380 research outputs found
Mechanisms and ecological role of carbon transfer within coastal seascapes
Worldwide, coastal systems provide some of the most productive habitats, which potentially influence a range of marine and terrestrial ecosystems through the transfer of nutrients and energy. Several reviews have examined aspects of connectivity within coastal seascapes, but the scope of those reviews has been limited to single systems or single vectors. We use the transfer of carbon to examine the processes of connectivity through multiple vectors in multiple ecosystems using four coastal seascapes as case studies. We discuss and compare the main vectors of carbon connecting different ecosystems, and then the natural and human-induced factors that influence the magnitude of effect for those vectors on recipient systems. Vectors of carbon transfer can be grouped into two main categories: detrital particulate organic carbon (POC) and its associated dissolved organic and inorganic carbon (DOC/DIC) that are transported passively; and mobile consumers that transport carbon actively. High proportions of net primary production can be exported over meters to hundreds of kilometers from seagrass beds, algal reefs and mangroves as POC, with its export dependent on wind-generated currents in the first two of these systems and tidal currents for the last. By contrast, saltmarshes export large quantities of DOC through tidal movement, while land run-off plays a critical role in the transport of terrestrial POC and DOC into temperate fjords. Nekton actively transfers carbon across ecosystem boundaries through foraging movements, ontogenetic migrations, or ‘trophic relays’, into and out of seagrass beds, mangroves or saltmarshes. The magnitude of these vectors is influenced by: the hydrodynamics and geomorphology of the region; the characteristics of the carbon vector, such as their particle size and buoyancy; and for nekton, the extent and frequency of migrations between ecosystems. Through a risk-assessment process, we have identified the most significant human disturbances that affect the integrity of connectivity among ecosystems. Loss of habitat, net primary production (NPP) and overfishing pose the greatest risks to carbon transfer in temperate saltmarsh and tropical estuaries, particularly through their effects on nekton abundance and movement. In comparison, habitat/NPP loss and climate change are likely to be the major risks to carbon transfer in temperate fjords and temperate open coasts through alteration in the amount of POC and/or DOC/DIC being transported. While we have highlighted the importance of these vectors in coastal seascapes, there is limited quantitative data on the effects of these vectors on recipient systems. It is only through quantifying those subsidies that we can effectively incorporate complex interactions into the management of the marine environment and its resources
Gathering Abundance: An Exploration of Urban Foraging Practices in Toronto
This paper explores different urban foraging practices within Toronto aiming to understand the motivations for foraging within an urban centre, how this is enacted, and how the context of Toronto affects this practice. As an emerging field of study, there are few articles directly about urban foraging, but a wide body of literature which informs the topic. Seventeen semi-structured interviews were conducted, two with land managers, three with land managers/foragers, and twelve with foragers while walking through greenspaces in Toronto. The themes that emerged from the interviews were those of forager identity, environmental stewardship, (re)connection from nature, and private property, laws and transgression. Through foraging practices in the city people are able to interact with public greenspaces, and become participants within ecological and social communities. Eating weedy species and distinctions between native and introduced species heavily influence foraging practice. The embodied process of this work through harvesting and utilizing the plant materials creates a strong sense of connection to local seasonal cycles and food systems. Decisions to transgress bylaws are grounded in different notions of the role of nature and public spaces in the city. There is the potential for foraging practices to be part of sustainable and dynamic urban ecologies
Understanding patch foraging strategies across development
Patch foraging is a near-ubiquitous behaviour across the animal kingdom and characterises many decision-making domains encountered by humans. We review how a disposition to explore in adolescence may reflect the evolutionary conditions under which hunter-gatherers foraged for resources. We propose that neurocomputational mechanisms responsible for reward processing, learning, and cognitive control facilitate the transition from exploratory strategies in adolescence to exploitative strategies in adulthood - where individuals capitalise on known resources. This developmental transition may be disrupted by psychopathology, as there is emerging evidence of biases in explore/exploit choices in mental health problems. Explore/exploit choices may be an informative marker for mental health across development and future research should consider this feature of decision-making as a target for clinical intervention
A Caribbean-wide survey of marine reserves: spatial coverage and attributes of effectiveness
