Upload
others
View
1
Download
0
Embed Size (px)
Citation preview
10/7/2015
1
What have ecological studies of fishes in kelp forests
contributed to our broader ecological understanding?
How has application of broader ecological
understanding contributed to our understanding of the
ecology of kelp forest fishes?
Theme numero uno:
10/7/2015
2
Life History Traits
Population Attributes
Community Attributes
distribution
structure (size, age, genetic, spatial)
dynamics
(species-wide, genetic, reproductive success)
reproductive modes
longevity, fecundity
life cycle
biogeography
structure (composition, abundance)
dynamics
diversity
Theme numero dos:
“Bipartite” life cycle of marine organismwith pelagic larvae
Benthic Environment
Adult
Larvae
Juvenile
Pelagic Environment
survive, grow, mature
survive, grow, disperse, develop
settlementreproduce
10/7/2015
3
“Bipartite” life history of marine speciesand “open” populations
Larval recruitment replenishes local populations!!
“OPEN” POPULATIONS“CLOSED” POPULATIONS
SupplyProduction
Little or no exchange among
populations
Significant exchange among
populations
SupplyProduction
Supply ProductionSupplyProduction
10/7/2015
4
Conclusion: 76% of these species moved less than 0.5 km
Home ranges of 25 west coast rocky habitat fish species
Median max. distance (km)
num
ber
of s
peci
es
0
4
8
12
Freiwald, J. 2012 Can. Jor. Fish. Aquat. Sci.
Reef Fish Adult Movement Ranges
Western North American Coastal FishTime in Larval Stage
midpoint (range)
Shanks et al. 2003AVERAGE = 94 days
Time in the larval stage (fish)
10/7/2015
5
The larval stage of the majority of (reef) fish is 1-3 months.
Time in the larval stage (fish)
Photo - G. Jones
<1 day
1 month
1-3 months
>3 months
Data from Carr and Syms 2006
Fraction of fish species
Time as larvae (hours)
Dis
per
sal D
ista
nce
(k
ilom
eter
s)
Shanks et al. 2003 Ecological Applications
Dispersal of invertebrate larvae: <1-100 km
0.0001
0.001
0.01
0.1
1
10
100
1000
10000
0.01 0.1 1 10 100 1000 10000
invertebrates
passive dispersal
r2= 0.61, P= 0.001
fishes
2 mo = 1440 hr
10/7/2015
6
Genetic difference estimate dispersal distance
“ Isolation by Distance”G
enet
ic
dif
fere
nce
Geographic distance (kilometers)
Slope measures average distance of dispersal
short
low
long
high
populations nearby one another
populations further apart
Slopes estimate dispersal distances
8000 200 400 600
Geographic distance (kilometers)
Copper rockfish
CA snailsRosethorn rockfish
CA corals
Gen
etic
dif
fere
nce
low
high
10/7/2015
7
Fish: 20-200 kilometers
Palumbi 2003Kinlan and Gaines 2003
Larval dispersalBased on geneticdifference
Inverts: <1-100 kilometers
Num
ber
of s
peci
es
Temperate reef fish assemblages comprised of BOTH
“open” and “closed” populations
10/7/2015
8
Ecological consequences of larval dispersal:
(1) decouples local recruitment (replenishment) from local production
(2) larval recruitment critical to replenishment of local populations
(3) recruitment and post-recruitment mortality is important source ofpopulation regulation (i.e density dependence)
(4) “open” spatial structure of local and regional populations
But remember that “openness” is a function of:
(1) spatial scale: openness decreases as scale of population increases
(2) adult movement: openness decreases as movement increases
(3) “retention”: openness decreases as likelihood that larvae return to adult population increases
Sources of spatial and temporal variation in recruitment
Larval production
Larval dispersal
Settlement
Post-settlement
10/7/2015
9
Sources of spatial and temporal variation in recruitment
Larval production:
- regional adult abundance- adult fecundity (eggs per female)
size/age structure / sex ratioadult condition
- reproductive mode
Reproductive modes of kelp forest fishes:
(1) internal vs. external fertilization
(2) internal vs. external eggs
(3) external eggs: benthic or “broadcast”
