scholarly journals Shore-level size gradients and thermal refuge use in the predatory sea star Pisaster ochraceus: the role of environmental stressors

2015 ◽  
Vol 539 ◽  
pp. 191-205 ◽  
Author(s):  
CJ Monaco ◽  
DS Wethey ◽  
S Gulledge ◽  
B Helmuth
Keyword(s):  
Environmental Stressors ◽  
Sea Star ◽  
Refuge Use ◽  
Shore Level ◽  
Pisaster Ochraceus ◽  
Thermal Refuge

Testing ecological release as a compensating mechanism for mass mortality in a keystone predator

2020 ◽  
Vol 637 ◽  
pp. 59-69 ◽  
Author(s):  
J Sullivan-Stack ◽  
BA Menge
Keyword(s):  
Community Dynamics ◽  
Limiting Factor ◽  
Sea Star ◽  
Top Predator ◽  
Oregon Coast ◽  
Ecological Release ◽  
Keystone Predator ◽  
Pisaster Ochraceus ◽  
Wasting Syndrome

Top predator decline has been ubiquitous across systems over the past decades and centuries, and predicting changes in resultant community dynamics is a major challenge for ecologists and managers. Ecological release predicts that loss of a limiting factor, such as a dominant competitor or predator, can release a species from control, thus allowing increases in its size, density, and/or distribution. The 2014 sea star wasting syndrome (SSWS) outbreak decimated populations of the keystone predator Pisaster ochraceus along the Oregon coast, USA. This event provided an opportunity to test the predictions of ecological release across a broad spatial scale and determine the role of competitive dynamics in top predator recovery. We hypothesized that after P. ochraceus loss, populations of the subordinate sea star Leptasterias sp. would grow larger, more abundant, and move downshore. We based these predictions on prior research in Washington State showing that Leptasterias sp. competed with P. ochraceus for food. Further, we predicted that ecological release of Leptasterias sp. could provide a bottleneck to P. ochraceus recovery. Using field surveys, we found no clear change in density or distribution in Leptasterias sp. populations post-SSWS, and decreases in body size. In a field experiment, we found no evidence of competition between similar-sized Leptasterias sp. and P. ochraceus. Thus, the mechanisms underlying our predictions were not in effect along the Oregon coast, which we attribute to differences in habitat overlap and food availability between the 2 regions. Our results suggest that response to the loss of a dominant competitor can be unpredictable even when based in theory and previous research.

scholarly journals The Gene Regulatory Roles of Herbal Extracts on the Growth, Immune System, and Reproduction of Fish

Animals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2167
Author(s):  
Ehsan Ahmadifar ◽  
Hamideh Pourmohammadi Fallah ◽  
Morteza Yousefi ◽  
Mahmoud A. O. Dawood ◽  
Seyed Hossein Hoseinifar ◽  
...  
Keyword(s):  
Immune System ◽  
Mode Of Action ◽  
Medicinal Herbs ◽  
Environmental Stressors ◽  
Fish Diet ◽  
Sustainable Aquaculture ◽  
Herbal Supplements ◽  
Aquatic Animals ◽  
Gene Regulatory

The crucial need for safe and healthy aquatic animals obligates researchers in aquaculture to investigate alternative and beneficial additives. Medicinal herbals and their extracts are compromised with diverse effects on the performances of aquatic animals. These compounds can affect growth performance and stimulate the immune system when used in fish diet. In addition, the use of medicinal herbs and their extracts can reduce oxidative stress induced by several stressors during fish culture. Correspondingly, aquatic animals could gain increased resistance against infectious pathogens and environmental stressors. Nevertheless, the exact mode of action where these additives can affect aquatic animals’ performances is still not well documented. Understanding the mechanistic role of herbal supplements and their derivatives is a vital tool to develop further the strategies and application of these additives for feasible and sustainable aquaculture. Gene-related studies have clarified the detailed information on the herbal supplements’ mode of action when administered orally in aquafeed. Several review articles have presented the potential roles of medicinal herbs on the performances of aquatic animals. However, this review article discusses the outputs of studies conducted on aquatic animals fed dietary, medicinal herbs, focusing on the gene expression related to growth and immune performances. Furthermore, a particular focus is directed to the expected influence of herbal supplements on the reproduction of aquatic animals.

