Marine Climate Change in Australia · Marine Climate Change in Australia Impacts and Adaptation Responses 2012 REPORT CARD Zooplankton Anthony J. Richardson 1, David McKinnon 2, and

Marine Climate Change in Australia Impacts and Adaptation Responses 2012 REPORT CARD

Zooplankton

Anthony J. Richardson1, David McKinnon2, and Kerrie M. Swadling3 1University of Queensland, School of Mathematics and Physics, St Lucia, QLD 4072

Climate Adaptation Flagship, CSIRO Marine and Atmospheric Research, Ecosciences Precinct, GPO Box 2583, Brisbane, Queensland 4102, Australia

[email protected] 2Australian Institute of Marine Science, P. M. B. No. 3, Townsville M. C., Qld, 4810 3Institute for Marine and Antarctic Science, University of Tasmania, Private Bag 129,

Hobart, TAS 7001 Richardson, A.J. (2012) Zooplankton. In A Marine Climate Change Impacts and Adaptation Report Card for Australia 2012 (Eds. E.S. Poloczanska, A.J. Hobday and A.J. Richardson). <http://www.oceanclimatechange.org.au>. ISBN: 978-0-643-10928-5

What is happening

Decline of cold-water zooplankton and increase in warm-water species with warming off eastern Tasmania from the 1970s to the present. Reduced calcification of pteropod snail shells over the past 40 years in north-east and north-west Australia. What is expected Range shifts toward higher latitudes, earlier zooplankton blooms with warming, changes in nutrient enrichment and thus zooplankton abundance, and reduction in pteropod and foram abundance due to acidification will reorganize foodwebs in time and space and impact fish, seabirds and marine mammals.

What we are doing about it

Australia is now better placed to track and respond to changes in zooplankton abundance, distribution and timing through the IMOS AusCPR (Australian Continuous Plankton Recorder) survey and National Reference Stations program.

Executive Summary Zooplankton are (generally) microscopic animals that float and have limited ability to swim against currents. Zooplankton play many important roles in marine systems, including directly and indirectly feeding most fish, turtles, seabirds, mammals, and bottom-dwelling animals, shaping the pace of climate change, and producing oil and natural gas deposits by their death and decomposition. In the first Report Card in 2009, there were no published impacts of climate change on Australian zooplankton, but now we have two studies. Between the early 1970s and 2000-2009 off eastern Tasmania, abundances of key cold-water zooplankton species have declined and

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242 www.oceanclimatechange.org.au

warm-water species have increased. The second study suggested thinning and increased porosity of shells of two pteropod snails in NW and NE Australia over the past 40 years as ocean pH declined. These changes are likely to be the first of many in the future that could have profound effects on marine foodwebs. We have HIGH CONFIDENCE that the distribution of smaller and less abundant subtropical and tropical zooplankton species will expand poleward, and that larger and more abundant temperate and polar species will retract poleward. We have HIGH CONFIDENCE that the phenology of temperate and polar species will move earlier as temperatures warm. We have MEDIUM CONFIDENCE that calcifying plankton will be detrimentally affected by ocean acidification as pH declines. We also have MEDIUM CONFIDENCE that the abundance of zooplankton will change as temperature warms, with a mosaic of increases and decreases in zooplankton abundance in response to climate change. Collectively, these changes are likely to cause spatial reorganization of foodwebs in temperate and polar regions, trophic mismatch in temperate regions, changes in nutrient enrichment, and direct effects on zooplankton calcifiers. These impacts of climate change on zooplankton will cause widespread and significant changes (often negative, some positive) to higher trophic levels. Australia is well placed to track and respond to such changes through the Integrated Marine Observing System.

Introduction Zooplankton is a generic term describing animals that have limited locomotive ability relative to the water bodies they inhabit. Zooplankton vary hugely in size, ranging from about 20 µm (microzooplankton) to 20 m in length (some gelatinous zooplankton). Zooplankton communities contain representatives of at least a dozen phyla. Almost all marine animals, whether they live in the water column or on the seafloor, have an early dispersive phase that is part of the zooplankton; examples include eggs or larvae of lobsters, seastars, most fish and corals.

The most important role of zooplankton is as grazers in ocean foodwebs, providing the principal pathway for energy from plants to consumers at higher trophic levels such as tuna, sharks, seabirds and seals. Regeneration of nitrogen through excretion by zooplankton helps support phytoplankton and bacterial production. Microbes also colonize zooplankton faecal pellets and carcasses, making them rich sources of organic carbon for detrital feeders. This decomposing zooplankton matter consistently rains down onto the seabed, sustaining diverse benthic communities of sponges, crabs and fish (Ruhl and Smith 2004). Zooplankton also play an important role in the cycling of nitrogen and carbon in the oceans, and they are important in sequestering carbon to the deep ocean. Much of the CO2 that is fixed by phytoplankton is eaten by zooplankton and is subsequently exported to deeper layers through sinking of faeces and carcasses. Zooplankton migrate each day into the ocean depths to avoid near-surface predatory fish, thus aiding the export of carbon to deeper waters. Zooplankton that have died tens of millions of years ago have formed the oil and natural gas deposits upon which modern society depends. Without the diverse roles performed by zooplankton, our oceans would be devoid of almost all the large fish, mammals, and turtles that are of such immense aesthetic, social, financial and ecological value.

