The impact of zooplankton size structure on phosphorus cycling in field enclosures

Hydrobiologia ◽  
1985 ◽  
Vol 120 (1) ◽  
pp. 3-9 ◽  
Author(s):  
Robert L. Henry
Keyword(s):  
Size Structure ◽  
Phosphorus Cycling ◽  
Zooplankton Size ◽  
The Impact

scholarly journals The Impact of Fish Predation and Cyanobacteria on Zooplankton Size Structure in 96 Subtropical Lakes

PLoS ONE ◽  
2013 ◽  
Vol 8 (10) ◽  
pp. e76378 ◽  
Author(s):  
Jing Zhang ◽  
Ping Xie ◽  
Min Tao ◽  
Longgen Guo ◽  
Jun Chen ◽  
...  
Keyword(s):  
Size Structure ◽  
Fish Predation ◽  
Subtropical Lakes ◽  
Zooplankton Size ◽  
The Impact

Elements in the development of conservation plans for Atlantic salmon (Salmo salar)

1998 ◽  
Vol 55 (S1) ◽  
pp. 312-323 ◽  
Author(s):  
Julian J Dodson ◽  
R John Gibson ◽  
Richard A Cunjak ◽  
Kevin D Friedland ◽  
Carlos Garcia de Leaniz ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Size Structure ◽  
Public Awareness ◽  
Biological Information ◽  
Conservation Unit ◽  
Atlantic Salmon Salmo Salar ◽  
Conservation Plan ◽  
Conservation Plans ◽  
The Impact

This paper examines two areas to be considered in developing conservation plans for Atlantic salmon (Salmo salar): goal statements and the general framework for the implementation of a conservation plan. From a biological perspective, the appropriate conservation unit for Atlantic salmon is the Evolutionary Significant Unit (ESU). As conservation decisions will rarely be based solely on biological information, the Operational Conservation Unit (OCU) is defined as resulting from the interplay between biological requirements and socio-economic issues. A multi-scale habitat inventory of Atlantic salmon rivers to know what their status is relative to historical conditions is the first step in a functional conservation plan. The viability of salmon populations may be assessed according to 6 variables: abundance, resilience, age and size structure, sex ratio, spatial and geographical distribution. A genetically viable population possesses the species' evolutionary legacy and the genetic variation on which future evolutionary potential depends. Four factors important to monitoring changes in a population's genetic health are genetic diversity, effective population size, genetic bottlenecks and founder effects and gene flow. Implementation of a conservation plan must be proactive to maintain the quality of the OCUs. Commercial and recreational fisheries need to be limited and several case studies are reviewed. The importance of avoiding the introduction of exotics and minimizing the impact of sampling methodology, as well as the pitfalls of planting eggs, fry, or parr, are addressed. Finally, the importance of fostering public awareness of the value of conservation is essential to apply the political pressure necessary to preserve natural resources.

Reconstructing the baseline population structure of the exploited bivalve Arca noae in the Northern Adriatic Sea

2021 ◽  
Author(s):  
Saskia Macharia ◽  
Rafał Nawrot ◽  
Michaela Berensmeier ◽  
Ivo Gallmetzer ◽  
Alexandra Haselmair ◽  
...  
Keyword(s):  
Adriatic Sea ◽  
Size Structure ◽  
Anthropogenic Impacts ◽  
Natural State ◽  
Published Data ◽  
Northern Adriatic Sea ◽  
Important Species ◽  
Northern Adriatic ◽  
Shell Bed ◽  
The Impact

