scholarly journals Population development and status of harbour seals (Phoca vitulina) in the Wadden Sea

2010 ◽  
Vol 8 ◽  
pp. 95 ◽  
Author(s):  
Peter JH Reijnders ◽  
Sophie MJM Brasseur ◽  
Svend Tougaard ◽  
Ursula Seibert ◽  
Thomas Borchardt ◽  
...  
Keyword(s):  
Health Status ◽  
Wadden Sea ◽  
Conservation Status ◽  
Health Condition ◽  
Harbour Seal ◽  
Population Development ◽  
Sex Structure ◽  
Phocine Distemper Virus ◽  
Favourable Conservation Status ◽  
Seal Population

An index for the condition of a population should include a measure of the recuperative power or resilience of the population in question. This measure needs to cover both the demographic and physiological condition of the population. Applied to the harbour seal population in the Wadden Sea we therefore address respectively the population development and distribution, and its health condition, and relate these to environmental conditions. The harbour seal population has been severely depleted by hunting in the first half of the 20th century. After hunting was stopped in the mid-1970s the population recovered gradually. This recovery was twice interrupted by Phocine Distemper Virus (PDV) outbreaks in 1988 and 2002. These PDV-epizootics reduced the population by 57% and 50% respectively. They also lead to changes in age and sex structure of the population, which gradually returned to a stable age-structure. Despite the reduction in population size by respectively 57% and 50%, the population showed a strong recovery with a growth rate close to the considered maximum possible for this species. The observed changes in the distribution of the population over the 4 sub-regions indicate that distribution is not a static phenomenon. Long term field and pathological investigations point out that the general health status of the population has improved, particularly that of newborn seals (0-6months old). The increasing prevalence of parasites in lungs and intestine warrants continued monitoring of the health status of seals. This is especially relevant in view of the exponential increase of the population, which may finally approach the carrying capacity of the area. Concluding, we canstate that the condition of the population in terms of demographic and health parameters is satisfactory. The best guarantee for maintaining such a favourable conservation status is to abstain from human interferences (e.g. rescue, rehabilitation and release) with natural population processes. However, in practice there is increasing exploitation of marine waters. This requires a continuous monitoring of the potential impacts on the population, particularly of the effect on foraging and migratory behaviour.

Assessing the impact of mowing on Common Redshanks Tringa totanus breeding on saltmarshes: lessons for conservation management

2017 ◽  
Vol 27 (3) ◽  
pp. 440-453 ◽  
Author(s):  
KLAUS-MICHAEL EXO ◽  
ARNDT H. J. WELLBROCK ◽  
JULIA SONDERMANN ◽  
MARTIN MAIER
Keyword(s):  
At Risk ◽  
Wadden Sea ◽  
Conservation Status ◽  
Habitats Directive ◽  
Positive Effects ◽  
Management Measures ◽  
Favourable Conservation Status ◽  
Study Sites ◽  
The Impact ◽  
Tringa Totanus

SummaryInformed application of habitat management measures is crucial, especially in saltmarshes that function as last refuges for breeding waders in Europe. Despite a reduction in agricultural use of saltmarshes since the establishment of the Wadden Sea National Parks at the end of the 1980s, there remains controversy regarding management measures such as the timing of mowing. We modelled the proportion of nests and chicks that would be jeopardised by mowing at different dates, using long-term breeding data of the Common Redshank Tringa totanus – an endangered and widespread indicator species of saltmarshes – from four study sites in the German Wadden Sea. At two study sites in the western Jadebusen, the proportion of broods that were at risk of being killed when mowing began on 1 July ranged between 78% in early, to 96% in late, breeding years, averaging 87%. Although Common Redshanks in the eastern Jadebusen started breeding one week earlier, the model still predicted a loss of 73% of chicks; while 97% of broods were at risk on the island of Wangerooge. Postponement of mowing to 1 August reduced these proportions to 21%, 11% and 32%, respectively. This study is the first to model the positive effects of delayed mowing of saltmarshes on ground-nesting birds. By implementing adjusted mowing dates in addition to previously suggested reductions in artificial drainage, direct and indirect adverse effects caused by mowing and drainage, such as an increased predation risk, are likely to be reduced, such that a ’favourable conservation status’ according to the EC Habitats Directive may be achieved.

scholarly journals Continued presence of phocine distemper virus in the Dutch Wadden Sea seal population

1993 ◽  
Vol 133 (13) ◽  
pp. 320-322 ◽  
Author(s):  
I. Visser ◽  
E. Vedder ◽  
H. Vos ◽  
M. van de Bildt ◽  
A. Osterhaus
Keyword(s):  
Wadden Sea ◽  
Phocine Distemper Virus ◽  
Seal Population

scholarly journals Harbour seals are regaining top-down control in a coastal ecosystem

