Vernal pools are small, seasonal wetlands that are a common landscape feature contributing to biodiversity in northeastern North American forests. Basic information about their biogeochemical functions, such as carbon cycling, is limited. Concentrations of dissolved methane (CH4) and carbon dioxide (CO2) and other water chemistry parameters were monitored weekly at the bottom and surface of four vernal pools in central and eastern Maine, USA, from April to August 2016. The vernal pools were supersaturated with respect to CH4 and CO2 at all sampling dates and locations. Concentrations of dissolved CH4 and CO2 ranged from 0.4 to 210 μmol L−1 and 72–2300 μmol L−1, respectively. Diffusive fluxes of CH4 and CO2 into the atmosphere ranged from 0.2 to 73 mmol m−2 d−1, and 30–590 mmol m−2 d−1, respectively. During the study period, the four vernal pools emitted 0.1–5.8 kg C m−2 and 9.6–120 kg C m−2 as CH4 and CO2, respectively. The production fluxes (production rates normalized to surface area) of CH4 and CO2 ranged from − 0.02 to 0.66 and 0.40–4.6 g C m−2 d−1, respectively, and increased significantly over the season. Methane concentrations were best predicted by alkalinity, ortho-phosphate and depth, while CO2 concentrations were best predicted with only alkalinity. Alkalinity as a predictor variable highlights the importance of anaerobic respiration in production of both gases. Our study pools had large concentrations and effluxes of CH4 and CO2 compared to permanently inundated wetlands, indicating vernal pools are metabolically active sites and may be important contributors to the global carbon budget.

The behavioral phenotypes of hybrids vary in degree of similarity to their parent species. Unisexual salamanders (Ambystoma laterale sp.), the result of ancient hybridization, contain nuclear DNA of multiple sperm-host species whose habitat preferences differ from one another. We radio tracked unisexual salamanders from four vernal pools to quantify migration distances and post-breeding habitat selection and compared these to published accounts for Blue-Spotted Salamanders (A. laterale) and Jefferson Salamanders (Ambystoma jeffersonianum). Unisexual salamanders used sites with higher numbers of small mammal burrows, lower substrate temperatures, and lower cover by forest floor vegetation than available sites, similar to the sperm-hosts. Unisexual salamanders also migrated distances within the range reported for these sperm-hosts. Even so, individual migration distances were context specific. We implore managers to use caution when designating management zones around breeding pools by considering that some populations may move farther than those reported in published accounts.

The introduction of a novel competitor can dramatically alter community dynamics, and competition-mediated impacts often result from biological invasions. Interference competition can be especially problematic as a source of methodological bias for studies seeking to evaluate population and community-level impacts of invasive species. We used polyvinyl chloride (PVC) refugia to conduct laboratory trials to determine whether behavioral or chemical cues of invasive Cuban treefrogs (Osteopilusseptentrionalis) interfere with artificial refuge use by conspecifics or treefrogs native to Florida (USA). We found no evidence of behavioral or chemical competition for refuges by Cuban treefrogs or native treefrogs. The inability of native treefrogs to avoid chemical cues from Cuban treefrogs, despite living sympatrically with the invasive treefrogs for 10–20 years, has important implications for predation risk.

Light pollution is problematic for many nocturnal organisms, but our understanding of its effects on vernal pool-breeding amphibians is limited. Further, we know little about leaf litter preference of these amphibians in their recently metamorphosed stage. Our objectives were to determine if newly metamorphosed Wood Frogs (Rana sylvaticus) and unisexual Blue-spotted Salamanders (Ambystoma laterale x jeffersonianum) prefer either deciduous or coniferous leaf litter when given a choice between these two common cover types and if artificial light affects microhabitat preference of either of these species. We conducted choice experiments in outdoor tanks with recently metamorphosed frogs and salamanders. We divided each tank into two compartments, filling one half with soil and leaf litter from a coniferous stand and the other with soil and leaf litter from a deciduous stand. Animals had one night to choose a substrate in the dark, as a control, and we recorded their positions the next morning. We then conducted illuminated trials in the same tanks, with a flashlight illuminating one substrate one night and the other substrate the following night. Frogs did not have a leaf litter preference in the dark and did not show a preference when either substrate was illuminated. Salamanders preferred deciduous litter in dark trials and when it was illuminated, however, they chose coniferous litter more often when it was illuminated. Additionally, artificial lighting could attract unisexual Blue-spotted salamanders to substrates they would not normally prefer and possibly settle in drier habitat.