Finally, zooplankton are sensitive indicators of climate change (Hays et al. 2005) because they are short-lived (weeks to months), poikilothermic (physiological processes are controlled by temperature), and largely not commercially exploited so long-term trends in response to environmental change are less confounded with

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exploitation than those of higher trophic-level taxa, and can be sampled over ocean basin scales using plankton recorders.

Multiple stressors Fishing (through top-down processes) and eutrophication (through bottom-up processes) are indirect stressors on zooplankton and will interact with climate change. The effect of human-produced eutrophication on zooplankton is likely to be substantial near the coast, and the effect of fishing on zooplankton is likely to play more of a role in semi-enclosed bays and seas. These interactive effects on the abundance of different trophic levels, including zooplankton, are likely to be synergistic, antagonistic or additive (Crain et al. 2008, Griffith et al. 2011, 2012).

Observed impacts Table 1. Observed and predicted impacts of climate change on zooplankton in Australia.

Physical variables

Observed changes Projected changes

2030s 2100s

Temperature Increased abundance of warm-water copepod species and decline in cold-water species off east coast of Tasmania

Increased expansion of tropical and subtropical species into temperate waters

Decline in zooplankton size and abundance in temperate waters as they warm

Spatial reorganization of zooplankton will start to affect some higher trophic levels in temperate foodwebs

Earlier peaks of zooplankton abundance

Widespread and significant changes (positive or negative) to higher trophic levels because of changes in nutrient enrichment conditions

Range shifts towards higher latitudes evident for most species. Major spatial reorganization of zooplankton could have widespread impacts on fish and other higher trophic levels in temperate foodwebs

Little endemism in pelagic zooplankton, so low risks of extinction

In temperate areas, possible temporal mismatch between phyto-, zooplankton and fish, could result in lower fish abundances

Acidification Potential thinning and increased porosity of shells of pteropods in NW and NE Australia

Increased impact of ocean acidification on zooplankton that produce aragonite, such as pteropods, and those such as other molluscs and echinoderms that have magnesium-bearing calcite

Impact on calcifiers that produce calcite such as Foraminifera. Decline in abundance in aragonite and calcite producers. Impact on top predators reliant upon calcifiers as a food source

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Impacts of climate change and ocean acidification on zooplankton can manifest as poleward movements in their distribution (range shifts), earlier timing of important life cycle events (phenology), changes in abundance and community structure, and declines in abundance of calcifiers (summarized in Table 1). In the 2009 Report Card, there were no studies on the effect of long-term climate change or ocean acidification on zooplankton in Australian waters. Since then, in Australia there has been one study assessing impacts of ocean acidification (Roger et al. 2012), one study on changes in distribution of warm-water and cold-water species that has led to changes in local abundance (Johnson et al. 2011), and one study that alludes to changes in abundance of a warm-water species (Henschke et al. 2011). Each study will be described below in relation to the primary climate variables considered.

Temperature

Johnson et al. (2011) investigated the change in flora and fauna near Maria Island (off the east coast of Tasmania), associated with the strong warming in the region. There was a consistent signal in the response of giant kelp, nearshore fishes, and the plankton community. For zooplankton between the early 1970s and 2000-2009, the community exhibited a shift from species typical of colder water to those typical of much warmer conditions (Fig. 1). Warm-water copepod species are typical of those found in the warm East Australia Current. The East Australian Current now makes more incursions into eastern Tasmanian waters than in previous decades (Ridgway 2007, Hill et al. 2008). The increase in strength of the EAC is likely to be a response to climate change (Johnson et al. 2011) and has contributed to ocean off south eastern Australia warming at ~3–4 times the global average over recent decades (Ridgway 2007). This change from cold- to warm-water zooplankton species is likely to have impacts on the food web, as the historical cold-water species are generally larger in size and are thought to provide a better food environment for higher trophic levels such as fish, seabirds and marine mammals (Beaugrand et al. 2003).

www.oceanclimatechange.org.au

Figure 1. Changes in zooplankton abundance (mean±SE) in samples collected off Maria Island for (a) cold-water ‘signature’ species (first column of plots) and (b) Australia Current) ‘signature’ species (second and third columns of plots). species are generally more abundant in samples collected during the 1970s, while water species have become more prominent in samples collFrom Fig. 4 in Johnson et al. (2011) The decline of cold-water zooplankton species are expanding their rangehappening in other systems.2002), Northeast Atlantic (Bonnet et al. 2005; Beaugrand et al. 2002, Lindley & Daykin 2005) and Northwest Atlantic (Johns et al. 2001).

