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Flashcards in monitoring change Deck (12):

name two examples of chemical inputs into the marine environment

oil spills



name five examples of human impacts on the environment

-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)



What changes following a disturbance?

-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)



describe macrofaunal succession 

less successive diversity the higher the artificial stressors


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


display the impacts of multiple impacts comparing stable and unstable assemblage

stable- populatoin goes back to initiate number

unstable - populatoin declines over time


what are three potential problems when detecting impacts?

•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)


describe a survey design to detect impacts

BACI - Before After Control Impact (common sampling design)

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


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

Beyond BACI and MBACI


What is the problem with this curve?

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


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

•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


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

Multivariate techniques 

commonly used method

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