[ILLUSTRATION OMITTED] a spring morning in Maine, traps made of nets rise above vernal pools in a small wetland, ready to collect salamanders (Figure 1, p. 38). The traps were designed by groups of rural urban high school students from Maine Massachusetts participating in the University of Maine Upward Bound Math Science Program (UBMS) at the university campus in Orono, Maine. I had reached out to UMaine scientists to provide our UBMS students a hands-on design experience. Responding to my request was my co-author, Kristine Hoffmann, a wildlife ecology PhD candidate who served as our collaborating scientist. Student groups chose from a variety of authentic design problems involving sustainability research. Four of our groups chose to design build traps to help the ecologist compare the types of habitat selected by two genetically related salamanders. The students developed models through trial error presented them with a final paper video (see On the web). The design project was consistent with the Next Generation Science Standards (see box, p. 42). We divided students into heterogeneous groups mixing age, gender, cultural background, home school, experience with the design project before they arrived on campus for the six-week residential program, which was free for qualifying students. Facilitators I informally assessed each student's abilities needs, making modifications for students with special needs. Instructors students came up with a group name, ground rules for group function, roles for student pairs to manage sections of the trap design, research paper, video. The design project curriculum used a hands-on, minds-on approach, giving students decision-making power through group discussion. Having students come up with ideas solutions on their own, rather than giving them instructions, allowed them to devise a creative solution for the frame of the trap, said Jessie Darkis, a staff member facilitator for the Confused Kangaroos, the group whose trap design was ultimately selected by the collaborating scientist as most aligned with her work. [FIGURE 1 OMITTED] The research question At the beginning of the program, Hoffman, the collaborating scientist, presented background information about her research salamander ecology. She explained that little research had been done to determine whether blue-spotted salamanders (Ambystoma laterale) unisexual salamanders (A. laterale x jeffersonianum, Figure 2) needed the same or different conservation measures to ensure their survival. (Unisexuals are a unique, all-female that reproduce using the sperm of the closely related blue-spotted salamander.) Blue-spotted unisexual salamanders look identical but are genetically distinct may play different ecological roles. Both species breed in vernal pools, which are wetlands that dry annually. It is unknown if the two species favor breeding in large or small pools or pools surrounded by pine trees or maple trees; perhaps they have no preference. Hoffmann's research question was: Do these genetically distinct salamanders favor the same types of breeding habitat? To answer that, she needed to trap release salamanders at a variety of vernal pools to collect DNA samples. Minnow traps composed of cages entrance funnels have been used to capture but they are expensive, bulky, hard to store, difficult to transport. Positioning these traps underwater is difficult due to trap size shape; minnow traps are most effective in deeper parts of the wetlands where salamanders congregate, but salamanders trapped underwater can't reach the surface to breathe in these locations (Figure 3). The engineering problem As an ecologist, I definitely don't want to kill salamanders, Hoffmann told the students, and I can't be at every wetland multiple times a day to release animals, so I can't do my study unless we have a better trap. …

Amphibians can be very difficult to mark because of their extraordinary powers of regeneration. Although many amphibian marking techniques have been developed, few meet the rigorous assumptions of capture-mark-recapture models. Also, excessive toe-clipping may affect frog survivorship adversely. We tested the efficacy of a new hybrid marking technique (VIE-C) that combines Visible Implant Elastomer (VIE) and toe-clipping on four species of treefrogs in West-Central Florida. Of the 840 treefrogs recaptured over a 15-month period, only one mark was unreadable. A significantly higher percentage of VIE marks (80%) than toe-clips (55%) remained viable for the duration of the study. On average, toe-clips remained readable for 100 days, and VIE marks remained readable for 112 days. There were no significant species differences in the length of time that either type of mark lasted. The hybrid VIE-C method represents an improvement over either method used alone, but the VIE mark will be more helpful in correctly reading and clarifying toe-clipping errors than will toe-clips be helpful in reading and clarifying VIE marks. (C) Koninklijke Brill NV, Leiden, 2009

We report on the use of a hybrid technique (VIE-C) combining Visible Implant Elastomer (VIE) marks with toe-clipping (C) to mark individuals of several species of treefrogs (Hylidae). Our marking strategy entailed injecting elastomer into the plantar surface of the digits and clipping only one toe. This method allows large numbers of frogs to be individually marked. reduces the potential for negative effects due to clipping multiple toes, and minimizes the frequency of elastomer migration from the injection site, a common problem with VIE marks on the body or limbs. We found retention rate of VIE marks in the digits to be similar to that of toe-clips, indicating that VIE provides a satisfactory alternative to multiple toe-clips. In addition, cost of materials, frog handling time, and ill effects were minimal. This VIE-C marking scheme is highly recommended when considering techniques for marking anurans, as it reduces potential negative effects of clipping multiple toes, and provides a large number of inexpensive and long-lasting individual marks that can be easily applied and quickly read in the field by trained observers.