A&E Lab 2

Define the term community

All the organisms living in a particular area; a group of different species populations that live close enough together to interact.

True or False: There is a diverse community of plants and animals associated with the streambed

True

Can macroinvertebrates be seen with the naked eye?

Yes

Define Invertebrates

An animal without a backbone.

If Invertebrates are animals without a backbone, then what are macroinvertebrates

Invertebrates that can be seen with naked eye (without the aid of a microscope).

What is meant by the physical feature of a stream?

The streams observable characteristics like size (width and depth) ,water velocity, temperature, and frequency of floods, which affect community composition.

What are the environmental factors affecting stream community composition?

Key factors include water quality, temperature, habitat structure, and nutrient availability. For example, sunny streams support algae growth, while shaded streams depend more on leaf litter for energy.

How does the diversity of riparian plant species also affects the streams community composition?

Different riparian riparian plant species provide different food sources, and shade ect.

These affect temperature and nutrient input in the water.

Thus the invertebrate communities will differ in their functional organization.

define riparian plant species

Plants that grow alongside riverbanks/streams.

What is meant by anthropogenic factors?

Human related factors that affect the environment, such as the conversion of forest to farmland, and pollution.

What is the difference between environmental and anthropogenic factors?

Environmental factors are natural influences on ecosystems; while anthropogenic factors are human-induced ones.

How does the anthropogenic factor of pollution effect the communities composition?

Different species have different levels of tolerance to pollution/enrichment.

What is the Macroinvertebrate Community Index (MCI)?

The basis of the MCI is that each type of invertebrate is assigned a score from 1 to 10 that reflects its sensitivity to pollution (where 1 = highly tolerant and 10 = highly sensitive).

The species present in the stream can thus provide an estimate of stream quality

What does it mean if many of the communities species have a high Macroinvertebrate Community Index (MCI)?

A high MCI value indicates that the species are highly sensitive to pollution.

If the stream community has several species that are highly sensitive to pollution (e.g., MCI scores of 8 - 10), then we can infer that stream is relatively free from pollution.

What does it mean if many of the communities species have a low Macroinvertebrate Community Index (MCI)?

A low MCI value indicates that the species are very tolerant to pollution.

If the stream is dominated by species with low MCI scores (1-2) it is indicative of pollution.

Why would we expect the Turitea stream to be relatively polluted and have a dominant number of species with a low MCI value?

The Turitea stream is not pristine due to impoundment for water supply and pollution from farms and suburban areas, including runoff, septic effluent, and pesticides. Additional pollution sources include leachate from the old Massey landfill), and stormwater drains.

Define Species Richness;

The number of different species present in a given area or community.

( I.e. How many different species are there?)

Define Species Evenness;

A measure of the relative abundance of different species in a community.

(I.e. How many individuals of each species are there?)

The turitea stream is made of alternating pools and riffles; what does pools refer too in this context?

deep slow, flowing pools

The turitea stream is made of alternating pools and riffles; what does riffles refer too in this context?

Shallower fast flowing, stony bottomed riffles

What is the Macrovertebrate community Index: (MCI index value)?

Assesses the presence and abundance of macroinvertebrate species, providing insight into the quality of a stream.

What does a MCI index value greater than 120 indicate?

Indicates clean water.

What does a MCI index value between 80-120 indicate?

Moderate enrichment

What does a MCI index value less than 80 indicate?

Severe enrichment and pollution

What is the MCI index formula?

MCI= 20 x the sum of all MCI / The number of species found.

Species Diversity

The variety of different kinds of organisms that make up the community—has two components (species richness and species evenness. )

Imagine two small forest communities, each with 100 individuals distributed among four tree species (A, B, C, and D) as follows:

Community 1: 25A, 25B, 25C, 25D

Community 2: 80A, 5B, 5C, 10D

Is species richness or species evenness the same?

The species richness is the same for both communities because they both contain four species of trees, but the relative evenness is very different.

Does A or B have greater species diversity?

A has a greater evenness than B, and can therefore be said to have a higher species diversity.

Given a sample of macroinvertebrates including 10 mayflies (MCI:1), 5 caddisflies (MCI=3), and 2 dragonflies(MCI=5), how do you calculate the Macroinvertebrate Community Index (MCI)?

1. Assign tolerance values (mayflies = 1, caddisflies = 3, dragonflies = 5). 2. Calculate total MCI: (10 x 1) + (5 x 3) + (2 x 5) = 35. 3. Count total species (3). 4. Apply formula: MCI = (35 / 3) x 20 = 233.33.

What is the MCI score/tolerance value of Potamophyrgus?

4

What is the MCI score/tolerance value of Oxyethira?

The MCI score/tolerance value of Oxyethira is 2.

What does the Shannon-Wiener Index (H’) calculate?

It quantifies species diversity in a community, accounting for both abundance and evenness.

What does a higher Shannon-wiener diversity index value indicate.

A higher value indicates a more diverse community.

What is the formula for the Shannon-Wiener diversity index?

The sum of all the individual p_ilogp_i but made positive ( multiplied by negative 1).

p_i represents the proportion of each species

(no. of the individual organisms in a species/ the total no. of organisms in the whole community)

How would you use this part of the Shannon-Wiener diversity Index p_ilogp_i ?

p_i represents the proportion of each species

(no. of the individual organisms in a species/ the total no. of organisms in the whole community)

So you do p_i times the log of p_i.

What is the Shannon wiener diversity index?

The total of the column pi log pi is -0.3226. To calculate H’ (the diversity index) change the sign, so H’ = 0.3226.

What is the maximum diversity index (H' max)?

Maximum diversity, often referred to as evenness, is achieved when each species in a community has the same number of individuals.

How is the species evenness of the community calculated?

Through the maximum diversity index (H' max)

If all species were present had the same abundance, then H’max = H’(Shannon-Wiener Index Value). Thus, we can infer the species evenness of a community based on how different H’ is from H’max.

How but you can calculate the maximum diversity for a given number of species (k)?

H'max = log k.

In which k = the total number of species

This shows that there is no upper bound on the diversity index.

In a space that has evergreen trees versus deciduous trees what would you except to see with the MCI index and Shannon wiener index?

Evergreen trees (native bush) have less leaves dumping in water and more shade leading to less algal bloom => better water quality and thus a higher MCI and Shannon-Wiener Index

compared to

Deciduous trees (introduced trees), which produce more leaf litter and have less shade which lead to increased algal blooms (which respire taking up oxygen from invertebrates)

=> worse water quality and thus a lower MCI and Shannon-Wiener Index values.