Intra-specific responses of Cymodocea nodosa to macro-nutrient, irradiance and copper exposure

Abstract

Excess macro-nutrients, metal contamination and light limitation are three of the most commonly encountered anthropogenic stressors affecting seagrass meadows. In this study, the effects of different combinations of nutrients (N-NO 3 , P-PO 4 ), copper and irradiance were investigated in shoots of Cymodocea nodosa collected from three meadows in the N. Aegean Sea, one (Nea Karvali) impacted by anthropogenically-derived environmental stressors and two in more pristine condition (Thasos, Brasidas). In a series of laboratory experiments, shoots were exposed to varying nutrient and heavy metal concentrations, as well as varying irradiance levels, for 8 days and the effective quantum yield (ΔF/Fm′) and leaf elongation were quantified. Results showed that C. nodosa increased ΔF/Fm′ under high nutrient concentrations (30 μΜ N-NO 3− -2 μΜ P-PO 4 3− ) but significant differences were only apparent in shoots collected from the oligotrophic-less stressed meadows. Irradiance affected ΔF/Fm′ significantly in all shoots irrespective of source and PO 4 -P concentration, while higher values were measured under low light conditions and it was identified as the main pathway of eutrophication stress in N. Aegean Cymodocea meadows. Shoots, independently of acclimation were tolerant to copper enrichment, with only the highest copper concentrations (4.7 and 7.9 μM) having significant negative effects on ΔF/Fm′. Shoots from the more pristine meadows were less affected by Cu than those from the highly stressed meadow.

Heavy metal spatial variation, bioaccumulation, and risk assessment of Zostera japonica habitat in the Yellow River Estuary, China

“…The potential of heavy metal accumulation in seagrass has been investigated for bioremediation purposes (e.g., Bunluesin et al, 2007;Govers et al, 2014). Although some of elements are essential to plant growth (e.g., Cu, Fe, Mn, Ni, and Zn), several studies have shown that heavy metals negatively impact seagrass photosynthetic physiology (Prange and Dennison, 2000;Macinnis-Ng and Ralph, 2002;Papathanasiou et al, 2015). For instance, Prange and Dennison (2000) found that two Halophila species were affected by exposure to Fe and Cu, whereas Zostera capricorni was only impacted by Cu.…”

Status Padang Lamun Pantai-Pantai Wisata di Pacitan

“…Selain itu, lamun juga mempunyai ciri-ciri sebagai berikut yaitu tidak ada stomata, mempunyai kutikula yang tipis, perkembangan schizogenous dari sistem lakunar, pollinasi yang hidrofil, dan tidak ada diafragma pada sistem lakunar (Goltenboth et al 2012). Distribusi dan stabilitas komunitas lamun ditentukan oleh faktor-faktor antara lain: nutrien, cahaya, sedimen, salinitas, dan suhu (Papathanasiou et al 2015;Kilminster et al 2014;Koch et al 2007;Moreno et al 2014;Kaldy et al 2015).…”

“…Pada sedimen karbonat (mineral sedimen berasal dari terumbu karang), fosfat berinteraksi dengan karbonat dan kurang tersedia sebagai fosfat bebas. Di padang lamun, hal tersebut mungkin menyebabkan fosfor terbatas (Kilminster et al 2014;Papathanasiou et al 2015). Tetapi hal ini masih terbantu oleh kelebihan lamun yang dapat mengambil zat hara seperti amonia dan fosfat melalui daun walaupun konsentrasi hara pada kolom air pada umumnya sangat rendah.…”

“…Seperti yang telah disebutkan sebelumnya, distribusi dan stabilitas komunitas lamun ditentukan oleh faktor-faktor antara lain: nutrien, cahaya, sedimen, salinitas, dan suhu (Papathanasiou et al 2015;Kilminster et al 2014;Koch et al 2007;Moreno et al 2014;Kaldy et al 2015). Hasil pengukuran faktor-faktor fisiko kimia ditunjukkan pada Tabel 4.…”

“…Kedua tipe blooming algae tersebut mengurangi jumlah cahaya yang mencapai lamun. Hal ini mengurangi efektifitas fotosintesis sehingga menekan produktivitas lamun dan menyebabkan penurunan komunitas lamun di seluruh dunia (Papathanasiou et al 2015;Waycott et al 2007;Christianen et al 2011).…”