Food web consequences of long-term invasive crayfish control

Controlling invasive species can restore ecosystems while also quantifying species interaction strengths. We experimentally removed invasive rusty crayfish (Orconectes rusticus) from a Wisconsin lake. Rusty crayfish abundance declined by 99% in 8 years and did not significantly increase 4 years postharvest, with no compensatory recruitment response observed. Native crayfish (Orconectes virilis) and sunfish (Lepomis spp.) abundances increased by two orders of magnitude as rusty crayfish abundance declined, and macrophyte cover increased significantly in 2–4 m waters. We expected benthic macroinvertebrate densities to increase as rusty crayfish were removed; however, fish consumption of invertebrates increased as rusty crayfish density declined, and macroinvertebrate responses varied among families and habitats. Total Gastropoda density increased 300-fold in cobble, while the density of one gastropod family declined in macrophytes. Ephemeroptera, Odonata, and Amphipoda densities also declined in certain habitats as rusty crayfish were removed, suggesting that they are indirectly facilitated by rusty crayfish. This study highlights the importance of considering indirect effects when assessing the impacts of invasive species and demonstrates that these impacts may be reversed over relatively short time scales.

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Measures to Control Invasive Crayfish Species in Switzerland: A Success Story?

Frontiers in Environmental Science ◽

10.3389/fenvs.2020.609129 ◽

2020 ◽

Vol 8 ◽

Author(s):

Raphael Krieg ◽

Alex King ◽

Armin Zenker

Keyword(s):

Population Density ◽

Water System ◽

Predatory Fish ◽

Success Story ◽

The Past ◽

Invasive Crayfish ◽

Negative Impacts ◽

Native Crayfish ◽

Crayfish Species

Invasive crayfish species were first documented in Switzerland in the 1970s. Today, North American crayfish species dominate in most major lakes and streams in Switzerland. In combination with the crayfish plague, they pose a substantial threat to our native crayfish. Over the past 20 years, various techniques have been applied to reduce negative impacts of these invasive crayfish in Switzerland: eradication (temporary drainage or destruction of a water system, biocides), suppression (intensive trapping, electricity introduction of predatory fish) and containment (construction of crayfish barriers). Temporary drainage or filling-in of isolated ponds, in combination with calcium hydroxide application has been successful in eradicating populations of invasive crayfish. However, trapping and introduction of predatory fish led to a reduction in population density but neither method has ever caused the extinction of a population. Invasive crayfish have not yet reached crayfish barriers, therefore, long-term functionality of these barriers still needs to be proven. Nevertheless, functional controls with native crayfish have shown that barriers prevent their upstream movement. Implementation of crayfish barriers is the most promising method to protect native crayfish from displacement by invasive crayfish species. Many measures are expensive, time consuming, and show little or no success in controlling invasive crayfish. Therefore, we recommend to focus on implementing drastic measures, such as filling-in or draining of isolated waters or a combination of various methods to maximise the reduction of population size.

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How Do Indirect Effects of Contaminants Inform Ecotoxicology? A Review

Processes ◽

10.3390/pr8121659 ◽

2020 ◽

Vol 8 (12) ◽

pp. 1659

Author(s):

John W. Fleeger

Keyword(s):

Indirect Effects ◽

Field Studies ◽

Species Interaction ◽

Sensitive Species ◽

Chemical Contaminants ◽

Cascading Effects ◽

Natural Systems ◽

As Species ◽

Long Term Ecological Research

Indirect effects in ecotoxicology are defined as chemical- or pollutant-induced alterations in the density or behavior of sensitive species that have cascading effects on tolerant species in natural systems. As a result, species interaction networks (e.g., interactions associated with predation or competition) may be altered in such a way as to bring about large changes in populations and/or communities that may further cascade to disrupt ecosystem function and services. Field studies and experimental outcomes as well as models indicate that indirect effects are most likely to occur in communities in which the strength of interactions and the sensitivity to contaminants differ markedly among species, and that indirect effects will vary over space and time as species composition, trophic structure, and environmental factors vary. However, knowledge of indirect effects is essential to improve understanding of the potential for chemical harm in natural systems. For example, indirect effects may confound laboratory-based ecological risk assessment by enhancing, masking, or spuriously indicating the direct effect of chemical contaminants. Progress to better anticipate and interpret the significance of indirect effects will be made as monitoring programs and long-term ecological research are conducted that facilitate critical experimental field and mesocosm investigations, and as chemical transport and fate models, individual-based direct effects models, and ecosystem/food web models continue to be improved and become better integrated.

