Review of the Edwards Aquifer Habitat Conservation Plan Report 3 (2018) / Chapter Skim
Currently Skimming:
3 Will the Biological Objectives Meet the Biological Goals?
3 Will the Biological Objectives Meet the Biological Goals?
Pages 67-96
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 67... ...
As discussed previously, the biological objectives are different for each species, although they generally have three components: flow, water quality, and habitat. This chapter addresses whether the combined effects of the flow objective, the water quality objective, and the habitat objective achieve the biological goals for the fountain darter, Texas wild rice, the Comal Springs riffle beetle (CSRB)
|
From page 68... ...
For example, there is extensive information on fountain darters and Texas wild rice, and so the determinations are offered with a relatively high degree of confidence. In contrast, for the CSRB and the San Marcos salamander, much less is known, which prevents determi
|
From page 69... ...
Determination and Information Used Will the biological objectives for the fountain darter achieve the biological goals? The Committee determined that, based on the available information, it is likely that the biological objectives will meet the biological goals for the fountain darter.
|
From page 70... ...
. Evidence that the habitat, flow, and water quality objectives can meet the goals for fountain darters can be gleaned from past performance.
|
From page 71... ...
The data are from EAA biomonitoring using the drop-net method for sampling fountain darters. Only SAV types with at least three to four measurements per year per SAV type and measurements spanning roughly April to November were included.
|
From page 72... ...
SOURCE: Committee manipulation of Edwards Aquifer Authority data. but not sufficient; good water quality is needed but alone would not likely result in increased fountain darter abundance.
|
From page 73... ...
SOURCE: Committee ma nipulation of Edwards Aquifer Authority data. FIGURE 3-4 Range of tempera ture observed during the drop-net sampling.
|
From page 74... ...
. In addition, Texas wild rice is now being credited as fountain darter habitat.
|
From page 75... ...
For example, during development of the HCP, it was not anticipated that Texas wild rice would expand as it did, nor was it considered habitat in the calculations of fountain darter abundance. Despite these risks, the responses of SAV to the recent drought and floods are encouraging and support a high degree of stability.
|
From page 76... ...
The biological basis for the objectives, especially the 10 percent deviations, should be confirmed using empirical data. Conclusion and Actions Needed to Improve the Rating The evidence in support of the biological objectives meeting the biological goals is based on empirical observations and the cumulative input (including the development of the HCP)
|
From page 77... ...
. The biological goals for Texas wild rice are to maintain a range of areal coverage in four reaches of the San Marcos River and to maintain a range of percentages of the coverage in a given reach (see Table 2-2 for details)
|
From page 78... ...
Although not every section of the San Marcos River saw a spectacular resurgence of Texas wild rice, some areas, such as the City Park reach and Spring Lake, were remarkable, with the coverage of Texas wild rice increasing threefold in a single year. This bodes well for achievement of the longterm goals in future years, and it is the foremost reason that it was decided that they were likely to be met by 2027.
|
From page 79... ...
As for the fountain darters, the habitat suitability modeling may be out of date now because it was completed almost 10 years ago and the systems have changed. Water Quality Objective.
|
From page 80... ...
to count Texas wild rice coverage as fountain darter habitat in the San Marcos River, thereby eliminating a source of conflict in the goals of the HCP. This should eliminate the situation where Texas wild rice was essentially pitted against the other SAV species in terms of coverage.
|
From page 81... ...
The main action that the EAA could take to move the determination of likely toward very likely would be to create a water quality objective for Texas wild rice, especially during low-flow conditions. If a water quality objective were to be created for Texas wild rice, an upper value for temperature in the San Marcos River could be chosen by local experts after consulting the existing scientific literature.
|
From page 82... ...
It considered how well the flow objective reflects the habitat suitability modeling done for the CSRB as found in Hardy (2009) and Hardy et al.
|
From page 83... ...
