Marty D. Matlock

Change in ecosystem service values in the San Antonio area, Texas☆

San Antonio is one of the fastest growing metropolitan areas in the USA. Urban sprawl may significantly impact ecosystem services and functions but such effects are difficult to quantify and watershed-level estimates are seldom attempted. The objective of the study reported here was to determine whether LANDSAT MSS could be used to quantify changes in land-use and ecosystem services due to urban sprawl in Bexar County, TX, in which San Antonio is centered. The size of six land cover categories in the summer of 1976, 1985, and 1991 were estimated in the 141 671 ha of three watersheds in Bexar County. Coefficients published by Costanza and co-workers in 1997 [Nature 387 (1997) 253] were used to value changes in ecosystem services delivered by each land cover category, and a sensitivity analysis was conducted to determine the effect of manipulating these coefficients on the estimated values. Although we estimated that there was a 65% decrease in the area of rangeland and a 29% increase in the area of urbanized land use between 1976 and 1991, there appeared to be only a 4% net decline in the estimated annual value of ecosystem services in the study area (i.e.

Measuring variability in trophic status in the Lake Waco/Bosque River Watershed

5.58 ha − 1 per year, with a 15-year cumulative total value of

ANALYSIS OF THE HSPF WATER QUALITY PARAMETER UNCERTAINTY IN PREDICTING PEAK IN-STREAM FECAL COLIFORM CONCENTRATIONS

6.24 million for the whole study area). This relatively small decline could be attributed to the neutralizing effect of the estimated 403% increase in the area of the woodlands, which were assigned the highest ecosystem value coefficient. When we assumed that the shift of rangelands to woodlands produced no net change in the value of ecosystem services per hectare, the estimated annual ecosystem service value declined by 15.4% (

PHOSPHATE EQUILIBRIUM BETWEEN STREAM SEDIMENTS AND WATER: POTENTIAL EFFECT OF CHEMICAL AMENDMENTS

23.22 ha − 1 per year) between 1976 and 1991. When conducting time-series studies of ecosystem services, it is important to identify parallel changes in land cover types in order to quantify the potentially neutralizing influence of positive land cover changes on the negative effects of urban sprawl on ecosystem services.

Ecological engineering: A rationale for standardized curriculum and professional certification in the United States

BackgroundNutrient management in rivers and streams is difficult due to the spatial and temporal variability of algal growth responses. The objectives of this project were to determine the spatial and seasonal in situ variability of trophic status in the Lake Waco/Bosque River watershed, determine the variability in the lotic ecosystem trophic status index (LETSI) at each site as indicators of the systems nutrient sensitivity, and determine if passive diffusion periphytometers could provide threshold algal responses to nutrient enrichment.MethodsWe used the passive diffusion periphytometer to measure in-situ nutrient limitation and trophic status at eight sites in five streams in the Lake Waco/Bosque River Watershed in north-central Texas from July 1997 through October 1998. The chlorophyll a production in the periphytometers was used as an indicator of baseline chlorophyll a productivity and of maximum primary productivity (MPP) in response to nutrient enrichment (nitrogen and phosphorus). We evaluated the lotic ecosystem trophic status index (LETSI) using the ratio of baseline primary productivity to MPP, and evaluated the trophic class of each site.ResultsThe rivers and streams in the Lake Waco/Bosque River Watershed exhibited varying degrees of nutrient enrichment over the 18-month sampling period. The North Bosque River at the headwaters (NB-02) located below the Stephenville, Texas wastewater treatment outfall consistently exhibited the highest degree of water quality impact due to nutrient enrichment. Sites at the outlet of the watershed (NB-04 and NB-05) were the next most enriched sites. Trophic class varied for enriched sites over seasons.ConclusionSeasonality played a significant role in the trophic class and sensitivity of each site to nutrients. Managing rivers and streams for nutrients will require methods for measuring in situ responses and sensitivities to nutrient enrichment. Nutrient enrichment periphytometers show significant potential for use in nutrient gradient studies.

Development and application of a lotic ecosystem trophic status index

Salado Creek in Bexar County, Texas, is one of 65 streams listed in section 303(d) of the Clean Water Act as an impaired waterbody for its high concentration of fecal coliform bacteria. The Hydrological Simulation Program-FORTRAN (HSPF) in Better Assessment Science Integrating Point and Nonpoint Sources (BASINS) was applied to the Salado Creek watershed for studying its applicability as a prediction tool for in-stream fecal coliform bacterial concentration from both point and nonpoint sources associated with different land use types in the watershed. The sensitivity of simulated peak values of in-stream fecal coliform concentrations to changes in parameters associated with the bacterial simulation was evaluated. The hydrology of the watershed was calibrated for a period from January 1, 1990, to December 31, 1993. The model was validated for hydrology for a period from January 1, 1994, to December 31, 1996. The simulated peak value of in-stream fecal coliform concentrations was found to be most sensitive to the first-order decay constant, the rate of accumulation of fecal coliform on the land surface, the rate of surface runoff that is required to remove 90% of fecal coliform from the land surface, the temperature correction coefficient for the first-order decay rate of fecal coliform, and in-stream water temperature. A first -order analysis (FOA) was conducted to determine the fraction of the variance of the simulated peak in-stream fecal coliform concentration that can be attributed to the uncertainty in these five most sensitive parameters. The FOA indicated that the major portion of the variance in simulated in-stream peak fecal coliform concentration was caused by the variance and sensitivity of the maximum storage of fecal coliform on the pervious land surface. Thus, small errors in parameterizing the maximum storage of fecal coliform over a given land use class may result in large errors in predicted coliform counts.

