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Background Mangrove forests provide many ecosystem services, including the provision of habitat that supports avian biodiversity. However, hurricanes can knock down trees, alter hydrologic connectivity, and affect avian habitat. In 1995, Hurricanes Opal and Roxanne destroyed approximately 1,700 ha of mangrove forest in Laguna de Términos, Mexico. Since then, hydrological restoration has been implemented to protect the mangrove forest and its biodiversity. Methods Since avian communities are often considered biological indicators of ecosystem quality, avian diversity and species relative abundance were evaluated as indicators of mangrove restoration success by comparing undisturbed mangrove patches with those affected by the hurricanes. Using bird surveys, similarity analyses, and generalized linear models, we evaluated the effects of water quality variables and forest structure on the relative abundance and diversity of the avian community in disturbed, restored, and undisturbed mangrove patches. Results Higher bird species richness and relative abundances were found in disturbed and restored sites compared to the undisturbed site. After restoration, values of frequency of flooding, water temperature, tree density, and the number of tree species were more similar to that of the undisturbed site than to the values of the disturbed one. Such variables influenced the relative abundance of bird guilds in the different habitat conditions. Furthermore, some insectivorous bird species, such as the Yellow Warbler and Tropical Kingbird, were found to be similarly abundant in both undisturbed and restored sites, but absent or very low in occurrence at the disturbed site. Conclusions Collectively, our results strongly suggest that hydrologic restoration helps to enhance niche availability for different bird guilds, including water and canopy bird species. Our work can help inform management strategies that benefit avian communities in mangrove forests and wetland systems.

Antecedentes: Cambios en los patrones hidrológicos degradan la estructura forestal y afectan la productividad primaria. Con acciones de restauración hidrológica, se pretende restablecer condiciones biogeoquímicas para facilitar el establecimiento, sobrevivencia y crecimiento de la vegetación del manglar que permitan la recuperación de la estructura forestal y la productividad de raíces subterráneas (< 20 mm). Pregunta: ¿Pueden los cambios ambientales inducidos por la restauración hidrológica reactivar la productividad de raíces? Especie en estudio: Los cambios en biomasa y productividad de raíces subterráneas de Avicennia germinans fueron usadas como indicador de éxito de la restauración. Sitio de estudio y fechas: Isla del Carmen, Laguna de Términos, Campeche, agosto de 2013 a febrero de 2015. Métodos: Se seleccionaron tres sitios de manglar en restauración y uno natural como referencia. En ellos se evaluó la concentración de algunos nutrientes (nitratos, nitritos, amonio y fosfatos) y reguladores como la salinidad y el hidroperíodo. Se evaluó entre sitios la biomasa y productividad de raíces en núcleos de crecimiento enterrados a 30 cm de profundidad durante 18 meses. Resultados: La productividad de raíces < 20 mm de diámetro fue menor en los sitios en restauración (17 a 233 g m2 año-1) que en el sitio de referencia (414 g m2 año-1). La productividad de raíces estuvo asociada con la estructura forestal y las condiciones hidrológicas. Conclusiones: La proporción de raíces >2 mm de diámetro fue mayor en el sitio de referencia y decreció hacia los sitios restaurados, indicando que la estructura forestal (regeneración natural) y el tiempo (años) después de la restauración fue importante para la recuperación funcional del ecosistema de manglar.

Mangroves are coastal wetlands with high biodiversity and productivity, with great interaction with coastal environments. In the face of worldwide mangrove loss, restoration projects attempt to recover ecosystem composition and functioning over time. Our objective was to examine and compare the food webs in mangrove areas with different restoration times and in a reference mangrove in Términos Lagoon, Mexico. We estimated the trophic structure, identified the carbon resources that maintain aquatic consumers through the analysis of stable isotopes, and compared the trophic niche of the restored mangroves with the reference mangrove. We analyzed environmental variables, trophic structure, and contributions of resources during three seasons: rainy, dry, and “nortes”. Environmental changes and food structure changed in response to regional seasons. Bayesian mixing models indicated that food webs varied seasonally as a response to the primary productivity developed at Términos Lagoon. As expected, the assimilation of C3 plants in the reference mangrove was highest, as a primary (“nortes” season) and secondary resource (dry and rainy seasons). The restored mangroves depended mainly on allochthonous resources (seagrass, epiphytes, and phytoplankton). The assimilation of these resources highlighted the importance of connectivity and the input of sources of carbon from nearby coastal environments. Trophic niche analysis showed that the area with longer restoration time was more similar to the reference mangrove, which is evidence of the importance and efficacy of the restoration process, as well as the restoration of the ecosystem function over time.