2018 ◽  
Author(s):  
Geert Aarts ◽  
Sophie Brasseur ◽  
Jan Jaap Poos ◽  
Jessica Schop ◽  
Roger Kirkwood ◽  
...  
Keyword(s):  
North Sea ◽  
Marine Mammal ◽  
Wadden Sea ◽  
Demersal Fish ◽  
Fish Growth ◽  
Harbour Seal ◽  
Top Down ◽  
Harbour Seals ◽  
Seal Population ◽  
The Impact

ABSTRACTHistoric hunting has led to severe reductions of many marine mammal species across the globe. After hunting ceased, some populations have recovered to pre-exploitation levels, and may again act as a top-down regulatory force on marine ecosystems. Also the harbour seal population in the international Wadden Sea grew at an exponential rate following a ban on seal hunting in 1960’s, and the current number ∼38,000 is close to the historic population size. Here we estimate the impact of the harbour seal predation on the fish community in the Wadden Sea and nearby coastal waters.Fish remains in faecal samples and published estimates on the seal’s daily energy requirement were used to estimate prey selection and the magnitude of seal consumption. Estimates on prey abundance were derived from demersal fish surveys, and fish growth was estimated using a Dynamic Energy Budget model. GPS tracking provided information on where seals most likely caught their prey.Harbour seals from the Dutch Wadden Sea fed predominantly on demersal fish, e.g. flatfish species (flounder, sole, plaice, dab), but also sandeel, cod and whiting. Total fish biomass in the Wadden Sea was insufficient to sustain the estimated prey consumption of the entire seal population year-round. This probably explains why seals also acquire prey further offshore in the adjacent North Sea, only spending 13% of their diving time in the Wadden Sea. Still, seal predation was estimated to cause an average annual mortality of 43% and 60% on fish in the Wadden Sea and adjacent coastal zone, respectively. There were however large sources of uncertainty in the estimate, including the migration of fish between the North Sea and Wadden Sea, and catchability estimates of the fish survey sampling gear, particularly for sandeel and other pelagic fish species.Our estimate suggested a considerable top-down control by harbour seals on demersal fish. However predation by seals may also alleviate density-dependent competition between the remaining fish, increasing fish growth, and partly compensating for the reduction in fish numbers. This study shows that recovering coastal marine mammal populations could potentially become an important component in the functioning of shallow coastal systems.

scholarly journals Natura 2000 sites and fisheries in German offshore waters

2008 ◽  
Vol 66 (1) ◽  
pp. 155-169 ◽  
Author(s):  
Søren Anker Pedersen ◽  
Heino Fock ◽  
Jochen Krause ◽  
Christian Pusch ◽  
Anne L. Sell ◽  
...  
Keyword(s):  
Marine Mammals ◽  
Fishery Management ◽  
Conservation Status ◽  
Natura 2000 ◽  
Management Measures ◽  
Favourable Conservation Status ◽  
Management Plans ◽  
Natura 2000 Site ◽  
Environmentally Sound ◽  
Fishing Impacts

Abstract Pedersen, S. A., Fock, H., Krause, J., Pusch, C., Sell, A. L., Böttcher, U., Rogers, S. I., Sköld, M., Skov, H., Podolska, M., Piet, G. J., and Rice, J. C. 2009. Natura 2000 sites and fisheries in German offshore waters.–ICES Journal of Marine Science, 66: 155–169. The principal objective of sites selected as part of Natura 2000 is to achieve or maintain a favourable conservation status of habitats and species named in the EU Birds and Habitats directives. In the German exclusive economic zone, the habitat types protected by this legislation are sandbanks and reefs; protected species include marine mammals, seabirds, and specific migratory fish species. The ICES project Environmentally Sound Fishery Management in Protected Areas (EMPAS) aims to answer two questions: (i) To what extent do specific fishing activities significantly threaten attainment of the conservation objectives of the Natura 2000 sites? (ii) What management measures would reduce these conflicts and how effective would they be at helping to ensure the favourable condition of these sites? Assessments of fishing impacts on Natura 2000 sites require basic data on the conservation status of individual habitats and species, as well as data for fine-scale distributions of ongoing fishing activities. This paper describes and discusses the process used by the EMPAS project in developing fishery-management plans for each Natura 2000 site in German offshore waters.

