Jorge A. Herrera-Silveira

Evaluation of the health status of a coastal ecosystem in southeast Mexico : Assessment of water quality, phytoplankton and submerged aquatic vegetation

The coastal environment of the Yucatan Peninsula (SE, Mexico) includes a wide variety of ecosystems ranging from mangroves to coral reefs, resulting in a heterogeneous landscape. Specifically, the marine system is characterized by environmental differences which respond to regional and local forcing functions such as marine currents and groundwater discharges (GD). Such functional characteristics were used here to define four subregions across the Yucatan coast and diagnose the health status of this coastal marine ecosystem. To achieve this goal, we conducted an analysis and integration of water quality variables, an eutrophic assessment, evaluated changes in submerged aquatic vegetation (SAV), and analyzed the community structure and distribution of harmful phytoplankton. The first step was to determine the reference values for each subregion based on data previously collected from 2002 to 2006 along the coast of Yucatan, 200m offshore. The trophic index (TRIX) and Canadian index for aquatic life (CCMEWQI) were used to diagnose each subregion and then the ASSETS approach was conducted for Dzilam and Progreso, sampling localities on each end of the health status continuum (those with the best and worst conditions). Overall, results indicated that the marine coastal ecosystem of Yucatan is in good condition; however, differences were observed between subregions that can be attributed to local forcing functions and human impacts. Specifically, the central region (zone HZII, Progreso-Telchac) showed symptoms of initial eutrophication due to nutrient inputs from human activities. The eastern region (zone HZ III, Dzilam-Las Bocas) showed a meso-eutrophic condition linked to natural groundwater discharges, while the other two subregions western (zone HZI Celestun-Palmar) and caribbean (zone HZ IV Ria Lagartos-El Cuyo) exhibited symptoms of oligo-mesotrophic condition. These findings may be considered baseline information for coastal ecosystem monitoring programs in Yucatan, and the approach used could be replicated for other coastal areas.

A Conceptual Framework to Develop Long-Term Ecological Research and Management Objectives in the Wider Caribbean Region

Abstract The Caribbean Sea and its watersheds show signs of environmental degradation. These fragile coastal ecosystems are susceptible to environmental impacts, in part because of their oligotrophic conditions and their critical support of economic development. Tourism is one of the major sources of income in the Caribbean, making the region one of the most ecotourism dependent in the world. Yet there are few explicit, long-term, comprehensive studies describing the structure and function of Caribbean ecosystems. We propose a conceptual framework using the environmental signature hypothesis of tropical coastal settings to develop a series of research questions for the reef–sea-grass–wetland seascape. We applied this approach across 13 sites throughout the region, including ecosystems in a variety of coastal settings with different vulnerabilities to environmental impacts. This approach follows the strategy developed by the Long Term Ecological Research program of the National Science Foundation to establish ecological research questions best studied over decades and large spatial areas.

Overview and characterization of the hydrology and primary producer communities of selected coastal lagoons of Yucatán, México

Abstract The major hydrological characteristics of the coastal lagoons of Yucatan and their relationship with the space-time pattern of the primary producer communities are described. The weather patterns in the region play an important role in the seasonal changes of nutrient inputs, which are related to the groundwater discharges. The fluctuations of the mean sea level in response to freshwater discharges and frontal systems influenced the differences observed in the residence time of water, which could play an important role in the accumulation of toxic substances from sewage discharges and biological metabolism. The spatial distribution of primary producers was heterogeneous with high biomass production in the middle zone of the lagoons. The dominant group in each system changed seasonally in response to the coupling between external forces and their life cycles; however, the submerged macrophytes might be the principal group in these shallow aquatic ecosystems. The mangrove vegetation experienced str...

Selecting cost-effective areas for restoration of ecosystem services

Selection of areas for restoration should be based on cost-effectiveness analysis to attain the maximum benefit with a limited budget and overcome the traditional ad hoc allocation of funds for restoration projects. Restoration projects need to be planned on the basis of ecological knowledge and economic and social constraints. We devised a novel approach for selecting cost-effective areas for restoration on the basis of biodiversity and potential provision of 3 ecosystem services: carbon storage, water depuration, and coastal protection. We used Marxan, a spatial prioritization tool, to balance the provision of ecosystem services against the cost of restoration. We tested this approach in a mangrove ecosystem in the Caribbean. Our approach efficiently selected restoration areas that at low cost were compatible with biodiversity targets and that maximized the provision of one or more ecosystem services. Choosing areas for restoration of mangroves on the basis carbon storage potential, largely guaranteed the restoration of biodiversity and other ecosystem services.

