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The authors have developed and field-tested high school-level curricular materials that guide students to use biology, mathematics, and physics to understand plankton and how these tiny organisms move in a world where their intuition does not apply. The authors chose plankton as the focus of their materials primarily because the challenges faced by plankton are novel problems to most students, forcing adoption of new perspectives and making the study of plankton exciting. Additional reasons that they chose plankton to focus on include their ecological importance, their availability to most teachers and students, the ease with which they can be collected and observed, and the current focus of some scientific researchers on their movement and behavior. These curricular materials include a series of inquiry-based, hands-on exercises designed to be accessible to students with a range of backgrounds. Many of these materials could be adapted for use by middle-school, and/or college-level students. In this article, the authors describe sample lessons, summarize what worked well, and flag obstacles they encountered while integrating mathematics and physics into the biology classroom. (Contains 1 table and 6 figures.)

Ocean acidification (OA), the reduction of ocean pH due to hydration of atmospheric C[O.sub.2], is known to affect growth and survival of marine invertebrate larvae. Survival and transport of vulnerable planktonic larval stages play important roles in determining population dynamics and community structures in coastal ecosystems. Here, we show that larvae of the purple urchin, Strongylocentrotus purpuratus, underwent high-frequency budding (release of blastula-like particles) when exposed to elevated pC[O.sub.2] level (> 700 µatm). Budding was observed in > 50% of the population and was synchronized over short periods of time (~ 24 h), suggesting this phenomenon may be previously overlooked. Although budding can be a mechanism through which larval echinoids asexually reproduce, here, the released buds did not develop into viable clones. OA-induced budding and the associated reduction in larval size suggest new hypotheses regarding physiological and ecological tradeoffs between short-term benefits (e.g. metabolic savings and predation escape) and long-term costs (e.g. tissue loss and delayed development) in the face of climate change., Introduction Anthropogenic carbon dioxide concentration in the atmosphere (pC[O.sub.2]) has been rising and is expected to increase to 700 ppm by 2100 (Sabine et al. 2004). The world's oceans represent [...]

The National Science Education Standards have highlighted the importance of active learning and reflection for contemporary scientific methods in K-12 classrooms, including the use of models. Computer modeling and visualization are tools that researchers employ in their scientific inquiry process, and often computer models are used in collaborative projects across disciplines. The goal of this project was to develop and field-test a module that used a computer model to teach marine sciences content in an applied, inquiry-based, and collaborative manner. Students used an estuarine transport model to explore the question of how circulation patterns affect planktonic organisms, demonstrating the interdisciplinary interaction of physics and biology. Our experience suggests that computer models, when used for inquiry, can help foster students' understanding of the nature of science and critical-thinking skills. Key Words: Interdisciplinary lesson; environmental science; estuarine transport; STEM., Project Motivation Calls from the National Research Council (1996) and National Science Foundation (2000) emphasized the importance of providing students with authentic science experiences through active inquiry. They also highlighted [...]

The evolutionary significance of egg size in marine invertebrates is commonly perceived in energetic terms. Embryonic size should also have direct effects upon the forces that govern swimming, a behavior common to early larval development in the plankton. If swimming is ecologically important, early larvae may need to perform to a certain 'standard', or threshold of speed and/or stability. The existence of performance standards in early development could therefore act to constrain the evolution of egg size and the evolution of development. Here we present the key parameters that characterize the upward swimming speed of ciliated spheroidal larvae moving at very low Reynolds numbers. The dependence of maximum supported mass upon larval size, and the independence of neutral-weight swimming speed from size, lead to hypotheses about scaling of swimming speed with size. Experimental studies with thirteen broadcastspawning planktotrophs demonstrate that flee-living embryonic swimmers in all of these species conform to a strong negative scaling of density with size that offsets increases in mass with increasing size. This trend suggests that swimming ability is broadly under selection in early development. In experimental studies and in a hydrodynamic model of larval swimming, the performance of trochophore larvae provides support for our hypothesized scaling relationships, and also for the concept of a standard in swimming speed. Echinoid blastulae, however, show relationships between speed and size that are not predicted by our scaling arguments. Results for echinoids suggest that differences in ciliary tip speed, or possibly in spatial density of cilia over the blastula's surface, result in significant differences in species' performance. Strong phyletic differences in the initial patterning and growth of structures used for swimming thus appear to cause significant differences in the relationship of swimming ability with embryo size. doi: 10.1093/icb/icq090