Fully-protected marine reserves can function at several spatial scales, from a single area encompassing few habitats, to local networks of many habitats, to large-scale networks connected by larval dispersal. However, the amount, spatial distribution, and associated administrative attributes of Caribbean marine reserves are collectively unknown. We compiled information on reserves from 21 countries in order to 1) assemble a spatial framework to aid development of networks of reserves at the most effective spatial scales, and 2) aid policy makers in establishing reserves that are science-based and possess optimal management attributes. Since 1961 there have been over 50 reserves established in the Caribbean (an additional 30 in Bermuda) with the rate of implementation increasing since the mid 1980’s. Most reserves are small (\u3c 1,200 ha) and few contain the range of habitats necessary for protecting species through their ontogeny. Habitats are often not fully characterized, and the role of reserves in protecting and networking different habitats cannot be ascertained. Reserves are distributed throughout the region, with the highest density in Mesoamerica; but significant geographic gaps exist. It is unlikely that reserve-enhanced larval production significantly networks populations on a regional basis, although this may occur subregionally (e.g., Mesoamerica). Less than 20% of the reserves were scored as fully compliant, but half offer potentially significant levels of protection
Resource intensification and late Holocene human impacts on Pacific coast bird populations: evidence from the Emeryville shellmound avifauna
Book ChapterAnthropologists and conservation biologists have commonly assumed that the distributions and abundances of vertebrate resources recorded during the early historic period in North America reflected a "pristine" condition. This view follows from the perception that Native American population densities and technological capabilities were simply too low to deplete or extirpate vertebrate populations, or, alternatively, that native peoples were "children of nature" and the original conservationists (Alvard 1993, 1994; Kay 1994). In fact, these perceptions underlie modern wildlife management policies and practices. For example, because pre-Columbian environments are routinely viewed as "primordial wilderness" (Hewes 1973:150), restoring ecosystems to their "original condition" simply requires the elimination of European influences; this is the principle behind "hands-off" or "natural regulation" management (Kay 1994)
CONSERVATION BIOLOGY OF THE DIAMONDBACK TERRAPIN IN NORTH AMERICA
Reptiles are experiencing global declines and pond turtles (Emydidae) are particularly vulnerable. The diamondback terrapin uses multiple habitats to fulfill its life history requirements, in the estuarine environments of the Gulf Coast and Atlantic states (US). Interacting effects of coastal development, overharvesting, abandoned crabbing gear, road mortality, climate change, and nest predation are likely causing population declines throughout its distribution. Protection levels were assessed by referencing each state\u27s Wildlife Action Plan for the species\u27 Conservation Status Ranking Code. At least 7 federal laws directly or indirectly regulate take, wetland, and/or coastal activities (Lacey Act, CWA, FWCA, NAWCA, WPFPA, CBRA, NEPA). I propose the use of a new term (policy hub species) to describe species that could be used to bring together currently unused laws and protect an entire ecosystem. The majority of terrapin studies have focused on nesting success, road mortality, or incidental take in crab pots or other fishing gear. Patches of upland habitat could facilitate cover for common terrapin nest predators on Virginia barrier islands and high rates of depredation on nests would be encountered near the edges of these patches or other habitat features utilized by these predators. GIS analysis was used to determine if there were any relationships between a depredated nest\u27s location and habitat variables that could increase the likelihood of predation. As a case study of terrapin management in an island marsh system, I summarized three years of field research on the diamondback terrapin population of Fisherman Island National Wildlife Refuge
NMDA Receptor Inhibition on Rodent Optimal Decision-Making in the Diminishing Returns Task
There has been growing interest in using N-methyl-D-aspartate (NMDA) receptor antagonists as treatments for mood disorders, but there is still much to learn about their cognitive effects. Research shows NMDA receptors can affect decision-making, and the antagonist MK-801 has had varying effects in rodents. Specifically, some have reported impairments in working memory while foraging behaviors remained intact, while others have demonstrated changes in choice behavior related to delay or risk in behavior tasks. We investigated the role of NMDA receptors in the specific paradigm of optimal decision-making to further confirm MK-801’s effects and to explore whether inhibiting NMDA receptors alters optimal decision-making processes. To accomplish this, we used the Diminishing Returns task, in which rats were placed in a chamber containing two levers that returned rewards after delays. One lever had a fixed delay (FD) returning a reward after 10 s. The other lever had a progressive delay (PD) that increased by 1 s after each press. The task included two conditions allowing rats to change the delay schedule: no-reset and reset. In both conditions, there was an optimal response rate