University of California, Santa Barbara

About: University of California, Santa Barbara is a education organization based out in Santa Barbara, California, United States. It is known for research contribution in the topics: Population & Laser. The organization has 30281 authors who have published 80852 publications receiving 4626827 citations. The organization is also known as: UC Santa Barbara & UCSB.

Multiple stressors on coral reefs: a long-term perspective

Abstract: Coral reefs are subject to a high frequency of recurrent biological and physical disturbances. The temporal and spatial scales of these are often large and difficult to study, so that most of our knowledge of disturbances on coral reefs comes from investigations conducted at one or a few sites, over short periods of time. We argue that studying single events in isolation can be misleading and that a longer term approach is necessary for understanding the responses of coral reef assemblages to multiple stressors. We present first a brief review of the impacts of physical disturbance (e.g., cyclones, hurricanes) on the community dynamics of coral reefs, with special attention to the effects of recurrent events. We then examine two unusually detailed, long-term data sets from Heron Island, Australia, and Jamaica which demonstrate some of the complexities of multiple stressors (broadly defined as natural or man-made disturbances). Both case studies illustrate that the effect of a particular disturbance often depends critically on the impact of previous perturbations. Consequently, even the same type of recurrent stressor can have different effects at different times, depending on history. Accordingly, when the added dimension of time is considered, the distinction between single and multiple stressors becomes blurred. Even a single event such as a hurricane can be viewed mechanistically as a multiple stressor, with short- and long-term impacts. We emphasize that multiple stressors often have significant effects on recruitment and regenerative processes of assemblages. These impacts are much less obvious than catastrophic or chronic mortality, but they play a crucial role in community dynamics over longer time scales. Importantly, chronic anthropogenic impacts can impede the ability of coral assemblages to recover from natural disasters, even where there is little detectable effect on rates of adult mortality. Once a reef has been degraded, it is usually impossible to ascertain retrospectively the precise mechanisms that were involved or the relative importance of different events. A single survey will provide a snapshot of the status of coral reefs, but a longer term approach is required to understand the processes underlying changes in assemblages.

Stimuli-responsive polypeptide vesicles by conformation-specific assembly.

Abstract: In biology, lipids are well known for their ability to assemble into spherical vesicles. Proteins, in particular virus capsids, can also form regular vesicle-like structures, where the precise folding and stable conformations of many identical subunits directs their self-assembly. Functionality present on these subunits also controls their disassembly within the cellular environment, for example, in response to a pH change. Here, we report the preparation of diblock copolypeptides that self-assemble into spherical vesicular assemblies whose size and structure are dictated primarily by the ordered conformations of the polymer segments, in a manner similar to viral capsid assembly. Furthermore, functionality was incorporated into these molecules to render them susceptible to environmental stimuli, which is desirable for drug-delivery applications. The control of assembly and function exhibited in these systems is a significant advance towards the synthesis of materials that can mimic the precise three-dimensional assembly found in proteins.

Learning to coexist with wildfire

Abstract: The impacts of escalating wildfire in many regions - the lives and homes lost, the expense of suppression and the damage to ecosystem services - necessitate a more sustainable coexistence with wildfire. Climate change and continued development on fire-prone landscapes will only compound current problems. Emerging strategies for managing ecosystems and mitigating risks to human communities provide some hope, although greater recognition of their inherent variation and links is crucial. Without a more integrated framework, fire will never operate as a natural ecosystem process, and the impact on society will continue to grow. A more coordinated approach to risk management and land-use planning in these coupled systems is needed.

Applying the Science of Learning: Evidence-Based Principles for the Design of Multimedia Instruction

Abstract: During the last 100 years, a major accomplishment of psychology has been the development of a science of learning aimed at understanding how people learn. In attempting to apply the science of learning, a central challenge of psychology and education is the development of a science of instruction aimed at understanding how to present material in ways that help people learn. The author provides an overview of how the design of multimedia instruction can be informed by the science of learning and the science of instruction, which yields 10 principles of multimedia instructional design that are grounded in theory and based on evidence. Overall, the relationship between the science of learning and the science of instruction is reciprocal.

Impacts of Biodiversity Loss Escalate Through Time as Redundancy Fades

Abstract: Plant diversity generally promotes biomass production, but how the shape of the response curve changes with time remains unclear. This is a critical knowledge gap because the shape of this relationship indicates the extent to which loss of the first few species will influence biomass production. Using two long-term (≥13 years) biodiversity experiments, we show that the effects of diversity on biomass productivity increased and became less saturating over time. Our analyses suggest that effects of diversity-dependent ecosystem feedbacks and interspecific complementarity accumulate over time, causing high-diversity species combinations that appeared functionally redundant during early years to become more functionally unique through time. Consequently, simplification of diverse ecosystems will likely have greater negative impacts on ecosystem functioning than has been suggested by short-term experiments.