A complete ecosystem consists of the geosphere (earth), hydrosphere (water), atmosphere (air), and biosphere (life). The essential elements exist in different forms in each sphere and pass between them by chemical and physical processes called biogeochemical cycles. Students are initially introduced to these concepts in grades 4À6, but do not usually study them intensively until secondary environmental science classes. 1 Incorporating games into a class (or lab) is a nonthreatening way to refresh a student's memory, and the interactive format provides a stimulating environment in which to reinforce important concepts. Such games have been developed to address a wide variety of chemical concepts. 2 "Element Cycles" is a simple board game designed to familiarize students in grades 4À12 with the most common essential elements and their roles in the environment. The students initially gain knowledge about the elements and their biogeochemical cycles by researching them online. This knowledge is then reinforced by constructing a game board with ecological sections and element cards to pass the elements between ecosystems. When the students play the game and are passed from ecosystem to ecosystem, the forms of the elements change and they gain greater appreciation of the cyclic nature of matter in the environment.The game can be customized for different grade levels. For elementary students, the ecosystems can be defined as earth, air, water, and life, and the forms of the elements are simply the names of the compounds and ions, such as carbonate rocks, carbon dioxide gas, nitrogen gas, and so forth. For more advanced students, the ecosystems are defined as geosphere, atmosphere, hydrosphere, and biosphere, the forms of the elements are the actual chemical formulas, such as CO 3 2À , CO 2 , and N 2 , and mechanisms of transformation can be included, such as oxidation, reduction, precipitation, and so forth.This game format is also adaptable to other chemical concepts and is an entertaining alternative to rote memorization of specific facts. One example of such a concept is solubility. The four sections of the board can be labeled as þ1 cations, À1 anions, þ2 cations, and À2 anions. The track is then marked with appropriate anions and cations, and when the student lands on a symbol, he or she is sent to an oppositely charged ionic section and must draw a specific ion card and correctly predict solubility. Other units, such as oxidationÀreduction, are also potential game topics. ' MATERIALS• List of essential elements for students to research: The suggested minimum is C, N, P, and S, but the list may also be expanded to include O and H. Some good references, in ABSTRACT: "Element Cycles" is an activity designed to reinforce correlation of essential elements and their different forms in the ecosystem. Students are assigned essential elements to research as homework, then share results, and construct game boards with four ecosphere sections: geosphere (earth), hydrosphere (water), atmosphere (air), and biosphere (life). Th...

Predator naiveté has been invoked to explain the impacts of non-native predators on isolated populations that evolved with limited predation. Such impacts have been repeatedly observed for the endangered Pahrump poolfish, Empetrichthys latos , a desert fish species that evolved in isolation since the end of the Pleistocene. We tested Pahrump poolfish anti-predator responses to conspecific chemical alarm cues released from damaged epidermal tissue in terms of fish activity and water column position. Pahrump poolfish behavioural responses to conspecific alarm cues did not differ from responses to a dechlorinated tap water control. As a positive control, the well-studied fathead minnow, Pimephales promelas , showed significant alarm cue responses in terms of reduced activity and lowered water column position. The density of epidermal club cells, the presumptive source of alarm cues, was significantly lower in Pahrump poolfish relative to fathead minnows. Therefore, anti-predator competence mediated by conspecific alarm cues does not seem to be a component of the ecology of Pahrump poolfish. These findings provide a proximate mechanism for the vulnerability of Pahrump poolfish to non-native predators, with implications for the conservation and management of insular species.

Basic life history information can be useful for informing the management of protected species such as the Pahrump Poolfish Empetrichthys latos, a goodeid (Cyprinodontiformes) that is endemic to the Mojave Desert in southern Nevada, USA, and the last surviving remnant of Empetrichthys. Critically endangered and extirpated from its native range, Pahrump Poolfish has been managed among constructed refuge habitats since 1971. To better understand sex‐specific age demographics, we used thin‐sectioned otoliths to age 121 Pahrump Poolfish from one population, collected in June 2017. These samples suggested a maximum age of 10 years for females and 7 years for males, with a substantial portion of all fish greater than 4 years old. This is more than twice the previously reported maximum age for this species. We report on the inadequacy of reading whole otoliths, opercula, and scales for age analysis of this species. Based on thin‐sectioned otoliths, we also model growth in length as a function of age among individuals. We found significant sexual dimorphism across this fish’s ontogeny, which has implications for selecting an appropriate sex ratio for founding populations.

Many desert fishes, which evolved in isolated aquatic “islands” with limited predation pressure, have been severely impacted by non-native predators. These impacts have been attributed to the evolutionary loss of antipredator competence, known as the predator naiveté hypothesis. Recent work provided support for this hypothesis for one desert fish species. We sought to examine the generality of the predator naiveté hypothesis by evaluating antipredator competence in five populations of Red River pupfish (Cyprinodon rubrofluviatilis), a species that occupies habitats that vary in the degree of isolation and levels of fish species richness. Fish were exposed to a conspecific chemical alarm cue released from damaged epidermal tissue as a general assay of antipredator response. We found that pupfish from all five populations exhibited antipredator behavior in response to the alarm cue, regardless of the isolation duration or exposure to predation risk. These data provide evidence that antipredator responses to alarm cues are conserved in Red River pupfish, even in populations isolated from piscivorous species.