<p>The Northern Adriatic Sea is one of the most impacted ecosystems worldwide with a long history of anthropogenic impacts, ranging from overfishing and bottom trawling to eutrophication, deoxygenation and pollution. The impact of these multiple pressures on populations of economically important species is often difficult to evaluate due to paucity of long-term monitoring data. The edible bivalve Noah’s Ark shell (<em>Arca noae </em>L.) was intensively harvested in the eastern Adriatic Sea until 1949-1950 when it suffered a catastrophic population collapse due to unknown agents. The assessment of its subsequent recovery is hindered by the lack of data on the population size structure prior to that event. To reconstruct the natural baseline state of populations of <em>A. noae</em> before the onset of extensive harvesting, we studied fossil assemblages from two 1.5-m-long sediment cores collected in the southern Gulf of Trieste (off Piran, Slovenia), both recording the last ~9,500 years.</p><p>The abundance and shell length of <em>A. noae</em> remained low in the lower part of the cores but increased strongly within the oyster-<em>Arca</em> shell bed corresponding to maximum flooding and early highstand sea-level phases (6,500-1,000 years ago). In contrasts, the top 8 cm of the core (the late highstand phase), marked by high concentration of pollutants and organic enrichment, contained only few and small (< 10 mm) <em>A. noae</em> shells. Moreover, no living individuals were found in grab samples taken from the two stations suggesting that the dense populations of <em>A. noae, </em><span>persisting </span><span>there</span> <span>for</span><span> several thousand years, </span>were locally extirpated in the 20<sup>th</sup> century. To evaluate population recovery in other parts of the NE Adriatic, we compared the size distribution of<em> </em>fossil<em> </em><em>A. noae</em> from the shell bed interval to the previously published data on living populations of this species sampled<em> </em>along Istrian peninsula between 1966 and 1978. Both fossil and extant populations were characterized by similar <span>median </span><span>size, </span><span>modal size </span><span>class and</span><span> proportion of </span><span>specimens > 50 mm </span><span>(minimal legal landing size). </span><span>These results suggest that within few </span><span>decades</span><span> after the </span><span>1949-1950 </span><span>mass mortality event </span><span>the size structure of populations </span><span>of</span> <span><em>A. noae</em></span> <span>have largely returned to their earlier, natural state.</span><span> The recovery was </span><span>spatially variable, however, as attested by</span><span> the decline of</span> <span><em>A. noae</em></span> <span>populations </span><span>due to loss of </span><span>suitable shell-bed habitat</span><span>s</span><span> in</span><span> the two </span><span>studied</span><span> station</span><span>s</span><span> off Piran.</span></p>

population dynamics, rational fishing, intensity and selectivity of fishing, emissions, regulation of the level of fishing impact, stock-market-fishing system

Fisheries ◽  
2021 ◽  
Vol 2021 (6) ◽  
pp. 63-71
Author(s):  
Artur Maiss ◽  
Natalya Maiss
Keyword(s):  
Size Structure ◽  
Negative Impact ◽  
Sustainable Use ◽  
Aquatic Organisms ◽  
Fishing Impact ◽  
New Strategy ◽  
The Russian Federation ◽  
Far Eastern ◽  
The Impact ◽  
Far Eastern Seas

The article proposed to discuss a concept of new strategy for the sustainable use of populations of aquatic organisms using as an example a fishery for Walleye Pollock in the Far Eastern seas of the Russian Federation. It is shown that the current regulations governing the impact of fishing contained in the Fishing Regulations do not quite consider changes related to the dynamics of pollock populations parameters. As a result, there is an uncontrolled and often negative impact of fishing, which leads to changes in the phenotypic and size-age structure of W. Pollock populations being fished, which ultimately affects the profitability of fishing. It is proposed to develop a separate strategy for each W. Pollock stock unit, which annually regulates the level of fishing impact, depending on the state of the stocks and market conditions. The proposed strategy concept makes it possible to regulate not only the allowable volume of catch, but also the size structure of catches, by changing the fishing parameters every year. It will keep the harvested stocks stable and will help to obtain the maximum possible fishing profitability.