Generally, range shifts exhibited by za mean translocation of ~200 km per decade and largest of any group globallyanalysis of range shifts across 99 species of birds, butterflies, and alpine herbs found that they moved polewards (or upwards) by an average of only 6.1 km per decade (Parmesan and Yohe 2003).

Henschke et al. (2011) climate change on zooplankton. They during a cruise in 2008 and only briefly mentionUsing an identical net to those used in a study of the same area in 1938found an order of magnitude increase in the salp increase in salps with warming Ocean (Atkinson et al. 2004). evidence of the impacts of climate changeephemeral blooms. More estimates of the abundance of salps

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Changes in zooplankton abundance (mean±SE) in samples collected off Maria water ‘signature’ species (first column of plots) and (b) warm

‘signature’ species (second and third columns of plots). species are generally more abundant in samples collected during the 1970s, while

ecies have become more prominent in samples collected between 2000 and 2009.From Fig. 4 in Johnson et al. (2011).

water zooplankton species and increase in warm-are expanding their ranges as water temperature increases is consistenthappening in other systems. These regions include the North Sea (Beaugrand et al. 2002), Northeast Atlantic (Bonnet et al. 2005; Beaugrand et al. 2002, Lindley & Daykin 2005) and Northwest Atlantic (Johns et al. 2001).

exhibited by zooplankton in response to globalmean translocation of ~200 km per decade (Richardson 2008), are among the fastest

globally, marine or terrestrial. By comparison, a global metaof range shifts across 99 species of birds, butterflies, and alpine herbs found

that they moved polewards (or upwards) by an average of only 6.1 km per decade Yohe 2003).

provide another Australian study of possible imclimate change on zooplankton. They studied salp blooms off New

n 2008 and only briefly mention possible effects of climate changeUsing an identical net to those used in a study of the same area in 1938found an order of magnitude increase in the salp Thalia democraticaincrease in salps with warming since the 1970s has been suggested in the Southern

2004). As Henschke et al. (2011) make cleare impacts of climate change, as salps are notorious for massive yet

estimates of the abundance of salps through time are needed.

245

Changes in zooplankton abundance (mean±SE) in samples collected off Maria

warm-water (East ‘signature’ species (second and third columns of plots). Cold-water

species are generally more abundant in samples collected during the 1970s, while warm-ected between 2000 and 2009.

-water ones that tent with what is

These regions include the North Sea (Beaugrand et al. 2002), Northeast Atlantic (Bonnet et al. 2005; Beaugrand et al. 2002, Lindley &

ooplankton in response to global warming, with are among the fastest

By comparison, a global meta-of range shifts across 99 species of birds, butterflies, and alpine herbs found

that they moved polewards (or upwards) by an average of only 6.1 km per decade

of possible impacts of ew South Wales

possible effects of climate change. Using an identical net to those used in a study of the same area in 1938-1943, they

Thalia democratica (Fig. 2). An has been suggested in the Southern

make clear, it is weak as salps are notorious for massive yet

through time are needed.

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Figure 2. The aggregate form of the salp Thalia democratica. Image courtesy of Anita Slotwinski, CSIRO Marine and Atmospheric Research. Pink colouration is result of a stain.

Ocean acidification Calcium carbonate structures are present in a variety of important zooplankton groups including molluscs (snails), echinoderms (seastars, sea urchins), foraminifera and some crustaceans (Raven et al. 2005). The direct effect of ocean acidification on calcifying zooplankton will be to partially erode their shells, increasing shell maintenance costs and reducing growth. But even among marine organisms with calcium carbonate shells, susceptibility to acidification varies, depending on whether the crystalline form of their calcium carbonate is aragonite or calcite. Aragonite is more soluble under acidic conditions than calcite. As oceans continue to absorb CO2, undersaturation of aragonite and calcite in seawater will be initially most acute in the Southern Ocean and will then move northward. There will also be synergistic effects between impacts of acidification and warming on organisms.

