Potential impacts of Climate Change on Loliginid Squid: Biology, - - PowerPoint PPT Presentation

Potential impacts of Climate Change on Loliginid Squid:

Biology, Ecology & Fisheries

Gretta Pecl & George Jackson

Cephalopod research

…Beyond O’Dor

Squid & Climate Change….

• Increased ocean temperatures

–Faster growth –Shorter life spans

• Will climate change be beneficial to

inshore squid fisheries?

• Growth rates increase, pop’s larger,

turnover of populations more rapid?

• Population expansion at the expense
• f slower growing teleost competitors?

Response of squid populations may be much more complex!!

Pecl, G. T. & Jackson, G. D. (2004). The potential effects of climate change on southern calamary in Tasmanian waters: biology, ecology & fisheries. Short paper for WWF U.S.

http://www.panda.org/about_wwf/what_we_do/marine/publications/index.cfm?u

NewsID=51982

Being revised to : Pecl, G.T. & Jackson, G.D. The potential impacts of climate change on inshore loliginid squid: biology, ecology and fisheries.

Basis of Talk…..

Cephalopod Fisheries

• Oceanic Ommastrephids & inshore Loliginids

– Basis of major cephalopod fisheries (80%)

• Major fished loliginids:

⎯ Loligo gahi ⎯ L. opalescens ⎯ L. pealei ⎯ L. forbesi ⎯ L. vulgaris ⎯ L. reynaudi

Biomass can be very high – very important components of local and National economies!

Loliginids & Environmental Change

• Large population fluctuations due

to environmental changes

• Is long-term sustainability possible

in the event of large changes in environmental regimes (Agnew et al 2005)?

• Climate change could have a major

impact

• Need to assess potential impacts

more thoroughly than just ‘temperature increases squid growth rates’.

Time Population size

Loliginid Life History

• Geared towards life in the fast lane

– efficient digestion, protein based metabolism – continuous growth – efficient use of oxygen – low levels of antioxidative defense

• Short life-spans (~ 1yr or less)

– high growth rates – fast metabolisms – ravenous appetites

Age Size

Loliginid dynamics

• Recruitment highly variable & every year a

new cohort

• Huge flexibility and plasticity in life history

Better poised than many other species to adapt to changes, however, is our perception of how squid may respond to climate change too simplistic?

Climate Change……

• What are proposed changes?

– Temperature increases – ↑ El Niño’s and more extreme El Niño’s – ↑ Ocean acidity – Changes in upwelling intensity, size and location – change in productivity zones?

• Ecologists, physiologists & resource managers

face challenge of predicting effects of climate change on species and communities

Impact of Climate Change on Loliginids

Taking a ‘bottom up’ approach to explore how climate change may impact on:

• Physiology & morphology of individuals
• Phenology of individuals & populations
• Distribution/density of species
• Changes in species interactions, communities,

ecosystems & fisheries

Physiology and morphology of individuals

Growth & body size Reproduction Energetics/ respiration/metabolism

Growth & body size - Hatchlings (1)

• ↑ temperature,

↓embryo development time

• ↓ embryo development time,

↓ hatchling size

• Smaller hatchlings unless

females compensate with larger (but fewer) eggs!

Growth & body size - Hatchlings (2)

• Size at hatching may affect

growth and final size-at-age!!

• Growth exponential - small

differences between individuals amplified through the lifespan

• How you start the race important
• Initial research with octopus

shows relationship between hatchling size and growth IS important - but complex

(Leporati et al in review)

Growth at 6% per day at different hatchling sizes

5 10 15 20 25 30 5 15 25 35 45 55 65 75 85 95 Days 0.02 0.03 0.04 0.05 0.06 0.07

Weight

Pecl et al (2004a) Mar FreshW Biol.

Growth & body size - Adults (3)

• Growth also linked to prey availability
• Faster life history but mature younger & smaller
• Growth rate ↑↓ depending on food x metabolism x temp

relationship

• Some species will grow faster but not all
• ↑ temperature usually ↑ variance in growth rate

(more in males in Loliginids) e.g. Sepioteuthis australis

(Pecl et al 2004 b)

Loligo opalescens

Jackson & Domeier (2003)

• Can act as ecosystem indicators
• Data collected over dramatic ’97/’98 El

Niño/La Niña – biggest climatic event of century

• ↑temp ↓productivity; ↓temp ↑productivity

Win 97,98 Sum 98 Aut 98 Win 98,99 Spr 99 Sum 99 100 110 120 130 140 150 160 Win 97,98 Sum 98 Aut 98 Win 98,99 Spr 99 Sum 99 20 30 40 50 60 70 80 e f cde de a bcd bc bcd bc abc ab a Males Females

Season of hatch Mean weight (g)

B A

ef f def ef cde bc bcd bc bcd ab ab a

Mean mantle length (mm)

Body size with time

Jun 98 Dec 98 Jan 99 Feb 99 Mar 99 Apr 99 May 99 Jun 99 Jul 99 Aug 99 Sept 99 Oct 99 Nov 99 Dec 99 Jan 00 Feb 00 Mar 00 20 40 60 80 100 100 120 140 160 180 200 Weight (g)

B

Mean age (days) 100 120 140 160 180 Mean mantle length (mm)