Populations, communities, and conservation

2020 ◽  
pp. 140-154
Author(s):  
Graham Scott
Keyword(s):  
Climate Change ◽  
Range Expansion ◽  
Population Change ◽  
Size Structure ◽  
Conservation Strategies ◽  
Habitat Availability ◽  
Natural Range ◽  
Avian Diseases ◽  
The Impact

In this final chapter populations, population change, and population regulation are discussed, particularly in the context of threats to species and the conservation strategies employed to protect them. Population size, structure, and distribution in relation to ecology and habitat availability are analysed. The movements and establishment of species through natural range expansion and through introduction are considered in the context of climate change, conservation, and threat. The impact and management of emerging avian diseases is discussed. Extinction, the threat of extinction, and conservation efforts are considered and throughout the chapter the roles of professional and citizen scientist ornithologists are emphasized.

Short-term Behavioural Equations for Developing Countries

2020 ◽  
pp. 249-262
Author(s):  
Giovanni Andrea Cornia
Keyword(s):  
Developing Countries ◽  
Money Demand ◽  
Size Structure ◽  
Structural Difference ◽  
Policy Changes ◽  
Access To Credit ◽  
Aggregate Consumption ◽  
Advanced Economies ◽  
The Impact

This chapter discusses the structural difference in family size, structure, location, and preferences, as well as the features of the formal and informal financial markets that determine the access to credit of various types of firms. It also reviews the role of the exchange rate, interest, rate and inflation in determining money demand. It then discusses behavioural equations for aggregate consumption, investment, and money demand that fit the reality of developing countries, and compares them with those discussed in Chapter 3 for the advanced economies. It shows that their inclusion in the IS-LM and AS-AD models often modifies the impact of policy changes and endogenous shocks in relation to those obtained in the advanced economies.

scholarly journals A Computational Framework for Exploring the Socio-Cognitive Features of Teams and their Influence on Design Outcomes

2019 ◽  
Vol 1 (1) ◽  
pp. 1-10
Author(s):  
Harshika Singh ◽  
Gaetano Cascini ◽  
Hernan Casakin ◽  
Vishal Singh
Keyword(s):  
Size Structure ◽  
Critical Role ◽  
Computational Framework ◽  
New Members ◽  
Learning Abilities ◽  
Team Members ◽  
Agent Based ◽  
Proposed Model ◽  
Dependent Parameter ◽  
The Impact

AbstractThe dynamics of design teams play a critical role in product development, mainly in the early phases of the process. This paper presents a conceptual framework of a computational model about how cognitive and social features of a design team affect the quality of the produced design outcomes. The framework is based on various cognitive and social theories grounded in literature. Agent-Based Modelling (ABM) is used as a tool to evaluate the impact of design process organization and team dynamics on the design outcome. The model describes key research parameters, including dependent, independent, and intermediates. The independent parameters include: duration of a session, number of times a session is repeated, design task and team characteristics such as size, structure, old and new members. Intermediates include: features of team members (experience, learning abilities, and importance in the team) and social influence. The dependent parameter is the task outcome, represented by creativity and accuracy. The paper aims at laying the computational foundations for validating the proposed model in the future.

Limited effects of stocked trout on littoral invertebrates in boreal foothills lakes

2012 ◽  
Vol 69 (1) ◽  
pp. 178-190 ◽  
Author(s):  
Leslie E. Nasmith ◽  
William M. Tonn ◽  
Cynthia A. Paszkowski ◽  
Garry J. Scrimgeour
Keyword(s):  
Community Composition ◽  
Size Structure ◽  
Invertebrate Community ◽  
Negative Effects ◽  
High Productivity ◽  
Recreational Angling ◽  
Key Characteristics ◽  
Littoral Zones ◽  
Littoral Invertebrates ◽  
The Impact

Stocking lakes with trout for the purposes of recreational angling is a management strategy that introduces a new predator into these systems and thus deserves careful scrutiny. To assess the impact of non-native trout on littoral invertebrates in naturally fish-bearing lakes in the boreal foothills of Alberta, Canada, we compared their community composition, abundance, and size structure in stocked (n = 5) and unstocked (n = 6) lakes over a 2-year period. We detected no clear negative effects of introduced trout on invertebrate community composition and only few taxa-specific examples of decreased or increased invertebrate abundance. Furthermore, predation by trout had inconsistent direct effects on the size structure of invertebrate populations. Indirect effects were suggested by increased abundances and sizes of some invertebrate taxa in stocked lakes and might also contribute to the limited overall differences that we observed. We propose that net effects of stocked trout on littoral invertebrates are influenced by key characteristics of receiving ecosystems. In our boreal foothills lakes, dense macrophyte cover in warm littoral zones, high productivity, abundant forage fish, and limited densities of trout all likely combine to allow littoral invertebrate communities to withstand the impact of introduced trout with minimal effects.

