Rossana Sallenave

Morphologic and Genetic Variation in Triops (Branchiopoda: Notostraca) from Ephemeral Waters of the Northern Chihuahuan Desert of North America

Abstract Tadpole shrimp are known to be important animals in the ecology of ephemeral wetlands. In the northern Chihuahuan Desert of North America, the tadpole shrimp fauna is composed of possibly three species in the genus Triops, which have variously been referred to as species, subspecies, and intraspecific variation. Our results support the presence of three morphologically distinct forms, which will be referred to herein as T. newberryi, T. longicaudatus “short,” and T. longicaudatus “long.” We report analyses of Triops spp. sampled in summer 2008 from 14 natural playas and man-made flood retention ponds. Data were recorded on meristic counts and quantitative measurements of morphological features. We also sequenced portions of the mitochondrial COI and ND1 genes for 72 shrimp, including individuals from all three morphological forms and for multiple ponds for each form where possible. The three forms were morphologically distinct for multiple characters and molecular analyses showed large differences in DNA nucleotide sequence and the presence of multiple unique amino acid substitutions in each form. Finally, prior literature suggests the three forms exhibit different reproductive systems, with populations of T. longicaudatus “long” thought to be gonochoric (equal sex ratios and obligate outcrossing), T. longicaudatus “short” having only self-fertilizing hermaphrodites, and T. newberryi being androdioecious, having both self-fertilizing hermaphrodites and males. While these three forms may be sufficiently distinct in morphology, mitochondrial DNA, and reproductive life history to warrant elevation to species level, additional geographical sampling and an examination of the various type specimens are necessary for a formal taxonomic revision.

Competition between Hatchery-Raised Rio Grande Cutthroat Trout and Wild Brown Trout

Abstract An important problem for conservation of cutthroat trout Oncorhynchus clarkii is the presence of nonnative trout. We used eight 20-m instream enclosures on the Rio Cebolla, New Mexico, to evaluate competition between hatchery-raised Rio Grande cutthroat trout O. clarkii virginalis and similar-sized wild, nonnative brown trout Salmo trutta. Four control enclosures each contained 20 fish of the same species; four treatment enclosures each contained equal numbers of like-sized fish of the two species. Results indicated that wild brown trout were superior competitors to hatchery-raised Rio Grande cutthroat trout. Significant interspecific competition was inferred from comparisons of treatment fish with their controls. Among Rio Grande cutthroat trout, control fish grew in length and body weight, whereas growth of fish confined in enclosures with brown trout was significantly lower than that of controls (P < 0.001). In contrast, brown trout enclosed with Rio Grande cutthroat trout experienced signific...

Aquatic resources in arid lands: Issues and opportunities

No Abstract..

Microsatellites for North American species of Triops (Branchiopoda: Notostraca)

We used 454 pyrosequencing to discover more than 3000 candidate microsatellite markers for three putative species of tadpole shrimp in the genus Triops. We selected 42 of these candidates, consisting of 12 systems identified in Triops longicaudatus “long,” 16 identified in Triops longicaudatus “short,” and 14 identified in Triops newberryi. Out of these potential loci we identified between five and eight polymorphic microsatellite systems per “species.” By implementing an additional cross amplification experiment with the microsatellite markers mentioned above and further testing 15 microsatellite markers initially identified in the European Triops cancriformis, we successfully transferred 17 microsatellite markers within the three North American Triops and found three new microsatellites, one polymorphic, that will amplify in T. cancriformis. The reported genetic methods are powerful molecular tools to acquire new detailed information at the interface of ecology, evolution and development, which will facilitate understanding phenotypic plasticity, breeding systems, and adaptation in this taxonomically-confusing group of “living fossils.”

