Global climate change and local watershed management as potential drivers of salinity variation in a tropical coastal lagoon (Laguna de Terminos, Mexico)

Abstract

Aquatic SciencesGlobal climate change and local watershed management as potential drivers of salinity variation in a tropical coastal lagoon (Laguna de Terminos, Mexico).--Manuscript Draft-- Abstract:The wide range of ecological goods and services provided by tropical coastal lagoons and wetlands are under considerable pressure due to the synergistic effects of local anthropogenic impact and global climate change. Salinity is an essential ecological driver which depends on the balance between marine and estuarine inputs, and the ongoing decline in fisheries recruitment in the Gulf of Mexico has been linked to environmental degradation of coastal ecosystems, among which long-term changes in salinity is a potential key factor. As part of a joint study of the wide and shallow coastal lagoon of Terminos in south eastern Mexico, we established that salinity variability was directly related to river discharge variability. Minimum discharge from the Usumacinta River and its tributary the Palizada River during the wet season of 2009 maintained led to very unusually high salinity in the lagoon. Data collected over the past 60 years revealed a sustained long-term increase in river flow rates in the Usumacinta watershed, even though precipitation rates during the same period were constant. This indicates that the increase in river flow rates may be attributable to anthropogenic alteration of the watershed rather than to a long-term impact of climate change. The 2009 positive salinity anomaly was further related to an El Niño Modoki episode. Through the study of potential short-to long-term interactions between salinity, river discharges, precipitation and El Nino-La Nina oscillations, we reached conclusions that should be of great value to environmental management and sustainable development. Powered by Editorial Manager® and ProduXion Manager® from Aries Systems CorporationSuggested Reviewers:James Cloern, PhD Senior scientist, United States Geological Survey, Menlo Park, USA jecloern@usgs.gov Dr. James Cloern is a renowned senior research scientist working on comparative ecology and biogeochemistry of estuaries to understand how they respond as ecosystems to climatic-hydrologic variability and human disturbance Carlos Gay-García, PhD Centro de Ciencias de la Atmósfera, Universidad Nacional Autónoma de México, México D.F., Mexico cgay@unam.mx Dr. Carlos Gay García is the top climate change specialist in Mexico and will be able to assess the local to global dimension of the presented work. However, is position in the same research center as 2 co-authors could present a potential conflict of interest 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 2- Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation 1- Global climate change and local watershed management as potential drivers of salinity vari...

Spatiotemporal variability in Terminos Lagoon (Mexico) waters during the 2009–2010 drought reveals upcoming trophic status shift in response to climate change

“…Average yearly precipitation and evaporation of 1805 mm yr. −1 and 1512 mm yr. −1 , respectively, result in a net rainfall of 293 mm yr. −1 (David and Kjerfve 1998;Espinal et al 2007) and freshwater groundwater inputs to Terminos Lagoon have been averaged at 4 × 10 6 m 3 yr. −1 (David 1999). The resulting freshwater input budget for Terminos Lagoon yielded a total net yearly input of 12.57 × 10 9 m 3 yr. −1 , of which river discharge, precipitation net input, and groundwater seepage accounted for 95.44%, 4.53%, and 0.03%, respectively, river discharge, therefore, remaining by far the main source of freshwater inputs to Terminos Lagoon (Fichez et al 2017). The Chumpán River is the lowest contributor, with an average annual freshwater discharge of 0.6 × 10 9 m 3 yr. −1 which passes through the Balchacah Lagoon before reaching Terminos Lagoon midway along its southern coast.…”

Spatio-temporal variability in benthic exchanges at the sediment-water interface of a shallow tropical coastal lagoon (south coast of Gulf of Mexico)

“…Inversely during the dry season, mean salinities were higher (around 30) and the lowest salinities were found only near the River mouths (March). A salinity distribution close to the one observed during the dry season was observed in October 2009, a period of strong positive salinity anomaly related to an El Niño Modoki driven drought episode (Fichez et al, 2017). Surface water temperatures were less variable, ranging from 25.5 to 30°C (mean 27.7°C).…”

“…No correlation was found between temperature and the 16 remaining variables. River inputs accounting for 95% of freshwater inputs to Laguna de Términos (Fichez et al, 2017), each significant correlation with salinity could be used as an indicator of river influence. Salinity was negatively correlated with porosity and bottom water nitrate and Si(OH) 4 and positively correlated with the C:N ratio of the organic matter.…”

Biogeochemical cycling and phyto- and bacterioplankton communities in a large and shallow tropical lagoon (Términos Lagoon, Mexico) under 2009–2010 El Niño Modoki drought conditions

“…1) from 21 to the 27 October 2009. In 2009, a yearly cumulative discharge of 4.83 ± 1.71 × 10 9 m 3 broke a historical deficit record over the 1992-2011 period for the Palizada River (average yearly cumulative discharge of 7.19 ± 4.22 × 10 9 m 3 yr −1 ) (Fichez et al, 2017). That exceptional drought period impacted the entire formerly Mesoamerican region during the 2009-2010 El Niño Modoki episode.…”