Eutrophication of mangroves linked to depletion of foliar and soil base cations Received: 8 July 2013 /Accepted: 21 August 2014 /Published online: 11 September 2014 # Springer International Publishing Switzerland 2014 Abstract There is growing concern that increasing eutro- phication causes degradation of coastal ecosystems. Studies in terrestrial ecosystems have shown that increas- ing the concentration of nitrogen in soils contributes to the acidification process, which leads to leaching of base cations. To test the effects of eutrophication on the avail- ability of base cations in mangroves, we compared paired leaf and soil nutrient levels sampled in Nypa fruticans and Rhizophora spp. on a severely disturbed, i.e. nutrient loaded, site (Mahakam delta) with samples from an undis- turbed, near-pristine site (Berau delta) in East Kalimantan, Indonesia. The findings indicate that under pristine condi- tions, the availability of base cations in mangrove soils is determined largely by salinity. Anthropogenic distur- bances on the Mahakam site have resulted in eutrophica- tion, which is related to lower levels of foliar and soil base cations. Path analysis suggests that increasing soil nitrogen reduces soil pH, which in turn reduces the levels of foliar and soil base cations in mangroves. Keywords Mangroves . Eutrophication . Base cation . Path analysis . Nutrient enrichment Introduction Eutrophication is one of the major causes of coastal ecosystem degradation. Eutrophication leads to an in- crease of the occurrence of algal blooms (Paerl 1997), degradation of coral reefs (Lapointe 1997) and reduc- tions in sea grass cover (van Katwijk et al. 2011). Persistent eutrophication can also adversely affect man- groves, which have the potential to assimilate nutrients in eutrophicated coastal environments (Robertson and Phillips 1995). Lovelock et al. (2009) have suggested that nitrogen enrichment may reduce the resilience of mangroves to environmental stress, thereby increasing mortality. Nitrogen enrichment of terrestrial and coastal ecosys- tems produces similar effects. In a terrestrial system with little or no harvesting, for example wooded (semi-) natural terrestrial systems, nitrogen may be taken up into the local nutrient cycles. Nitrogen enrichment of the terrestrial forest floor usually increases growth and nutrient (soil and foliar) levels (White et al. 1999). Similar effects have been found in mangrove ecosys- tems. Mangroves showed enhanced growth and in- creased foliar nitrogen (N) and phosphorus (P) concen- trations under conditions of N and P enrichment (Lovelock et al. 2014). Addition of N and P (each 300 g/tree) to mangrove soils resulted in increases of up to 30 % for foliar N and 40–100 % for foliar P levels (Feller et al. 2002). In a similar study, Boto and Wellington (1983) reported that addition of N and P (each 100 kg/ha) increased mangrove foliar N and P levels by 22 and 7 %, respectively. Environ Monit Assess (2014) 186:8487–8498 DOI 10.1007/s10661-014-4017-x A. Fauzi (*) : A. K. Skidmore : H. van Gils : M. Schlerf Faculty for Geoinformation Science and Earth Observation, University of Twente, P.O. Box 217, Enschede 7500 AE, The Netherlands e-mail: anasf69@gmail.com I. M. A. Heitkönig Resource Ecology Group, Wageningen University, Droevendaalsesteeg 3a, 6708 PB Wageningen, The Netherlands Anas Fauzi & Andrew K. Skidmore & Ignas M. A. Heitkönig & Hein van Gils & Martin Schlerf