scholarly journals Predator-induced selection on urchin activity level depends on urchin body size

2019 ◽  
Author(s):  
Justin Pretorius ◽  
James L.L. Lichtenstein ◽  
Erika J. Eliason ◽  
Adrian C. Stier ◽  
Jonathan N. Pruitt
Keyword(s):  
Body Size ◽  
Sea Urchins ◽  
Spiny Lobster ◽  
Activity Level ◽  
Kelp Forests ◽  
Ecological Processes ◽  
Panulirus Interruptus ◽  
Negative Effect ◽  
Slow Moving ◽  
The Stability

ABSTRACTTemporally consistent individual differences in behavior impact many ecological processes. We simultaneously examined the effects of individual variation in prey activity level, covering behavior, and body size on prey survival with predators using an urchin-lobster system. Specifically, we tested the hypothesis that slow-moving purple sea urchins (Strongylocentrotus purpuratus) and urchins who deploy extensive substrate (pebbles and stones) covering behavior will out-survive active urchins that deploy little to no covering behavior when pitted against a predator, the California spiny lobster (Panulirus interruptus). We evaluated this hypothesis by first confirming whether individual urchins exhibit temporally consistent differences in activity level and covering behavior, which they did. Next, we placed groups of four urchins in mesocosms with single lobster and monitored urchin survival for 108 hours. High activity level was negatively associated with survival, whereas urchin size and covering behavior independently did not influence survival. The negative effect of urchin activity level on urchin survival was strong for smaller urchins and weaker for large urchins. Taken together, these results suggest that purple urchin activity level and size jointly determine their susceptibility to predation by lobsters. This is potentially of great interest, because predation by recovering lobster populations could alter the stability of kelp forests by culling specific phenotypes, like foraging phenotypes, from urchin populations.

scholarly journals Pattern and reset analysis of the gastric mill rhythm in a spiny lobster, Panulirus interruptus

1985 ◽  
Vol 114 (1) ◽  
pp. 71-98
Author(s):  
D. F. Russell
Keyword(s):  
Spiny Lobster ◽  
Activity Level ◽  
Cycle Period ◽  
Gastric Mill ◽  
Panulirus Interruptus ◽  
Terrestrial Locomotion ◽  
Variable Duration ◽  
Burst Pattern ◽  
Constant Duration

The burst pattern of the gastric mill rhythm was studied by varying its cycle period in in vitro preparations comprising the stomatogastric (STG), oesophageal and (paired) commissural ganglia. Reset tests using intracellular polarization of identified STG neurones showed that the CI, LC, GP and GM cells can all strongly affect the cycle period, and therefore apparently play a role in generating the gastric rhythm. Variation in the cycle period could be obtained by: (i) cutting certain input nerves; (ii) relative coordination between the gastric and oesophageal rhythms; or (iii) intracellular polarization of identified STG cells, especially the LC motoneurone. Variation in the cycle period by any of these means showed that the gastric pattern (in such preparations) comprises two basic alternating phases: a variable-duration ‘powerstroke’ and a constant-duration ‘returnstroke’. The powerstroke is taken to include bursts in the LC, GP and GM motoneurones (since they evoke closing of the gastric mill teeth and mastication of food), along with the interburst intervals of the other cells. The durations of all these events co-varies over a large range, as a linear function of the cycle period. The activity level of neurones bursting during the powerstroke is directly proportional to their burst length, and hence appears to be a basic parameter affecting the cycle period. The returnstroke is taken to include bursts in the CP, AM and LG motoneurones (since they evoke opening and resetting of the gastric mill teeth), along with the interburst intervals of the powerstroke cells. All these events tended to assume a fixed duration. The two-part gastric mill pattern can be analogized to other two-part rhythms, e.g. for terrestrial locomotion, in which the load-bearing phase has a variable duration and accounts for most of the variation in the cycle period whereas the unloaded phase tends to assume a constant duration.

