Jane C. Marks

Bio: Jane C. Marks is an academic researcher from Northern Arizona University. The author has contributed to research in topics: Plant litter & Ecosystem. The author has an hindex of 32, co-authored 85 publications receiving 3877 citations. Previous affiliations of Jane C. Marks include Royal Victoria Infirmary & Bowling Green State University.

Exercise conditioning decreases downstream movement of pond-reared razorback suckers released into a stream environment

Abstract: Despite augmentation stocking efforts, wild populations of razorback suckers (Xyrauchen texanus) continue to decline. Endangered razorback suckers are commonly raised in off-channel ponds until maturity (approximately 300 mm TL) and then stocked into the Colorado River or its tributaries. After fish are stocked, they commonly move large distances downstream. We conducted an experiment to determine if downstream dispersal could be reduced through exercise condi- tioning. Two groups of razorback suckers, exercised and nonexercised, were released into Fossil Creek, Arizona. Prior to release, a subsample from each treatment group was tested in a laboratory flow chamber. Razorback suckers that had been exercise conditioned were able to maintain a position in the flow chamber 2 times longer and at velocities 25 cm ⋅ s-1 higher than nonexercised fish. Although the intended method of field data collection via passive-integrated-transponder (PIT) antennas and a remote communication station failed because river otters (Lontra canadensis) preyed upon the released razor- back suckers, implanted PIT tags were retained in otter scat. Recovered PIT tags enabled distributional analysis, which indi- cated that exercised razorback suckers did not move as far downstream from the point of release as nonexercised razorbacks. Exercise conditioning may increase overall fitness of pond-reared razorback suckers, and, consequently, increase the effective- ness of augmentation stocking. RESUMEN.—A pesar de los esfuerzos de repoblacion, las poblaciones silvestres del matalote jorobado (Xyrauchen texanus) siguen en declive. Los matalotes jorobados, que estan en peligro de extincion, se crian en estanques fuera del cauce hasta la etapa adulta (~300 mm) y despues son liberados en el Rio Colorado o uno de sus afluentes. Los peces suelen desplazarse largas distancias rio abajo despues de su introduccion al rio. Llevamos a cabo un experimento para determinar si la dispersion rio abajo se podia reducir mediante el acondicionamiento por ejercicio. Dos grupos de matalotes fueron liberados en Fossil Creek, Arizona, uno que habia sido acondicionado y otro que no. Antes de liberarlos, examinamos una submuestra de cada grupo en una camara de flujo en el laboratorio. Los matalotes que habian sido acondicionados por ejercicio pudieron mantener sus posicion en la camara de flujo dos veces mas tiempo y a velocidades de 25 cm ⋅ s-1 mas altas que los peces no acondiciona- dos. Aunque fallo el metodo de colecta de datos mediante antenas de sistema PIT (passive integrated transponder) y una estacion remota de comunicacion, los matalotes liberados fueron depredados por nutrias de rio (Lontra canadensis) y las mar- cas PIT implantadas se quedaron en las heces de las nutrias. La recuperacion de estas etiquetas PIT permitio un analisis de distribucion que indico que los matalotes acondicionados no se desplazaron rio abajo tan lejos del punto de liberacion como los matalotes no acondicionados. El acondicionamiento por ejercicio podria mejorar la condicion fisica de los matalotes joroba - dos criados en cautiverio y asi aumentar la eficacia de la reintroduccion.

Population response of the invasive crayfish Orconectes virilis (Hagen, 1870) (Decapoda: Astacoidea: Cambaridae) to restoration: What are the consequences of changes in predatory regulation and physical habitat in Fossil Creek, Arizona, USA?

Abstract: We examined the response of a population of an invading non-indigenous crayfish, Orconectes virilis (Hagen, 1870), to a stream restoration project in travertine-forming Fossil Creek, Arizona, USA. Restoration included the re-establishment of the natural flow regime after the decommissioning of a dam and removal of non-native predatory fishes. The goal was to determine if changes in the dominant predatory fishes or changes in physical habitat variables, including substrate modification and base flow influence changes in crayfish abundance. We predicted that increased and unregulated flows and velocities would not generally decrease crayfish abundance, and that the removal of non-native fishes would increase the number of crayfish while local substrate modification by travertine deposition, a form of limestone which fills in interstitial spaces, would decrease the number of crayfish. Consistent with our predictions, there were not generalized decreases in crayfish abundance throughout the river following restoration. More detailed observations of different reaches, however, indicates that fish species and density exert some regulation over crayfish numbers. Crayfish abundance decreased following restoration where exotic fishes remain but slightly increased in numbers where they were removed. Areas in the river with increased travertine deposition had the largest declines following restoration. These observations suggest that crayfish abundance in this system is limited by substrate modification by travertine and to a lesser extent by regulation of fish predation.