(i) internal fertilization, internal eggs: viviparitye.g., rays, sharks, surfperch, rockfish
(ii) internal fertilization, external eggs: ovoviviparitye.g., skates, sharks (swell, horn), sculpins
(iii) external fertilization (oviparity), broadcast eggse.g., kelp bass, wrasses (senorita, sheephead)
(iv) external fertilization (oviparity), benthic eggse.g., greenlings, gobies, damselfishes, kelpfishes
10/7/2015
10
Consequences of reproductive modes:
(2) behavior and social structure
e.g., benthic eggs -- nest guarding, territorialitybroadcast eggs -- spawning aggregations
(3) Defines resources that influence populationdistribution and abundance
e.g., competition for nest sites
Also, some species are hermaphroditic
e.g., kelp bass, wrasses (sequential, protogynous)gobies (sequential, protandrous)
(1) “openness” of a population
Sources of spatial and temporal variation in recruitment
Larval production:
- adult abundance- adult fecundity (eggs per female)
Size/age structure / sex ratioadult condition
- reproductive mode
10/7/2015
11
Bigger fish produce far more larvae
Approx. 11-fold increase
Approx. 7-fold increase
Older mothers produce better larvae
GR
OW
TH
(WT
)G
RO
WT
H (
LE
NG
TH
)L
AR
VA
L
SU
RV
IVA
L
Maternal age (yr)
black rockfishSebastes melanops
Larvae produced by older femalesgrow faster and survive better
Berkeley et al. 2004 Ecology; 2004 Fisheries
10/7/2015
12
Sources of spatial and temporal variation in recruitment
Larval production:
- adult abundance- adult fecundity (eggs per female)
size/age structure / sex ratioadult condition – e.g., Pacific Decadal Oscillation
- reproductive mode
Climatic variability effect larval production?
- Bight-wide patterns of juvenile impingement
- declines in recruitment for many spp. (1980 - 1991)
- attributed to reduced larval production (but maybe larval survival)
- reflecting large-scale decline in productivity
Power plant impingement of fish larvae:Ocean climate change
1) Love et al. 1998 Fishery Bulletinincluded commercial species
2) Brooks et al. 2002 Mar. Freshwater Res.no commercial spp.
10/7/2015
13
Offspring production: climatic variability
Perch recruitment
Population responses:4 surfperch
species
Benthic productivity
Surfperch production
Holbrook et al. 1997 Ecological Applications
Ocean climate change
Sources of spatial and temporal variation in recruitment
Larval dispersal (direction, distance, delivery):
- larval behavior- larval duration
- oceanographic features- interaction among these
Larval production:
- location of reproduction- timing of reproduction
10/7/2015
14
Sources of spatial and temporal variation in recruitment
Larval dispersal (direction, distance, delivery):
- larval behavior- larval duration
- oceanographic features- interaction among these
Larval production:
- location of reproduction- timing of reproduction
e.g., Norris 1963, Ecological Monographs
Physical processes and larval behavior
(1) Larval cues: (light, pressure, temperature, structure)
- Opal eye (Girella nigricans)
- recruitment related to tide pool temp.
- lab experiments: thermal preference
- coast-wide patterns of recruitment
- hypothesized mechanisms of larval delivery:- internal waves
- thermal / structural cues
- upwelling
Shanks 1983Mar. Ecol. Prg. Ser.ONSHORE TRANSPORT
10/7/2015
15
Large-scale (biogeographic) processes
currents — e.g., California current - El Nino
Cowen 1985 Jour. Mar Research
Large scale patterns of temporal (episodic) variability
Normal year (La Nada)
El Nino
Hypothesis: Change in current patterns influences spatial patterns of sheephead recruitment
Specifically, northward El Nino currents would increase recruitment in northern portion of sheephead range.
Hypothesis: Recruitment of sheephead will be greater in northern portion of range during 1983 El Nino
Test: Use annual otolith increments and settlement mark to back-calculate what year individuals settled…
Use this to construct strength of year-class recruitment
San Nicolas Is.