Influence of local-scale and landscape-scale habitat characteristics on California spiny lobster (Panulirus interruptus) abundance and survival

2007 ◽  
Vol 58 (5) ◽  
pp. 419 ◽  
Author(s):  
Thien T. Mai ◽  
Kevin A. Hovel
Keyword(s):  
Habitat Use ◽  
Habitat Structure ◽  
Spiny Lobster ◽  
Kelp Forest ◽  
Relative Survival ◽  
Landscape Scale ◽  
Habitat Characteristics ◽  
Ecological Processes ◽  
Panulirus Interruptus ◽  
Landscape Scales

For many marine systems, little is known about the effects of habitat structure on ecological processes that dictate population dynamics. This study focused on the effects of habitat structure on behaviour, abundance, and survival of California spiny lobster (Panulirus interruptus Randall) in the Point Loma kelp forest, San Diego, California. Habitat characteristics were quantified in 400-m2 landscapes to determine the role of shelter and understorey kelp characteristics at local (shelter) scales and landscape scales on lobster habitat use. A tethering experiment determined the effects of the presence of understorey kelp on lobster survival. At the shelter scale, lobsters preferred permanent shelters to ephemeral shelters, but did not respond to shelter size. At the landscape scale, lobster density increased with Pterygophora californica (stipitate kelp) density and decreased with Laminaria farlowii (prostrate kelp) density, but lobster density did not vary with shelter density or dispersion. Lobster size increased with P. californica density in two of three surveys, while lobster size did not vary with L. farlowii density. Lobster relative survival was higher in the presence of understorey kelp than when kelp was absent. We conclude that lobsters respond to habitat characteristics at local and landscape scales, and that understorey kelp has strong effects on lobster habitat use and survival.

The scaling of acceleratory aquatic locomotion: body size and tail-flip performance of the california spiny lobster panulirus interruptus

1999 ◽  
Vol 202 (22) ◽  
pp. 3181-3193 ◽  
Author(s):  
J.C. Nauen ◽  
R.E. Shadwick
Keyword(s):  
Body Size ◽  
Angular Displacement ◽  
Rotational Velocity ◽  
Spiny Lobster ◽  
Angular Acceleration ◽  
Rotational Acceleration ◽  
Panulirus Interruptus ◽  
Wide Range ◽  
Tail Flip ◽  
Translational Acceleration

Tail-flipping is a crucial escape locomotion of crustaceans which has been predicted to be limited by increased body mass (M(b)). Given isometric growth, one may predict that with growth event duration will decrease as M(b)(−)(1/3), translational distances will increase as M(b)(1/3), translational velocity will be independent of M(b), translational acceleration will decrease as M(b)(−)(1/3), angular displacement will be independent of M(b) and angular velocity and angular acceleration will decrease as M(b)(−)(1/3). We tested these hypotheses by examining the scaling of 12 morphological variables, five kinematic variables and six performance variables of tail-flipping by the California spiny lobster Panulirus interruptus. Growth approximated isometry, which validated the use of the proposed scaling hypotheses. For animals from 1 to 1000 g M(b), the predicted scaling relationships for tail-flip duration and translational distance and velocity variables were supported; however, translational acceleration performance was much better than predicted. Predictions for rotation and rotational velocity variables were not supported, while the rotational acceleration data closely matched the predicted relationship. The increase in tail-flip duration as predicted suggests that muscle shortening velocity decreases with growth; the sustained acceleration performance (similar to findings for shrimp and fish fast-starts) suggests that muscle force output may increase at a greater rate than predicted by isometry. The scaling of rotational acceleration indicates that the torque produced during the tail-flip scales with a mass exponent greater than 1. Comparison of the tail-flip performance of Panulirus interruptus with those of other crustacean species reveals a wide range in performance by animals of similar body size, which suggests that the abdominal muscle may show interesting differences in contractile properties among different species.

scholarly journals Impacts of vigorous and non-vigorous activity on daily energy expenditure

2003 ◽  
Vol 62 (3) ◽  
pp. 645-650 ◽  
Author(s):  
Klaas R. Westerterp
Keyword(s):  
Physical Activity ◽  
Body Size ◽  
Energy Expenditure ◽  
Exercise Training ◽  
Physical Activity Level ◽  
High Intensity ◽  
Activity Level ◽  
Daily Energy Expenditure ◽  
Activity Intensity ◽  
Daily Energy

Activity intensity is a potential determinant of activity-induced energy expenditure. Tri-axial accelerometery is the most objective measurement technique for the assessment of activity intensity, in combination with doubly-labelled water for the measurement of energy expenditure under free-living conditions. Data on the effects of subject characteristics, including body size and age, and exercise training on the relationship between activity intensity and daily energy expenditure are reviewed. Average daily metabolic rate and non-basal energy expenditure are positively related to body size. The duration and intensity of physical activities do not need to be equivalent to the energy spent on activity. Obese subjects spend more energy on physical activity but can perform fewer activities, especially high-intensity (weight-bearing) activities, because of their higher body weight. Physical activity generally declines gradually from about 60 years of age onwards. Most subjects >80 years have an activity level well below the level defined for sedentary middle-aged adults. Spending relatively more time on low-intensity activities has a negative effect on the mean physical activity level. To obtain a higher physical activity level does not necessarily imply high-intensity activities. In an average subject 25% of the activity-induced energy expenditure may be attributed to high-intensity activities. Exercise training, as a form of high-intensity activity, affects the physical activity level more in younger subjects than in elderly subjects.