Spatial population structure of a widespread aquatic insect in the Colorado River Basin: Evidence for a Hydropsyche oslari species complex

Abstract: Structural connectivity and dispersal ability are important constraints on functional connectivity among populations. For aquatic organisms that disperse among stream corridors, the regiona...

Do movement patterns differ between laboratory and field suction feeding behaviors in a Mexican cichlid

Abstract: We analyzed feeding behavior of individuals of Herichthys minckleyi, the Cuatro Cienegas cichlid, under laboratory conditions and freely behaving in their natural environment using high-speed video imaging. In a multivariate analysis of suction feeding behaviors there was no clear grouping of feeding events based on the environment, which suggests that most of the variability in the data was unrelated to differences between lab and field behaviors. In fact, the variability within an environment was far greater than the variability between the two environments. These results suggest that laboratory studies can accurately describe the kinematics of behaviors seen in the field. However, although lab based studies can quantify behaviors seen in the field, natural habitats are complex and provide individuals with the opportunity to exploit a wide range of food types and microhabitats, which may elicit behaviors not observed in the laboratory. However, feeding behaviors observed in the lab are representative of frequently used feeding behaviors in the field, at least for this species. Thus, we suggest that laboratory studies of feeding behavior, particularly those that test biomechanical or performance-based hypotheses can be extrapolated to natural environments.

Influence of Diet On the Distribtion of Nitrogen Isotopes in Animals

Abstract: The influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition. The isotopic composition of the nitrogen in an animal reflects the nitrogen isotopic composition of its diet. The δ^(15)N values of the whole bodies of animals are usually more positive than those of their diets. Different individuals of a species raised on the same diet can have significantly different δ^(15)N values. The variability of the relationship between the δ^(15)N values of animals and their diets is greater for different species raised on the same diet than for the same species raised on different diets. Different tissues of mice are also enriched in ^(15)N relative to the diet, with the difference between the δ^(15)N values of a tissue and the diet depending on both the kind of tissue and the diet involved. The δ^(15)N values of collagen and chitin, biochemical components that are often preserved in fossil animal remains, are also related to the δ^(15)N value of the diet. The dependence of the δ^(15)N values of whole animals and their tissues and biochemical components on the δ^(15)N value of diet indicates that the isotopic composition of animal nitrogen can be used to obtain information about an animal's diet if its potential food sources had different δ^(15)N values. The nitrogen isotopic method of dietary analysis probably can be used to estimate the relative use of legumes vs non-legumes or of aquatic vs terrestrial organisms as food sources for extant and fossil animals. However, the method probably will not be applicable in those modern ecosystems in which the use of chemical fertilizers has influenced the distribution of nitrogen isotopes in food sources. The isotopic method of dietary analysis was used to reconstruct changes in the diet of the human population that occupied the Tehuacan Valley of Mexico over a 7000 yr span. Variations in the δ^(15)C and δ^(15)N values of bone collagen suggest that C_4 and/or CAM plants (presumably mostly corn) and legumes (presumably mostly beans) were introduced into the diet much earlier than suggested by conventional archaeological analysis.

Biofilms: an emergent form of bacterial life.

Abstract: Bacterial biofilms are formed by communities that are embedded in a self-produced matrix of extracellular polymeric substances (EPS). Importantly, bacteria in biofilms exhibit a set of 'emergent properties' that differ substantially from free-living bacterial cells. In this Review, we consider the fundamental role of the biofilm matrix in establishing the emergent properties of biofilms, describing how the characteristic features of biofilms - such as social cooperation, resource capture and enhanced survival of exposure to antimicrobials - all rely on the structural and functional properties of the matrix. Finally, we highlight the value of an ecological perspective in the study of the emergent properties of biofilms, which enables an appreciation of the ecological success of biofilms as habitat formers and, more generally, as a bacterial lifestyle.

Going back to the roots: the microbial ecology of the rhizosphere.

Abstract: The rhizosphere is the interface between plant roots and soil where interactions among a myriad of microorganisms and invertebrates affect biogeochemical cycling, plant growth and tolerance to biotic and abiotic stress. The rhizosphere is intriguingly complex and dynamic, and understanding its ecology and evolution is key to enhancing plant productivity and ecosystem functioning. Novel insights into key factors and evolutionary processes shaping the rhizosphere microbiome will greatly benefit from integrating reductionist and systems-based approaches in both agricultural and natural ecosystems. Here, we discuss recent developments in rhizosphere research in relation to assessing the contribution of the micro- and macroflora to sustainable agriculture, nature conservation, the development of bio-energy crops and the mitigation of climate change.