Manta and devil rays are filter-feeding elasmobranchs that are found circumglobally in tropical and subtropical waters. Although relatively understudied for most of the 20th century, public awareness ...and scientific research on these species has increased dramatically in recent years. Much of this attention has been in response to targeted fisheries, international trade in mobulid products, and a growing concern over the fate of exploited populations. Despite progress in mobulid research, major knowledge gaps still exist, hindering the development of effective management and conservation strategies. We assembled 30 leaders and emerging experts in the fields of mobulid biology, ecology and conservation to identify pressing knowledge gaps that must be filled to facilitate improved science-based management of these vulnerable species. We highlight focal research topics in the subject areas of taxonomy and diversity, life history, reproduction and nursery areas, population trends, bycatch and fisheries, spatial dynamics and movements, foraging and diving, pollution and contaminants, and sub-lethal impacts. Mobulid rays remain a poorly studied group, and therefore our list of important knowledge gaps is extensive. However, we hope that this identification of high priority knowledge gaps will stimulate and focus future mobulid research.
Intraspecific colour polymorphisms have been the focus of numerous studies, yet processes affecting melanism in the marine environment remain poorly understood. Arguably, the most prominent example ...of melanism in marine species occurs in manta rays (
and
). Here, we use long-term photo identification catalogues to document the frequency variation of melanism across Indo-Pacific manta ray populations and test for evidence of selection by predation acting on colour morph variants. We use mark-recapture modelling to compare survivorship of typical and melanistic colour morphs in three
populations and assess the relationship between frequency variation and geographical distance
While there were large differences in melanism frequencies among populations of both species (0-40.70%), apparent survival estimates revealed no difference in survivorship between colour morphs. We found a significant association between phenotypic and geographical distance in
, but not in
. Our results suggest that melanism is not under selection by predation in the tested
populations, and that frequency differences across populations of both species are a consequence of neutral genetic processes
As genetic colour polymorphisms are often subjected to complex selection mechanisms, our findings only begin to elucidate the underlying evolutionary processes responsible for the maintenance and frequency variation of melanism in manta ray populations.
The characterization of diet for the giant manta ray Manta birostris has been problematic given their large-scale movement patterns and the difficulty in obtaining stomach contents from this species. ...The large majority of existing information is based on observational data limited to feeding events at the sea surface during daylight. Recently discovered aggregation sites for the giant manta ray off mainland Ecuador are some of the most accessible to date and provide a unique opportunity for researchers to gather much needed information on this elusive species. To assess how important surface zooplankton is to giant manta ray diet, we conducted stable isotope analysis (15N and 13C) on M. birostris muscle and surface zooplankton. Trophic position estimates placed M. birostris overall at a secondary consumer level of approximately 3.4 but there was large variation in δ15N and δ13C values among individuals. Manta birostris muscle tissue δ13C values were also not consistent with this species feeding predominantly on surface zooplankton and suggest that the majority of dietary intake is of mesopelagic origin. Given the conservative life history and fisheries pressure on large planktivores, knowledge of their trophic role and foraging strategies is essential to better understand their ecology and develop effective conservation measures.
The whale shark Rhincodon typus is a popular focal species in the marine tourism industry. We analysed 689 encounters with at least 142 individual sharks during 2008–2010 to assess their behaviour in ...the presence of swimmers at Tofo Beach, Mozambique. Sharks varied in size (estimated 3.0–9.5 m total length) and the majority (74%) were males. The sharks displayed avoidance behaviours during 64.7% of encounters. Encounter duration decreased significantly, from 12 minutes 37 s with undisturbed sharks to 8 minutes 25 s when sharks expressed avoidance behaviours, indicating that interactions with tourists affected the sharks’ short-term behaviour. However, during the 2.5-year study period we found no trend in the mean encounter duration, the overall expression of avoidance behaviour or the likelihood of an individual shark exhibiting avoidance behaviours. Potential effects of tourism may be mitigated by the non-breeding status and transient behaviour of sharks at this aggregation site.
Whale sharks Rhincodon typus are globally threatened, but a lack of biological and demographic information hampers an accurate assessment of their vulnerability to further decline or capacity to ...recover. We used laser photogrammetry at two aggregation sites to obtain more accurate size estimates of free-swimming whale sharks compared to visual estimates, allowing improved estimates of biological parameters. Individual whale sharks ranged from 432-917 cm total length (TL) (mean ± SD = 673 ± 118.8 cm, N = 122) in southern Mozambique and from 420-990 cm TL (mean ± SD = 641 ± 133 cm, N = 46) in Tanzania. By combining measurements of stranded individuals with photogrammetry measurements of free-swimming sharks, we calculated length at 50% maturity for males in Mozambique at 916 cm TL. Repeat measurements of individual whale sharks measured over periods from 347-1,068 days yielded implausible growth rates, suggesting that the growth increment over this period was not large enough to be detected using laser photogrammetry, and that the method is best applied to estimating growth rates over longer (decadal) time periods. The sex ratio of both populations was biased towards males (74% in Mozambique, 89% in Tanzania), the majority of which were immature (98% in Mozambique, 94% in Tanzania). The population structure for these two aggregations was similar to most other documented whale shark aggregations around the world. Information on small (<400 cm) whale sharks, mature individuals, and females in this region is lacking, but necessary to inform conservation initiatives for this globally threatened species.
Managerial Coaching Beattie, Rona S.; Kim, Sewon; Hagen, Marcia S. ...