The flow objective was developed to sustain flow sufficient to maintain habitat, and therefore populations of the listed species, which in the case of the Comal system are the fountain darter and the CSRB. The habitat suitability modeling done for the fountain darter played a significant role in determining the flow objectives in the Comal system; hence, the criticism of that HSI modeling discussed previously (see Fountain Darter section)
|
From page 84... ...
This assessment is also dependent on how well the habitat suitability modeling actually predicts CSRB populations, an issue discussed earlier for the fountain darter. There is an important disconnect between the habitats for which the habitat suitability modeling was done (Spring Runs 1, 2, and 3)
|
From page 85... ...
. As discussed earlier for the fountain darter, the water quality objectives are necessary, but not sufficient, to ensure that the biological goals are met.
|
From page 86... ...
Finally, if the habitat suitability modeling was repeated in the LTBG reaches, it would increase confidence in the ability of the flow objectives to meet those goals. SAN MARCOS SALAMANDER The biological goals for the San Marcos salamander are to maintain specific salamander populations (number/m2)
|
From page 87... ...
; progress to date implementing numerous recreation-associated M&M measures in Spring Lake and just below the dam spillway; and various reports already cited for the other species. Evidence for and Against the Objectives Achieving the Goals Like the CSRB, evidence in the form of positive trends in abundance is not as easy to come by for San Marcos salamanders as it is for fountain darters and Texas wild rice.
|
From page 88... ...
Therefore, the flow objective for fountain darters should be adequate for San Marcos salamanders. As with fountain darters, protection and maintenance of salamander habitat in Spring Lake during excessively high-flow events is uncertain and needs to be considered.
|
From page 89... ...
The y-axis is number per square meter. SOURCE: Committee manipulation of Edwards Aquifer Authority data.
|
From page 90... ...
In addition to removing vegetation, trained divers will "fin the area around the springs to remove accumulated sediment." The process of aquatic gardening is important to meeting the biological goal of silt-free gravel. Although it is not explicitly identified in the HCP as an objective, an implicit habitat objective for the San Marcos salamander is the management of riparian areas along a short stretch of the San Marcos River just downstream from Spring Lake Dam.
|
From page 91... ...
This objective is given for fountain darters in both the Comal and San Marcos systems and for the CSRB, Peck's Cave amphipod, Comal Springs dryopid beetle, and Texas blind salamander. In the case of the latter four organisms, the water quality under consideration is that of the aquifer water measured at the spring openings, while for the fountain darter the water being considered is the river water in both systems.
|
From page 92... ...
For oxygen, a 10 percent deviation is of little consequence until the oxygen reaches critically low levels that lead to organism stress or death. There is little clarity for most organisms as to how a 10 percent deviation in the water quality objective is to be applied and little information as to critical water quality levels that lead to adverse effects on the listed species.
|
From page 93... ...
The rating could be improved by repeating the habitat suitability modeling using more recent data, by creating a defined water quality objective for Texas wild rice, and by adding a habitat objective to continue to remove nonnative SAV. It is somewhat likely that the biological objectives will meet the biological goals for the Comal Springs riffle beetle.
|
From page 94... ...
The rating could be improved by creating a water quality objective for San Marcos salamanders, better regulating recreational access to the 50-meter reach of the San Marcos River just below Spring Lake Dam, quantifying the outcomes of aquatic gardening and maintenance of silt-free gravel at the salamander study reaches, and augmenting the current sampling protocol with a new method to estimate proportion of area occupied and detection probability of San Marcos salamanders. Controlling access just below Spring Lake Dam and quantifying the maintenance of silt-free gravel should be made high priorities because they could be implemented soon and will help ensure that the stated salamander goals are met.
|
From page 95... ...
2017. Fountain Darter Modeling System for the Comal and San Marcos Rivers.
|
From page 96... ...
2017. Review of the Edwards Aquifer Habitat Conservation Plan: Report 2.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.