The drift of Trichoptera larvae in a river with a disturbed hydrological regime

The aim of the study, carried out in a section of the Drzewiczka River downstream of a dam reservoir and a white-water canoeing track, was to estimate seasonal changes in the number of drifting invertebrates, especially Trichoptera and their body size and weight as compared with individuals living in benthos. It was also important to determine environmental factors which have the most significant influence on transported invertebrate fauna. The abundance of Trichoptera in benthos and drift was estimated for stonegravel habitats at 2 study sites; one just downstream of a canoeing track, which underwent flow fluctuations, marked as disturbed (D), and the other, control site (N), 10 km farther downstream, where no changes caused by 2 hydro-constructions were noticed. The percentage of dominant Trichoptera in drift [U coefficient, %] ranged from 0.0001 (Hydropsyche contubernalis McLachlan) to 0.06 (Halesus sp.). The U value for Trichoptera was 0.0005 and 0.012 at the 2 study sites, respectively, which indicates that when there was no correlation with the flow/current velocity, drifting preferences of Trichoptera were random or dependent on seasons, seasonal reservoir management, and larval concentration in the benthos, and at the same time independent of canoeist training. The highest number of drifting individuals was observed between March/April and August/September. This might be connected with a release of a larger amount of water from the impoundment after spring thaw and autumn rain, especially because sudden increases in water level and current velocity were noticed at that time. The increase in abundance of early developmental stages (juvenile) of caddis larvae in drift took place mainly in autumn and winter, whereas larvae at more advanced developmental stages were more frequently noticed in late spring. The differences in Trichopteran sizes at their 3th, 4th and 5th larval instars representing benthos and drift were observed by comparing the width of the head capsule [mm] and body mass [mg] of the examined individuals. Organisms transported in running water were definitely smaller than benthic ones, with the exception of the most developed larvae of H. pellucidula (Curtis).

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Vulnerability of coastal areas to increased aquifer saturation due to climate change

10.5194/egusphere-egu21-14870 ◽

2021 ◽

Author(s):

Alexandre Gauvain ◽

Ronan Abhervé ◽

Jean-Raynald de Dreuzy ◽

Luc Aquilina ◽

Frédéric Gresselin

Keyword(s):

Climate Change ◽

Sea Level ◽

Large Scale ◽

Regional Scale ◽

Drainage System ◽

Hydrological Regime ◽

Coastal Areas ◽

Western Coast ◽

Study Sites ◽

The Impact

Like in other relatively flat coastal areas, flooding by aquifer overflow is a recurring problem on the western coast of Normandy (France). Threats are expected to be enhanced by the rise of the sea level and to have critical consequences on the future development and management of the territory. The delineation of the increased saturation areas is a required step to assess the impact of climate change locally. Preliminary models showed that vulnerability does not result only from the sea side but also from the continental side through the modifications of the hydrological regime.We investigate the processes controlling these coastal flooding phenomena by using hydrogeological models calibrated at large scale with an innovative method reproducing the hydrographic network. Reference study sites selected for their proven sensitivity to flooding have been used to validate the methodology and determine the influence of the different geomorphological configurations frequently encountered along the coastal line.Hydrogeological models show that the rise of the sea level induces an irregular increase in coastal aquifer saturations extending up to several kilometers inland. Back-littoral channels traditionally used as a large-scale drainage system against high tides limits the propagation of aquifer saturation upstream, provided that channels are not dominantly under maritime influence. High seepage fed by increased recharge occurring in climatic extremes may extend the vulnerable areas and further limit the effectiveness of the drainage system. Local configurations are investigated to categorize the influence of the local geological and geomorphological structures and upscale it at the regional scale.

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Developing a census method based on sight counts to estimate rabbit (Oryctolagus cuniculus) numbers

Wildlife Research ◽

10.1071/wr02014 ◽

2003 ◽

Vol 30 (5) ◽

pp. 487 ◽

Cited By ~ 15

Author(s):

Dylan W. Poole ◽

Dave P. Cowan ◽

Graham C. Smith

Keyword(s):