scholarly journals Valuation of kelp forest ecosystem services in the Falkland Islands: A case study integrating blue carbon sequestration potential

One Ecosystem ◽  
2021 ◽  
Vol 6 ◽  
Author(s):  
Daniel Bayley ◽  
Paul Brickle ◽  
Paul Brewin ◽  
Neil Golding ◽  
Tara Pelembe
Keyword(s):  
Ecosystem Services ◽  
Kelp Forest ◽  
Blue Carbon ◽  
Falkland Islands ◽  
Kelp Forests ◽  
Storm Damage ◽  
Ecological Processes ◽  
True Value ◽  
Sequestration Potential

Kelp forests provide many important ecosystem services to people, including mitigating storm damage, cycling nutrients, and providing commercially-harvestable resources. However, kelp forests’ ability to sequester carbon dioxide, and therefore help regulate the climate, has until recently, been overlooked in assessments of the beneficial services they provide. In this study we incorporate updated knowledge on the potential of kelp to sequester ‘blue carbon’, and use the extensive kelp forests of the Falkland Islands as a case study to assess the value of kelp forest to society through multiple associated ecosystem services. Our analysis shows kelp forests provide a highly valuable range of direct and indirect services, which if managed correctly, will continue to benefit people, both now and in the future. The total estimated value of the Falkland Islands’ kelp system is currently equivalent to ~ £2.69 billion per year (or £3.24 million km-2 year-1). However, the true value of the kelp forest surrounding the Falkland Islands is likely to be higher still, given that our estimate does not account for elements such as associated scientific research, tourism, and cultural services, due to the necessary data currently being unavailable. Similarly, the full value of these highly biodiverse ecosystems in supplying habitat and food to a large range of associated species is crucial, yet extremely difficult to fully quantify. This study illustrates the importance of maintaining kelp ecosystems in a healthy state to ensure they continue to supply valuable ecological processes, functional roles, and ecosystem services, including their overlooked role as significant long-term carbon sinks.

scholarly journals Effect of early determinants on adolescent fat-free mass

2020 ◽  
Vol 54 ◽  
pp. 113
Author(s):  
Raina Jansen Cutrim Propp Lima ◽  
Rosângela Fernandes Lucena Batista ◽  
Cecília Claudia Costa Ribeiro ◽  
Vanda Maria Ferreira Simões
Keyword(s):  
Physical Activity ◽  
Socioeconomic Status ◽  
Birth Weight ◽  
Physical Activity Level ◽  
Structural Equation ◽  
Activity Level ◽  
Fat Free Mass ◽  
Equation Modeling ◽  
Adolescent Physical Activity ◽  
Negative Effect

OBJECTIVE: To analyze the effects of early determinants on adolescent fat-free mass. METHODS: A c ohort s tudy w ith 5 79 a dolescents e valuated a t b irth a nd a dolescence i n a birth cohort in São Luís, Maranhão. In the proposed model, estimated by structural equation modeling, socioeconomic status (SES) at birth, maternal age, pregestational body mass index (BMI), gestational smoking, gestational weight gain, type of delivery, gestational age, sex of the newborn, length and weight at birth, adolescent socioeconomic status, “neither study/nor work” generation, adolescent physical activity level and alcohol consumption were tested as early determinants of adolescent fat-free mass (FFM). RESULTS: A higher pregestational BMI resulted in higher FFM in adolescence (Standardized Coefficient, SC = 0.152; p < 0.001). Being female implied a lower FFM in adolescence (SC = -0.633; p < 0.001). The negative effect of gender on FFM was direct (SC = -0.523; p < 0.001), but there was an indirect negative effect via physical activity level (SC = -0.085; p < 0.001). Women were less active (p < 0.001). An increase of 0.5 kg (1 Standard Deviation, SD) in birth weight led to a gain of 0.25 kg/m2 (0.106 SD) in adolescent FFM index (p = 0.034). Not studying or working had a negative effect on the adolescent’s FFM (SC = -0.106; p = 0.015). Elevation of 1 SD in the adolescent’s physical activity level represented an increase of 0.5 kg/m2 (0.207 SD) in FFM index (p < 0.001). CONCLUSIONS: The early determinants with the greatest effects on adolescent FFM are gender, adolescent physical activity level, pregestational BMI, birth weight and belonging to the “neither-nor” generation.

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