Harvey Shear

The development and implementation of indicators of ecosystem health in the great lakes basin

This paper describes a process for the selection of a suite of ecosystem health indicators for the Great Lakes, as called for in the Great Lakes Water Quality Agreement. The paper also presents some preliminary data on status and trends in ecosystem components based on those indicators. The indicator selection process was carried out by over 150 scientists and managers from both Canada and the USA, and involved the presentation of the proposed indicators at the State of the Lakes Ecosystem Conferences (SOLECs). An open period for comment followed the conferences where input from scientists involved in Great Lakes programs was received. The suite of indicators will, over time, present information in an understandable format that will allow for more informed management decisions.

An investigation into the possible light-shielding role of gas vacuoles in a planktonic blue-green alga

When the gas vacuoles of Anabaena flos-aquae Breb. ex Born. et Flah. are collapsed, the optical properties of the alga change. While this may suggest a light-shielding role, photosynthetic measurements indicate that intact gas vacuoles reduce the light falling on the thylakoids by only 4%, or less. Intact gas vacuoles offer no protection against the lethal effects of ultraviolet light. When the alga is grown at high light intensity the gas vacuoles are fewer in number but are oriented peripherally in the cells. However, this does not markedly affect their light shielding efficiency. Spectrophotometric measurements carried out by others indicate a light shielding role by gas vacuoles in a non-planktonic blue-green alga, Nostoc muscorum Kutz., but do not give a quantitative estimate of this effect. In Anabaena no definite evidence of light-shielding is obtained by such a method. All of the experiments described were conducted with dilute algal suspensions to investigate shielding effects in individual cells...

Bi-National Assessment of the Great Lakes: SOLEC Partnerships

Many administrative jurisdictions have authority over parts of the Great Lakes, sometimes with competing purposes as well as governance at differing scales of time and space. As demand increases for high quality information that is relevant to environmental managers, environmental and natural resource agencies with limited budgets must look to interdisciplinary, collaborative approaches for the collection, analysis and reporting of data. The State of the Lakes Ecosystem Conferences (SOLEC) were begun in 1994 in response to reporting requirements of the Great Lakes Water Quality Agreement between Canada and the U.S. The biennial conferences provide independent, science-based reporting on the state of health of the Great Lakes ecosystem components. A suite of indicators necessary and sufficient to assess Great Lakes ecosystem status was introduced in 1998. and assessments based on a subset of the indicators were presented in 2000. Because SOLEC is a multi-agency, multi-jurisdictional reporting venue, the SOLEC indicators require acceptance by a broad spectrum of stakeholders in the Great Lakes basin. The SOLEC indicators list is expected to provide the basis for government agencies and other organizations to collaborate more effectively and to allocate resources to data collection, evaluation and reporting on the state of the Great Lakes basin ecosystem.

Challenges Facing Municipal Wastewater Treatment in Mexico

Globally, more than 1 billion people lack access to a safe water supply, and more than 2.4 billion people lack access to proper wastewater treatment. This situation leads to repeated outbreaks of preventable diseases. In 2005 in Mexico, only 28.2% of municipal wastewaters received any kind of treatment. This article examines the present and projected situation with respect to wastewater treatment and the implications of these trends on water supply and on public health. Possible technical solutions are also analyzed so that the country can increase the ratio between treated and discharged municipal wastewaters.

Mercury concentrations in common carp (Cyprinus carpio) in Lake Chapala, Mexico: A lakewide survey

Previous studies, based on limited data, found elevated levels of mercury in carp in Lake Chapala, Mexico. The extent of mercury contamination in carp throughout the Lake has not been determined. In order to obtain reliable information about total mercury concentration in carp (Cyprinus carpio), 262 fish from 27 sites (approximately 10 fish per site) throughout the lake were analyzed. Results were expressed as the mean and median of the results at each site. Only one of the samples exceeded Mexican National Standard (1.0 ppm) for mercury in fish flesh. We discuss these results in comparison to World Health Organization (WHO), US Food and Drug Administration (FDA) and US Environmental Protection Agency (US EPA) criteria; many of our samples exceed these criteria based on Tolerable Daily Intake (TDI) or Reference Dose (RfD). ANOVA of four groups of mercury results clustered by distance from the Lerma showed statistically significant differences (P = 0.0071) between the group closest to, versus farthest from, the Lerma River.