Is. Guadalupe
Cabo Thurloe
0 0 0
0ND
ND ND
0ND
10
20
10
20
20
20
10
10
30
40
Is. San Benito
75 77 79 81 83
Year
10/7/2015
16
“Structure - schooling”Long larval duration(3 - 4 months)
“Benthic - solitary”Short larval duration(1-2 months)
Black-&-yellow rockfish
Gopher rockfish
Kelp rockfish
Black rockfish
Yellowtail rockfish
Olive rockfish
(1998) (1999) (2000)El Nino La Nina La Nada
Mid-water complexLong larval duration(3 - 4 months)
Benthic complexShort larval duration(1-2 months)
Kelp, Black-&-yellow, and Gopher rockfish
Olive, Yellowtail and Black rockfish
1007550250
255075
100
Rel
ativ
e A
bu
nd
ance
1986 1992
1.0
0.5
0.5
1.0
0
Pro
po
rtio
n
Lenarz et al. 1995 CalCOFI
El Nino
10/7/2015
17
Mid-water complexLong larval duration(3 - 4 months)
Upwelling
10
30
50
70
(1998) (1999) (2000)
El NiñoLa Niña
Normal
Fis
h p
er 2
40 m
3
Olive, Yellowtail and Black rockfish
Black rockfish
Olive rockfish
Yellowtail rockfish
Benthic complexShort larval duration(1-2 months)
Relaxation
(1998) (1999) (2000)
El NiñoLa Niña
Normal
Fis
h p
er 2
40 m
3
0
4
8
12
16
20 Kelp, Black-&-yellow, and Gopher rockfish
Black-&-yellow rockfish
Gopher rockfish
Kelp rockfish
10/7/2015
18
biologicaldynamics
physical processes
&
Sampling Strategy
May June July August
Nu
mb
er o
f fi
shp
er s
amp
lin
g u
nit Benthic complex
n = 363 0.5
0.3
0.4
0.2
0.1
0.0
Mid-water complexn = 227
Nu
mb
er o
f fi
shp
er s
amp
lin
g u
nit
0.5
0.3
0.4
0.2
0.1
0.0
Tem
per
atu
re (
°C)
May June July August
Year 2000
9
10
11
12
13
14
(3) Smaller-scale, more frequent events(Ammann unpublished)
10/7/2015
19
e.g., Larson et al. 1994, Lenarz et al. 1995, CalCOFI Rpt.s
shifts in vertical distribution with ontogeny -- upwelling
- vertical distribution of early and late larval rockfishes
0 0.2 0.4 0.6
13
37
87-117
proportion
depth (m)
“structure - schooling” spp.
“benthic - solitary” spp.
Physical processes and larval distribution
offshore
onshore
depthearly
larvae
latelarvae
pelagicjuveniles
kelp bed
Sources of spatial and temporal variation in recruitment
Settlement:
- habitat structure- priority effects
conspecific cues
predation
- larval cues
competition
10/7/2015
20
e.g., Carr 1991, JEMBE
Settlement (post-settlement): habitat structure
(1) Macrocystis (rockfishes in central California)
- manipulated presence of giant kelp- some species recruit to kelp, others to rocky reef
(2) Macrocystis vs. understory (southern California)
e.g., Carr 1989, JEMBE
- manipulated presence of giant kelp and monitored recruitment
- recruitment of some species higher to kelp plots
- recruitment of some species higher to understory
e.g., Carr 1994, Ecology
Settlement (post-settlement): habitat structure
(3) Macrocystis (kelp bass in southern California)
- manipulated kelp density- positive correlation between recruitment and kelp biomass
(4) Macrocystis (kelp surfperch in southern California)
e.g., Anderson 1994, MEPS
- manipulated presence of giant kelp canopy and monitored recruitment
(5) Sea urchins (blue-banded goby in southern California)
- manipulated presence of urchins and monitored recruitment
e.g., Hartney and Grorud 2002, Oecologia
10/7/2015
21
0
10
20
30
Macrocystis
Absent Present
P < 0.0001
Den
sity
of
kel
p b
ass
recr
uit
s
(No.
per
60 m
3)
Greater density of kelp bass settlers in areas of a reef with giant kelp compared to areas without
Relationship within reefs…
Variation in giant kelp (Macrocystis) influences variation in settlement of kelp bass (Paralabrax clathratus)
10
20
30
0 100 200 300 4001
2
3
5
Macrocystis density (Stipes per 30 m2)
kelp
ba
ss re
crui
t d
ensi
ty(N
um
ber
per
60 m
)3
Spatial and temporal variation among reefs and years…
Density of kelp bass settlers increases with increasing density of giant kelp… but it is not linear!
