굴 양식수역의 환경용량 산정 -II. 거제 · 한산만의 환경용량-

Summary 1. Management of the effects of stress on populations – for instance in ecotoxicology – requires understanding of the effects of stressors on populations and communities. Attention to date has too rarely been directed to relevant ecological endpoints, such as carrying capacity and density dependence. Established procedures are instead based on measuring the Life Tables of individual organisms exposed to differing concentrations of a pollutant at low population density, but this approach does not take into account population effects that may occur through interactions between individuals. Here we introduce an approach that allows direct measurement of the effects of stressors on carrying capacity and density dependence. 2. Using the marine copepod Tisbe battagliai Volkmann‐Rocco, we report replicated experiments establishing the effects of 100 µg L−1 pentachlorophenol (PCP) in combination with varying diet and food concentrations. Population density was measured as population biomass in 10 mL volumes. Diet was either the alga Isochrysis galbana Parke (here designated ‘poor diet’) or a mix of two algal species (I. galbana and Rhodomonas reticulata Novarino: ‘good diet’). Each was given at three food concentrations (520, 1300 and 3250 µgC L−1), selected on the basis that at low population density these cover the range between limited and maximal population growth. 3. Carrying capacity increased linearly with food concentration. On the poor diet the increase was 1·2 μg L−1 for each μgC L−1 increase in food concentration. On the good diet the increase was 2·3 μg L−1/μgC L−1 in the absence of PCP, and 1·9 μg L−1/μgC L−1 with PCP. Maximum carrying capacity was in the region of 60–80 μg per 10 mL volume. Population growth rate (pgr) decreased linearly with population biomass when the latter was plotted on a logarithmic scale. Increasing biomass reduced pgr by 1·70 week−1 for each unit increase in log10 biomass. Increasing food concentration and improving diet both increased pgr, but did not affect the slope of the density‐dependent relationship. Presence or absence of PCP had no effect except that at some higher food concentrations non‐PCP populations initially increased faster than PCP populations, and at high concentration on the good diet the effect of density‐dependence was decreased in PCP populations. 4. The results show that a stressor's effects at high population density may differ from its effects at low density, and emphasizes the importance of finding new protocols, such as those introduced here, with which to study the joint effects of a stressor and population density. Managers and researchers of threatened species, harvested species and pest species need to know the joint effects of stressors and population density, in order to be able to predict the effects of stressors on carrying capacity and on the course of recovery from environmental perturbations.

Estimating the carrying capacity of a coastal inlet for mussel culture

Predicting the impacts of Mississippi River diversions and sea-level rise on spatial patterns of eastern oyster growth rate and production

Tourist carrying capacity at Islas Marietas National Park: An essential tool to protect the coral community

Psychophysical determination and modeling of load carrying capacity

A study has been made of the oxygen uptake, glucose utilization, lactate release and cellular content of adenine nucleotides of isolated sheep ovarian follicles (4-6 min in diameter) maintained in organ culture, and of the effects on these parameters of the addition of human chorionic gonadotrophin (hCG). The mean oxygen consumption of the entire follicles when freshly isolated and of the theca and membrana components was 0-56, 1-08 and 0-05 mumol per milligram wet weight of tissue per hour respectively. About 8 mumol of glucose was taken up and 16 mumol of lactate released per milligram wet weight of follicular tissue per hour during the first 24-h period of culture. This rate reduced by about 30% for each subsequent day of culture, but was significantly increased by the addition of hCG. The mean ATP content of theca and granulosa tissues was 4-6 and 2-8 nmol/mg wet weight of tissue respectively. There was no discernable change in tissue adenine nucleotide content or energy charge ratio during the 3-day culture period, and prolonged exposure to hCG was without effect. Untreated follicles produced both oestrogen and androgens throughout the culture period. The addition of hCG resulted in a transitory stimulation in oestrogen secretion, inhibition of androgen secretion, and a marked and sustained rise in progestin secretion. It is proposed that the increase in glycolytic activity following exposure to hCG may relate to the activation of the granulosa cells coincident with a transference of steroid synthetic capacity from theca interna to membrana granulosa.

