L10 - Monitoring for Change Flashcards Preview

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Flashcards in L10 - Monitoring for Change Deck (16):
1

 

Aim

•Overview of human impacts on coastal systems

•Detecting impacts in soft sediment communities

–Disturbance theory

–Designing monitoring programs

–What to measure?

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•Studying temperate marine environments, Kingsford & Battershill Chapters 1-3 (desk copy)

 

•Marine Biology, Levinton Chapter 19 (desk copy)

 

2

 

Human impacts in coastal waters

 

•Chemical inputs

 

'Rena oil spill' case study

The closer to sure the more visable the impacts

 

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Human impacts in coastal waters

 

Dredging in Tauranga Harbour 

Dumped offshore and distrubes the habitats out there as well as having various effects in the actual dredging area itself.

 

 

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3

 

Human impacts in coastal waters

 

•Terrestrial runoff

 

 

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•Nutrient loading

Toxic algae blooms of california coast

More info:  http://www.redtide.whoi.edu/hab/default.html

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4

 

Human impacts in coastal waters

 

•Organic enrichment

Right pic- 150m of fjords British Columbia community subject to excessive organic loading - no large benthic organisms to process nutrience

 

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5

 

•Impacts best studied for soft-sediment systems

–Most common habitat

–Eventually pollutants end up in the sediments

–Invertebrate fauna mostly sessile – environmental integrators

–Numerous indicator species and assemblage types identified for impacted systems

•Human impacts generally occur at higher frequencies and over larger spatial scales than natural disturbances

 

 

6

 

What changes following a disturbance?

 

•Loss of some or all members of the community

(freeing up other space)

•Near-bed hydrodynamics

–Removal of biogenic structure

–Alteration of channel flows

•Food supply

–Increase if there is organic loading

–Decrease if surface organic layer is removed

•Chemical gradients

–RPD disturbed

•Sediment grain size

–Smaller or larger dependent on disturbance

•RESULT: Alteration of density, size frequency or behaviour of some members of an assemblage

 

7

 

•Loss of some or all members of the community

•Near-bed hydrodynamics

–Removal of biogenic structure

–Alteration of channel flows

•Food supply

–Increase if there is organic loading

–Decrease if surface organic layer is removed

•Chemical gradients

–RPD disturbed

•Sediment grain size

–Smaller or larger dependent on disturbance

•RESULT: Alteration of density, size frequency or behaviour of some members of an assemblage

 

 

 

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8

 

Disturbance and species diversity

 

 

 

 

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9

 

Assemblage responses

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Effects of multiple impacts

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10

 

Detection of impacts: potential problems

•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)

 

 

11

 

Detection of impacts: BACI

 

•Before After Control Impact

•Common sampling design

 

•Problematic – why?

 

 

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12

 

Detection of impacts: Beyond BACI & MBACI

 

 

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Quantifying impacts: Abundance

 

•e.g.. Effects of sewage outfall on the benthic fauna of Kiel Bay

 

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

 

 

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13

 

Quantifying impacts: Changes in diversity

 

 

•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

 

 

 

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14

 

Quantifying impacts: Changes in diversity

•Problem with species richness indices

 

 

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Quantifying impacts: Changes in diversity

 

•Species abundance models ABC

–Abundance Biomass Comparison

–Uses all community information

–E.g. impacts of salmon aquaculture (Ritz et al. Mar. Biol. 103: 211-214 (1989))

•r and k community curves 

 

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15

 

•Based on species abundance data

–Commonly used method

–Based on analyzing similarity (abundance & composition) among sites

–Involves advanced statistical routines (cluster analysis, multi- dimensional scaling) A

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16

 

Quantifying impacts: Multivariate techniques

 

•e.g..  Frierfjord Norway (from Clarke & Warwick 2001)

 

 

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