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Markets, Technological Change and Economic Growth (The Quaid-i-Azam Lecture)

The Pakistan Development Review ◽

10.30541/v33i4ipp.327-356 ◽

1994 ◽

Vol 33 (4I) ◽

pp. 327-356 ◽

Cited By ~ 7

Author(s):

Richard G. Lipsey

Keyword(s):

United States ◽

Economic Growth ◽

Developing Countries ◽

Common Ground ◽

The United States ◽

Industrial Countries ◽

Canadian Institute ◽

Primary Focus ◽

Short Time

I am honoured to be invited to give this lecture before so distinguished an audience of development economists. For the last 21/2 years I have been director of a project financed by the Canadian Institute for Advanced Research and composed of a group of scholars from Canada, the United States, and Israel.I Our brief is to study the determinants of long term economic growth. Although our primary focus is on advanced industrial countries such as my own, some of us have come to the conclusion that there is more common ground between developed and developing countries than we might have first thought. I am, however, no expert on development economics so I must let you decide how much of what I say is applicable to economies such as your own. Today, I will discuss some of the grand themes that have arisen in my studies with our group. In the short time available, I can only allude to how these themes are rooted in our more detailed studies. In doing this, I must hasten to add that I speak for myself alone; our group has no corporate view other than the sum of our individual, and very individualistic, views.

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The Spread of Pollutants from Harbour Sludge Depots

Water Science & Technology ◽

10.2166/wst.1984.0096 ◽

1984 ◽

Vol 16 (3-4) ◽

pp. 623-633

Author(s):

M Loxham ◽

F Weststrate

Keyword(s):

Time Scales ◽

Molecular Diffusion ◽

Near Field ◽

Parameter Analysis ◽

Migration Patterns ◽

Long Time ◽

Dilution Effects ◽

Short Time ◽

Harbour Sludge

It is generally agreed that both the landfill option, or the civil techniques option for the final disposal of contaminated harbour sludge involves the isolation of the sludge from the environment. For short time scales, engineered barriers such as a bentonite screen, plastic sheets, pumping strategies etc. can be used. However for long time scales the effectiveness of such measures cannot be counted upon. It is thus necessary to be able to predict the long term environmenttal spread of contaminants from a mature landfill. A model is presented that considers diffusion and adsorption in the landfill site and convection and adsorption in the underlaying aquifer. From a parameter analysis starting form practical values it is shown that the adsorption behaviour and the molecular diffusion coefficient of the sludge, are the key parameters involved in the near field. The dilution effects of the far field migration patterns are also illustrated.

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Long Term Interactions of Native and Invasive Species in a Marine Protected Area Suggest Complex Cascading Effects Challenging Conservation Outcomes

Diversity ◽

10.3390/d13020071 ◽

2021 ◽

Vol 13 (2) ◽

pp. 71

Author(s):

Charalampos Dimitriadis ◽

Ivoni Fournari-Konstantinidou ◽

Laurent Sourbès ◽

Drosos Koutsoubas ◽

Stelios Katsanevakis

Keyword(s):

Invasive Species ◽

Native Species ◽

High Performance ◽

Marine Protected Area ◽

Habitat Degradation ◽

Population Increase ◽

Rocky Reef ◽

Cascading Effects ◽

High Level

Understanding the interactions among invasive species, native species and marine protected areas (MPAs), and the long-term regime shifts in MPAs is receiving increased attention, since biological invasions can alter the structure and functioning of the protected ecosystems and challenge conservation efforts. Here we found evidence of marked modifications in the rocky reef associated biota in a Mediterranean MPA from 2009 to 2019 through visual census surveys, due to the presence of invasive species altering the structure of the ecosystem and triggering complex cascading effects on the long term. Low levels of the populations of native high-level predators were accompanied by the population increase and high performance of both native and invasive fish herbivores. Subsequently the overgrazing and habitat degradation resulted in cascading effects towards the diminishing of the native and invasive invertebrate grazers and omnivorous benthic species. Our study represents a good showcase of how invasive species can coexist or exclude native biota and at the same time regulate or out-compete other established invaders and native species.