A field and modeling study of the food supply and demand of mussel (Mytilus edulis) rafts in Maine established the hydrodynamic and particle consumption characteristics of shellfish aquaculture structures. Mussels on rafts filtered about 8 × 106 L/h and consumed about 40 g chlorophyll a (chl a)/h under favorable conditions. Because of the drag of the culture ropes and predator nets, velocity inside the rafts was reduced by 75%–80% in relation to ambient conditions. Chlorophyll consumption by mussels increased with increased food (chl a) concentration and also with increased water velocity inside the rafts. Clearance rates per raft also increased with food concentration. Model results allow for an estimation of water flux and seston depletion within the rafts through the use of point measurements and correction factors. Water velocity measurements taken mid depth in the middle of the rafts underestimated the mean flow through the raft by 10%. Measurements of current velocity and chl a concentration taken mid depth in the middle of the rafts underestimated the mean particle consumption rates by 13%. Model results and field data indicate that mussel raft hydrodynamics are a function of raft orientation to current direction, mussel raft size, raft aspect ratio, the presence of predator nets, the presence of multiple rafts, rope spacing, and rope diameter. Mussel raft design, placement, and biomass may be adjusted to optimize hydrodynamics and conditions favorable for improved mussel growth rates. Recommended flow speeds through experimental mussel rafts with a cross-sectional area of 121 m2 require a minimum outside flow speed of 14–23 cm/sec.

Food wedges: Framing the global food demand and supply challenge towards 2050

Environmental Carrying Capacity is the ability of the environment to support the life of humans and other living creatures and the balance between the two. Food availability and agricultural land are variables to quantify the carrying capacity of the environment for food Availability. This study aimed to analyze the carrying capacity of the field and agricultural land for sustainable food availability in Pandeglang Regency and to analyze how food availability is in Pandeglang Regency. The study used the quantitative methodology approach with literature. The results of the study showed environmental supporting capacity in Pandeglang Regency in all sub-districts, the availability of food produced from the area of agricultural land be exceeded the need or demand for food. This means that Pandeglang Regency has the potential to achieve food Availability and food independence. The carrying capacity of the environment, in this case is the carrying capacity of agricultural land, could be managed properly to meet the food needs of the entire population and able be developed to obtain a surplus in food production. The achievement of sustainable food Availability in Pandeglang Regency is determined by environmental management, especially the optimization of food and land carrying capacity in the local area.

ABSTRACTThe carrying capacity (Ca) in column flotation can be determined by experiments in terms of mass of solids per unit time per unit column cross-sectional area. The estimation of Ca has been typically defined by a simplified statement on the basis of representative particle size and the floatable mineral density. Although this statement encountered with several assumptions and limited ranges of the data that increase errors for other applications, in Ca expressions, the effect of particular variables, such as particle size, feed solids rate, bubble diameter, air flow rate, feed solid content, frother dosage, and froth height should be considered. In this study, the effects of these parameters on the Ca were investigated in column flotation using copper sulfide ore. It was found that when the feed solid rate increased, the concentrate solid rate increased to a certain point, whereafter it started to decrease. When the air flow rate increased, the Ca first increased then drastically decreased. In low feed flow rates, the increase in frother rate led to the higher carrying capacity, whereas in feed flow rates over 1.2 cm/s, the carrying capacity in frother rate of 45 ppm was more than 75 ppm. By decreasing the froth height and increasing the solid percentage (up to 30%), Ca increased. The results of the experiments at various feed particles sizes showed that the particles with size 45–63 µm had the maximum carrying capacity.

The European wild rabbit (Oryctolagus cuniculus) is a staple prey species in Mediterranean ecosystems. The arrival and subsequent spread of rabbit hemorrhagic disease throughout southwestern Europe, however has caused a decline in rabbit numbers, leading to considerable efforts to enhance wild rabbit populations, especially through habitat management. Because rabbit population dynamics depend on habitat suitability and changes in habitat structure and composition subsequent to habitat management, I evaluated the effects of population dynamics on the long-term impact of rabbit hemorrhagic disease on rabbit populations. I used an age-structured model with varying degrees of population productivity and turnover and different habitat carrying capacities, and I assumed the existence of a unique, highly pathogenic virus. My results suggest that disease impact may be highly dependent on habitat carrying capacity and rabbit population dynamics, and the model provided some insight into the current abundance of wild rabbits in different locations in southwestern Europe. The highest disease impact was estimated for populations located in habitats with low to medium carrying capacity In contrast, disease impact was lower in high-density populations in habitats with high carrying capacity, corresponding to a lower mean age of rabbit infection and a resulting lower mortality from rabbit hemorrhagic disease. The outcomes of the model suggest that management strategies to help rabbit populations recover should be based on improving habitats to their maximum carrying capacity and increasing rabbit population productivity. In contrast, the use of strategies based on temporary increases in rabbit density, including vaccination campaigns, translocations, and temporal habitat improvements at medium carrying capacities, may increase disease impact, resulting in short-term decreases in rabbit population density.