that returned the most rewards at the least amount of delay. A total of 24 male and female Sprague-Dawley rats were injected with doses of MK-801 (0.06 mg/kg, 0.1 mg/kg, 0.2 mg/kg) and saline as the control before testing in the task. We hypothesized MK-801 would diminish the ability to make optimal decisions. In the no-reset condition, rats on the 0.2 mg/kg dose made significantly more choices for the PD lever compared to the other treatments (56.9% ± 4.8%). In the reset condition, females made significantly more PD lever presses than males after receiving saline (females: 93.8% ± 1.1%, males: 88.7% ± 1.8%). Also, males and females on the 0.2 mg/kg dose made more optimal sequences of choices (females: 3.38 ± 0.87, males: 6.48 ± 1.67). These results reveal complex effects of sex and NMDA receptors on optimal foraging behaviors and overall task responsiveness. Therefore, the findings suggest inhibiting NMDA receptors may not detrimentally affect the cognitive mechanisms involved in optimal decision-making as it is measured in this task
The Complexities of Wildcrafting: A study of knowledge systems\u27 influences on wildcrafting in Chittenden County, VT
Social-ecological systems are based in the belief that the well-being of human systems relies on the well-being of ecological systems (Martin-Lopez, 2015). In a time of diminishing cultural and ecological diversity, many researchers are using the framework of social-ecological systems to find solutions to large-scale problems (Armitage, 2009). A subset of social-ecological systems is known as Traditional Ecological Knowledge (TEK) (Pretty, 2011). This knowledge often encompasses information as to how to collect wild edible plants and fungi (also known as wildcrafting) (Naah, 2017). The act of wildcrafting has been present in human behavior for centuries. However, today some people are experiencing shifts away from collecting wild edible plants and fungi (Pieroni, 2005), while other populations of people are contributing to a resurgence of wildcrafting across the globe (Schackleton, 2017). The ways in which people are learning about how to collect wild edible plants and fungi have historically been rooted in Traditional Ecological Knowledge (TEK), a system of learning which is based off experience and long-term relationships with ecosystems (Berkes, 2000). Foundational aspects of TEK are often seen as starkly different than those of Western Science (WS). WS is most commonly described as a more reductionist approach (Martin, 2010). Many environmental initiatives argue that the integration of both forms of knowledge is necessary for ameliorating large-scale cultural and ecological degradation (Berkes, 2000). My research looked to understand the various ways in which wildcrafting in Chittenden County, VT relies on TEK, WS or both learning systems to inform the basis of wildcrafting practices. Subsequently this research looked understand how wildcrafting fits within a larger conversation of social-ecological systems and the amelioration of human and environment relationships. I interviewed 10 participants using a semi-structured interviewing technique. Then, I carried out a detailed analysis of participant responses using NVivo, a qualitative coding software. The results of this study demonstrated that the majority of participants engaged in both TEK and WS knowledge to inform their wildcrafting practices and motivations. An analysis of the data shows that wildcrafting is complex. Wildcrafting more specifically addresses conservation as wildcrafters practice reciprocity with the natural world and establish a desire to conserve the natural world though interaction. This desire then results practice of sustainable harvesting and active conservation
Food-web structure in relation to environmental gradients and predator-prey ratios in tank-bromeliad ecosystems
Little is known of how linkage patterns between species change along environmental gradients. The small, spatially discrete food webs inhabiting tank-bromeliads provide an excellent opportunity to analyse patterns of community diversity and food-web topology (connectance, linkage density, nestedness) in relation to key environmental variables (habitat size, detrital resource, incident radiation) and predators: prey ratios. We sampled 365 bromeliads in a wide range of understorey environments in French Guiana and used gut contents of invertebrates to draw the corresponding 365 connectance webs. At the bromeliad scale, habitat size (water volume) determined the number of species that constitute food-web nodes, the proportion of predators, and food-web topology. The number of species as well as the proportion of predators within bromeliads declined from open to forested habitats, where the volume of water collected by bromeliads was generally lower because of rainfall interception by the canopy. A core group of microorganisms and generalist detritivores remained relatively constant across environments. This suggests that (i) a highly-connected core ensures food-web stability and key ecosystem functions across environments, and (ii) larger deviations in food-web structures can be expected following disturbance if detritivores share traits that determine responses to environmental changes. While linkage density and nestedness were lower in bromeliads in the forest than in open areas, experiments are needed to confirm a trend for lower food-web stability in the understorey of primary forests
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