Health status and lifestyle of the Oraon tea garden labourers of Jalpaiguri district, West Bengal

2017 ◽  
Author(s):  
Subrata K. Roy ◽  
Tanaya Kundu Chowdhury
Keyword(s):  
Health Status ◽  
Work Environment ◽  
West Bengal ◽  
Health Condition ◽  
Physical Health Status ◽  
Health Lifestyles ◽  
The Poor ◽  
Medical Facilities ◽  
Tea Garden ◽  
Sufficient Food

This chapter looks at the health and lifestyle factors among tea garden labourers in West Bengal. Tea garden labourers enjoy access to some free facilities like education for children, medical facilities, piped drinking water, housing, and subsidised food. Yet they still suffer from several health problems. This might be due to insufficient or inadequately maintained facilities, poor lifestyles, or a mixture thereof. The chapter then focuses on the work environment, lifestyles, and physical health status of Oraon tea garden labourers of Jalpaiguri district, West Bengal. The results reveal that around 60 per cent of the labourers are underweight, despite reporting that they were getting sufficient food to eat. Poor hygienic practices may explain these results. Anaemia was also high for both sexes. Ultimately, the overall health condition of the labourers may be explained by the poor health lifestyles that they have adopted in response to their work environment.

scholarly journals Pruning treatment: A possible method for improving the conservation status of a Ellisella paraplexauroides Stiasny, 1936 (Anthozoa, Alcyonacea) population in the Chafarinas Islands?

2017 ◽  
pp. 479
Author(s):  
LUIS SANCHEZ-TOCINO ◽  
ANTONIO DE LA LINDE RUBIO ◽  
M SOL LIZANA ROSAS ◽  
TEODORO PÉREZ GUERRA ◽  
JOSE MANUEL TIERNO DE FIGUEROA
Keyword(s):  
Health Status ◽  
Pilot Study ◽  
Sexual Reproduction ◽  
Conservation Status ◽  
Substantial Improvement ◽  
General Increase ◽  
Progressive Decline ◽  
The Future ◽  
Study Population ◽  
Population Regeneration

 In the present paper, the results of a four-year conservation study on the giant gorgonian Ellisella paraplexauroides in the Chafarinas Islands are reported. This species, currently protected in Spain, is present as isolated colonies or as a low number of them, except in the Chafarinas Islands, where higher densities can be found below a depth of 20 m. Nevertheless, as revealed by a previous study, a great number of colonies are partially covered by epibionts or totally dead. As a first objective of the present work, seven transects were performed in 2013 and 2014 to evaluate the percentage of colonies affected in areas that had not been previously sampled. Approximately between 35% and 95% of the colonies had different degrees of epibiosis or were dead. In 2015, ten transects were performed to specifically locate young colonies smaller than 15 cm, which could be indicative of population regeneration by sexual reproduction. The high number of dead colonies as well as the colonies covered by epibionts, together with the inexistence of young colonies, indicated a progressive decline of the study population. The last aim of the study consisted of testing a restoration action by means of pruning the affected colonies between 2015 and 2016. The results of this restoration action showed a substantial improvement of the colonies (growth of branches, production of new branches and a general increase in the health status of the colonies). Our results recommend the employment of this technique for the future conservation of this species in the Chafarinas Islands. Nevertheless, this is a pilot study, and further experiments with a large number of samples should be performed to truly understand the significance of this technique.

Sources and Fate of PCBs in the North Sea: A Review of Available Data

1991 ◽  
Vol 24 (10) ◽  
pp. 77-85 ◽  
Author(s):  
J. Klamer ◽  
R. W. P. M. Laane ◽  
J. M. Marquenie
Keyword(s):  
Adverse Effects ◽  
North Sea ◽  
German Bight ◽  
Marine Mammals ◽  
Wadden Sea ◽  
Annual Basis ◽  
The North ◽  
Total Input ◽  
Seal Population ◽  
The North Sea

From literature data it is calculated that on an annual basis, 11 to 17 tonnes of PCBs enter the North Sea. Largest sources are the Atlantic Ocean and the atmosphere: together they account for 60-79% of the total input. Sources with greatest impact are the rivers, sewers and sludge. Highest concentrations are found close to the Dutch shore and in the German Bight. The PCB levels result in adverse effects on the seal population in the Wadden Sea. Of the total world PCB production, at least 57% is still in use and their future dispersal into the oceans cannot easily be controlled. If the increase in ocean PCB concentration continues, it may ultimately result in the extinction of fish-eating marine mammals.

scholarly journals Harm Perceptions of E-cigarettes Among Smokers With and Without Mental Health Conditions in England: A Cross-Sectional Population Survey