Population Size ◽

Field Trials ◽

Population Estimates ◽

Economic Costs ◽

Natural Conditions ◽

Commercial Farms ◽

The Mean ◽

The Difference ◽

Study Sites ◽

Autumn And Winter

A rabbit-census method, based on systematic counts conducted at night or at dawn and dusk, was developed and validated in terms of estimating the total number of rabbits present in a given area. Initially, models were developed under semi-natural conditions to describe the relationships between the numbers of rabbits counted and population size. Confidence limits were also calculated. The models were developed by comparing rabbit counts with the actual number of rabbits present, from a known population of animals. Only spotlight counts at night were considered reliable enough to estimate rabbit population size. During the autumn and winter months these represented ~60% of the population present. The model was subsequently validated, in two different exercises, following a series of field trials conducted under a variety of conditions on commercial farms. Initially, population estimates derived from the model were compared with those calculated using an alternative census technique. Population estimates, using the two techniques, were very similar at nine of the ten study sites. A second validation exercise was also conducted whereby the number of rabbits removed at each of the sites was compared with the difference between the mean pre- and post-removal spotlight counts. The results further supported the proposition that spotlight counts represent ~60% of the population present, with the difference between the two mean spotlight counts representing 61.2% (± 11.0, s.d.) of the number of rabbits removed. The census method therefore shows considerable promise as a means to estimate rabbit numbers under a range of agricultural conditions and therefore has the potential to predict accurately the economic costs of rabbit damage and also to gauge the effectiveness of various methods of rabbit control.

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The Developmental Stages of Bracon Tachardiae, Cam. (Hym.)

Bulletin of Entomological Research ◽

10.1017/s0007485300012876 ◽

1934 ◽

Vol 25 (4) ◽

pp. 521-539 ◽

Cited By ~ 12

Author(s):

P. M. Glover

Keyword(s):

Developmental Stages ◽

Head Capsule ◽

The Body ◽

The Other ◽

Head Size ◽

Head Width ◽

Volume Increase ◽

Larval Instars ◽

Actual Range ◽

Actual Figure

SummaryThe egg, the five larval instars, cocoon, prepupa and pupa of Bracon tachardiae, Cameron, are described.Two series of larvae, one male and one female, occur, these series overlap very considerably and it is only towards the maximum and minimum of the range that larvae are respectively entirely female or male.It is shown that the five larval instars of B. tachardiae may be grouped by the widths of the head-capsule, and that an instar can be characterised by the head-width, particularly if only averages are considered. The actual range of head-width in each instar is rather large, and in some cases the extremes overlap. In actual practice head-width is a safe indication of the instar of a larva as the extremes rarely occur; the widths calculated on Dyar's principle also approximate sufficiently closely to the observed widths to preclude the chance of an ecdysis having been overlooked.The length of the mandible is for practical purposes identical in a larva of any given instar and in its exuviae. The larval instars and their exuviae can be grouped by the lengths of the mandibles, particularly if averages are considered; the range for a given instar is wide but the extremes do not overlap. The lengths calculated on Dyar's head-width principle approximate closely with the observed lengths, sufficiently so to preclude the possibility of overlooking an ecdysis, and making possible the identification of the instar of fixed and mounted specimens of larvae or exuviae, for which purpose head-width is useless.The factors of increase of head-width and mandibular length are fairly similar, falling near to 3 √2 =1.26, and for practical purposes one may be substituted for the other, the calculated widths and lengths so obtained still approximating to the observed widths and lengths.Various uses of this fact are indicated. Preliminary investigations point to the fact that similar observations apply to Aphrastobracon flavipennis, Ashm., an ectoparasite of Eublemma scitula, Ramb. It is suggested that similar observations may be true for other ectoparasitic Braconids.The growth of the body of the larva from instar to instar is independent of the growth of the head-capsule, larvae increasing in weight and in volume by a figure lying between 3 and 4 times from instar to instar. The actual figure obtained theoretically for volume increase was 3–6. The head-size increases by the usual double at each moult.

