The seeds germination, stem and root elongation of water lettuces (Lactuca sativa L) were used to evaluate the phytotoxicity of water and soil of Champotón River, Campeche, Mexico. water and soil sample were collected from two sampling sites. Lettuce seeds were exposed to three different dilutions of water and aqueous extract of soil. Significant differences on germination, root and stem elongation of lettuce were detected. Water showed more phytotoxic effect than aqueous extract of soil and inhibitory concentration 50 (IC50) for radicle exposed to river water was 52% while stem elongation was 69%. Due to paucity the previously available phytotoxicological studies onto Champotón River, it is now essential to allocate time and resources to consider development of suitable chronic phytotoxicity tests.

Mangrove forests are conspicuous components of tropical wetlands that sustain continuous exposure to wastewater discharges commonly of municipal origins. Mangroves can remove nutrients from these waters to fulfill their nutrients demand, although the effects of continuous exposure are unknown. An experimental greenhouse imitating tidal regimes was built to measure the efficiency of mangrove seedlings to incorporate nutrients, growth and above biomass production when exposed to three periodic wastewater discharges. The experiment totaled 112 d. Nutrient removal by the exposed group, such as phosphates, ammonia, nitrites, nitrates and dissolved inorganic nitrogen (97%, 98.35%, 71.05%, 56.57% and 64.36%, respectively) was evident up to the second dumping. By the third dumping, all nutrient concentrations increased in the interstitial water, although significant evidence of removal by the plants was not obtained (p > 0.05). Nutrient concentrations in the control group did not change significantly throughout the experiment (p > 0.05). Treated plants increased two-fold in stem girth when compared to the control (p < 0.05), although control plants averaged higher heights (p < 0.05). Biomass of treated group increased up to 45% against 37% of the control during the duration of the experiment (p < 0.05). We suggest that nutrient removal efficiency of mangroves is linked to the maintenance of oxic conditions in the pore-water because of oxygen transference from their aerial to their subterranean radicular system that facilitates the oxidation of reduced nitrogen compounds and plants uptake. Nevertheless, continuous inflows of wastewater would lead to eutrophication, establishment of anoxic conditions in water and soil, and lessening of nutrient absorption of mangroves.

Mangrove forests have proven to be resilient to most environmental change, surviving catastrophic climate events over time. Our study aimed to evaluate the chemical variability of pore water and its effect on phenological production in three mangrove species (Rhizophora mangle, Avicennia germinans, and Laguncularia racemosa) along the coast of the state of Campeche during a year of severe drought (2009) and a year of average precipitation (2010). Pore water salinity and redox potential were measured monthly in a mangrove forest in 2009 and 2010. Litterfall production and reproductive phenology was measured monthly. We determined the relationships among litterfall production, reproductive phenology, pore water chemistry and precipitation of three species between years. Precipitation, pore water salinity and redox potential significantly differed among years, seasons and sites, and also showed significant interaction between years and seasons (p < 0.05). Significant variation was observed in litterfall production, propagules, flowers, and leaf litter among sites (p < 0.05). A significant change was observed in propagules and flowers among years, and in total litterfall and leaf litter between seasons and species (p < 0.05). Under severe drought, salinity had the strongest effect on total litterfall and propagules in R. mangle, while A. germinans, had the strongest effect on propagule/flower precipitation. Both A. germinans and L. racemosa showed higher resilience than R. mangle at all sites under severe drought conditions. These findings can support activity allocation for mangrove conservation and restoration by providing the tolerance thresholds of the three species that dominate in the regional area of Campeche state. Likewise, this research provides knowledge to the Intergovernmental Experts Group on climate change about drought intensity and its magnitude of impact on mangrove productivity, reproduction and integrity.

La reserva de carbono en los manglares que bordean el sistema estuarino de San Blas-laguna Grande de Mexcaltitán, Nayarit, México en el periodo de 1980-2015, definió 3 zonas ambientales con base en las diferentes presiones antrópicas y cantidad de carbono almacenado en la biomasa arbórea y en el suelo. Estas zonas muestran diferenciascon respecto a los comportamientos en amplitud y tiempo de residencia del agua intersticial. La biomasa y carbono (aéreo y subterráneo), así como el secuestro de carbono en el suelo a 20 cm de profundidad se incrementó de la zona sur a la norte. Estos parámetros indican valores bajos, comparados con reportes de diversos autores en manglares de tipo primario. Lo anterior, causado por la pérdida de la estructura y función del ecosistema, se define como bosques secundarios, con desplazamiento de Rhizophora mangle por Avicennia germinans y Laguncularia racemosa. Razón por la cual es fundamental generar información que permita confirmar el estado de conservación del ecosistema, considerando la capacidad de captura y secuestro de carbono, así como su valor monetario y pérdida. Se calcula, para esta investigación, un valor monetario por almacén de carbono arbóreo del manglar de $4,431,826.7 dólares americanos por ton CO2 ha-1; con pérdidas de $132,414.3 dólares americanos por ton CO2 ha-1 en 1980-2015.

We evaluated the phenological response and litterfall production of Rhizophora mangle to changes in pore water chemistry over a five-year period (from 2009 to 2014 and 2010 to 2016) along the coast of Campeche, México. Severe drought conditions were recorded in 2009 with a Standardized Precipitation Index (SPI) of −1.5 and again in 2015 with a SPI of −1.16). A precipitation deficit of 22.1% was recorded between 2009 and 2016 ranging from 9.5% in Laguna de Terminos in the south to 64.4% in Los Petenes Biosphere Reserve in the north. Precipitation varied significantly per year (p < 0.001), seasonally (p < 0.001), and between years and seasons (p < 0.001). An interaction was observed in the salinity (p < 0.05), redox potential (p < 0.001), and precipitation (p < 0.001) of the Laguna de Terminos, Rio Champoton, and Los Petenes Biosphere Reserve regions. Significant differences were found between the years in the leaf and propagule production (p < 0.001), and between seasons in production of leaves, flowers, and propagules (p < 0.001). The determining factor in the production of flowers during both the rainy and dry seasons was the salinity, and the determining factors for the production of propagules were the redox potential and salinity. The results of this study suggest a low phenotypic plasticity in R. mangle.

For decades, mangroves have been exposed to various pressures, resulting in the loss of large swathes around the world. For this reason, ecological restoration actions are presented as alternatives to recover mangroves that can restore their ecosystem services while helping to mitigate climate change’s effects. Mangroves are crucial, as they capture and sequester carbon in biomass and soil, highlighting their importance in environmental conservation and in the fight against climate change. In this research, the amount of carbon sequestered in a mangrove area restored eight years ago and its relationship with soil physicochemical parameters were evaluated and compared to those of a reference forest. Soil cores were collected at a depth of 30 cm from both sites, and in situ measurements of physical chemistry were made at different depths. In addition, soil salinity, bulk density, and carbon concentration were determined. The results revealed a similar amount of carbon sequestered both in the reference forest (BR) (470.17 ± 67.14 Mg C/ha) and in the restoration area (RA) (444.53 ± 86.11 Mg C/ha) (p > 0.05). A direct relationship was observed between carbon sequestration and soil depth. In the case of the RA, a direct relationship was found between carbon sequestration and soil salinity. In conclusion, the results of this study indicate that the behavior of carbon sequestration in soil is determined by the physicochemical conditions in both the BR and the RA, as well as by the presence or absence of vegetation.