2020 ◽  
Author(s):  
Charlie Albert Smith ◽  
Lion Shahab ◽  
Ann McNeill ◽  
Sarah E Jackson ◽  
Jamie Brown ◽  
...  
Keyword(s):  
Mental Health ◽  
Health Status ◽  
Health Condition ◽  
Mental Health Status ◽  
Health Conditions ◽  
Similar Proportion ◽  
Cross Sectional ◽  
Mental Health Conditions ◽  
Disadvantaged Groups ◽  
Nationally Representative

Abstract Introduction E-cigarettes (ECs) may benefit smokers with mental health conditions who are more likely to smoke, and smoke more heavily, than those without mental health conditions. This could be undermined if harm misperceptions in this group are high as is the case in the general population. This study aimed to assess EC harm perceptions relative to cigarettes as a function of mental health status and a variety of characteristics. Methods Data were collected from 6531 current smokers in 2016/2017 in household surveys of representative samples of adults. The associations of mental health status (self-reported mental health condition and past year treatment), smoking and EC use characteristics, and characteristics relating to use of potential information sources with harm perceptions of ECs relative to cigarettes (measured by correct response “less harmful” vs. wrong responses “more harmful,” “equally harmful,” “don’t know”) were analyzed with logistic regression. Results A similar proportion of smokers without mental health conditions (61.5%, 95% CI 60.1–62.9) and with mental health conditions (both with [61.3%, 95% confidence interval [CI] 58.7–63.8] and without past year treatment [61.5%, 95% CI 58.1–64.7]) held inaccurate EC harm perceptions (all P > 0.05). Being female, nonwhite, aged 25–34 compared with 16–24, from lower social grades (C2, D, and E), not having post-16 qualifications, no EC experience, a daily smoker, unmotivated to quit <1 month, non-internet user and non-broadsheet reader were all associated with more inaccurate harm perceptions (all p < .05). Conclusions The majority of smokers in England have inaccurate harm perceptions of ECs regardless of mental health status. Implications This study is the first to use a nationally representative sample in order to investigate whether smokers with and without mental health conditions differ with regard to harm perceptions of ECs. Findings show that the majority of smokers in England hold inaccurate harm perceptions of ECs, and this does not differ as a function of mental health status. A number of characteristics associated with disadvantaged groups were significantly associated with inaccurate harm perceptions. These findings highlight the need to improve awareness and understanding among disadvantaged groups regarding the relative harms of ECs compared with tobacco.

Interrogating the health condition of rails using the narrowband Rayleigh waves emitted by an innovative design of non-contact laser transduction system

2020 ◽  
pp. 147592172096760
Author(s):  
Faeez Masurkar ◽  
Kim Ming Ng ◽  
Peter W Tse ◽  
Nitesh P Yelve
Keyword(s):  
Health Status ◽  
Optical System ◽  
Rayleigh Waves ◽  
Rail Steel ◽  
Second Harmonic ◽  
Laser Doppler Vibrometer ◽  
Health Condition ◽  
Innovative Design ◽  
Scanning Laser Doppler Vibrometer ◽  
Contact Experiment

The article reports an innovative optical system that is designed to interrogate the health condition of macroscopically intact rail specimens by measuring its inherent nonlinearity using the narrowband Rayleigh waves. A line-arrayed pattern is developed through the optical system that generates narrowband Rayleigh waves with high power on the surface of the rail. As a result of lattice-anharmonicity, a second harmonic is produced in the wave that is sensed by a scanning laser Doppler vibrometer. The spectral amplitudes of the first and generated second harmonics are used to calculate the inherent nonlinearity using an amplitude-based nonlinearity equation. These measurements are carried out on the head, web, and foot of the rail. The performance of the non-contact experiment is also compared with that of a contact experiment carried out using wedge transducers. The experimentally evaluated nonlinearity of the rail steel is further compared with that obtained using a physics-based nonlinearity equation that relies on the higher-order elastic constants. Agreement of the results shows that the new optical system is effective in generating Rayleigh waves in rails and thereby measuring the inherent nonlinearity of the rail track. The estimation of inherent nonlinearity may help in diagnosing the health status of the macroscopically intact rail specimens in terms of their microstructural consistency and level of dissolved impurities before fixing them on a track.

scholarly journals Framework for assessing impacts of pile-driving noise from offshore wind farm construction on a harbour seal population

2013 ◽  
Vol 43 ◽  
pp. 73-85 ◽  
Author(s):  
Paul M. Thompson ◽  
Gordon D. Hastie ◽  
Jeremy Nedwell ◽  
Richard Barham ◽  
Kate L. Brookes ◽  
...  
Keyword(s):  
Wind Farm ◽  
Harbour Seal ◽  
Offshore Wind ◽  
Pile Driving ◽  
Offshore Wind Farm ◽  
Seal Population
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