scholarly journals Multiple Lines of Evidence Indicate Limited Natural Recruitment of Golden Perch (Macquaria ambigua) in the Highly Regulated Lachlan River

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1636
Author(s):  
Foyez Shams ◽  
Fiona Dyer ◽  
Ross Thompson ◽  
Richard P. Duncan ◽  
Jason D. Thiem ◽  
...  
Keyword(s):  
Habitat Restoration ◽  
Population Decline ◽  
Environmental Water ◽  
Stock Enhancement ◽  
Freshwater Ecosystems ◽  
Factors Affecting ◽  
Management Actions ◽  
Natural Spawning ◽  
Murray Darling Basin ◽  
Lines Of Evidence

Freshwater ecosystems and their associated biota have been negatively impacted by the human development of water resources. Fundamental to restoration activities for target species is an understanding of the factors affecting population decline or recovery. Within Australia’s Murray–Darling Basin, recovery efforts to address the population decline of native freshwater fish include stock enhancement, habitat restoration, and the delivery of environmental water. Essential to guiding future management actions is information to assess the efficacy of these efforts. We undertook a study to investigate whether natural spawning and recruitment, stock enhancement, or a combination of the two is contributing to sustaining populations of golden perch (Macquaria ambigua) in the highly regulated Lachlan River, Australia. Otolith microchemistry and genetic analyses were used as complementary tools to determine the source (hatchery origin or wild-spawned) of existing populations in the catchment. We identified that natural spawning and recruitment was contributing to riverine populations in some years but that populations were heavily reliant on stocking. It was not possible to distinguish hatchery and wild-born fish using genetic tools, highlighting the value of using multiple lines of evidence to establish causal mechanisms contributing to population recovery.

scholarly journals Shifting Goalposts: Setting Restoration Targets for Waterbirds in the Murray-Darling Basin Under Climate Change

2021 ◽  
Vol 9 ◽  
Author(s):  
Gilad Bino ◽  
Kate Brandis ◽  
Richard T. Kingsford ◽  
John Porter
Keyword(s):  
Climate Change ◽  
Environmental Sustainability ◽  
Life Histories ◽  
River System ◽  
Biodiversity Loss ◽  
Environmental Water ◽  
Freshwater Ecosystems ◽  
Future Climate Change ◽  
Restoration Targets ◽  
Murray Darling Basin

The Murray-Darling Basin (the Basin) is the largest river system in Australia, supplying about 40% of the country’s irrigated agricultural output. Associated water resource development has come with a heavy price for the Basin’s freshwater ecosystems degrading them over decades. Australian governments are attempting to achieve environmental sustainability by returning water to the environment through buy-back of irrigation licences and improved water efficiencies. To determine effectiveness, basin-wide management objectives were established for key indicators, including waterbird populations and life histories which can effectively indicate ecosystem function and condition, driven by flow and flooding regimes. Ongoing monitoring of waterbird numbers indicates continued declines. We evaluated the feasibility of meeting established waterbird objectives under existing and predicted climates. We modelled long-term waterbird numbers using one of the world’s largest ongoing waterbird surveys (1983–2020), covering about 13.5% of the area of the entire Basin. Our findings suggest that under near future climate change projections, waterbird numbers will likely continue to decline, and remain below restoration targets set for the Basin. We discuss the current policy settings for using environmental water to support waterbird populations, recommending adjustments to restore the Basin’s waterbird populations and their wetlands in order to meet Australia’s conservation targets in relation to the ongoing global crisis of biodiversity loss.

scholarly journals Caddisflies (Trichoptera, Insecta)as Bioindicator of Water Quality Assessment in a Small Stream in Northern Thailand

2021 ◽  
Vol 50 (3) ◽  
pp. 655-665
Author(s):  
THAMSENANUPAP P. ◽  
SEETAPAN K. ◽  
PROMMI T.
Keyword(s):  
Water Quality ◽  
Water Quality Assessment ◽  
Environmental Water ◽  
Freshwater Ecosystems ◽  
Northern Thailand ◽  
Small Stream ◽  
Factors Affecting ◽  
Larval Stages ◽  
Study Results ◽  
Caddisfly Larvae