A recent study investigated implications of the declining aragonite saturation state in tropical waters off Northwest Australia and on the Great Barrier Reef for two pteropod molluscs (Roger et al. 2012). These winged snails (“sea butterflies”) are likely to be the zooplankton group most vulnerable to ocean acidification because of their aragonite shells. The shell structures of two tropical pteropod species, Creseis acicula and Diacavolinia longirostris (Fig. 3), were analyzed for the period 1963 to 2009. Roger et al. (2012) described a thinning of shell thickness of both species (C. acicula by -4.43 µm, D. longirostris by -5.37 µm) and an increase in shell porosity (Fig. 4, C. acicula by +1.43%, D. longirostris by +8.69%). Simultaneously, the aragonite saturation level of tropical surface waters showed a decline by 10% from 1963 to 2009. Both the decline in shell thickness and increase in shell porosity are consistent with the hypothesis that ocean acidification is affecting shell structures. The work, although not conclusive because of irregular sampling, does suggest that pteropods off northern Australia may have been influenced by the decline in aragonite saturation state over the past few decades. Such adverse effects could ultimately affect pteropod survival and that of their predators such as fish.


Figure 3. The pteropod Diacavolinia longirostrisUniversity of Alaska, Fairbanks.

Figure 4. SEM image subsamples for the porosity index (PI, % per 100 nm~100,000 times) measurements of the shell surface of PI=0.29), (b) 2009 (average PI=1.66), and of and (d) 2009 (average PI=8.93). These findings are consistent with other studies globallyWiddicomb and Spicer 2008)show shell deterioration in the pteropod approximating those likely around 2100 under a business(Orr et al. 2005).

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Diacavolinia longirostris. Image courtesy of Russ Hopcroft,

University of Alaska, Fairbanks.

SEM image subsamples for the porosity index (PI, % per 100 nm~100,000 times) measurements of the shell surface of C. acicula in (a) 1985 (average PI=0.29), (b) 2009 (average PI=1.66), and of D. longirostris in (c) 1985 (average PI=0.23) and (d) 2009 (average PI=8.93). From Fig. 6 in Roger et al. (2012).

These findings are consistent with other studies globally (Fabry et al. 2008, Widdicomb and Spicer 2008). For example, experiments over as little as 48 hours show shell deterioration in the pteropod Clio pyrimidata at atmospheric COapproximating those likely around 2100 under a business-as-usual emissions scenario

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. Image courtesy of Russ Hopcroft,

SEM image subsamples for the porosity index (PI, % per 100 nm2, magnification in (a) 1985 (average

in (c) 1985 (average PI=0.23)

(Fabry et al. 2008, xperiments over as little as 48 hours

at atmospheric CO2 levels usual emissions scenario

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Confidence Assessment: Observed Impacts

Amount of Evidence (theory, observations, models) Temperature

We currently have LIMITED EVIDENCE of the impact of temperature on zooplankton distribution within Australia. We have MEDIUM EVIDENCE of the impact of temperature on zooplankton distribution globally. There are several studies describing changes in zooplankton distribution with warming (Richardson 2008, Beaugrand et al. 2002, Lindley & Daykin 2005, Johns et al. 2001).

Ocean acidification We currently have LIMITED EVIDENCE of the impact of ocean acidification on zooplankton within Australia, as we only have a single study (Roger et al. 2012) and it is not conclusive. We have LIMITED EVIDENCE of the impact of ocean acidification on zooplankton globally. There have been few studies of ocean acidification based on time series. Studies by Ohman et al. (2009) concluded that there had been no observed changes in zooplankton in response to declining ocean acidification in the California Current. Data from the North Atlantic show that there is no consistent decline in zooplankton in response to pH declines (see www.sahfos.ac.uk).

Degree of Consensus (high level of statistical agreement, model confidence) Temperature

Within Australia, there is only a single study describing the change in distribution with warming, so no consensus rating can be provided. Globally, we have a HIGH LEVEL of agreement on the changes in distribution of zooplankton in response to warming globally, with warm-water species showing poleward movements and cold-water species concomitantly showing poleward retractions (Beaugrand et al. 2002, Johns et al. 2001).

Ocean acidification Within Australia, there is only a single study describing the effect of ocean acidification on zooplankton, so no consensus rating can be provided. Globally, we have a LOW LEVEL of agreement in the response of zooplankton to ocean acidification. There appears to be no consistent response yet observed. Experimental evidence is contradictory, with significant impacts on zooplankton of lower net calcification rates, reduced fertilization success, slower developmental rates, and smaller larval size, but the results are species specific (Raven et al., 2005; Fabry et al., 2008; Doney et al., 2009).

Confidence Level Temperature

Within Australia, we have VERY LOW confidence that zooplankton distributions are responding to warming, as we have only a single study (Johnson et al. 2011). Globally, we have HIGH CONFIDENCE that zooplankton distributions are moving poleward in response to climate change because we have MEDIUM EVIDENCE and HIGH AGREEMENT among these studies.

Ocean acidification

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Within Australia, we have VERY LOW CONFIDENCE that zooplankton is responding to ocean acidification, as we have only a single study (off tropical Australia). Further, the study was not conclusive, but suggestive that acidification could play a role. Globally, we have VERY LOW CONFIDENCE in the response of zooplankton to ocean acidification because we have LIMITED EVIDENCE and a LOW LEVEL OF AGREEMENT between these studies.

