monitoring change Flashcards

1
Q

name two examples of chemical inputs into the marine environment

A

oil spills

runoff

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2
Q

name five examples of human impacts on the environment

A
  • 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)
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3
Q

What changes following a disturbance?

A
  • 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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4
Q

describe macrofaunal succession

A

less successive diversity the higher the artificial stressors

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5
Q

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

A
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6
Q

display the impacts of multiple impacts comparing stable and unstable assemblage

A

stable- populatoin goes back to initiate number

unstable - populatoin declines over time

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7
Q

what are three potential problems when detecting impacts?

A
  • 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)
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8
Q

describe a survey design to detect impacts

A

BACI - Before After Control Impact (common sampling design)

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

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9
Q

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

A

Beyond BACI and MBACI

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10
Q

What is the problem with this curve?

A

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

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11
Q

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

A

•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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12
Q

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

A

Multivariate techniques

commonly used method

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

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