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Seasonal variation in development and survival of Ascaris suum and Trichuris suis eggs on pastures

Parasitology ◽

10.1017/s0031182099004503 ◽

1999 ◽

Vol 119 (2) ◽

pp. 209-220 ◽

Cited By ~ 65

Author(s):

M. N. LARSEN ◽

A. ROEPSTORFF

Keyword(s):

Developmental Stages ◽

Ascaris Suum ◽

Bare Soil ◽

Disappearance Rate ◽

Trichuris Suis ◽

Helminth Infections ◽

Autumn And Winter ◽

Post Deposition ◽

Experimental Plots ◽

Study Development

Pig faeces were deposited on experimental plots in the spring, summer, autumn and winter to study development and survival of Ascaris suum and Trichuris suis eggs under outdoor conditions. Faeces were placed either in short grass or 2 cm below the surface of bare soil, imitating pastures used by nose-ringed, grazing pigs or normally rooting pigs, respectively. The numbers and developmental stages of the eggs were recorded in faeces and soil for up to 50 weeks post-deposition. Embryonation took place only during the summer months and seemingly was independent of the microclimate. The majority of A. suum and T. suis eggs, which are generally considered to be extremely resistant and long-lived, seems to disappear rather fast. The disappearance rate for A. suum eggs was higher than for T. suis eggs, and both egg types disappeared significantly faster in the summer months than in the winter months, and when placed in short grass than when buried in soil (less exposed). We discuss how knowledge on egg development and survival may be used in the planning of pasture strategies for control of helminth infections in outdoor pigs.

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HEAD CAPSULE MEASUREMENTS OF THE LARCH SAWFLY, PRISTIPHORA ERICHSONII (HYMENOPTERA: TENTHREDINIDAE) IN KOUCHIBOUGUAC NATIONAL PARK, NEW BRUNSWICK

The Canadian Entomologist ◽

10.4039/ent112111-1 ◽

1980 ◽

Vol 112 (1) ◽

pp. 111-112 ◽

Cited By ~ 2

Author(s):

Patrick Maltais

Keyword(s):

New Brunswick ◽

Prince Edward Island ◽

National Park ◽

Developmental Stages ◽

Head Capsule ◽

Larix Laricina ◽

Maritime Provinces ◽

Eastern Canada ◽

Pristiphora Erichsonii ◽

Larch Sawfly

The larch sawfly, Pristiphora erichsonii (Htg.), is a serious defoliator of trees of the genus Larix and particularly of Larix laricina (Du Roi) K. Koch in eastern Canada. According to Reeks (1954), four outbreaks occurred in the Maritime Provinces between 1883 and 1942. Following the last outbreak, few specimens of the insect were found in New Brunswick, Nova Scotia, and Prince Edward Island until 1960 when an outbreak started near Fredericton, New Brunswick. Since, outbreaks varying in degree from moderate to severe have persisted throughout this province.In the course of a study on the ecology and population dynamics of the insect it was found necessary to verify and separate the various developmental stages of the larvae.

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Malaria Rapid Diagnostic Test (HRP2/pLDH) Positivity, Incidence, Care Accessibility and Impact of Community WASH Action in DR Congo: Mixed Method Study involving 625 Households

10.21203/rs.3.rs-27950/v1 ◽

2020 ◽

Author(s):

Nlandu Roger Ngatu ◽

Basilua Andre Muzembo ◽

Sakiko Kanbara ◽

Roger Wumba ◽

Mitsunori Ikeda ◽

...

Keyword(s):