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Long-Term Monitoring Reveals Differential Responses of Mussel and Host Fish Communities in a Biodiversity Hotspot

Diversity ◽

10.3390/d13030122 ◽

2021 ◽

Vol 13 (3) ◽

pp. 122

Author(s):

Irene Sanchez Gonzalez ◽

Garrett W. Hopper ◽

Jamie Bucholz ◽

Carla L. Atkinson

Keyword(s):

Invasive Species ◽

Life History ◽

Biodiversity Hotspot ◽

Biodiversity Hotspots ◽

Host Fish ◽

Long Term Monitoring ◽

Differential Responses ◽

Taxonomic Groups ◽

Term Monitoring

Biodiversity hotspots can serve as protected areas that aid in species conservation. Long-term monitoring of multiple taxonomic groups within biodiversity hotspots can offer insight into factors influencing their dynamics. Mussels (Bivalvia: Unionidae) and fish are highly diverse and imperiled groups of organisms with contrasting life histories that should influence their response to ecological factors associated with local and global change. Here we use historical and contemporary fish and mussel survey data to assess fish and mussel community changes over a 33 year period (1986–2019) and relationships between mussel abundance and their host fish abundance in Bogue Chitto Creek, a tributary of the Alabama River and a biodiversity hotspot. Mussel abundance declined by ~80% and community composition shifted, with eight species previously recorded not found in 2019, and a single individual of the endangered Pleurobema decisum. Fish abundances increased and life history strategies in the community appeared stable and there was no apparent relationship between mussel declines and abundance of host fish. Temporal variation in the proportion of life history traits composing mussel assemblages was also indicative of the disturbances specifically affecting the mussel community. However, changes and declines in mussel assemblages in Bogue Chitto Creek cannot be firmly attributed to any specific factor or events because of gaps in historical environmental and biological data. We believe that mobility differences contributed to differential responses of fish and mussel communities to stressors including habitat degradation, recent droughts and invasive species. Overall, our work indicates that monitoring biodiversity hotspots using hydrological measurements, standardized survey methods and monitoring invasive species abundance would better identify the effects of multiple and interactive stressors that impact disparate taxonomic groups in freshwater ecosystems.

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A 20-Year Follow-Up Study of Objectively Measured Physical Activity

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18063076 ◽

2021 ◽

Vol 18 (6) ◽

pp. 3076

Author(s):

Anders Raustorp ◽

Andreas Fröberg

Keyword(s):

Physical Activity ◽

Early Adolescence ◽

Total Sample ◽

Short Time Span ◽

Steps Per Day ◽

Objectively Measured ◽

Short Time ◽

Objectively Measured Physical Activity

Background: The objectives of this study were to explore the effect of time, long-term tracking, and the proportion of objectively measured physical activity (PA) from early adolescence to the mid-thirties. Methods: PA was measured as mean steps per day (SPD) with pedometers during 2000 (T1), 2003 (T2), 2005 (T3), 2010 (T4), 2016 (T5) and 2020 (T6). Data from 64 participants (n = 32 males) were analysed from their early adolescence (T1) to their mid-thirties (T6). Results: SPD decreased in the total sample and among males and females (all, p < 0.001). Males took more mean SPD than females during T1 (p = 0.002), whereas females took more mean SPD during T2 (p = 0.009) and T6 (p = 0.008). Males’ mean SPD tracked between T1 and T2 (p = 0.021), T2 and T3 (p = 0.030), T3 and T4 (p = 0.015) and T4 and T5 (p = 0.003). Females’ mean SPD tracked between T3 and T4 (p = 0.024) and T5 and T6 (p < 0.001). In the total sample, more mean SPD were found on weekdays compared to weekend days at T3 (p = 0.017) and T5 (p < 0.001). Conclusions: SPD decreased between T1 and T6. Mean SPD tracked low-to-moderate in the short time span. From late adolescence to the mid-thirties, more mean SPD was observed during weekdays compared to weekend days.

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Inferring Long-Term Demand of Newly Established Stations for Expansion Areas in Bike Sharing System

Applied Sciences ◽

10.3390/app11156748 ◽

2021 ◽

Vol 11 (15) ◽

pp. 6748

Author(s):

Hsun-Ping Hsieh ◽

Fandel Lin ◽

Jiawei Jiang ◽

Tzu-Ying Kuo ◽

Yu-En Chang

Keyword(s):

New York ◽

Feature Extraction ◽

Real World ◽

Extraction Methods ◽

Real World Data ◽

Urban Dynamics ◽

Bike Sharing ◽

The Government ◽

Short Time

Research on flourishing public bike-sharing systems has been widely discussed in recent years. In these studies, many existing works focus on accurately predicting individual stations in a short time. This work, therefore, aims to predict long-term bike rental/drop-off demands at given bike station locations in the expansion areas. The real-world bike stations are mainly built-in batches for expansion areas. To address the problem, we propose LDA (Long-Term Demand Advisor), a framework to estimate the long-term characteristics of newly established stations. In LDA, several engineering strategies are proposed to extract discriminative and representative features for long-term demands. Moreover, for original and newly established stations, we propose several feature extraction methods and an algorithm to model the correlations between urban dynamics and long-term demands. Our work is the first to address the long-term demand of new stations, providing the government with a tool to pre-evaluate the bike flow of new stations before deployment; this can avoid wasting resources such as personnel expense or budget. We evaluate real-world data from New York City’s bike-sharing system, and show that our LDA framework outperforms baseline approaches.