Potential impacts by 2030 (and/or 2100) There are likely to be substantial changes in distribution, phenology and abundance by both 2030 and 2100 (Table 1). Although, we have little knowledge of likely quantitative changes of zooplankton at different times and under different emissions scenarios into the future, we do have some qualitative information.

Abundance The effect on plankton abundance of changes in nutrient enrichment in response to climate change will probably have the most profound impacts on marine foodwebs. Indirect impacts of climate change on nutrient enrichment could outweigh direct impacts of temperature change and acidification on foodwebs. In particular, oligotrophic (low nutrient) tropical regions with little seasonality, such as those in Northern Australia, could be sensitive to changes in nutrient enrichment (McKinnon et al. 2007). Physical atmospheric and oceanic processes, such as upwelling, fronts and eddies, drive nutrient enrichment and thus phytoplankton and zooplankton abundance, size structure, and community composition (Fig. 5). Changes to these physical processes as a consequence of climate change will alter nutrient enrichment and plankton communities, with lower nutrient concentrations leading to less and smaller-sized plankton, while enhanced nutrient concentrations result in greater abundance of and larger plankton. Phytoplankton and zooplankton community structure will also change, with picoplankton and the nitrogen-fixing cyanobacterium Trichodesmium (in tropical regions) likely to be more important if nutrient input declines. Such changes in plankton community structure have profound impacts on zooplankton.

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Figure 5. The role of nutrient enrichment, determined by physical processes, in regulating plankton ecosystem structure. Changes to physical processes that lead to nutrient enrichment produce plankton communities dominated by large phytoplankton (diatoms) and crustacean zooplankton, whereas physical processes that lead to lower nutrient concentrations produce communities dominated by small phyto- and zooplankton. From Fig. 6.3 in McKinnon et al. (2007). There is one projection of plankton biomass into the future that provides some suggestion of what might happen in Australia. Brown et al. (2010) used a Nutrient-Phytoplankton-Zooplankton model forced by the CSIRO Mk3.5 GCM and an A2 emission scenario. They projected that phytoplankton biomass would increase around much of Australia by 2050 (Fig. 6). This could result in a concomitant increase in zooplankton biomass and higher fisheries yields (Brown et al. 2010). However, there is considerable uncertainty in projections of changes in primary production and even more on its consequent effect on zooplankton abundance. Many modeling studies predict declines in phytoplankton abundance globally, especially in the tropics (Sarmiento et al. 2004, Bopp et al. 2004, 2005, Steinacher et al. 2010). However, observational studies generally show an increase in primary production over recent decades (Chavez et al. 2011; McGallop-Quatters et al. 2007), although exceptions do exist (Boyce et al. 2010). Many models are still relatively simple and do not include such important processes as different scaling of respiration, and changes in pH that make carbon more available.

Phenology There is no information on phenology changes in zooplankton in Australian waters, but there are many observations from temperate regions of the North Atlantic and North Pacific that might provide some clues. These studies show that zooplankton phenology is sensitive to warming and generally advances more than three times faster (7.6 days per decade, Richardson 2008) than terrestrial plants and animals (2.3 days per decade, Parmesan & Yohe 2003). Of most concern is that plankton functional groups do not respond to ocean warming synchronously. With warming of about 1°C in the North Sea over 45 years (1958-2002), phytoplankton abundance has peaked earlier by three weeks, but zooplankton by only about one week. This could result in predator–prey mismatches that reduce energy transfer to higher trophic levels, diminishing fish recruitment (Edwards and Richardson 2004). Large changes in phenology are likely in temperate and polar Australian waters.


Figure 6. Predicted relative percent change in phytoplankton production rate from the 20002004 mean to 2050. The CSIRO Mk 3.5 global climate model was used to force a nutrientphytoplankton-zooplankton submodel under the A2 emission scenario. Phytoplankton biomassis predicted to generally increase around Australia and this would likely lead to higher zooplankton biomass. From Brown et al. (2010)

Although we have no quantitative projectionzooplankton distribution observed by Johnson et al. (2011) off eastern Tasmania will continue. Effects of this spatial reorganization of lower trophic levels could have a profound effect on higher trophic levels; possible effects on fish that we might expect. W(the most abundant zooplankton) water copepod assemblagelarge species that peak in abundance in spring, warmed, it has been replaced typically has lower biomass and containsautumn and not spring. This traditionally a major fishery of the North Searequire a diet of large copepodshigh and recruitment to the fished stock water assemblage was replaced by the warmcopepod biomass during spring (Beaugrand et al. 2003). North Sea has had considerable impacts on fisherieshappen off Southeast Australia