10/7/2015
22
kelp bass recruit density:
blade biomass(gm per 5 m3 )
0 500 1,000 1,500
0
2
4
6
(Num
ber
per
10 m
2)
(Nu
mb
er /
10
m )2
0 40 80 120 1600
1
2
3
4
5
A
BB
Macrocystis density (stipes / 30 m2 )
0
A
BB
400
800
1,200
(gra
ms
/ 1
0 m
)2
0 40 80 120
blade biomass per reef area:
kelp bass recruit density:
Local density of giant kelp DETERMINESlocal density of kelp bass settlers
Conclusions:
i) Local and “regional” patterns of kelp bass recruitment are influenced by dynamics of giant kelp abundance
ii) The relationship is not based strictly on plant density, but on biomass (shelter!). Because kelp biomass changes with plant density, recruitment relationship is asymptotic.
iii) Giant kelp facilitates recruitment of kelp bass by providing habitat that they encounter as they pass over reefs
10/7/2015
23
Sources of spatial and temporal variation in recruitment
Settlement:
- habitat structure- priority effects
conspecific cues
predation
- larval cues
competition
Very little information available!
Sources of spatial and temporal variation in recruitment
Early post-settlement:
- growth- movement
competition
predation
- survival
10/7/2015
24
0 20 40 60 80 100
kelp rockfish
0.0
0.2
0.4
0.6
0.8
0 5 10 15
black eyed goby
Initial density
Early post-settlement: predation
per-capitamortality
Anderson 2002 Ecology
kelp perch
Steele 1997 Oecologia
Johnson unpublished
predators present
predators absent
1.0
1.01.0
0 20 40 60
15m
15m
(P+) Predator exposed
(P-) Predator excluded
Johnson 2006a,b Ecology
r2 = 0.039, P = 0.67
+ Predators
-- Predators
r2 = 0.949, P < 0.001
10/7/2015
25
Does local density-dependent predation scale up ?
Post-settlement mortalityis density-dependent
Predation isthe source
Local scale densitydependence manifestedwithin and across reefs
Johnson 2006a,b Ecology
e.g., Steele 1997a, Ecology
Conspecific and interspecific resident effects
- black-eyed and blue-banded gobies in So. California
- manipulated presence of adults of both
- settlement of black-eyed decreased in presence of adult conspecifics
- settlement of black-eyed not influenced by presence of adult blue-banned
- settlement of blue-banded (+) influenced in presence of adult conspecifics
- settlement of blue-banded not influenced in presence of adult black-eyed
Early post-settlement: competition
10/7/2015
26
Sources of spatial and temporal variation in recruitment
Late post-settlement:
- growth- movement
competitionpredation
- survival
adult and juvenile interactions
(1) Hixon 1980, Schmitt and Holbrook 1990, etc.
Late post-settlement: interspecific competition
- striped and black surfperch in So. California
- two species exhibit depth stratified distributions- manipulated presence of either species
- monitored change in depth distribution
shallow
deep
stripe
black
10/7/2015
27
Late post-settlement: interspecific competition
Striped (+)
Black (+)
Striped (+)
Black (+)
Striped (+)
Black (+)
reef: 1 32time:
pre-
Striped (+)
Black (+)
Striped (--)
Black (+)
Striped (+)
Black (--)
Striped (+)
Black (+)
Striped (+)
nobody home
manipulation
post-Black (+)
Black (+)
Conclusion: striped perch competitively dominant:excludes (interference) black perch from shallow.
Late post-settlement: interspecific competition
(2) Larson 1980, Ecological Monographs
- same as above for sibling surfperches
- black-and-yellow and gopher rockfish in So. Calif.
shallow
deep
black and yellow
gopher
10/7/2015
28
Territory size limits local density and pop. size
Late post-settlement: intraspecific competition
(1) Garibaldi in So. California -- Clarke 1970
- map territory sizes and distribution
- monitored change in territory sizes and density
(2) striped and black surfperch in So. California
- same as above
- Larson 1980 a, b Marine Biology
- Schmitt & Holbrook
(3) black-and-yellow and gopher rockfish in So. Calif.
