamics in the Spanish Mediterranean

Cited by 88 publications

References 50 publications

Inter-annual variation of shoot density and biomass, nitrogen and phosphorus content of the leaves, and epiphyte load of the seagrass <i>Posidonia oceanica</i> (L.) Delile off Mallorca, western Mediterranean

Inter-annual variation of shoot density and biomass, nitrogen and phosphorus content of the leaves, and epiphyte load of the seagrass <i>Posidonia oceanica</i> (L.) Delile off Mallorca, western Mediterranean

The Charisma of Coastal Ecosystems: Addressing the Imbalance

Effects of seagrasses and algae of the Caulerpa family on hydrodynamics and particle-trapping rates

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