Self‐thinning and site maximum carrying capacity are key concepts for understanding and predicting ecosystem dynamics as they represent the outcome of several fundamental ecological processes (e.g., mortality and growth). Relationships are often derived using alternative modeling strategies, depending on the statistical approach, model formulation, and underlying data with unclear implications of these various assumptions. In this analysis, the influence of contrasting modeling strategies for estimating the self‐thinning relationship and maximum carrying capacity in long‐term, permanent plot data (n = 130) from the mixed Nothofagus forests in southern Chile was assessed and compared. Seven contrasting modeling strategies were used including ordinary least squares, quantile, and nonlinear regression that were formulated based on static (no remeasurements) or dynamic data (with remeasurements). Statistically distinct differences among these seven approaches were identified with mean maximum carrying capacity ranging from 1,050 to 1,912 stems/ha depending on the approach. The population‐level static approach based on quantile regression produced an estimate closest to the overall mean with site‐level carrying capacity depending on tree species diversity and climate. Synthesis and applications. Overall, the findings highlight strong variability within and between contrasting methods of determining self‐thinning and site maximum carry capacity, which may influence ecological inferences.

The importance of aquafarming is increasing all over the world, however the coastal environment in the semi-closed inner bay has been aggravated due to the long term production and the high stocking density. For the sustainable aquafarming, there is a requirement for a eco-friendly fishery management by the estimation of ecological carrying capacity. The model development and application is still in the initial step, because it has to consider the whole ecosystem and all culture activities. As an alternative, there is a requirement for ecological indicator to assess the ecological performance. This study tried the estimation of ecological carrying capacity using ecological indicator. The production and the facility of the oyster farms was 4,935M/T, in Geoje-Hansan Bay(2008). Filtration pressure indicator was 0.203 which could provide a guidance on the present level of culture development. According to the environmental characteristics and the present oyster farms in Geoje-Hansan Bay, the newly assessed filtration pressure for the acceptable ecological carrying capacity was 0.102. Consequently, ecological carrying capacity in Geoje-Hansan Bay was 2,480M/T, and this represents the level of culture that can be introduced into Geoje-Hansan Bay without leading to significant changes to ecological process, species, populations or communities. Our study utilized the ecological indicator to estimate ecological carrying capacity of oyster farming for sustainable productivity and this could be the scientific basis for the eco-friendly fishery management.

Mass tourism is a major driver of economic growth in the Caribbean. One major trade-off of this economic growth model is the loss of natural areas due to tourism activities and increasing urbanization. Aruba is one of the most tourist intense destinations within the region with a total of 1.1 million stay-over tourists in 2019. Moreover, this island has one of the largest population densities in the Caribbean and high-speed urbanization takes place in this formerly rural island state. Therefore, this study aims to assess the islands' carrying capacity in relation to its limited land resources by means of a geospatial methodological analysis coupled with a correlation analysis between socio-economic indicators and statistics. First, the past and present drivers and characteristics of urbanization are analyzed. Second, the correlation between socio-economic indicators and the number of tourists was assessed. Third, two future scenarios were developed to assess the maximum carrying capacity. From 1986 till 2020, Aruba's built environment increased from ~29–60 km2 and translates to one-third of the island. Expansion was characterized by sprawl in the earlier years and changed to infilling in the latter. Furthermore, the results indicate that all socio-economic indicators are strongly positive correlated to tourism. Lastly, the possible maximum physical carrying capacity for yearly visitors and number of inhabitants was calculated to be ~1.7 million and 150.000, respectively. We conclude that the proposed methodological framework is robust and adequate to serve as a low budget decision-making tool for sustainable tourism development on islands.

In this paper, we take a two-level distribution grid as the infrastructure of a multilevel distribution grid and study the comprehensive carrying capacity assessment model in depth. The minimum value of the maximum access capacity under each scenario is used to assess the maximum carrying capacity of the distribution network, and the maximum access volume of the multilevel distribution network is taken as the objective function, and the particle swarm algorithm is improved to establish the maximum carrying capacity assessment model. Using the alternating direction multiplier method, a two-level distribution grid carrying capacity distributed optimization model is established, and the multilevel distribution grid access volume problem is transformed into the maximum access volume subproblem at all levels of the distribution grid. Comparing the whale algorithm and particle swarm algorithm, the model in this paper converges at 7465 kW access capacity and about 12 iterations, respectively, and the weak degree is below 0.4 at different distribution network states, which is a good performance in terms of optimization accuracy and weak degree. We conduct simulation experiments with the modified IEEE33 nodes and find that using this paper’s model to participate in optimal scheduling reduces the total operating cost of the distribution network system by more than 6.24% compared to not using it. Finally, we use the model in this paper to evaluate the comprehensive carrying capacity of the distribution network in Ningxia, China.