Although the study by Roger et al. already affecting pteropods, it is highly likely that such effects will increase throughout this century. Flarge portion of Australian

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Predicted relative percent change in phytoplankton production rate from the 20002004 mean to 2050. The CSIRO Mk 3.5 global climate model was used to force a nutrient

zooplankton submodel under the A2 emission scenario. Phytoplankton biomassis predicted to generally increase around Australia and this would likely lead to higher

From Brown et al. (2010)

Distribution Although we have no quantitative projections, it is highly likely that

tion observed by Johnson et al. (2011) off eastern Tasmania will Effects of this spatial reorganization of lower trophic levels could have a

profound effect on higher trophic levels; work from the Northeast Atlantic highlights that we might expect. Warm-water communities

(the most abundant zooplankton) have expanded poleward by 1,100 km.copepod assemblage, which has high biomass and is dominated

that peak in abundance in spring, has retracted polewards has been replaced in the North Sea by the warm-water assemblage

typically has lower biomass and contains smaller species that peak in abundance in . This has reduced numbers of Atlantic cod Gadus morhua

fishery of the North Sea. When cod spawn in spring, a diet of large copepods. If this food source is not available, larval

to the fished stock is poor. Since the late 1980s, water assemblage was replaced by the warm-water one, there has been

during spring in the North Sea, and cod recruitment has plummeted This spatial reorganization of zooplankton species in the

North Sea has had considerable impacts on fisheries, and similar resphappen off Southeast Australia.

Calcification Roger et al. (2012) is suggestive that ocean acidification

pteropods, it is highly likely that such effects will increase First the aragonite and then the calcite saturation state of

Australian waters could decline below levels needed for shell

251

Predicted relative percent change in phytoplankton production rate from the 2000–

2004 mean to 2050. The CSIRO Mk 3.5 global climate model was used to force a nutrient-zooplankton submodel under the A2 emission scenario. Phytoplankton biomass

is predicted to generally increase around Australia and this would likely lead to higher

s, it is highly likely that the changes in tion observed by Johnson et al. (2011) off eastern Tasmania will

Effects of this spatial reorganization of lower trophic levels could have a theast Atlantic highlights communities of copepods

poleward by 1,100 km. As the cool-has high biomass and is dominated by relatively

polewards as waters have assemblage, which

that peak in abundance in Gadus morhua,

spawn in spring, their larvae . If this food source is not available, larval mortality is

1980s, when the cool-has been very low

in the North Sea, and cod recruitment has plummeted on of zooplankton species in the

and similar responses could

ocean acidification is pteropods, it is highly likely that such effects will increase

irst the aragonite and then the calcite saturation state of a eeded for shell

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formation and maintenance in calcifying plankton. Under-saturation of aragonite and calcite in seawater is likely to be more acute at higher latitudes, but these conditions will subsequently move toward the equator. Pteropods are likely to decline in abundance, and may eventually disappear in response to ocean acidification in some areas. Larvae of sea urchins and molluscs form skeletal parts consisting of magnesium-bearing calcite that form through an amorphous precursor phase, which is 30 times more soluble than calcite (Politi et al 2004). The same type of skeletal material is used by most adult echinoderms. Thus, the meroplanktonic larvae of molluscs and echinoderms are particularly sensitive to ocean acidification and this could negatively affect their adult populations and thus benthic community structure. Another zooplankton group potentially sensitive to ocean acidification is the Foraminifera. Tests (shells) of dead Foraminifera contribute a significant proportion of the sediments in many sandy regions of tropical Australia. Although they are formed from calcite and are thus less susceptible to ocean acidification than organisms composed of aragonite, calcite-producing Foraminifera are likely to be negatively impacted by reduced pH in the longer term. There is currently no observational evidence on the effect of ocean acidification on Foraminifera in Australia, but they have shown a decline in calcification rate in the Southern Ocean (Moy et al. 2009). Confidence Assessment: Projected Impacts

Amount of Evidence (theory, observations, models) Abundance

We have ROBUST EVIDENCE that zooplankton abundances will change as a result of changes in nutrient enrichment from climate change. This evidence comes from nutrient-phytoplankton and zooplankton models linked to global climate models, our theoretical knowledge of the response of plankton to nutrient enrichment, and current observations.

Phenology We have ROBUST EVIDENCE from physiology and observations that the earlier phenology of many species in temperate and polar regions will continue.

Distribution We have ROBUST EVIDENCE from theory and observations that the poleward penetration of warm-water zooplankton communities and the retraction of cold-water communities, already observed in Australia and globally, will continue and accelerate?.

Calcification We have MEDIUM EVIDENCE from physiology, from some present observations and from palaeontological data that by the end of the century the calcification rates of some calcifying zooplankton species will be affected.