Diagnostic Test ◽

Rapid Diagnostic Test ◽

Mixed Method ◽

Malaria Incidence ◽

Control Site ◽

Post Intervention ◽

Stagnant Water ◽

Household Level ◽

Malaria Burden ◽

Study Sites

Abstract Background Malaria is one of the most prevalent and deadliest illnesses in sub Saharan Africa (SSA). Despite recent gains made towards its control or elimination in past decades, many African countries still have endemic malaria transmission. Thus, the search for disease control strategies is indispensable. This study aimed to assess malaria burden at household level in Kongo central province, Democratic Republic of Congo (DRC), and the impact of community participatory water, sanitation and hygiene (WASH) action.Methods Mixed method research was conducted in two semi-rural towns, Mbanza-Ngungu (WASH action site) and Kasangulu (WASH control site) between July 2017 to March 2018, involving 625 households (3,712 individuals). Baseline and post-intervention malaria surveys were conducted in 2017 and 2018, respectively, using the World Bank/WHO Malaria Indicator Questionnaire. In addition, an action research consisting of a six-month (September 2017 - February 2018) prospective study was carried out which comprised two interventions: (1) a community participatory WASH action aiming at eliminating mosquito breeding sites in the residential environment and a (2) community anti-malaria education campaign. The latter was implemented at both study sites. In addition, baseline and post-intervention rapid diagnostic test (RDT) for malaria was performed among respondents. Furthermore, a six-month prospective hospital-based epidemiological study was simultaneously conducted using records of patients admitted at health settings located at both study sites.Results Prevalence of positive malaria RDT among respondents decreased significantly at WASH-action site (38% vs. 20%; p < 0.05), but no significant change was observed at the WASH control site. There were 96% of respondents (heads of households) who reported at least one malaria event occurring in the previous six-month period, only 66.5% of them received malaria care at a health setting. At household level, long-lasting insecticide-treated net (LLIN) was the most commonly used preventive measure (55%), followed by mosquito repellent (15%), indoor residual spraying (IRS) (2%), LLIN-IRS combination (2%); however, 24% of households did not use any measures. Mean household malaria incidence decreased at the WASH action site; 2.3 ± 2.2 cases vs. 1.2 ± 0.7 cases (p < 0.05), whereas no significant change was noted in control site. Moreover, malaria incidence rate was highest (60.9%) among households living in proximity to grassy and/or stagnant water spots. Low household monthly income (ORa = 2.37; 95%CI: 1.05–3.12; p < 0.05), Proximity to high risk area (grassy/stagnant water spots) for malaria (ORa = 5.13; 95%CI: 2-29-8.07; p < 0.001), poor general WASH status in residential area (ORa = 4.10; 95%CI: 2.11–7.08; p < 0.001) were determinants of household malaria. Furthermore, data collected from referral health settings showed high malaria frequency, 67.4% (1,108/1,645) occurring during the first semester of 2017, including 772 (70%) of pediatric malaria cases and 336 (30%) of cases from Internal medicine departments.Conclusion Findings from this research suggest the necessity for DRC government to scale up the fight against malaria by integrating efficient indoor and outdoor preventive measures, including WASH intervention in residential environment, and improve malaria care accessibility to reduce malaria burden. This would be a step towards achieving universal health coverage (UHC) in the Congo.

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Thermal summation model and instar determination of all developmental stages of necrophagous beetle,Sciodrepoides watsoni(Spence) (Coleoptera: Leiodidae: Cholevinae)

PeerJ ◽

10.7717/peerj.1944 ◽

2016 ◽

Vol 4 ◽

pp. e1944 ◽

Cited By ~ 4

Author(s):

Pavel Jakubec

Keyword(s):

Forensic Entomology ◽

Developmental Stages ◽

Larval Instar ◽

Head Capsule ◽

Common Species ◽

Standard Errors ◽

Future Studies ◽

Post Mortem Interval ◽

Holarctic Region

Necrophagous beetles are underrepresented in forensic entomology studies despite their undeniable utility for the field. In the present article, information is presented regarding the developmental biology and instar determination ofSciodrepoides watsoni(Spence, 1813), a very common species occurring across the Holarctic region. Wild collected beetles were kept in climate chambers at constant temperature (12, 15, 18, 21 and 28 °C) and their development was regularly documented. Parameters of thermal summation models and standard errors were calculated for each developmental stage. These models may be used for an estimation of post-mortem interval in legal investigations after further validation on local populations ofS. watsoni. An additional methodology is introduced for future studies of size-based characteristics, addressing instar identification bias. The methodology provided estimations (mean, standard error and standard deviation) ofS. watsonilarval head capsule width for preliminary larval instar determination. The methodology may be used with other morphological features to improve instar determination accuracy.

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Behavioural responses of spinner dolphins to human interactions

Royal Society Open Science ◽

10.1098/rsos.172044 ◽

2018 ◽

Vol 5 (4) ◽

pp. 172044 ◽

Cited By ~ 8

Author(s):

Maddalena Fumagalli ◽

Amina Cesario ◽

Marina Costa ◽

John Harraway ◽

Giuseppe Notarbartolo di Sciara ◽

...

Keyword(s):

