Tutor profile: Rachel G.
Subject: Environmental Science
Describe and explain two main forms of environmental change occurring on coral reef ecosystems
1) Coral bleaching: Coral bleaching occurs when sea surface temperatures are higher than average for an extended period of time. Corals contain zooxanthellae, tiny photosynthetic organisms. At high temperatures, there is too much energy available for photosynthesis. The zooxanthellae use this extra energy to create reactive oxygen series (ROS). ROS are toxic to corals, which are forced to expel the zooxanthellae. The photosynthetic nature of the zooxanthellae provides corals with their colour, as well as most of their food supply. When zooxanthellae are expelled, the coral loses its colour, hence the term 'bleaching'. 2) Rising carbon dioxide: The ocean absorbs a huge amount of CO2 from the atmosphere. Due to increased emissions, the amount of CO2 in the atmosphere is increasing, thus the amount of CO2 in the oceans is also increasing. CO2 affects the pH of the ocean. The ocean is therefore becoming more acidic. This can have damaging effects on coral reefs. If the ocean continues to become more acidic, calcium carbonate structures in the ocean, such as corals or shelled organisms could start to break down.
What is the intermediate disturbance hypothesis?
The intermediate disturbance hypothesis is an ecological concept concerning the makeup and diversity of a community within an ecosystem. The hypothesis states, that in a stable environment, with low disturbance, and in an unstable environment with high disturbance, biodiversity will be low, because a few specialised species will out-compete other species. At intermediate disturbance levels, there will be a large number of different habitats available, and the diversity of species will be highest at these intermediate levels of disturbance,
In animal behaviour, what is a widely used method of calculating the consistency of a behaviour, and what specific data would be required to calculate this consistency?
The consistency of behaviour, or behavioural repeatability, refers to the proportion of variance accounted for my differences between individuals, can be calculated from ANOVA (Analysis of Variance) tables. To calculate repeatability, two forms of variance are required: Variance in behaviour between study individuals, and variance in behaviour within individuals. Therefore, each study individual must have been tested more than once, in order to calculate the within individual variance. In an ANOVA table, between individual variance is mean sum of squares for the individual ID factor, and the within individual variance is the mean sum of squares for the residual: Df Sum Sq Mean Sq F P Group Between Residuals Within The overall sample size, i.e. the number of study individuals, and the number of time each individual was studied, must also be known. If all of the above data is present, then repeatability can be calculated as: R= Between group variance/(Between group variance + within group variance)
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