The influence of environmental variables and the potential as bioindicators of larval stages of the species of Trichoptera were evaluated in a small stream in northern Thailand from January to November 2017. A total of 1,191 individual caddisfly larvae belonging to 7 families and 13 genus were found. The larvae of the family Glossosomatidae were the most abundant, followed by Hydropsychidae and Calamoceratidae. The genus Glossosoma, Hydromanicusand Hydropsyche were the most abundant genus in this study. Results of the CCA ordination showed that total dissolved solids, electrical conductivity, and water temperature were the most important factors affecting the abundance and diversity of caddisfly larvae. Changes in the caddisfly larvae may indicate changes in physicochemical factors owing to urbanization or other anthropogenic. The results showed that the order Trichoptera, identified to the species or genus level, can potentially be used to assess environmental water quality status in freshwater ecosystems. This study suggested that species richness of aquatic insects may indicate the conservation value of the habitats because of their significant responses to environmental factors.

scholarly journals Population estimates of Antillean manatees in Puerto Rico: an analytical framework for aerial surveys using multi-pass removal sampling

2019 ◽  
Vol 100 (4) ◽  
pp. 1340-1349
Author(s):  
Jaime A Collazo ◽  
Matthew J Krachey ◽  
Kenneth H Pollock ◽  
Francisco J Pérez-Aguilo ◽  
Jan P Zegarra ◽  
...  
Keyword(s):  
Puerto Rico ◽  
Detection Probability ◽  
Analytical Framework ◽  
Population Estimates ◽  
High Concentration ◽  
Imperfect Detection ◽  
Factors Affecting ◽  
Management Actions ◽  
Aerial Surveys ◽  
Population Size Estimates

AbstractEffective management of the threatened Antillean manatee (Trichechus manatus manatus) in Puerto Rico requires reliable estimates of population size. Estimates are needed to assess population responses to management actions, and whether recovery objectives have been met. Aerial surveys have been conducted since 1976, but none adjusted for imperfect detection. We summarize surveys since 1976, report on current distribution, and provide population estimates after accounting for apparent detection probability for surveys between June 2010 and March 2014. Estimates in areas of high concentration (hotspots) averaged 317 ± 101, three times higher than unadjusted counts (104 ± 0.56). Adjusted estimates in three areas outside hotspots also differed markedly from counts (75 ± 9.89 versus 19.5 ± 3.5). Average minimum island-wide estimate was 386 ± 89, similar to the maximum estimate of 360 suggested in 2005, but fewer than the 700 recently suggested by the Puerto Rico Manatee Conservation Center. Manatees were more widespread than previously understood. Improving estimates, locally or island-wide, will require stratifying the island differently and greater knowledge about factors affecting detection probability. Sharing our protocol with partners in nearby islands (e.g., Cuba, Jamaica, Hispaniola), whose populations share genetic make-up, would contribute to enhanced regional conservation through better population estimates and tracking range expansion.El manejo efectivo del manatí antillano amenazado en Puerto Rico requiere estimados de tamaños de poblaciónes confiables. Dichas estimaciones poblacionales son necesarias para evaluar las respuestas a las acciones de manejo, y para determinar si los objetivos de recuperación han sido alcanzados. Se han realizado censos aéreos desde 1976, pero ninguno de ellos han sido ajustados para detecciones imperfectas. Aquí resumimos los censos desde 1976, actualizamos la distribución, y reportamos los primeros estimados poblacionales ajustados para la probabilidad de detección aparente en los censos de Junio 2010 a Marzo 2014. Las estimaciones poblacionales en áreas de mayor concentración del manatí promedió 317 ± 103, tres veces más abundante que los conteos sin ajuste (104 ± 0.56). Las estimaciones poblacionales en tres áreas fuera de las áreas de mayor concentración del manatí también fueron marcadamente diferentes (75 ± 9.89 vs 19.5 ± 3.5). El estimado mínimo poblacional en la isla entera fue de 386 ± 89, similar al estimado máximo de 360 sugerido en el año 2005, pero menor a los 700 sugeridos recientemente por el Centro de Conservación de Manatíes de Puerto Rico. Documentamos que el manatí tiene una distribución más amplia de lo que se sabía con anterioridad. El mejoramiento de los estimados poblacionales locales o a nivel de isla requerirá que se estratifique a la isla en forma diferente y que se investiguen los factores que influencian a la probabilidad de detección. Compartir protocolos como este con colaboradores de islas vecinas (por. ej., Cuba, Jamaica, Española), cuyas poblaciones de manatíes comparten material genético, contribuiría a la conservación regional mediante mejores estimaciones poblacionales y monitoreo de la expansión de su ámbito doméstico.