Macrozoobenthos response to environmental degradation in a heavily modified stream: Case study the Upper Elbe River, Czech Republic

Biologia ◽  
2010 ◽  
Vol 65 (3) ◽  
Author(s):  
Zdeněk Adámek ◽  
Claus Orendt ◽  
Georg Wolfram ◽  
Jan Sychra
Keyword(s):  
Water Quality ◽  
Size Structure ◽  
Habitat Characteristics ◽  
Macroinvertebrate Communities ◽  
Elbe River ◽  
Important Indicator ◽  
Natural Stream ◽  
River Bed ◽  
Macrophyte Community ◽  
The Impact

AbstractBenthic macroinvertebrates are an important indicator of river health. However, their response upon water quality development downstream the pollution outlets considerably depends on the environmental habitat characteristics. Three successive stretches, each of them providing three different mesohabitats in stillwater (S), torrential (T) and riparian (R) zones were selected for evaluation of the impact of altered metapotamal river bed morphology (channelization) and chemical determinants of water quality on the Upper Elbe River. In downstream direction, the stretches are separated by weirs and characterized as a low polluted low modified natural stream (N), a low polluted channelized stream (C) and a channelized polluted stream (CP). Altogether, 111 benthic macroinvertebrate taxa were recorded in the Pardubice hotspot between Němčice and Přelouč. Despite different levels of stream bed and water quality degradation, micro- and mesohabitat characteristics appeared to be the most important factors determining the diversity of macrozoobenthos in riffle (substrate size structure) and in shoreline (macrophyte community composition and structure) mesohabitats. The diversity of macroinvertebrate communities was highest in riparian mesohabitats compared to stillwater and torrential ones. Saprobic indices increased in downstream direction, thus indicating the decline of water quality.

A comparison of pre-industrial and present-day changes in Bosmina and Daphnia size structure from soft-water Ontario lakes

2010 ◽  
Vol 67 (4) ◽  
pp. 754-762 ◽  
Author(s):  
Jennifer B. Korosi ◽  
Andrew M. Paterson ◽  
Anna M. DeSellas ◽  
John P. Smol
Keyword(s):  
Body Size ◽  
Size Structure ◽  
South Central ◽  
Zooplankton Size ◽  
Copepod Predation ◽  
Post Impact ◽  
North Temperate Lakes ◽  
Impact Data ◽  
Shield Lakes

Understanding the long-term controls on cladoceran size structure has important implications for aquatic ecosystems. Although there has been considerable interest in zooplankton size trends for Canadian Shield lakes, data are not available for zooplankton size structure prior to the period of anthropogenic disturbances. Here, we present pre- and post-impact size data for the common pelagic cladocerans Bosmina and Daphnia for 44 well-studied Shield lakes in south-central Ontario (Canada). We show that Daphnia were larger and that the length of Bosmina body appendages (mucrones and antennules) was longer in pre-industrial times than they are today. The reduction in Bosmina appendage length we observed may suggest a reduction in copepod predation pressure since pre-industrial times. Reduced maximum body size in Daphnia is a predicted response to a warming climate in north temperate lakes; however, we suggest that alternate explanations, specifically acidification and subsequent recovery following emission reductions, should also be explored as the primary drivers of Daphnia size changes in this lake set. Overall, our results highlight the importance of pre-impact data for understanding the long-term controls on cladoceran body size from pre-1850 to present.

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