scholarly journals Suppression of personality variation in boldness during foraging in three-spined sticklebacks

2021 ◽  
Vol 75 (4) ◽  
Author(s):  
Hannah E. A. MacGregor ◽  
Aislinn Cottage ◽  
Christos C. Ioannou
Keyword(s):  
Negative Feedback ◽  
Risk Taking ◽  
Positive Feedback ◽  
Gasterosteus Aculeatus ◽  
Control Treatment ◽  
Refuge Use ◽  
Individual Level ◽  
Behavioural Type ◽  
State Behaviour

Abstract Consistent inter-individual variation in behaviour within a population, widely referred to as personality variation, can be affected by environmental context. Feedbacks between an individual’s behaviour and state can strengthen (positive feedback) or weaken (negative feedback) individual differences when experiences such as predator encounters or winning contests are dependent on behavioural type. We examined the influence of foraging on individual-level consistency in refuge use (a measure of risk-taking, i.e. boldness) in three-spined sticklebacks, Gasterosteus aculeatus, and particularly whether changes in refuge use depended on boldness measured under control conditions. In the control treatment trials with no food, individuals were repeatable in refuge use across repeated trials, and this behavioural consistency did not differ between the start and end of these trials. In contrast, when food was available, individuals showed a higher degree of consistency in refuge use at the start of the trials versus controls but this consistency significantly reduced by the end of the trials. The effect of the opportunity to forage was dependent on behavioural type, with bolder fish varying more in their refuge use between the start and the end of the feeding trials than shyer fish, and boldness positively predicted the likelihood of feeding at the start but not at the end of the trials. This suggests a state-behaviour feedback, but there was no overall trend in how bolder individuals changed their behaviour. Our study shows that personality variation can be suppressed in foraging contexts and a potential but unpredictable role of feedbacks between state and behaviour. Significance statement In this experimental study, we examined how foraging influences consistency in risk-taking in individual three-spined sticklebacks. We show that bolder individuals become less consistent in their risk-taking behaviour than shyer individuals during foraging. Some bolder individuals reinforce their risk-taking behaviour, suggesting a positive feedback between state and behaviour, while others converge on the behaviour of shyer individuals, suggesting a negative feedback. In support of a role of satiation in driving negative feedback effects, we found that bolder individuals were more likely to feed at the start but not at the end of the trials. Overall, our findings suggest that foraging can influence personality variation in risk-taking behaviour; however, the role of feedbacks may be unpredictable.

scholarly journals The Influence ofNrf2on Cardiac Responses to Environmental Stressors

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Reuben Howden ◽  
Eva Gougian ◽  
Marcus Lawrence ◽  
Samantha Cividanes ◽  
Wesley Gladwell ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
High Frequency ◽  
Low Frequency ◽  
Therapeutic Strategies ◽  
Environmental Stressors ◽  
Total Power ◽  
Airborne Pollutants ◽  
Cardiac Responses

Nrf2protects the lung from adverse responses to oxidants, including 100% oxygen (hyperoxia) and airborne pollutants like particulate matter (PM) exposure, but the role ofNrf2on heart rate (HR) and heart rate variability (HRV) responses is not known. We hypothesized that genetic disruption ofNrf2would exacerbate murine HR and HRV responses to severe hyperoxia or moderate PM exposures.Nrf2-/-andNrf2+/+mice were instrumented for continuous ECG recording to calculate HR and HRV (low frequency (LF), high frequency (HF), and total power (TP)). Mice were then either exposed to hyperoxia for up to 72 hrs or aspirated with ultrafine PM (UF-PM). Compared to respective controls, UF-PM induced significantly greater effects on HR (P<0.001) and HF HRV (P<0.001) inNrf2-/-mice compared toNrf2+/+mice.Nrf2-/-mice tolerated hyperoxia significantly less thanNrf2+/+mice (~22 hrs;P<0.001). Reductions in HR, LF, HF, and TP HRV were also significantly greater inNrf2-/-compared toNrf2+/+mice (P<0.01). Results demonstrate thatNrf2deletion increases susceptibility to change in HR and HRV responses to environmental stressors and suggest potential therapeutic strategies to prevent cardiovascular alterations.