A

100 120 140 160 180 200 Mean age (days)

Males

Body size vs. age

90 100 110 120 130 140 150 160 170 180

• 50

50 100 150 200 250 300 350 Dec 97 Jan 98 Feb 98 Jun 98 Jul 98 Aug 98 Sep 98 Oct 98 Nov 98 Dec 98 Jan 99 Feb 99 Mar 99 Apr 99 May 99 Jun 99 Jul 99 Aug 99 90 100 110 120 130 140 150 160 170 180

• 50

50 100 150 200 250 300 350

mantle length

Mean mantle length (mm)

upwelling index

B A

Males Upwelling index

Month of hatch

Mean mantle length (m) Females Upwelling index

Body size vs upwelling index

Californian study showed:

• Squid act as ecosystem indicators of

environmental change

• Squid responded quickly to change
• Food was over-riding factor not Temp.
• El Niño/La Niña effects were dramatic
• Potential model of climate change

Reproduction (1)

• How do changes in growth rates and body size

impact on reproduction?

• Cool conditions – larger body & gonad =

↑ reproductive output

• Warm conditions – smaller body size & although

greater relative gonad investment, ↓ absolute gonad weight = ↓ reproductive output

Jackson & Moltschaniwskyj (2002) S. lessoniana Gonad weight (g) Body weight (g)

Reproduction (2)

Hot Cool Cool Hot

Warmer temperatures…

• Shorter embryonic phase
• Smaller hatchlings
• Faster growth??
• Earlier maturity
• Smaller adult size
• Lower reproductive output?
• Shorter lifespan

Energetics, respiration, metabolism (1)

• High metabolic rates in squid – growth costs will

dominate energy flux through an individual

• Feeding rate ↑ with ↑ temperature
• Cannibalism can allow for trophic flexibility so individuals

still thrive

• ↑ temp ↓ time hatchlings can survive without food
• Hatchlings will need more food but have less time before

facing mortality

Energetics, respiration, metabolism (2)

• O2 consumption ↑ linearly with weight but

metabolism ↑ continuously with ↑ temp

• At ↑ temp, smaller squids do better than larger
• ↑ CO2 , ↓ ocean pH, impair O2 transport in squid

– may limit scope for activity (Seibel and Fabry 2003)

• Higher metabolism but less access to oxygen!!

Phenology of individuals & populations

– Advances in life cycle events (migrations, egg laying)

• Expect larger changes near poles than equator (Root et al 2003)

– Climate change will likely result in shorter life-spans

• Temporal synchronicity of spawning activities of temperate

populations reduced?

– De-synchronisation of peak spawning & peak productivity may have implications for juvenile growth rate and survival

Distribution/density of species (1)

– Biomass

• Biomass may be affected by the carrying capacity of

the changing ecosystem

• If productivity ↓ the rate of cannibalism within

populations may ↑ however , biomass may be reduced if the level of cannibalism is high.

– Location of peak abundance and range shifts

• Climate change may influence population movements

by altering temperature, quality and quantity of food, or in the case of benthic spawning squids, altering the characteristics of the seafloor habitat.

Distribution/density of species (2)

Pecl & Jackson 2004 – Figure largely adapted from Boyle & Boletzky 1996

Timing of peak abundance

• Cephalopod biomass production strongly cyclical and

usually an annual phenomenon except in some small/tropical species

• What happens as life spans shorten as a function of ↑

temps?

Distribution/density of species (3)

– General predictions include (Hughes 2000):

• Extension of species geographic range boundaries

towards poles

• Extinction of local populations along range

boundaries

• Increasing invasion of weedy and/or highly mobile

species especially where local populations of other species are declining

Species interactions, Communities, Ecosystems & Fisheries

– Largely unknown & hard to predict in the absence of detailed & complex ecosystem models – Progressive decoupling of species interactions due to mismatched phenology – e.g. one species cued by day length (no change) and other by temperature – Changing currents may affect larval dispersal and retention – Many pathogens temperature sensitive – warmer waters increase susceptibility?

Some Additional Considerations….

• Synergism of several pressures at once –

habitat destruction, over fishing etc in addition to climate change (Root et al 2003)

• Maybe no fisheries by 2048 (Worm et al. 2006)
• Climate change will effect species differently

depending on habitat – impact may depend on geographical region (eg. closed regions such as Mediterranean)

Impact Summary……

• Smaller hatchlings - unless females compensate with larger

(but fewer) eggs!

• Hatchlings will need more food but have less time to find food

before facing mortality - ↑ recruitment variability?

• Higher metabolism but less access to oxygen!!
• Smaller body size, shorter faster lifespans, reduced

reproductive output

• Squid will eat more and grow more rapidly than fish at

comparable sizes and temperatures

Data & Research Needs…..

• Longer data series needed!!!
• Telemetry can be used to track movement
• Understanding trophic links critical
• How does smaller hatching size affect growth and final size-at-age?
• At higher temperatures:

– Do females produce larger eggs to compensate for smaller hatchlings (caused by shorter embryo durations at higher temps)? – Do females spawn more frequently and/or for longer to compensate for smaller gonad weight?

• Impact of lowered pH & reduced O2 availability?? VERY CRUCIAL!!
• What life history characteristics are cued by day length vs temperature?