Riparian forest quality, land-use dynamics and their influence on macroinvertebrate communities. An evaluation of the ecological status of Pesquería River (N.E., Mexico)

Abstract

[eng] Worldwide, biological diversity is declining at an unprecedented rate. Current environmental changes are causing water, ecological and biodiversity crises that, coupled with climate change, are affecting landscape patterns and sustainable development efforts. Thus, anthropogenic pressures are changing the world's landscapes in pervasive ways. Additionally, these anthropogenic pressures on the natural landscape have been associated with changes in landscape and to the ecological condition of freshwater ecosystems. Therefore, freshwater ecosystems, particularly rivers, must be examined in detail, and it is important to consider their relationship with terrestrial ecosystems, particularly the “transitional land-water” ecosystems (i.e. the riparian channel). This is particularly important for developing countries given to their ecosystems are constantly threatened by anthropogenic activities. Additionally, the lack of research, proper legislation and management hinders the restoration and conservation plans for their freshwater ecosystems. Within this context, the overarching goal of this PhD thesis is to evaluate the ecological status of the Pesquería River and assess the effects of landscape degradation along its riparian channel. Since changes in landscape composition can significantly affect a riparian channel, we aimed to evaluate how said changes can also impact biological quality and subsequently affect the ecological integrity of a river ecosystem. We focused into provide simple and reliable methods to define the ecological status and discern the effects of landscape degradation on the ecological state of the Pesquería River using a variety of tools for diagnosis and monitoring. On this PhD thesis we explored land-use cover/change dynamics (LUCCD) in the riparian channel also we describe the land use processes in the riparian zone during the period 1976-2016 in order to ascertain whether land use dynamics can provide useful information about the current ecological status of a riparian zone (Chapter 1). Additionally, we evaluated the riparian forest quality of the Pesquería River (Chapter 2) using an adaptation of the riparian forest quality index (QBR), modifying it for the specific local conditions (QBR-RNMX). Finally, we investigate how the macroinvertebrate communities in the Pesquería River are affected by different land use covers and assess their potential use as bioindicators to evaluate the ecological status of Mexican semi-arid rivers with similar conditions (Chapter 3). On this PhD thesis we demonstrated that LUCCD analysis at riparian channel level should be viewed as a key tool for the improvement of conservation policies targeting freshwater ecosystems in Mexico. We remark the importance of consider the riparian buffer width as an ecosystem, not as a federal area, in order to protect the freshwater ecosystems in Mexico. We corroborated the efficiency of the adaptation of the QBR-RNMX also we recommend the application of the index annually to evaluate the riparian forest’s quality, and to assess its ecological status. This may be used for the establishment of restoration plans in high-impact zones and contingency plans to eliminate invasive species along the Pesquería River. This PhD thesis has provided eleven biological metrics and thirty-two representative taxa that can be used as bioindicators in future research. However, more studies, and especially the relationship of this index with the river pressures are necessary to establish an index for the Pesquería River in the future. Furthermore, in the general discussion we propose a macroinvertebrate-based index (BMWP-system) as a first step for the evaluation of the ecological status of the river. Finally, this thesis highlights the lack of research and the bad current ecological status of the Pesquería River. Our findings suggest the creation of a Mexican framework similar to the European Water Framework Directive, where the ecological quality of the river should be the main objective of riparian ecosystems recovery.

[spa] A nivel mundial, la diversidad biológica está disminuyendo a un ritmo sin precedentes. Los cambios ambientales actuales están causando crisis hídricas, ecológicas y de biodiversidad que, junto con el cambio climático, están afectando los patrones del paisaje y los esfuerzos de desarrollo sostenible. Por lo tanto, las presiones antropogénicas están cambiando los paisajes del mundo de manera generalizada. Además, estas presiones antropogénicas en el paisaje natural se han asociado con cambios en el paisaje y en las condiciones ecológicas de los ecosistemas de agua dulce. Esto es importante para los países en desarrollo, dado que sus ecosistemas están amenazados por actividades antropogénicas. Además, la falta de investigación, legislación y gestión dificultan los planes de restauración y conservación de sus ecosistemas de agua dulce. En este contexto, el objetivo general de esta tesis doctoral es evaluar el estado ecológico del río Pesquería y evaluar los efectos de la degradación del paisaje a lo largo de su canal ribereño. En esta tesis doctoral demostramos que el análisis de dinámicas de uso de suelo a nivel de los canales ribereños debe verse como una herramienta para la mejora de los ecosistemas acuáticos en México. Observamos la importancia de considerar el ancho del amortiguador ribereño como un ecosistema, no como un área federal, para proteger los ecosistemas acuáticos de México. Corroboramos la eficiencia de la adaptación del QBR-RNMX para usarse en el establecimiento de planes de restauración y contingencia para eliminar especies invasoras del río Pesquería. Esta tesis doctoral proporcionó once métricas biológicas y treinta y dos taxones representativos que pueden usarse como bioindicadores en futuras investigaciones. Sin embargo, se necesitan más estudios, y especialmente la relación de este índice con las presiones del río para establecer un índice para el río Pesquería en el futuro. Además, en la discusión general, proponemos un índice basado en macroinvertebrados como un primer paso para la evaluación del estado ecológico del río. Finalmente, nuestros hallazgos sugieren la creación de un marco mexicano similar a la Directiva Marco del Agua Europea, donde la calidad ecológica del río debería ser el objetivo principal de la recuperación de los ecosistemas ribereños.