Antecedentes: En la península de Yucatán, algunas zonas del manglar han sido rellenadas con escombros y basura, donde posteriormente se establecieron zonas habitacionales. Preguntas: ¿Puede usarse el conocimiento de la estructura forestal y el almacén de carbono para establecer la línea base para la conservación de los manglares urbanos? Especies de estudio: Rhizophora mangle L., Laguncularia racemosa Gaertn f., Avicennia germinans L. y Conocarpus erectus L. Sitio y años de estudio: Isla del Carmen, Campeche, año 2017. Métodos: Se establecieron unidades de muestreo para evaluar la vegetación y medir el carbono aéreo y subterráneo en dos zonas de manglar, la primera fue rellenada con escombros y otra sin cambios del suelo. Resultados: La zona rellenada con escombros presentó un área basal de 25.4 m2 ha-1, donde A. germinans fue la especie dominante con 675 árboles ha-1, con promedios de 5.5 m en altura y 13.4 cm de diámetro. La otra zona sin cambios del suelo presentó un área basal de 27.8 m2 ha-1, siendo también A. germinans la especie más abundante con 731 árboles ha-1, pero su altura fue más baja (5.0 m) y su diámetro a la altura del pecho mayor (15.2 cm) que en la otra zona. El carbono total almacenado en la segunda zona (383 Mg C ha-1) fue mayor que en la primera (321 Mg C ha-1). Conclusiones: El valor ecológico de la vegetación y la captura de carbono contribuye en el fortalecimiento de medidas de conservación y protección del manglar ante las invasiones urbanas.

The restoration of mangroves has gained prominence in recent decades. Hydrological rehabilitation has been undertaken to connect impaired mangroves with the sea, lagoons or estuaries. Because mangrove hydrodynamics occurs on the surface and interstitial spaces in the sediment, we propose to determine the hydrological flow paths to restore the hydrological regimes of the impaired mangroves. The hydrological flow paths were determined through a micro basin analysis based on microtopographic data to generate a digital elevation model. Applying this methodological approach, the hydrology of an impaired area on a barrier island in the Gulf of Mexico was restored by excavating, desilting or clearing the channels on the identified hydrological flow paths. This area was compared to one in which impaired mangroves were reconnected to the marine lagoon but disregarding the flow paths. Data collected in both areas were evaluated by flood level analysis, using two methods: (i) a simple linear regression model (SLRM) and (ii) spectral analysis (SA), also known as dominant frequency analysis. The results suggest that restoration based on the hydrological flow paths was more effective than the direct opening to the nearest main water body without accounting for the microtopography. In both areas, soil salinity and sulfides decreased after hydrological reconnection. However, a greater efficiency in the investment of time and human resources was achieved when preferential flow paths were identified and taken into account. The methodological procedures described in this study are of universal application to other mangrove restoration programs.

We evaluated the success of the ecological restoration of a degraded mangrove forest by monitoring the natural regeneration of Avicennia germinans (black mangrove). The restoration actions focused on hydrological rehabilitation by desilting tidal channels and modifying the microtopography to enhance or restore water flow. As a result of these efforts, a population of black mangrove established naturally. Six sampling sites including restored and reference areas were established. We measured seedling survival; tree density, height, and growth rate; and the physical and chemical characteristics of soil and water. According to a redundancy analysis, microtopography and hydroperiod contributed the most to the establishment and development of the black mangrove. Microtopography ranged from 0.08 to 0.14 m above sea level. In the case of the hydroperiod, water level ranged from 0.11 to 0.14 m, flooding duration ranged from 439 to 529 h per month, and frequency was 7 to 8 floods per month. Our results highlight the contribution of microtopography and hydroperiod to the natural establishment of black mangrove. It is important to consider these 2 variables in mangrove ecological restoration.