scholarly journals Pneumocystis Melanins Confer Enhanced Organism Viability

2006 ◽  
Vol 5 (6) ◽  
pp. 916-923 ◽  
Author(s):  
Crystal R. Icenhour ◽  
Theodore J. Kottom ◽  
Andrew H. Limper
Keyword(s):  
Fungal Pathogen ◽  
Pneumocystis Carinii ◽  
Environmental Stressors ◽  
Resonance Spectroscopy ◽  
Reverse Transcription Pcr ◽  
Spin Resonance ◽  
Opportunistic Fungal Pathogen ◽  
Adverse Environmental Conditions ◽  
Previous Identification

ABSTRACT Pneumocystis continues to represent an important opportunistic fungal pathogen of those with compromised immunity. Thus, it is crucial to identify factors that affect its viability and pathogenicity. We previously reported the first identification of melanins in Pneumocystis. In the present study, we sought to further characterize these components and define the function for these melanins. Melanins extracted from Pneumocystis and melanized Pneumocystis cells were analyzed by electron spin resonance spectroscopy, revealing spectra consistent with melanins from other fungi. Immunofluorescence assays using anti-melanin monoclonal antibodies showed that melanins are widely present across Pneumocystis host species, including mouse-, ferret-, and human-derived Pneumocystis organisms, as well as Pneumocystis carinii derived from rat. Using immunoelectron microscopy, melanins were found to localize to the cell wall and cytoplasm of P. carinii cysts, as well as to intracystic bodies within mature cysts. Next, the role of melanins on the maintenance of Pneumocystis viability was determined by using quantitative reverse transcription-PCR measurement of the heat shock protein mRNA under adverse environmental conditions. Using a new method to promote the melanization of Pneumocystis, we observed that strongly melanized Pneumocystis retained viability to a greater degree when exposed to UV irradiation or desiccation compared to less-pigmented organisms. These studies support our previous identification of Pneumocystis melanins across the genus, further characterize these Pneumocystis components, and demonstrate that melanins protect Pneumocystis from environmental stressors.

scholarly journals Central role of the habenulo-interpeduncular system in the neurodevelopmental basis of susceptibility and resilience to anxiety

2021 ◽  
Author(s):  
Malalaniaina Rakotobe ◽  
Niels Fjerdingstad ◽  
Nuria Ruiz-Reig ◽  
Thomas Lamonerie ◽  
Fabien D'Autréaux
Keyword(s):  
Stress Response ◽  
Brain Development ◽  
Chronic Stress ◽  
Environmental Stressors ◽  
Critical Node ◽  
Sensitive Periods ◽  
Early Stress ◽  
Effects Of Stress

Abstract Experiencing stress during sensitive periods of brain development has a major impact on how individuals cope with later stress. Although many become more prone to develop anxiety or depression, some appear resilient. The mechanisms underlying these differences are unknown. Key answers may lie in how genetic and environmental stressors interact to shape the circuits controlling emotions. Here we studied the role of the habenulo-interpeducuncular system (HIPS), a critical node of reward circuits, in early stress-induced anxiety. We found that a subcircuit of this system, characterized by Otx2 expression, is particularly responsive to chronic stress during puberty, which induces HIPS hypersensitivity to later stress and susceptibility to develop anxiety. We further show that Otx2 deletion restricted to the HIPS counteracts these effects of stress. Together, these results demonstrate that Otx2 and stress interact, around puberty, to shape the HIPS stress-response, revealed here as a key modulator of susceptibility/resilience to develop anxiety.

Sign in / Sign up

Export Citation Format

Share Document