Preliminary analysis of water pollution in a small lake in Western Mexico

Lake Zapotlan is a small (1100 ha) endorheic lake in western Mexico. The lake is an internationally recognized RAMSAR site, home to many migratory species of waterfowl. It receives point source pollution from partially treated sewage from Ciudad Guzman (population 85,000) and Gomez Farias (population 12,000), as well as non-point sources, including storm water, agricultural, and land clearing runoff from numerous farms and from deforestation surrounding the lake. Anthropogenic activities in the basin are putting the ecological sustainability of the lake at risk. The lake is hypertrophic and exhibits blooms of green algae and possibly cyanobacteria throughout much of the year. Along the shoreline of the lake, extensive beds of bulrush, called locally “tule” (Typha latifolia), are found, as well as floating mats of water hyacinth (Eichhornia crassipes) likely due to excessive nutrient levels in the lake. This paper compares nutrient levels (nitrogen and phosphorus) for three different years since 1994.

Nutrients/food chain model for Lake Zapotlan (Mexico)

Abstract A nutrients/food chain model was developed considering the linkage between water balance and energy balance models for Lake Zapotlan. Lake Zapotlan is located in the southern part of Jalisco State, Mexico, and is classified as a warm, tropical water body, endorheic, very shallow, and highly eutrophic. Kinetic parameters were calibrated using previously reported values in the literature for other lakes. The model simulates the concentration of eight state variables for the lake: algae, herbivore and carnivore zooplankton, nitrates, ammonium, SRP, DOC and POC. A set of eight simultaneous ordinary differential equations (ODE) were generated, assuming an initial set of conditions considering the existing hydrologic and water quality information of the streams flowing into the lake. The ODE system was solved and calibrated by using observed water quality data of the lake. In this way, we have estimated the internal fluxes of nutrients and dissolved oxygen in the lake and their interaction with the food chain.

Lake Superior in the 21st Century

Abstract Projections of population, industrial growth, phosphorus inputs, changes in land use patterns and waste disposal are given. Phosphorus loadings to the Lake from point sources are projected to increase only slightly by the year 2020, assuming all large sewage treatment plants meet a 1 mg/L effluent limitation. Increases in industrial and mining activities could have significant negative impacts on the Lake, but these impacts have not been quantified.

Nutrients and Eutrophication in Lake Chapala

The primary tributary to Lake Chapala is the Lerma river. Large quantities of domestic, agricultural, and industrial sewage from the entire Lerma-Chapala basin still flow untreated into the watershed and eventually into the lake, resulting in excessive inputs of phosphorus (P) and nitrogen (N), both known to cause eutrophication. Anthropogenic water demand from Lake Chapala surpasses the surface supply and groundwater recharge rate. This has resulted in a hydrologic imbalance in its basin. In addition, high nutrient concentrations in the lake have led to degraded water quality, resulting in growth of floating aquatic vegetation and blue green algae. Some studies establishing a P balance for the lake have been carried out, but none for an N balance. Spatial and temporal P and N distributions in the lake during the past 24 years are discussed in relation to hydrologic changes. A method based on the bathymetric features of the lake is proposed to estimate the amounts of total P and N. This method uses a digital elevation model (DEM) of the site and the water quality data monitored for 24 years in 28 lacustrine and 9 littoral monitoring stations. Many authors suggest that the most effective long-term measure for the control of eutrophication in a water body is a reduction in the input of external nutrients. Determining the nutrient balance of any lake or reservoir constitutes a very important tool to understand its chemical and biological processes. Similarly, the knowledge of existing relationships between hydrological variables, nutrient concentrations, and primary productivity could strongly help to determine the most appropriate restoration and clean-up policies wherever eutrophication problems are present. The different relationships are discussed in this chapter.

Great Lakes environmental indicators and state of the environment reporting: use, needs, and limitations

Perceptions and use of environmental indicators and state of environment (SOE) reports by local governments and conservation authorities within the Ontario portion of the Great Lakes and St Lawrence basin were examined through a web-based survey and follow-up telephone interviews. Indicator and SOE reporting use are described, as well as information needs and limitations and challenges in using indicators and SOE reports to formulate environmental policy. Information exchange among different levels of governance is also explored. The State of the Great Lakes environmental indicators and SOE reports, developed by the governments of Canada and the United States, were used as a case study.