Conservation Bio lecture 14 on

T or F: When a population gets depleted fishing typically moves on to target a new population

T

If environment varies how should you fish

more conservatively

What is a MPA (marine protected area)

• spatial management and conservation tool

• restricts some human activities- most often fishing

T or F: restrictions vary widely between MPAs

T

What has been happening to the global coverage of MPAs overtime

they have been increasing

What are the large effects of reserves

more biomass, more animals, larger animals, fecundity, more species, diveristy

Which fish size have the most young?

Bigger fish

T or F: Biological processes can also be different in MPAs

T

Marine reserves benefits, larval example

Marine reserves can help replenish fish populations outside protected areas, supporting both conservation and fisheries.

Biological effects outside of MPAs

larval export

adult spillover

concentration of fishing

Marine protected areas (MPAs) increase fish populations, allowing adults to

move into surrounding areas

Why can MPAs be better than traditional fisheries?

they protect entire ecosystems rather than just individual fish species

Do Effective fisheries management or MPAs require a lot of information?

Effective fisheries

What is the traditional approach to fishery management?

scientists estimate how many fish can be safely caught

what is the problem with traditional MSY based fishery management

you can crash your fishery if you make a mistake

Why are MPAs a safer form of management?

Its easier to be sure that enough fish are left after fishing

Sustainable Harvest / Maximum Sustainable Yield (MSY) graph

How can MPAs regulate harvest naturally?

without yearly management decisions or extensive population data

C

fishing the line

fishing is concentrated on the edge of MPAs

Appropriate MPA size depends on

mobility (home range size) of species

How can you compensate for smaller MPAs

by designing MPA network

T or F: Small reserves can have positive biological effects for some species

T

What is a MPA network

collection of MPAs designed with specific goals and ecologically connected

MPA networks are often a more feasible way to

protect sufficient amount of area (and different habitats)

MPA networks are often more or less disruption to human activities

less (less social and political opposition)

MPA networks spread out the risk for

environmental disaster

metapopulation

population with two or more discrete sub-populations

T or F: Natural habitats are patchy

T

T or F: people are making habitats less patchy

F

T or F: Regulations can make populations patchy even if habitat is not

T

Issues with small populations

demographic stochasticity, Allee effects, inbreeding depression, genetic drift, environmental stochasticity and catastrophes

Clicker Q: Imagine 10 small populations.

Each year, each population has a 10% chance

of going extinct. What is your best guess of

the number of years before they all go extinct?

A) About 10 years

B) About 22 years

C) About 100 years

D) Maybe never

B

Meta populations can make a set of individually small populations ..

persist longer

Discrete Habitat patches

areas of habitat that contain the necessary resources and conditions for a population to exist

discrete habitat patches diagram

metapopulation

consists of a group of spatially separated populations of the same species which interact to some degree

In a metapopulation what can can happen to individual populations

they may go locally extinct or be recolonized

How do metapopulations persist?

through a balance of extinctions and recolonization of subpopulations

Changes in the frequency of patch occupancy (f), are a

function of the balance between the probability of patch

colonization (p i) and probability of patch extinction (p e).

metapopulation model equation

colonization rate

speed at which unoccupied patches become colonized

extinction rate

speed at which occupied patches go extinct

extinction rate in the classic metapopulation model

extinction per year is proportional to

the number of occupied patches

Extinctions per year is proportional to the number of occupied patches

e.g., 10 patches => - extinction 20 patches = - extinctions

1,2

D

At low patch occupancy there are how many sources of potential colonizers?

few

At high patch occupancy there are how many sources of patches to become colonized?

few free

Few occupied patches means what

fewer colonizations in the next year

some occupied patches means

many colonizations in the next year

mostly occupied patches means

few colonizations in the next year

Change in occupied patches =

Colonization − Extinction

What does the intersection of colonization and extinction curves represent?

equilibrium

metapopulation size =

fraction of patches occupied

declines

stable

grows

c

Why might colonization go down

• the spaces between habitats become harder to cross

• the number of patches goes down, and each patch is more physically isolated from neighbors

T or F: The spatial pattern of a patch loss does not matter

F

C

If we remove unoccupied patches what will happen?

the number of occupied patched will fall over time to new equilibrium

Metapopulation will go extinct at what time point when all habitat is destroyed?

before

If the metapopulation persists through a balance between extinction and recolonization, then at equilibrium a fraction of suitable habitat patches will be -

empty

In order to conserve a species in a metapopulation, it is necessary to save suitable habitat patches even if

they are not currently occupied by the species

Do currently unoccupied patches matter?

yes

B

What size metapopulations are less likely to go extinct

larger

The number of occupied patches fluctuates around

an equilibrium

The number of extinctions increases with

the fraction of meadows occupied

What helps species persistence in metapopulations

migration between patches

T or F: in metapopulations some species require multiple patches of habitat

T

Multiple patches can dilute the risk of

stochastic extinction

San Rafael better connected to the rest of the habitats

source

sink

source:

area with a net surplus of individuals, from which migration occurs. Might be able to survive in isolation

sink:

Area with negative population growth rate, which is only occupied because of immigration. Would go extinct without input from source populations.

T or F: Metapopulation dynamics can mean species are present in habitat that is not appropriate for them

T

B

sources/sinks are defined by

growth rate (lambda), not population size

Mainland island dynamics

large stable population does not go extinct. Recolonizes smaller populations that go extinct more rapidly.

A

edge habitat

areas near the border between one habitat and another (often more human dominated habitat)

What size habitat patches is most affected by edge effects

small

smaller or more irregularly shaped patches have

more % edge habitat

lower % core/interior habitat

higher perimeter to area ratios

More edge means

less core

C

Large patches are mostly

internal habitat

small patches are mostly

edge habitats

Patches close to other patches have

low isolation, high connectivity

patches far from other patches have

high isolation, low connectivity

C

What major changes happen as habitat is destroyed

size: decreases

Isolation: increases

Perimeter/area ratio: increases

What does the metapopulation theory predict effects on

populations

What does island biogeography theory predict effects on

species diversity

Theory of island biogeography:

Observation 1)

there are more species on larger islands and habitat fragments

Number of bird species on Caribbean islands is higher on what islands

larger islands

What habitats are naturally island like

freshwater lakes, coral atolls, high alpine meadows

Destroying/ converting habitats can create

remnant “islands”