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 of slower growing teleost competitors? Response of squid populations may be much more complex!!
Basis of Talk….. 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.
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 Population size al 2005)? • Climate change could have a major impact • Need to assess potential impacts Time more thoroughly than just ‘temperature increases squid growth rates’.
Loliginid Life History • Geared towards life in the fast lane – efficient digestion, protein based metabolism – continuous growth – efficient use of oxygen Size – low levels of antioxidative defense • Short life-spans (~ 1yr or less) Age – high growth rates – fast metabolisms – ravenous appetites
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 at 6% per day at different hatchling sizes 0.02 30 • Growth exponential - small 0.03 25 0.04 differences between individuals 0.05 20 Weight 0.06 amplified through the lifespan 15 0.07 10 5 • How you start the race important 0 5 15 25 35 45 55 65 75 85 95 Days • Initial research with octopus shows relationship between Pecl et al (2004a) Mar FreshW Biol. hatchling size and growth IS important - but complex (Leporati et al in review)
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
Body size with time 160 A f Males 150 ef ef Mean mantle length (mm) Females 140 cde def 130 bcd bcd 120 bc bc ab 110 ab 100 a Win 97,98 Sum 98 Aut 98 Win 98,99 Spr 99 Sum 99 f B 80 70 de Mean weight (g) 60 e 50 bcd bcd 40 abc cde bc bc 30 a ab 20 a Win 97,98 Sum 98 Aut 98 Win 98,99 Spr 99 Sum 99 Season of hatch
Mean mantle length (mm) Weight (g) 100 100 120 140 160 180 20 40 60 80 0 Body size vs. age Jun 98 B A Dec 98 Jan 99 Feb 99 Mar 99 Apr 99 May 99 Males Jun 99 Jul 99 Aug 99 Sept 99 Oct 99 Nov 99 Dec 99 Jan 00 Feb 00 Mar 00 100 120 140 160 180 200 100 120 140 160 180 200 Mean age (days) Mean age (days) Mean mantle length (m) Mean mantle length (mm) 100 110 120 130 140 150 160 170 180 100 110 120 130 140 150 160 170 180 90 90 Body size vs upwelling index Dec 97 B A Jan 98 mantle length Feb 98 upwelling index Jun 98 Jul 98 Aug 98 Month of hatch Sep 98 Oct 98 Nov 98 Dec 98 Jan 99 Feb 99 Mar 99 Apr 99 May 99 Females Jun 99 Males Jul 99 Aug 99 -50 0 50 100 150 200 250 300 350 -50 0 50 100 150 200 250 300 350 Upwelling index 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
Reproduction (2) Gonad weight (g) Body weight (g) Hot Cool Cool Hot Jackson & Moltschaniwskyj (2002) S. lessoniana
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) • O 2 consumption ↑ linearly with weight but metabolism ↑ continuously with ↑ temp • At ↑ temp, smaller squids do better than larger • ↑ CO 2 , ↓ ocean pH, impair O 2 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) 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? Pecl & Jackson 2004 – Figure largely adapted from Boyle & Boletzky 1996
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
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