monitoring change Flashcards Preview

Marine Ecology & Monitoring > monitoring change > Flashcards

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

A image thumb

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

A image thumb

display the impacts of multiple impacts comparing stable and unstable assemblage

stable- populatoin goes back to initiate number

unstable - populatoin declines over time

A image thumb

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 

A image thumb

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

Beyond BACI and MBACI

A image thumb

What is the problem with this curve?

Q image thumb

•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

A image thumb

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)

A image thumb