The study of ecosystems in action, by measuring ecosystem recovery from disturbance, resistance to alterations, and the reversibility of ecosystem changes, highlights features of natural communities that contribute to resilience. […]

Compromises between swimming and feeding affect larval form and behavior. Two hypotheses, with supporting examples, illustrate these feeding-swimming trade-offs. (1) Extension of ciliated bands into long loops increases maximum clearance rates in feeding but can decrease stability of swimming in shear flows. A hydromechanical model of swimming by ciliated bands on arms indicates that morphologies with high performance in swimming speed and weight-carrying ability in still water differ from morphologies conferring high stability to external disturbances such as shear flows. Instability includes movement across flow lines from upwelling to downwelling water in vertical shear. Thus a hypothesis for the high arm elevation angles of sea urchin larvae, which reduce speed in still water, is that they reduce a downward bias imposed by the vertical shear in turbulence. Observations of sea urchin larvae in vertical shear and comparisons among brittle star larvae arc consistent with the performance trade-offs predicted by the model. (2) Structures and behaviors that reduce swimming speed can enhance filtering for feeding. In the opposed-band feeding mechanisms of veligers and many trochophores, cilia push water to swim but movement of cilia relative to the water occurs when cilia overtake and capture particles. Features that may increase clearance rates at the expense of speed and weight capacity include structures that increase drag or body weight and ciliary band that beats in opposition to the feeding-swimming current. Larval feeding mechanisms inherited from distant ancestors result in different swimming-feeding trade-offs. The different trade-offs further diversify larval form and behavior

Resource distributions in the ocean are heterogeneous in time and space. Theory predicts planktonic predators may exploit these resource patches by modifying their movements in response to mechanical or chemical stimuli. In the laboratory, we used the protistan predator Oxyrrhis marina to simultaneously quantify changes in predator population distributions on scales of centimeters and hours and predators' individual three-dimensional swimming behaviors on scales of micrometers and seconds. Movements of O. marina in a 0.3-m column were monitored for several hours before and after introducing a 5-mm layer of either Isochrysis galbana prey cells or cell-free I. galbana filtrate. Within both types of layers, significant increases in turning rates and decreases in vertical velocities were observed. O. marina swimming speed increased significantly in response to intact L galbana cells, but not in response to 1. galbana exudates. Changes in predators' microscopic movements were concurrent with rapid (minutes) and sustained (hours) increases in relative predator abundance within layers. After 4 h, predator abundance inside the thin layers was up to 20 times higher than before introduction of prey. Estimates of realized growth rates for predator populations with aggregate behaviors were an order of magnitude faster than estimates for hypothetical, nonaggregating predators. The observed foraging behaviors of O. marina, and by implication other planktonic predators, increase effective prey availability to the predators. Modulation of individual-level behaviors can result in significant changes in community-level characteristics, including population distributions, growth, and ingestion rates.

Many Antarctic seabirds depend on prey that are patchy, cryptic, ephemeral, and unpredictable in location. These predators typically employ two alternative behavioral strategies for locating resource patches: direct visual or olfactory detection, and indirect detection (local enhancement) by sighting other predators that are already exploiting a patch. We developed a model of direct detection and local enhancement in seabirds that predicts how foraging success varies with behavioral strategy, seabird densities, and prey swarm density and detectability. Application of the model to Black-browed Albatrosses foraging for Antarctic krill near South Georgia suggests that local enhancement is generally a highly effective foraging strategy, and that the fraction of time albatrosses spend in feeding flocks should show strong interactions between prey and conspecific densities. To test these predictions, we analyzed survey data collected near South Georgia in January-March 1986. Our analysis suggests a strong Allee-type density dependence in foraging success that was qualitatively and quantitatively consistent with model predictions. This density dependence suggests a potential for destabilizing patterns of resource utilization and reproductive success in Black-browed Albatrosses that may have important implications for conservation of albatrosses and other Antarctic species. Key words: Allee effect; Antarctic krill: area-restricted search; Black-browed Albatross; density dependence; Euphausial superba; foraging model; foraging strategy; local enhancement; South Georgia; Thalassarche melanophris.