Advances in developing human resources,
05/2014, Letnik:
16, Številka:
2
Journal Article
Recenzirano
The Problem
While managerial coaching becomes increasingly popular in both scholarly and practical circles, the line managers who need to execute this coaching may be neither capable nor interested ...in the coaching process. Furthermore, while the research on coaching seems promising, little is known about how to test the individual and environmental appropriateness of a coaching intervention.
The Solution
This review will inform and support evidence-based human resource development (HRD) professionals tasked with developing managers’ coaching capability. It is designed to help line managers who wish to enhance their managerial coaching practice.
The Stakeholders
This literature review and model will benefit organizations, HRD professionals, and line managers to determine whether coaching is an appropriate learning intervention for their context and at that particular time. Furthermore, if it is deemed appropriate, this review and resulting framework may aid in determining how practitioners should approach coaching within their organizational setting.
Sharks and rays are increasingly being identified as high-risk species for extinction, prompting urgent assessments of their local or regional populations. Advanced genetic analyses can contribute ...relevant information on effective population size and connectivity among populations although acquiring sufficient regional sample sizes can be challenging. DNA is typically amplified from tissue samples which are collected by hand spears with modified biopsy punch tips. This technique is not always popular due mainly to a perception that invasive sampling might harm the rays, change their behaviour, or have a negative impact on tourism. To explore alternative methods, we evaluated the yields and PCR success of DNA template prepared from the manta ray mucus collected underwater and captured and stored on a Whatman FTA™ Elute card. The pilot study demonstrated that mucus can be effectively collected underwater using toothbrush. DNA stored on cards was found to be reliable for PCR-based population genetics studies. We successfully amplified mtDNA ND5, nuclear DNA RAG1, and microsatellite loci for all samples and confirmed sequences and genotypes being those of target species. As the yields of DNA with the tested method were low, further improvements are desirable for assays that may require larger amounts of DNA, such as population genomic studies using emerging next-gen sequencing.
Manta rays are internationally threatened species and population declines have been reported in various locations worldwide. As iconic megafauna species, they are also major drawcards for wildlife ...tourism industries. Economic valuation of these industries can provide an incentive for
the protection of species and natural habitats through the creation of marine protected areas (MPAs) and the restriction of harvesting or trade. Site-specific estimates are essential, particularly in developing countries, to promote the nonconsumptive use of resources and develop appropriate
management strategies. This study represents the first localized estimate of the economic benefits of manta ray tourism in Mozambique. Data from 478 tourist expenditure surveys, 15 stakeholder surveys, and yearly diver numbers provided by coastal tour operators were used to estimate the economic
impact of manta ray tourism in the Inhambane Province. Manta ray-focused tours were estimated to be worth US$10.9 million per year in direct revenue to dive operators in the Inhambane Province, with an estimated direct economic impact (including associated tourism expenditures)
of US$34.0 million annually. In the absence of manta ray tourism, between $16.1 million and $25.7 million would be lost to the region each year. Tourist and stakeholder survey responses emphasized the importance of manta rays to Mozambican coastal tourism. Both parties
highlighted the need for increased protection of marine species and their environment and showed strong support for the implementation of MPAs along the Inhambane coast.
An opportunistic sighting of a reef manta ray (Mobula alfredi) along the northeastern corner of Cocos Island, Costa Rica, represents the first sighting of this species nearly 6000 km from the nearest ...confirmed sighting location in the Marquesas Islands and the first record of this species on either side of the American continent. Cocos Island is situated approximately 500 km away from mainland Costa Rica as well as any other suitable habitat for this species, suggesting the sighted individual may have migrated to this location. The individual was fitted with an acoustic transmitter (V16 Vemco Ltd., Nova Scotia, Canada) which will enable monitoring of its habitat use around the island and potential long-term residency patterns.
Background: Among patients with hepatitis C virus (HCV) monoinfection, 25-hydroxyvitamin D 25(OH)D concentrations are positively associated with a response to peg-interferon/ribavirin. Data on the ...relation between 25(OH)D concentrations and HCV treatment response in HIV-infected patients are limited.Objective: The objective was to determine whether baseline 25(OH)D concentrations predict virologic response in HIV/HCV co-infected patients and to examine variables associated with 25(OH)D concentrations ≥30 ng/mL.Design: Data and samples from 144 HCV genotype 1, treatment-naive patients from a completed HCV treatment trial were examined in this retrospective study. Early virologic response (EVR) was defined as ≥2 log10 reduction in HCV RNA and/or HCV RNA <600 IU/mL at week 12 of peg-interferon/ribavirin treatment. Baseline 25(OH)D was measured by liquid chromatography/tandem mass spectrometry.Results: Compared with the non-EVR control group (n = 68), the EVR group (n = 76) was younger, had fewer cirrhotic subjects, had a higher proportion with the IL28B CC genotype, had a higher albumin concentration, and had a lower HCV viral load at baseline (P ≤ 0.05). The difference in baseline 25(OH)D concentrations between EVR and non-EVR patients was not statistically significant (median: 25 ng/mL compared with 20 ng/mL; P = 0.23). Similar results were found for sustained virologic response (SVR). In multivariable analysis, white and Hispanic race-ethnicity (OR: 6.26; 95% CI: 2.47, 15.88; P = 0.0001) and ritonavir use (OR: 2.68; 95% CI: 1.08, 6.65; P = 0.033) were associated with higher 25(OH)D concentrations (≥30 ng/mL).Conclusion: Baseline 25(OH)D concentrations did not predict EVR or SVR. Because ritonavir impairs the conversion of 25(OH)D to the active metabolite, utilization of 25(OH)D may have been impaired in subjects taking ritonavir. This trial was registered at www.clinicaltrials.gov as NCT00078403.
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