Combined nutrient and macroalgae loads lead to response in seagrass indicator properties

Abstract

a b s t r a c t a r t i c l e i n f oExcess nutrients are potential factors that drive phase shifts from seagrasses to macroalgae. We carried out a manipulative field experiment to study the effects of macroalgae Ulva pertusa loading and nutrient addition to the water column on the nitrogen (N) and carbon (C) contents (i.e., fast indicators) as well as on the morphology and structure (i.e., slow indicators) of Zostera marina. Our results showed rapid impact of increased macroalgae and nutrient load on Z. marina C/N ratios. Also, macroalgae addition resulted in a trend of decreasing belowground biomass of seagrasses, and nutrient load significantly decreased above to belowground biomass ratio. Although some morphological/structural variables showed relatively fast responses, the effects of short-term disturbance by macroalgae and nutrients were less often significant than on physiological variables. Monitoring of seagrass physiological indicators may allow for early detection of eutrophication, which may initiate timely management interventions to avert seagrass loss.

Individual and population indicators of Zostera japonica respond quickly to experimental addition of sediment-nutrient and organic matter

“…For preventing nutrient and organic matter cross-contamination, a minimum distance of 5 m between plots in the same treatment and a minimum distance of 35 m between different treatments were implemented. In Swan Lake, hydrodynamics are weak (Han et al, 2016). Our results showing nutrient and organic matter effects also supported sufficient independence between the treatments.…”

“…Although Z. japonica seagrass population showed increasing trend worldwide (Short et al, 2011), it is declining in northern China coast (e.g. Swan Lake, Yellow River Delta) in recent years possibly due to human activities (Han et al, 2016). Shellfish aquaculture, sewage discharge and swans feces can enhance high nutrient and organic matter loads into sediments within seagrass habitats, which may contribute to the decline of seagrasses, Z. japonica in Swan Lake.…”

Latitudinal Patterns in European Seagrass Carbon Reserves: Influence of Seasonal Fluctuations versus Short-Term Stress and Disturbance Events

“…Short-term stress and small-scale disturbance events can occur at any time and severely affect seagrass meadows, independently from their geographical distribution. Short-term stress events range from waste water discharge ( Cabaço et al, 2007 ), or algal cover ( Han et al, 2016 ), while small-scale disturbances are related mainly to intense herbivory ( Christianen et al, 2014 ), trampling ( Eckrich and Holmquist, 2000 ), collection of fauna ( Cabaço et al, 2005 ). Our study showed that combined short-term stress and small-scale disturbances, i.e., nutrient enrichment and above-ground removal, may generate a decrease in carbon reserves, i.e., starch content (effect detected at site E10).…”

Komposisi Makroalga Yang Berasosiasi Di Ekosistem Padang Lamun Pulau Tumpul Lunik, Pulau Rimau Balak Dan Pulau Kandang Balak Selatan, Perairan Lampung Selatan

“…Masukan nutrien tersebut juga menyebabkan pertumbuhan makroalga yang melimpah, hal ini dapat menjadikan pesaing bagi lamun dalam memanfaatkan nutrien terlarut di perairan (Han et al, 2016). Untuk itu pengamatan untuk keanekaragaman jenis, sebaran tentang keberadaan makroalga di habitat tersebut perlu untuk dilakukan.…”