Toxic and harmful marine phytoplankton and microalgae (HABs) in Mexican Coasts.

Harmful Algal Blooms (HABs) are becoming an increasing problem to human health and environment (including effects on natural and cultured resources, tourism and ecosystems) all over the world. In Mexico a number of human fatalities and important economic losses have occurred in the last 30 years because of these events. There are about 70 species of planktonic and non-planktonic microalgae considered harmful in Mexican coasts. The most important toxin-producing species are the dinoflagellates Gymnodinium catenatum and Pyrodinium bahamense var. compressum, in the Mexican Pacific, and Karenia brevis in the Gulf of Mexico, and consequently the poisonings documented in Mexico are Paralytic Shellfish Poisoning (PSP) and Neurotoxic Shellfish Poisoning (NSP). Although there is evidence that Amnesic Shellfish Poisoning (ASP), Diarrhetic Shellfish Poisoning (DSP) and Ciguatera Fish Poisoning (CFP) also occur in Mexico, these problems are reported less frequently. The type of phytoplankton and epiphytic microalgae, their toxins and harmful effects as well as current methodology used to study these phenomena are presented in this paper. As an experienced group of workers, we include descriptions of monitoring and mitigation programs, our proposals for collaborative projects and perspectives on future research.

An assessment of natural and human disturbance effects on Mexican ecosystems: current trends and research gaps

Mexico harbors more than 10% of the planet’s endemic species. However, the integrity and biodiversity of many ecosystems is experiencing rapid transformation under the influence of a wide array of human and natural disturbances. In order to disentangle the effects of human and natural disturbance regimes at different spatial and temporal scales, we selected six terrestrial (temperate montane forests, montane cloud forests, tropical rain forests, tropical semi-deciduous forests, tropical dry forests, and deserts) and four aquatic (coral reefs, mangrove forests, kelp forests and saline lakes) ecosystems. We used semi-quantitative statistical methods to assess (1) the most important agents of disturbance affecting the ecosystems, (2) the vulnerability of each ecosystem to anthropogenic and natural disturbance, and (3) the differences in ecosystem disturbance regimes and their resilience. Our analysis indicates a significant variation in ecological responses, recovery capacity, and resilience among ecosystems. The constant and widespread presence of human impacts on both terrestrial and aquatic ecosystems is reflected either in reduced area coverage for most systems, or reduced productivity and biodiversity, particularly in the case of fragile ecosystems (e.g., rain forests, coral reefs). In all cases, the interaction between historical human impacts and episodic high intensity natural disturbance (e.g., hurricanes, fires) has triggered a reduction in species diversity and induced significant changes in habitat distribution or species dominance. The lack of monitoring programs assessing before/after effects of major disturbances in Mexico is one of the major limitations to quantifying the commonalities and differences of disturbance effects on ecosystem properties.

Conceptual Framework for Mangrove Restoration in the Yucatán Peninsula

Abstract Mangrove loss in Mexico led to the development of different recovery programs focused on building and maintaining greenhouses, reforestation, and the construction of drainage systems along coastal roads to reestablish surface water flows. However, these recovery strategies have not been as successful as expected because they were not based on an evaluation of environmental characteristics required for mangrove development in the context of new hydrological and sedimentary conditions. The studies performed over the last ten years by the mangrove group at Centro de Investigación y de Estudios Avanzados (CINVESTAV), in collaboration with other institutions, resulted in a conceptual framework that we present here as a methodological approach for the ecological restoration of mangroves in the Yucatán Peninsula. The conceptual framework is based on the relationships among the geomorphology, hydrology, and structural and functional characteristics of mangroves that are associated with the environmental services offered by these ecosystems. The methodological approach is fundamentally concerned with the particular characteristics of the karstic environmental setting of the Yucatán Peninsula as well as social and economic aspects of restoration. This approach to mangrove restoration includes stages for planning, implementing, and monitoring mangrove restoration programs in karstic environments. Resumen La pérdida de manglares en México ha llevado al desarrollo de diferentes programas para abordar su recuperación. En la Península de Yucatán estos programas se han centrado principalmente en la construcción y mantenimiento de invernaderos, la reforestación y la construcción de sistemas de alcantarillas en las carreteras costeras para restablecer los flujos de las aguas superficiales. Sin embargo, estas estrategias de recuperación no tuvieron el éxito que se esperaba, principalmente porque no se basaron en la caracterización ambiental como un criterio para identificar las condiciones hidrológicas y de sedimentos necesarias para el desarrollo de manglares. Los estudios realizados durante los últimos diez años por el grupo manglares en el Centro de Investigación y de Estudios Avanzados (CINVESTAV), en colaboración con otras instituciones, han dado lugar a un marco conceptual que se presenta aquí como un enfoque metodológico para la restauración ecológica de los manglares en la Península de Yucatán. El marco conceptual se basa en las relaciones que hay entre la geomorfología, la hidrología y características estructurales y funcionales de los manglares, y que están asociados con los servicios ambientales que ofrecen estos ecosistemas. El enfoque metodológico es fundamentalmente relacionado a las características particulares del entorno kárstico de la Península de Yucatán, así como aspectos sociales y económicos de la restauración. Este enfoque de la restauración de manglares incluye las etapas de la planificación, implementación y seguimiento de los programas de restauración de manglares en ambientes kársticos.