Science and Effective Policy for Managing Aquatic Resources

Scientists often feel powerless to affect policy on natural resource conservation or management, and managers frequently feel that there is not enough time or money to gather data to enlighten resource management decisions. This article summarizes the discussions in a facilitated workshop that brought together academicians, natural resource managers, and individuals from the private sector to discuss limitations in aquatic resource management policy and how science could be used more effectively in the decision-making process. A major impediment to including science in management and policy decision-making is insufficient dialogue between scientists and managers. For science-based resource management decisions, it is imperative to understand the distinction between science and professional judgment. The former is the acquisition of knowledge by applying the principles of the scientific method, whereas the latter may be based on science-in-progress, has not been subjected to peer review, and can be misrepresented to be science. Resource managers face significant problems making sound, science-based management decisions including: historical antecedents for resource use, changing social values, legal constraints, economics and politics, poorly focused management, plurality and diversity of stakeholders, and the credibility of agency-produced science. Effective conservation of aquatic resources can be undermined by distrust and disagreement between resource users, scientists, agencies, and even among academicians, leading to an atmosphere of “combat biology.” The principles of science should be introduced early in the decision-making process because they encourage articulation of multiple perspectives and fair but rigorous assessment of all hypotheses.

Preface: Conservation and Management of Aquatic Resources in Arid Lands

Water is clearly one of the most important natural resources in the western United States and drought is a major issue in states like New Mexico. Regulation of river flows and land uses in riparian zones and areas linked to them impair aquatic ecosystems and endanger the native biota in regions everywhere. The pervasive effects of humans on aquatic ecosystems reach their greatest magnitude in highly variable ecosystems situated in arid landscapes. The precious value of water, to humans and, in fact, to all life forms on Earth, demands that we look carefully at the changes we inflict on the landscape and seek an understanding of how we might inadvertently be affecting our own future existence. This issue contains articles contributed to a conference on “Aquatic Resources in Arid Lands” that was held in Las Cruces, New Mexico on April 30–May 2, 2003. We organized this conference to bring together prominent aquatic scientists, natural resource agency personnel, and water users to consider issues associated with management of aquatic resources. Invited experts spoke on paleoclimatology, terrestrial-aquatic linkages, ecology, invasive species, decision-support modeling, river restoration, and conservation genetics. The 2-day conference concluded with a half-day facilitated workshop on “Sound Science and Effective Policy for Managing Aquatic Resources.” This issue presents conference research papers on aquatic resources in five categories: climate, hydrology, endangered species, river restoration, and water policy. Climatic uncertainty is the major challenge in managing aquatic ecosystems in arid lands. The first article by Lioubimtseva and Cole addresses the global concern of climate change. Compelling evidence for global warming continues to accrue, although the potential consequence for arid lands is uncertain. Lioubimtseva and Cole argue that the extreme variability of deserts contributes to this uncertainty and they raise the possibility that local and regional human impacts, such as large-scale irrigation projects, may have a greater effect on regional climate than global climate change. In a second article on climate, Hall et al. examine a 40-year climatic record for the upper Rio Grande Basin of New Mexico and Colorado. They report that there is little consistency in time or space in climatic variations across the region. Local regions have climatic shifts in specific periods of the year that appear unrelated to trends in other periods and places. Hydrologic variations in the basin generally indicate trends for elevated river discharge and earlier onset of freshet in recent decades. Understanding hydrologic interactions between surface and groundwaters would enhance water resource management in many ways, especially in regions with most or all of the surface water appropriated for human uses. For the Alcalde Ditch in northern New Mexico, Fernald and Guldan have found that at least 5% of the total ditch flow seeps out

First Record of Daphnia lumholtzi (Sars) in the Rio Grande Basin, New Mexico

ABSTRACT The exotic cladoceran, Daphnia tumholtzi, was collected at several sites in Elephant Butte Reservoir, New Mexico, from spring through fall of 2003. Densities were always relatively low, suggesting that D. lumholtzi is in the early stages of invasion. There were two seasonal peaks in abundance of D. lumholtzi. One peak occurred in August and coincided with highest surface water temperature and declines in the densities of native Daphnia species; the second peak was in November.