Bottom Trawling

Question 1

Ocean biodiversity

Answer 1

Large structure former live in shallow water and small structure fprmers live in deep water ( esp the Abyssal Muddy plains)

Question 2

Creatures in large structure formers

Answer 2

Kelp forest - support diversity
Mangrooce - stabilize sediment, prevent over siltation
Coral reef - prevent erosion
Sea bed - prevent over siltation

Question 3

Creatures in small structure formers

Answer 3

Epifauna above the seafloor of sediments
Infauna- within the seafloor sediment where o2 penetrates

Question 4

Importance of benthic species

Answer 4

Nutrient cycling
Pollutamt distribution and fate - resuspension transport & metabolize
Secondary production - habitat, food, water
Water clarity- buffer nutrient loading
Sediment stability and transport

Question 5

Bottom trawls

Answer 5

Net dragged over the seafloor to catch fish

Question 6

Bottom trawling damages

Answer 6

Penetrate and scrape the seafloor , affecting marine lofe and structures

Question 7

Impacts of bottom trawling

Answer 7

Re-suspension of mud , infauna and pollutants
Loss of fauna
Loss of microstructure
Sediment trail
Cold-water/deeo coral reef affected by disturbances
Vulnerable matine ecosystem
Impacts a high biodiversity

Question 8

Magnitude of the issue

Answer 8

Most seafood from bottom trawling
Global continent shelf area trawled every year
- high sea impacts are unregulated
Fishing effort not randomly dostributed
Causes seascape fragmentation

Question 9

Long term impacts on benthic communities

Answer 9

1- species area relationship
2- Succession- change in community structure through time
Influence of sps richness btw disturbance ecvents
3- island biogeography theory
Size pf untrawlled habitat fragments & distance btw fragments influences sps richness

Question 10

Long term impacts on benthic communities

Answer 10

1- species area relationship
2- Succession- change in community structure through time
Influence of sps richness btw disturbance ecvents
3- island biogeography theory
Size pf untrawlled habitat fragments & distance btw fragments influences sps richness

Question 11

Disturbances

Answer 11

Event that affects ecosystem structure and function

Question 12

Dusturbance regime

Answer 12

= patterns if disturbance events
- intensity - idv or sps /event
- scale - spacial extent
- frequency - mean number (linked to int or scale)

Question 13

Scale : frequnecy : intensity

Answer 13

Small scale- high frequency, low intensity
Large scale- low freq, high int

Question 14

Succession

Answer 14

• change in comm structure through time
• colonization & extirpation rate

Question 15

Colonization vs extirpation

Answer 15

Colonization - high sps richness
Extirpation - dec sps richness

Question 16

Early colonizer / pioneer vs later colonizer / climax

Answer 16

R-selected- Early colonizer have high r , poor comp
K - selected- Later colonizer low r , better comp

Question 17

Disturbance frequency

Answer 17

High frequency -> early sps only - reduce sps richness

Question 18

Island biogeography theory- speciecs richness depends on

Answer 18

Colonization rate and extirpation rate

Question 19

Island biogeography theory - two prediction

Answer 19

• distance btw untrawled areas inc -> colonization rate dec = sps richness dec
• size btw untrawled areas dec ->extirpation rate inc = sps richness dec

Question 20

Practical solutions of bottom trawling

Answer 20

Full ban on bottom trawling & dredging in intn waters or high sea - 45% of searths surface

Stop trawling in sensitive areas like VULNERABLE MATINE ECOSYSTEM

Question 21

Bottom trawling effects on natural disturbance regime

Answer 21

Low natural disturbances in shaloow water
High in deeper water - adap to low disturbances

Question 22

Bottom trawling effect on trawling disturbance regime

Answer 22

Leads to large scale , high frequency and high intensity disturbances
Keading to only early species thrive - red sps richness

Question 23

Bottom trawling effect over time

Answer 23

Target sps catch DEC
recovery rate of pop DEC
HIGH bycatch -> LOW bycatch
Biodiversity of infauna DEC - less o2 penetration less diversity
Complexity in benthic structures DEC
rare scavabger sps INC feed on sus benthic sps

Question 24

Bottom trawling vs clearcutting

Answer 24

• Similarities:
o Alter substratum
o Remove structure-formers ]
o Maintain early and eliminate late successional stages (decrease biodiversity)
o Remove high biomass from ecosystem
• Differences:
o Larger area of seafloor impacted