Heterogeneous, 'aggregated' patterns in the spatial distributions of individuals are almost universal across living organisms, from bacteria to higher vertebrates. Whereas specific features of aggregations are often visually striking to human eyes, a heuristic analysis based on human vision is usually not sufficient to answer fundamental questions about how and why organisms aggregate. What are the individual-level behavioral traits that give rise to these features? When qualitatively similar spatial patterns arise from purely physical mechanisms, are these patterns in organisms biologically significant, or are they simply epi-phenomena that are likely characteristics of any set of interacting autonomous individuals? If specific features of spatial aggregations do confer advantages or disadvantages in the fitness of group members, how has evolution operated to shape individual behavior in balancing costs and benefits at the individual and group levels? Mathematical models of social behaviors such as schooling in fishes provide a promising avenue to address some of these questions. However, the literature on schooling models has lacked a common framework to objectively and quantitatively characterize relationships between individual-level behaviors and group-level patterns. In this paper, we briefly survey similarities and differences in behavioral algorithms and aggregation statistics among existing schooling models. We present preliminary results of our efforts to develop a modeling framework that synthesizes much of this previous work, and to identify relationships between behavioral parameters and group-level statistics., Types of Aggregations Aggregation occurs in the smallest organisms--bacteria--and the largest--whales--and spans virtually the entire extant diversity of taxon, habitat, trophic level, life-history strategy, degree of mobility, and many other [...]

Byline: Daniel Grunbaum (1) Keywords: Key words:aTaxis; Kinesis; Area-restricted search; Random walk; Advection; diffusion equation; Foraging strategy; Ideal-free distribution Abstract: aMany organisms search for limiting resources by using repeated responses to local cues, which cumulatively cause movement towards more favorable parts of their environment. This paper presents a general asymptotic expression, derived under the assumption of shallow environmental gradients, for the population-level flux of organisms moving at a constant speed and reorienting at rates determined by the environmental conditions experienced since the last reorientation. The expression takes the form of an advection-diffusion equation, in which the diffusivity and advection velocity are determined by statistics of the turning algorithm that are directly comparable to empirical observations. This work provides a mechanism with which to systematically evaluate a wide variety of tactic and kinetic strategies for determining turning behaviors. The model is applied to searchers on spatially-variable, random distributions of discrete resource patches. Such algorithms are functions of the integrated resource density encountered between turns. It is shown that behaviors in which the turning time distribution is a function of integrated density cannot result in taxis. In contrast, behaviors in which the turning rate is a function of integrated density can result in taxis. These two classes of search algorithm differ in that the latter requires the searcher to 'learn' about its local environment, whereas the former requires no such assessment. This suggests neural or physiological mechanisms for remembering previous encounters may be a biological requirement for searchers on discrete resource distributions. Author Affiliation: (1) Mathematics Department, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Y4, CA Article note: Received: 21 September 1995/Revised version: 18 July 1996

The functional consequences of the varied arm arrangements for larval swimming performance are studied using a hydromechanical model of idealized equal-armed larvae. It is observed that the vertical transport may affect diverse passively stable swimmers and not only the armed larvae.

Presents information on a study which examined the functional relationship and aspect of performance of parallel tentacular structures with lateral cilia. Materials and methods; Allometry abd geometrical variations; Results.

Many aquatic animals face a fundamental problem during foraging and migratory movements: while their resources commonly vary at large spatial scales, they can only sample and assess their environment at relatively small, local spatial scales. Thus, they are unable to choose movement directions by directly sampling distant parts of their environment. A common strategy to overcome this problem is taxis, a behavior in which an animal performs a biased random walk by changing direction more rapidly when local conditions are getting worse. Such an animal spends more time moving in right directions than wrong ones, andeventually gets to a favorable area. Taxis is inefficient, however, when environmental gradients are weak or overlain by 'noisy' small-scale fluctuations. In this paper, I show that schooling behavior can improve the ability of animals performing taxis to climb gradients, even under conditions when asocial taxis would be ineffective. Schooling is a social behavior incorporating tendencies to remain close to and align with fellow members of a group. It enhances taxis because thealignment tendency produces tight angular distributions within groups, and dampens the stochastic effects of individual sampling errors. As a result, more school members orient up-gradient than in the comparable asocial case. However, overly strong schooling behavior makes the school slow in responding to changing gradient directions. This trade-off suggests an optimal level of schooling behavior for given spatio-temporal scales of environmental variations. Social taxis may enhance the selective value of schooling in pelagic grazers such as herrings, anchovies and Antarctic krill. Furthermore, the degree of aggregation in a population of schooling animals may affect directly the rate and direction of migration and foraging movements. [ABSTRACT FROM AUTHOR]