Ecological and environmental factors affecting the foraging activity of the White-bellied Heron Ardea insignis (Hume, 1878) in Bhutan

2021 ◽  
pp. 1-18
Author(s):  
PEMA KHANDU ◽  
GEORGE A. GALE ◽  
SARA BUMRUNGSRI
Keyword(s):  
Relative Abundance ◽  
Habitat Restoration ◽  
Prey Species ◽  
Catch Per Unit Effort ◽  
Factors Affecting ◽  
Prey Biomass ◽  
Gravel Mining ◽  
Unit Effort ◽  
Prey Preferences ◽  
The Government

Summary White-bellied Heron Ardea insignis (WBH) is critically endangered, but we lack data on many aspects of its basic ecology and threats to the species are not clearly understood. The goal of this study was to analyse WBH foraging microhabitat selection, foraging behaviour, and prey preferences in two river basins (Punatsangchhu and Mangdechhu) in Bhutan which are likely home to one of the largest remaining populations of WBH. We also explored the relationship between the relative abundance of the WBH and prey biomass catch per unit effort within four foraging river microhabitats (pool, pond, riffle and run). Prey species were sampled in 13 different 100-m thalweg lengths of the rivers using cast nets and electrofishing gear. Riffles and pools were the most commonly used microhabitats; relative abundance was the highest in riffles. The relative abundance of WBH and prey biomass catch per unit effort (CPUE) also showed a weak but significant positive correlation (rs = 0.22). The highest biomass CPUE was observed in riffles while the lowest was found in the ponds. From the 97 prey items caught by the WBH, 95% of the prey were fish. The WBH mainly exploited three genera of fish (Garra, Salmo, and Schizothorax) of which Schizothorax (64%) was the most frequently consumed. This study provides evidence in support of further protection of critical riverine habitat and fish resources for this heron. Regular monitoring of sand and gravel mining, curbing illegal fishing, habitat restoration/mitigation, and developing sustainable alternatives for local people should be urgently implemented by the government and other relevant agencies. Further study is also required for understanding the seasonal variation and abundance of its prey species in their prime habitats along the Punatsangchhu and Mangdechhu basins.

scholarly journals Spatial distribution of the Barbary Partridge (Alectoris barbara) in Sardinia explained by land use and climate

2021 ◽  
Vol 67 (4) ◽  
Author(s):  
Gianpasquale Chiatante ◽  
Marta Giordano ◽  
Anna Vidus Rosin ◽  
Oreste Sacchi ◽  
Alberto Meriggi
Keyword(s):  
Land Use ◽  
Conservation Status ◽  
Distance Sampling ◽  
Strong Relationship ◽  
European Population ◽  
Factors Affecting ◽  
Brood Rearing ◽  
Management Actions ◽  
Negative Effect ◽  
Study Sites

AbstractMore than half of the European population of the Barbary Partridge is in Sardinia; nonetheless, the researches concerning this species are very scarce, and its conservation status is not defined because of a deficiency of data. This research aimed to analyse the habitat selection and the factors affecting the abundance and the density of the Barbary Partridge in Sardinia. We used the data collected over 8 years (between 2004 and 2013) by spring call counts in 67 study sites spread on the whole island. We used GLMM to define the relationships between the environment (topography, land use, climate) both the occurrence and the abundance of the species. Moreover, we estimated population densities by distance sampling. The Barbary Partridge occurred in areas at low altitude with garrigue and pastures, avoiding woodlands and sparsely vegetated areas. We found a strong relationship between the occurrence probability and the climate, in particular, a positive relation with temperature and a negative effect of precipitation, especially in April–May, during brood rearing. Furthermore, dry crops positively affected the abundance of the species. We estimated a density of 14.1 partridges per km2, similar to other known estimates. Our findings are important both because they increase the knowledge concerning this species, which is considered data deficient in Italy, and because they are useful to plan management actions aimed to maintain viable populations if necessary.

scholarly journals Participatory mapping of aquatic invasive species: a demonstration in a coastal lagoon

2020 ◽  
Author(s):  
Jacopo Cerri ◽  
Ernesto Azzurro
Keyword(s):  
Invasive Species ◽  
Coastal Lagoon ◽  
Coefficient Of Variation ◽  
Procambarus Clarkii ◽  
Freshwater Ecosystems ◽  
Aquatic Invasive Species ◽  
Spatial Gradient ◽  
Participatory Mapping ◽  
Ecological Requirements ◽  
Management Actions