NUTRIENT RETENTION, NUTRIENT LIMITATION, AND SEDIMENT-NUTRIENT INTERACTIONS IN A PASTURE-DOMINATED STREAM

Sediments often play an important role in the temporary storage and release of phosphorus (P) in streams, espe- cially streams receiving municipal wastewater treatment plant (WWTP) effluent. The objective of this study was to evaluate sedimentaqueous phase P equilibrium in four Ozark streams, and to determine the effect of alum (Al2(SO4)3) and calcium carbonate (CaCO3) on stream sedimentP interactions and content of exchangeable P. Stream physicochemical properties were significantly affected by the effluent discharge from the WWTPs; of particular interest to this study was that the increase in P concentrations varied greatly among streams. Phosphorus inputs from WWTP significantly increased sediment equilibrium P concentrations (sedimentEPC0) and readily exchangeable sedimentbound P, while decreasing the P buffering capacity of stream sediments. SedimentEPC0 values were as great as 7 mg L �1 downstream from one WWTP, suggesting that sediments are a transient storage pool of P and may release P back into the stream system when P inputs from the WWTP are reduced. The addition of alum and CaCO3 significantly reduced the sedimentEPC0 and readily exchangeable P, while increasing the ability of sediments to buffer increasing P loads.

Linking Watershed Subbasin Characteristics to Water Quality Parameters in War Eagle Creek Watershed

Abstract The demand for engineering solutions to ecosystem–level problems has increased as the impact of human activities has expanded to global proportions. While the science of restoration ecology has been developed to address many critical ecosystem management issues, the high degree of complexity and uncertainty associated with these issues demands a more quantitative approach. Ecological engineering uses science-based quantification of ecological processes to develop and apply engineering-based design criteria for sustainable systems. We suggest that in the United States ecological engineering curricula should be offered at the graduate level and should require rigorous Accreditation Board of Engineering and Technology-accredited (or equivalent) undergraduate preparation in engineering fundamentals. In addition to strengthening students’ mastery of engineering theory and application, the graduate curriculum should provide core courses in ecosystem theory including quantitative ecology, systems ecology, restoration ecology, ecological engineering, ecological modeling, and ecological engineering economics. Advanced courses in limnology, environmental plant physiology, ecological economics, and specific ecosystem design should be provided to address students’ specific professional objectives. Finally, professional engineering certification must be developed to insure the credibility of this new engineering specialization.

Determining the lotic ecosystem nutrient and trophic status of three streams in eastern Oklahoma over two seasons

We used the Matlock Periphytometer (Matlock et al., 1998) to measure in situ nutrient limitations and trophic status at five stream sites in the Bosque River Watershed in north-central Texas during July 1997. Periphytic chlorophyll a production from the Matlock Periphytometer was also used as an indicator of baseline primary productivity and of maximum primary productivity (MPP) in response to nutrient enrichment (nitrogen and phosphorus). The measured MPP was interpreted to represent the rate of periphytic growth when nutrients are not limiting. We developed a lotic ecosystem trophic status index (LETSI) using the ratio of baseline primary productivity to MPP. Nitrogen (N) and phosphorus (P) limitations were evaluated using a modified LETSI as the ratio of either N or P enriched growth to MPP. The LETSI is by definition a functional index, and may provide a classification tool for lotic ecosystem trophic status. Using the LETSI indices, we observed differences in nutrient limitations in the streams and detected co-limitations of nitrogen and phosphorus at two of the stream sites.

Climate adaptation imperatives: global sustainability trends and eco-efficiency metrics in four major crops - canola, cotton, maize, and soybeans

Even though agricultural land use is a principal source of nonpoint-source pollution, the in-stream movement and transport of nutrients and their interaction with benthic sediments are not well understood. The objectives of this study were to: (1) assess if nutrients were limiting algal growth, (2) assess equilibrium between sediments and water column phosphorus (P), (3) evaluate spatial and temporal variability in P buffering capacity and easily exchangeable P, and (4) evaluate variations in stream nutrient retention efficiency in Moores Creek, a pasture-dominated watershed in northwest Arkansas. This study used nutrient limitation bioassays, sediment nutrient extractions, and short-term nutrient injections to accomplish the study objectives. Results suggested that light, not nutrients, was limiting algal growth in Moores Creek. Sediment equilibrium P concentration measurements suggested that sediments may be releasing dissolved inorganic P during winter and spring; however, sediments were a potential temporary sink of dissolved inorganic P during summer and fall. Exchangeable P concentrations varied between 0.4 and 1.0 mg kg-1 of dry sediments, and P sorption index varied between 3.2 and 5. Concentrations of ammonia nitrogen (NH4-N) and ortho P (PO4-P) generally decreased between sampling stations during nutrient injections at all three sites; however, nitrate N (NO3-N) concentrations increased downstream. A significant retention of NO3-N was not observed in any of the experiments, indicating that agricultural headwater streams may be a source of downstream NO3-N transport. The results indicated that a riparian cover should be maintained in nutrient-rich headwater streams in order to minimize algal production in the streams. Even nutrient-rich streams may continue to assimilate, to some extent, increased loads of P, altering the timing and magnitude of downstream transport of P.