- remove individual
- same as above
Effects of habitat on fish assemblages
e.g., Larson and DeMartini 1984, U.S. Fishery Bull.
(1) Macrocystis (southern California)
- cobblestone bottom off San Onofre
(2) Macrocystis vs. Nereocystis (central California)
e.g., Bodkin 1986, U.S. Fishery Bull.
- difference in relative abundance of species
- compared fish assemblage in areas with and with giant kelp
- difference in relative abundance of species
- compared fish assemblages on either side ofPiedras Blancas (Nereo. north, Macro. south)
10/7/2015
29
e.g., Ambrose and Swarbrick 1989, Bull. Mar. Sci.
(3) Macrocystis (southern California)
- included artificial reefs
- little difference in relative abundance of species
- compared fish assemblage on reefs with and with giant kelp
e.g., Holbrook et al. 1990,1994, Austr. J. Ecol., Am. Zool.
(4) Macrocystis (southern California)
- same as (3) above, no difference in species richness
- planktivores and macro-invert eaters, reduced with kelp
Effects of habitat on fish assemblages
1999200020012002200320042005
Sites by Year Sampling Began
Monterey Bay
Pt. Conception
Large-scale biogeographic patterns
10/7/2015
30
2 m
2 m
Fishdensitysizes
Densitykelps
Coveralgaeinverts
macro inverts
Coastline
Fish transect distribution
5 m
10 m
15 m
20 m
12 m
5 m
20 m
Algae / invertebrate transect distribution
Approach: within-site sampling design
10/7/2015
31
Geographic Variation in Kelp Forest Fish Assemblages
Monterey Bay
Pt. Conception
Sedimentary
Granite
Basalt
Monterey Bay
Pt. Conception
Sedimentary
Granite
Basalt
SIMPROF (P= 0.01)
Regions North of Point Conception
PC4: Low Relief, Sand
-2 -1 0 1 2 3 4-3
-2
-1
0
1
2
3
4
5
-1 0 1 2 3-2
-1
0
1
2
3
4
5
-2 -1 0 1 2 3 4-2
-1
0
1
2
3
4
-2 -1 0 1 2 3-2
-1
0
1
2
3
4
5
High relief rocky reefs protected from high swell exposure
SIMPROF (P= 0.01)
P< 0.0001R2= 0.31
P< 0.0001R2= 0.28
P= 0.0007R2= 0.09
P< 0.015R2= 0.05
PC3: High Relief
PC1: NW Swell
PC2: South Swell
“cold water” assemblage
PC – cold water
10/7/2015
32
e.g., Cowen 1983, Oecologia
(1) “Top-down”: keystone predators
- manipulated local presence of sheephead and observed red sea urchin behavior
- urchins more exposed and mobile in absence of sheephead
- sheephead (Semicossyphus pulcher) in So. Calif.
Role of fishes in kelp forest communities
sheephead
Cascading Effects of Predator Removal
sea otterssheephead
sea urchins
barrenskelp forest
rockfishes
Southern California Central California
lobster
10/7/2015
33
e.g., Bray et al. 1991, Science
(2) “Bottom-up”: enhanced nutrient availability & productivity
- monitored nutrient availability and macroalgal production in crevices with and without blacksmith
Role of fishes in kelp forest communities
- planktivorous blacksmith (Chromis punctipinnis) hole up in crevices at night
- greater nutrient availability and macroalgal production in crevices with blacksmith
- example of planktivorous fishes directing planktonic production to benthos
e.g., Gaines and Roughgarden 1987, Science
(3) Planktivorous fishes reducing larval supply
- could be hydrodynamic influence of kelp or predation by planktivorous juvenile rockfishes
Role of fishes in kelp forest communities
- reduced recruitment of intertidal barnacles in years with thick Macrocystis forest at Hopkins
- used barnacle molts to decouple potential causes
- barnacle molts not reduced as they passed through forest, concluded reduction due to planktivory
- high recruitment of planktivorous juvenile rockfishes in years with thick Macrocystis forest
10/7/2015
34
Avoiding the swine flu: don’t do this