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EFFECT OF CORTICOSTEROIDS ON URINARY 5β AND 5α C19 STEROIDS IN MAN

Acta Endocrinologica ◽

10.1530/acta.0.0460197 ◽

1964 ◽

Vol 46 (2) ◽

pp. 197-206 ◽

Cited By ~ 7

Author(s):

Hildegard Wilson ◽

Steven Schenker

Keyword(s):

Testosterone Propionate ◽

Periodic Fever ◽

Term Treatment ◽

Long Term Treatment ◽

Dexamethasone Therapy ◽

Normal Women ◽

Normal Men ◽

Short Time

ABSTRACT A high proportion of urinary C19 5β to 5α steroid metabolites has been found on administration of glucocorticoids in a number of instances. During long term treatment with prednisone or dexamethasone, 100 mg testosterone propionate was administered to 3 patients. The ratios of the resulting metabolites etiocholanolone (E, 5β) to androsterone (A, 5α) were 2.7, 3.3 and 2.1, compared to 1.3 and 0.9 after withdrawal of corticoids from the first 2 patients. In 3 normal men, ratios of endogenously derived E and A while receiving corticoids, compared to control ratios were 2.3 to 1.0, 2.2 to 0.6 and 1.2 to 0.9. Ratios in normal women rose from 1.1 to 2.2 and 2.4 to 4.3 on receiving dexamethasone. Not all subjects gave the expected response. In 3 of these the dosage of corticoid was either low or given for a short time. The ratio of C19O3 metabolites of administered 11β-hydroxy-androst-4-ene-3,17-dione was also changed in favour of the 5β products during corticoid treatment. In a man with periodic fever the high E/A ratios observed were probably related to dexamethasone therapy rather than to the disease.

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The intersection of basic research and conservation: a 30-year study of the Critically Endangered Schiedea adamantis (Caryophyllaceae) on Lē‘ahi (Diamond Head Crater), Hawai‘i

Oryx ◽

10.1017/s0030605316001162 ◽

2017 ◽

Vol 52 (3) ◽

pp. 479-488 ◽

Cited By ~ 1

Author(s):

Ann K. Sakai ◽

Stephen G. Weller ◽

Weigang Yang ◽

Susan Ching Harbin ◽

Talia Portner ◽

...

Keyword(s):

Invasive Species ◽

Plant Species ◽

Basic Research ◽

Breeding Systems ◽

Critically Endangered ◽

Supplemental Irrigation ◽

Long Term Study ◽

And Storage ◽

Species Being

AbstractWe report on how a long-term study of the reproductive biology of the Critically Endangered Schiedea adamantis (Caryophyllaceae), one of Hawai‘i's rarest plant species, was leveraged for conservation purposes. Our major goals were to provide seeds with the greatest genetic variation possible for reintroduction and to ensure that both female and hermaphroditic plants of this wind-pollinated species were reintroduced in a manner that maximized both outcrossing and seed production. Schiedea adamantis was one of the first Hawaiian plant species listed under the Endangered Species Act (USA). The species has been studied intensively to test hypotheses addressing the evolution of breeding systems. Information on outcrossing levels and the extent of inbreeding depression was integrated into ongoing reintroduction efforts. Population size peaked in 1994, when 267 flowering individuals were found on Lē‘ahi (Diamond Head Crater). By 2016 only 17 flowering individuals were present, with drought and invasive species being possible causes of this decline. Reintroduction attempts in 1998 using genetically diverse seeds were unsuccessful because of drought and a lack of sufficient supplemental irrigation. Additional reintroduction attempts in 2012 and 2014 were more successful because of increased supplemental irrigation. Plants used in reintroductions represent genotypes long since absent in the natural population, and may contain the genetic variability essential for evolutionary responses to climate change and the spread of invasive species. The destruction of many plants reintroduced in 2015 and 2016 by a fire in March 2016 highlights the need for additional restoration areas at Lē‘ahi and elsewhere, and storage of seeds for future use.

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