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Degree of Consensus (high level of statistical agreement, model confidence)

Abundance There is little consensus about whether climate change will generally increase or decrease nutrient enrichment in the oceans, and this is the key to projecting whether zooplankton will increase or decrease. There is thus LOW CONSENSUS on whether zooplankton abundance will generally increase or decrease globally, or around Australia. Some models and some observations suggest that phytoplankton and zooplankton could increase in abundance in polar regions, whilst abundances in tropical areas might decline.

Phenology There is MEDIUM CONSENSUS that zooplankton timing will advance as waters warm. Rates at which timings shift are likely to be faster than those of most other groups.

Distribution There is MEDIUM CONSENSUS that zooplankton will move poleward as waters warm. Rates of movement are likely to be faster than those of most other groups.

Calcification There is MEDIUM CONSENSUS on the effects of ocean acidification on calcifying zooplankton. From experimental work it appears that only some species will be affected.

Confidence Level

Abundance We have MEDIUM CONFIDENCE that the abundance of zooplankton will change as temperature warms. There is likely to be a mosaic of increases and decreases in zooplankton abundance in response to climate change and it is currently difficult to predict responses in particular regions.

Phenology We have HIGH CONFIDENCE that the phenology of temperate and polar species will move earlier as temperatures warm. Responses of phytoplankton and of predators could influence the response, as will species-specific differences.

Distribution We have HIGH CONFIDENCE that the distribution of subtropical and tropical zooplankton species will expand poleward, and that temperate and polar species will retract poleward.

Calcification We have MEDIUM CONFIDENCE that calcifying plankton will be detrimentally affected by ocean acidification as pH declines. Responses could be complex and species-specific, as effects of temperature increases can interact with effects of ocean acidification.


Current and planned The Integrated Marine Observing Systsignificant research initiative communities to climate variability and changeon zooplankton observationshttp://imos.aodn.org.au/. Australian Continuous Plankton Recorder opportunity to tow CPRs and automatically regular routes on the east, westand across the Tasman Sea to New Zealand (km (one and a half times around the Earth) and counted 6 IMOS also has a network of measuring physical variables information on phytoplcomposition (Fig. 7). Zooplankton sampling from Port Hacking (ofback to 1998, with the remainder of the National References Stations having data since 2008 (North Stradbrokecapcity to observe trends in require further Commonwealth for zooplankton will provide communities.

Figure 7. The number of zooplankton samples collected as part of the IMOS Continuous Plankton Recorder survey Stations (pink).

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and planned research effort Integrated Marine Observing System (IMOS, www.imos.org.au

significant research initiative in Australia investigating the response of zooplankton climate variability and change. IMOS has two programmes

on zooplankton observations and all data are freely available . The larger of the two zooplankton programmes is the

Australian Continuous Plankton Recorder survey (AusCPR). AusCPRto tow CPRs and automatically collect plankton samples. There are

the east, west and south coasts of Australia, in the Southern Ocean, and across the Tasman Sea to New Zealand (Fig. 7). This survey has km (one and a half times around the Earth) and counted 6,936 samples.

network of nine National Reference Stations measuring physical variables and these are visited monthly to seasonallyinformation on phytoplankton and zooplankton abundance and community

Zooplankton sampling from Port Hacking (off Sydney) stretches, with the remainder of the National References Stations having data

since 2008 (North Stradbroke Island) or after. IMOS has filled much of capcity to observe trends in lower trophic levels in Australian watersrequire further Commonwealth funding in 2013 to continue. This observing system for zooplankton will provide an early warning of changes in Australian plankton

The number of zooplankton samples collected as part of the IMOS Australian Continuous Plankton Recorder survey (in red, green and yellow) and the National Reference

254

www.imos.org.au) is the most the response of zooplankton

has two programmes focused and all data are freely available from

The larger of the two zooplankton programmes is the AusCPR uses ships of

plankton samples. There are and south coasts of Australia, in the Southern Ocean,

). This survey has towed 65,000 936 samples.

with moorings to seasonally, collecting

ankton and zooplankton abundance and community f Sydney) stretches

, with the remainder of the National References Stations having data has filled much of the gap in our

lower trophic levels in Australian waters, and it will This observing system

rly warning of changes in Australian plankton

Australian and the National Reference

Zooplankton


Further information If you would like more information on the plankton component of IMOS, see http://imos.org.au/australiancontinuousplanktonr.html or contact [email protected] to be placed on the mailing list for the AusCPR newsletter.

References Atkinson, A., Siegel, V., Pakhomov, E., and Rothery, P. (2004). Long-term decline in

krill stock and increase in salps within the Southern Ocean. Nature 432, 100–103. Bonnet, D., Richardson, A. J., Harris, R., Hirst, A., Beaugrand, G., Edwards, M.,

Ceballos, S., et al. (2005). An overview of Calanus helgolandicus ecology in European waters. Progress in Oceanography 65, 1–53.