Control Site ◽

Experimental Setting ◽

Closure System ◽

Protection Measures ◽

Human Interactions ◽

Highly Sensitive ◽

Spinner Dolphins ◽

Study Sites ◽

Dolphin Watching

There is increasing evidence that whale and dolphin watching activities have detrimental effects on targeted cetacean populations. In Egypt, spinner dolphins regularly occur in the resting areas of Samadai, Satayah and Qubbat'Isa reefs. In-water human interactions with dolphins are regulated with a time-area closure system at Samadai, unregulated at Satayah and non-existent at Qubbat'Isa. This provided an ideal experimental setting to advance our understanding of the effects of tourism on a species highly sensitive to disturbances. Our study confirmed that the intensity and duration of interactions, and therefore, dolphin exposure to tourism, differed among the study sites. Compared with the Qubbat'Isa control site, behavioural reactions to boats and swimmers at the two tourism sites suggested that dolphin rest was disrupted, especially around the middle of the day and especially at Satayah, where dolphin tourism is unregulated. Our results indicate also that the dolphin protection measures at Samadai reduce the level of disturbance. We recommend that similar measures be implemented at other dolphin tourism locations, and that no new operations be initiated until the long-term impacts on dolphin populations are better understood. Our experience emphasizes the need to adopt precautionary approaches in research and management of whale and dolphin watching.

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Assessing the hydrological suitability of floodplains for species-rich meadow restoration: a case study of the Thames floodplain, UK

Hydrology and Earth System Sciences ◽

10.5194/hess-11-170-2007 ◽

2007 ◽

Vol 11 (1) ◽

pp. 170-179 ◽

Cited By ~ 12

Author(s):

A. J. Duranel ◽

M. C. Acreman ◽

C. J. Stratford ◽

J. R. Thompson ◽

D. J. Mould

Keyword(s):

Agricultural Land ◽

Hydrological Regime ◽

Grassland Restoration ◽

Rating Curve ◽

Groundwater Levels ◽

Digital Elevation ◽

Elevation Model ◽

Autumn And Winter ◽

Physical And Chemical

Abstract. The physical and chemical environment of a floodplain needs to be assessed to define conservation targets for restoring it to species-rich meadows from agricultural land. A straightforward technique, widely applicable by site managers for assessing the suitability of the hydrological and hydro-chemical regime of a floodplain for wet grassland restoration, has been tested by examining the feasibility of restoring plants characteristic of NVC MG4 and MG8 communities to the Castle Meadows, Wallingford (Oxfordshire, UK). Hydro-chemical suitability has been assessed by comparing phosphorus concentrations with species-rich meadows nearby. The flooding regime was estimated based on a rating curve and a digital elevation model and groundwater levels were measured monthly in dipwells and piezometers. The hydrological regime was then compared with published reference guidelines for communities of conservation interest. For the Castle Meadows, the maximum duration of flood events in autumn and winter exceeded MG4 and MG8 species requirements across half of the site, while the depth of the groundwater table in summer exceeded species requirements in the other half. It was shown that, depending on topography, MG5 or MG13 may be more realistic vegetation targets.

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Towards integrated assessments of water risks in deglaciating mountain areas: water scarcity and GLOF risk in the Peruvian Andes

Geoenvironmental Disasters ◽

10.1186/s40677-020-00159-7 ◽

2020 ◽

Vol 7 (1) ◽

Author(s):

Alina Motschmann ◽

Christian Huggel ◽

Randy Muñoz ◽

Angela Thür

Keyword(s):

Water Scarcity ◽

Hydrological Regime ◽

Local Context ◽

Mountain Areas ◽

Cultural Economic ◽

Integrated Water Management ◽

Peruvian Andes ◽

Outburst Floods ◽

Path Modelling ◽

Study Sites

Abstract Different water related risks such as lake outburst floods and water scarcity are typically assessed by separate methods and often by separate research communities. However, in a local context such as in mountain regions of the developing world different water risks are intertwined and shaped by multi-dimensional natural and socio-economic drivers. Progressing glacier melt and the associated growing number of lakes rises the threat of glacier lake outburst floods (GLOFs); at the same time declining melt water supply changes the hydrological regime, resulting in changing water availability, especially during dry seasons. Here, we address this challenge by integratively assessing water scarcity and GLOF risks and their interactions for two study sites in glacierized catchments in the Cordillera Blanca and Urubamba in the Peruvian Andes. We used hydrological modelling, GLOF flow path modelling, and interviews with local people and technical experts to assess the hazard and risks of water scarcity and GLOFs. We incorporate perspectives of people living in those areas in order to gain a more comprehensive view on risks. While metrics of flood and water scarcity hazards are difficult to compare, we found insightful results using a comparative analysis of elements at risk from different water related hazards with different probabilities of occurrence. Furthermore, our study shows that considering the diverse local perspectives on risks as well as the social, cultural, economic and political context is essential to more successful and sustainable disaster risk reduction, climate change adaptation and integrated water management.

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