The checkered puffer (Spheroides testudineus) and its helminths as bioindicators of chemical pollution in Yucatan coastal lagoons

The suitability of using helminth communities as bioindicators of environmental quality of the Yucatan coastal lagoons status was tested on the checkered puffer (Spheroides testudineus) in four coastal lagoons along the Yucatan coast. The concentration of chemical pollutants in sediments, water quality parameters, helminth infracommunity characteristics, as well as fish physiological biomarkers, including EROD (7-ethoxyresorufin-O-deethylase) and catalase activities, were measured. Results from sediment analyses demonstrated the presence of hydrocarbons, organochlorine pesticides and polychlorinated biphenyls at varying concentrations, some of which exceeded the Probability Effect Level (PEL). Significant negative associations among organochlorine pesticides, infracommunity characteristics and fish physiological responses were observed in most of the lagoons. Results suggest that EROD activity and parasite infracommunity characteristics could be useful tools to evaluate the effects of chemical pollutants on the fish host and in the environment. Importantly, certain parasites appear to influence biomarker measurements, indicating that parasites should be considered in ecotoxicological studies.

Wetland Restoration: Integrating Scientific-Technical, Economic, and Social Perspectives

ECOLOGICAL RESTORATION 23:3 ■ SEPTEMBER 2005 Ecological Restoration, Vol. 23, No. 3, 2005 ISSN 1522-4740 E-ISSN 1543-4079 ©2005 by the Board of Regents of the University of Wisconsin System. Wetlands are being restored around the world using a wide spectrum of different approaches from the application of well-grounded scientific knowledge to obtain a precise objective to trial-and-error practices just to have water for some time on a piece of land. Whatever the methodology, wetland restoration projects can provide good theoretical and practical knowledge because, compared to other ecosystems, wetland ecosystems react relatively soon to manipulations (Mitsch and Gosselink 2000, Zentner and others 2003). Given this range of approaches, it must also be noted that the success of an ecological restoration project depends on many factors that should be taken into account when planning and developing a project. These can be grouped into three types: 1) technical failures or lack of scientific information, 2) economic constraints, and 3) social disagreements. The integration of these three perspectives— scientific-technical, economic and social —is important to obtain all the values of an ecological restoration project (Comín 2002, Winterhalder and others 2004). In this article, we present a number of wetland restoration experiences developed under different conditions in northeastern Spain in order to look for common recommendations for planning future, highvalue projects.

Evidence of negative impacts of ecological tourism on turtlegrass (Thalassia testudinum) beds in a marine protected area of the Mexican Caribbean

Many marine protected areas (MPAs) have been established in recent years. Some MPAs are open to tourists to foster environmental education and generate revenue for the MPA. This has been coined “ecological tourism”. Here, we examine the impact of ecological tourism on turtlegrass (Thalassia testudinum) health in one area of the “Costa Occidental de Isla Mujeres, Punta Cancún y Punta Nizuc” MPA in the Mexican Caribbean. A heavily visited location was compared with an unvisited location. Turtlegrass leaves at the visited location were sparser, shorter, grew more slowly, and had more epiphytes than at the unvisited location. Vertical and horizontal rhizomes of turtlegrass also grew more slowly at the visited than at the unvisited location. There is reasonable evidence to suggest that the observed differences are likely due to the deleterious impacts of novice and careless snorkelers. If continuing, these impacts could cause severe degradation of the visited areas in this MPA and, thus, changes in management policies seem in order.