monitoring change

Question 1

name two examples of chemical inputs into the marine environment

Answer 1

oil spills

runoff

Question 2

name five examples of human impacts on the environment

Answer 2

• fishing (trawling)
• dredging/mining (e.g. Tauranga harbour)
• terrestrial runoff (important stressor in NZ)
• nutrient loading (causing algal blooms, eutrophication)
• organic enrichment (e.g. salmon farms)

Question 3

What changes following a disturbance?

Answer 3

• Loss of some or all members of the community
• near-bed hydrodynamics (removal of biogenetic structure, alteration of channel flow)
• food supply (increase if there is organic loading, decrease if the surface organic layer is removed)
• chemical gradients (RPD disturbed)
• sediment grain size (smaller or larger dependent on dusturbance)

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Question 4

describe macrofaunal succession

Answer 4

less successive diversity the higher the artificial stressors

Question 5

how is the population growth rate related to the frequency of disturbance?

Answer 5

Question 6

display the impacts of multiple impacts comparing stable and unstable assemblage

Answer 6

stable- populatoin goes back to initiate number

unstable - populatoin declines over time

Question 7

what are three potential problems when detecting impacts?

Answer 7

• Many populations sustained by recruits from elsewhere so loss of a species may not be indicative of environmental degradation
• Substantial natural variation in time and space which must be assessed
• Ensuring adequate sampling effort to be certain a species is not present (see previous lecture)

Question 8

describe a survey design to detect impacts

Answer 8

BACI - Before After Control Impact (common sampling design)

Problematic - temporal variation as two sights might not behave the same way

Question 9

What are other ways of detecting impacts (not BACI)?

Answer 9

Beyond BACI and MBACI

Question 10

What is the problem with this curve?

Answer 10

•Very simplistic measure and may miss fundamental changes in assemblage structure

Question 11

How are changes in diversity measured when studying impacts of disturbances?

Answer 11

•Species richness

–Number of species in a defined unit

–eg. Margalef’s index

• DMg = (S-1)/lnN
• N = total number of individuals
• S = total number of species
• Ignores information on relative abundances

•Indices that include proportional abundances

–eg. Shannon-Wiener diversity index

• pi = proportion of individuals found in ith species
• S = total number of species

species abundance models ABC (go to)

• Abundance Biomass Comparison
• uses all community information
• e.g. impacts of salmon aquaculture

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Question 12

Based on species abundance data, how is the similarity (abundance and composition) among sites analyzed?

Answer 12

Multivariate techniques

commonly used method

involves advanced statistical routines (cluster analysis, multi-dimensional scaling)