Aquatic Invasive species (AIS) are a growing driver of change across marine and freshwater ecosystems but spatially-explicit information is seldom available for supporting management actions and decision making. Here we conceived and tested a new participatory method to map the distribution of three invasive species (Callinectes sapidus, Procambarus clarkii and Oreochromis niloticus) in the coastal lagoon of Lesina (Italy). Local fishers were asked to draw the distribution of each species on pre-printed maps, indicating districts of the lagoon characterized by different abundance levels. Then, maps were converted to a lattice grid and a Bayesian hierarchical Generalized Additive Modeling was adopted to model species distribution in the lagoon, calculating the coefficient of variation for model fitted values to map fishers agreement about the distribution of each species.The spatial gradient in the abundance of the three species in the lagoon aligned with their ecological requirements. C. sapidus was abundant throughout the whole lagoon, peaking in correspondence of saltmarsh vegetation, while P. clarkii and O. niloticus, were much less abundant and remained distributed near to freshwater inputs. Experts agreed about the spatial distribution of C. sapidus in the lagoon, with a median coefficient of variation in model fitted values of 3.9%. On the other hand, the coefficient of variation was higher for P.clarkii (19.9%) O. niloticus (18.4%), indicating a higher level of uncertainty about their estimated distribution.With this example, we provided new metrics to evaluate the quality of LEK-based participatory mapping in terms of agreement and consistency among experts. The resulting information provides new insights for spatially informed management across aquatic realms in relation to the increasing ecological and socio-economical pressures posed by biological invaders.

scholarly journals Validation of a noninvasive technique to quantify stress in northern bobwhite (Colinus virginianus)

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Jessica L Mohlman ◽  
Kristen J Navara ◽  
Michael J Sheriff ◽  
Theron M Terhune ◽  
James A Martin
Keyword(s):  
Colinus Virginianus ◽  
Population Decline ◽  
Endocrine System ◽  
Northern Bobwhite ◽  
Noninvasive Technique ◽  
Acth Challenge ◽  
Non Invasive ◽  
Management Actions ◽  
Hunting Dog ◽  
Corticosterone Metabolites

Abstract Examination of the endocrine system through non-invasive fecal sampling may improve population management more than using demographic indicators alone. By addressing the physiological mechanisms that are influencing fitness, management actions can be proactively developed to alleviate stressors. Proactive determination of vulnerable populations is critical for species of concern, such as the Northern Bobwhite (Colinus virginianus), which have suffered decades of population decline. We validated an assay to noninvasively measure the adrenocortical response of captive reared bobwhite through fecal corticosterone metabolites (FCM). All individuals received three sequential 48-hour treatments in which samples were collected every 4 hours, including a reference period, an adrenocorticotropic hormone (ACTH) challenge and a biological stressor (exposure to a hunting dog). Reference FCM values had a mean concentration of 16.75 pg/mg (95% CrI: 13.68, 19.91) with adrenocortical activity increasing by 73% for the duration of the ACTH challenge (29.00 pg/mg; CrI: 25.01, 33.78). FCM concentrations remained similar to that of the reference levels during the biological stressor (16.56 pg/mg; CrI: 13.33, 19.92). Our study validates the use of feces to detect changes in FCM levels in our subject species but also demonstrates the complexity of FCM and the importance of both physiological and biological validation prior to field implementation.

scholarly journals Scavenging by threatened turtles regulates freshwater ecosystem health during fish kills

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Claudia Santori ◽  
Ricky-John Spencer ◽  
Michael B. Thompson ◽  
Camilla M. Whittington ◽  
Thomas H. Burd ◽  
...  
Keyword(s):  
Water Quality ◽  
Ecosystem Health ◽  
Freshwater Ecosystems ◽  
Freshwater Ecosystem ◽  
Freshwater Species ◽  
Freshwater Turtles ◽  
Fish Kills ◽  
Murray Darling Basin ◽  
Ecological Implications ◽  
Mesocosm Experiments

Abstract Humans are increasing the frequency of fish kills by degrading freshwater ecosystems. Simultaneously, scavengers like freshwater turtles are declining globally, including in the Australian Murray–Darling Basin. Reduced scavenging may cause water quality problems impacting both ecosystems and humans. We used field and mesocosm experiments to test whether scavenging by turtles regulates water quality during simulated fish kills. In the field, we found that turtles were important scavengers of fish carrion. In mesocosms, turtles rapidly consumed carrion, and water quality in mesocosms with turtles returned to pre-fish kill levels faster than in turtle-free controls. Our experiments have important ecological implications, as they suggest that turtles are critical scavengers that regulate water quality in freshwater ecosystems. Recovery of turtle populations may be necessary to avoid the worsening of ecosystem health, particularly after fish kills, which would have devastating consequences for many freshwater species.

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