Boyce, D.G., Lewis, M.R.,Worm, B. (2010). Global phytoplankton decline over the past century. Nature 466, 591–96.

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Beaugrand, G., Brander, K. M., Lindley, J. A., Souissi, S., and Reid, P. C. (2003). Plankton effect on cod recruitment in the North Sea. Nature 426, 661–664.

Beaugrand, G., Reid, P. C., Ibañez, F., Lindley, J. A., and Edwards, M. (2002). Reorganisation of North Atlantic marine copepod biodiversity and climate. Science 296, 1692–1694.

Bopp, L., Aumont, O., Cadule, P., Alvain, S., and Gehlen, M. 2005. Response of diatoms distribution to global warming and potential implications: a global model study. Geophysical Research Letters 32, L19606.

Bopp, L., Boucher, O., Aumont, O., Belviso, S., Dufresne, J-L., Pham, M., and Monfray, P. 2004. Will marine dimethylsulfide emissions amplify or alleviate global warming? A model study. Canadian Journal of Fisheries and Aquatic Sciences 61, 826–835.

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Hays, G.C., Richardson, A.J., and Robinson, C. (2005). Climate change and plankton. Trends in Ecology and Evolution 20, 337-344

Henschke, N., Everett, J.D., Baird, M.E., Taylor, M.D., and Suthers, I.M. (2011). Distribution of life-history stages of the salp Thalia democratica in shelf waters during a spring bloom. Marine Ecology Progress Series 430, 49-62.

Hill, K.L., Rintoul, S.R., Coleman, R., and Ridgway, K.R., (2008). Wind forced low frequency variability of the East Australia Current. Geophysical Research Letters 35, L08602.

Johns, D. G., Edwards, M., and Batten, S. D. (2001). Arctic boreal plankton species in the Northwest Atlantic. Canadian Journal of Fisheries and Aquatic Sciences 58, 2121–2124.

Johnson, C.R., Banks, S.C., Barrett, N.S., Cazzasus, F., Dunstan, P.K., Edgar, G.J., Frusher, S.D., Gardner, C., Helidoniotis, F., Hill, K.L., Holbrook, N.J., Hosie, G.W., Last, P.R., Ling, S.C., Melbourne-Thomas, J., Miller, K., Pecl, G.T., Richardson, A.J., Ridgway, K.R., Rintoul, S.R., Ritz, D.A., Ross, D.J., Sanderson, J.C., Shepherd, S., Slotwinski, A., Swadling, K.M., and Taw, N. (2011). Climate change cascades: shifts in oceanography, species’ ranges and marine community dynamics in eastern Tasmania. Journal of Marine Experimental Biology and Ecology 400, 17-32.

Lindley, J. A., and Daykin, S. (2005). Variations in the distributions of Centropages chierchiae and Temora stylifera (Copepoda: Calanoida) in the north-eastern Atlantic Ocean and western European shelf waters. ICES Journal of Marine Science 62, 869–877.

McKinnon, A.D., Richardson, A.J., Burford, M.A., and Furnas, M.J. (2007). Chapter 6. Vulnerability of Great Barrier Reef plankton to climate change. In Climate Change and the Great Barrier Reef. Great Barrier Reef Marine Park Authority and Australian Greenhouse Office, Australia. pp. 121-152.

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Roger, L.M., McKinnon, A.D., Knott, B., Matear, R., Scadding, C., Richardson, A.J. (2012). Comparison of shell structure of two tropical thecosomata (Creseis acria and Diacavolinia longirostris) from 1963-2009: potential implications of declining aragonite saturation state. ICES Journal of Marine Science 69, 465-474.

Ruhl, H.A., and Smith, K.L. (2004). Shifts in deep-sea community structure linked to climate and food supply. Science 305, 513–515.

Sarmiento, J. L., Slater, R., Barber, R., Bopp, L., Doney, S.C., Hirst, A.C., Kleypas, J., Matear, R., Mikolajewicz, U., Monfray, P., Soldatov, V., Spall, S. A., and Stouffer, R. (2004) Response of ocean ecosystems to climate warming. Global Biogeochemical Cycles 18, GB3003.

Widdicombe, S., Spicer, J.I. (2008). Predicting the impact of ocean acidification on benthic biodiversity: What can physiology tell us? Journal of Experimental Marine Biology and Ecology, 366, 187-197.

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Documents

Marine Climate Change in Australia · Marine Climate Change in Australia Impacts and Adaptation Responses 2012 REPORT CARD Zooplankton Anthony J. Richardson 1, David McKinnon 2, and