Threats & Losses II

Question 1

How do habitat fragments differ from the original habitat?

Answer 1

Increased edge effect, interior is much closer to its edge than in contiguous habitat
Abiotic changes ex; more sun = hotter &drier

Question 2

What does this mean for flora and fauna?

Answer 2

• Smaller habitat = smaller population, Genetic loss, more susceptible to random loss
• Disconnection from other population, limits genetic flow ( no rescue effect, less migrants due to isolation)
• Invasive species can penetrate deeper
• phenotypic/ specific characteristics that are acquired because of the changing habitat
• limit potential for dispersal and colonization
• reduce foraging ability

Question 3

humans and fragmented populations

Answer 3

roads= accidents, erosion, run-off, increased vulnerability, pollutants
-species can be less accustomed to humans, not as well adapted
- changes pop. of larger predators (wolves) who require space for all their ecological needs

Question 4

Biological dynamics of forest fragmentation project? (BDFFP)

Answer 4

• longest running experiment of tropical forest fragmentation
• fragments of different sizes created in 1980 and forest blocks of equivalent sizes served as controls
• surveyed for species composition, microclimate, and other ecosystems characteristics

Question 5

what did the bdffp find?

Answer 5

determined how far into the forest fragment a specified effect occurs
ex: trees growing within 300 m of an edge have a higher mortality rate

Question 6

What is the extinction debt?

Answer 6

inevitable time for extinction
- for longer lived species such as trees or primates there may be some time before population loss or extinction (persist but do not recruit)
- for short-lived organisms such as rodents that will go extinct faster

Question 7

species-area relationships and populations

Answer 7

• positive relationship between area and the number of species (for both continental and island biotas)
• studies require long term monitoring

Question 8

species = c. Area ^z

Answer 8

z is <1 and typically 0.1 -0.4
can make a prediction as a result of fragmentation
increase in slope (Z0 reflects loss of species in small forest fragments

Question 9

sources of pollution affecting biodiversity

Answer 9

more unnoticed than outright destruction
caused by pesticides, herbicides, sewage, fertilizers from agricultural fields, industrial chemicals and wastes, emissions from factories and automobiles and sediment deposits

Question 10

why are marine systems being drastically changed?

Answer 10

rivers, lakes, and oceans are often used as open sewers for industrial wastes and residential sewage

Question 11

biggest pollutant In marine systems

Answer 11

human sewage, agricultural fertilizers, detergents, etc. often release large amounts of nitrates and phosphates into freshwater systems
- leads to eutropication

Question 12

what is eutrophication ?

Answer 12

• increase in the rate of supply of organic matter in an ecosystem
• input of nutrients from waste ( nitrates and phosphates) increase the productivity of natural cycles
  -over productive algae blooms, outcompete plankton and other submergent species
  -decreases levels of oxygen in the water (hypoxia) = fish kills

Question 13

consequences of eutrophication

Answer 13

serious issue in coastal areas = stress and suffocation of marine life
- creation of dead zones

Question 14

what are dead zones?

Answer 14

large areas of hypoxia bottom water due to eutrophication that can stress and suffocate some marine organisms
e.g. Gulf of Mexico, increase of dead zones across the globe

Question 15

when does overexploitation occur?

Answer 15

occurs when the harvest rate of any population exceeds its natural replacement rate, either through reproduction or reproduction / immigration

Question 16

examples of overexploitation

Answer 16

fishing, hunting, wildlife trade

Question 17

overfishing Myers and Worm (2003)

Answer 17

-time trends of community biomass in oceanic (a-i) and shelf ecosystem (j.m)
- synthesized data by using the biomass of fishes
- in 15yrs of industrialization, the fishing stocks dramatically decreased

Question 18

missing fish Pauly and seller (2015)
*importance of high quality data to make informed decisions in conservation biology

Answer 18

• FAO fishery data underestimates artisanal and subsistence fisheries, bycatch, illegal and unreported catch
• Global fisheries cluster –> catch reconstruction, uses a wide variety of data and information sources to derive estimates for fisheries

Question 19

What does fishing down mean?

Answer 19

• successive loss of the largest individuals and species in favour of smaller, faster, and shorter-lived fishes
• systems can collapse very fast

Question 20

what is bycatch?

Answer 20

• the accidental catch of undesired marine invertebrates and vertebrates
• between 25% and 75% of the catch is dumped back into the sea

Question 21

benefits of bycatch

Answer 21

Innovation!
- huge numbers of sea turtles and dolphins killed by commercial fishing boats as bycatch have led to the development of improved nets and hooks to reduce bycatch

Question 22

examples of overexploitation of tropical forest vertebrate assemblages

Answer 22

• hunting (subsistence/commercial), worsened by the bushmeat crisis
• $240 billion dollar international wildlife trade

Question 23

Results of the bushmeat crisis

Answer 23

• populations of large primates, ungulates, and other mammals may be reduced by 80% OR MORE
• ‘HALF-EMPTY’ forest, land with a mostly intact plant community that is lacking an intact animal community

Question 24

international wildlife trade

Answer 24

major importers in developed countries (Canada, China etc.)
e.g. in 2015, 1338 African rhinos were killed, most killings were motivated by the international market for rhino horn

Question 25

how does the loss of large vertebrates affect community dynamics?

Answer 25

• change in seed dispersal
• large predators decrease
• increase in smaller predators and competitive species
• inbreeding depression (genetic loss)