Journal of Experimental Marine Biology and Ecology 493 (2017) 7–13
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Ocean acidiﬁcation and warming impacts the nutritional properties of the predatory whelk, Dicathais orbita Rick D. Tate a,⁎, Kirsten Benkendorff b, Roslizawati Ab Lah b,c, Brendan P. Kelaher a a b c
National Marine Science Centre, Southern Cross University, PO Box 4321, Coffs Harbour, NSW 2450, Australia Marine Ecology Research Centre, School of Environment, Science and Engineering, Southern Cross University, 2480 Lismore, NSW, Australia School of Fisheries Science and Aquaculture, University Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu, Malaysia
a r t i c l e
i n f o
Article history: Received 19 November 2016 Received in revised form 1 March 2017 Accepted 13 March 2017 Available online xxxx Keywords: Ocean acidiﬁcation Ocean warming Climate change Proximate composition Nutrition Muricidae Neogastropoda Food security
a b s t r a c t Ocean warming and acidiﬁcation have the potential to impact the quality of seafood with ﬂow on effects for future food security and ecosystem stability. Here, we used a 35-day experiment to evaluate how ocean warming and acidiﬁcation may impact the nutritional qualities and physiological health of Dicathais orbita, a predatory muricid whelk common on the east coast of Australia, and discuss the broader ecological implications. Using an orthogonal experimental design with four treatments (current conditions [~23 °C and ~380 ppm of pCO2], ocean warming treatment [~ 25 and ~ 380 ppm of pCO2], ocean acidiﬁcation treatment [CO2 ~ 23 °C and ~750 ppm of pCO2], and ocean warming and acidiﬁcation treatment [CO2, ~25 °C and ~750 ppm of pCO2]), we showed that changes in moisture and protein content were driven by signiﬁcant interactions between ocean warming and acidiﬁcation. Elevated ocean temperature signiﬁcantly decreased protein in the whelk ﬂesh and resulted in concurrent increases in moisture. Lipid, glycogen, potassium, sulfur, and phosphorus content also decreased under elevated temperature conditions, whereas sodium, boron and copper increased. Furthermore, elevated pCO2 signiﬁcantly decreased lipid, protein and lead content. Whelks from control conditions had levels of lead in excess of that considered safe for human consumption, although lead uptake appears to be lowered under future ocean conditions and will be site speciﬁc. In conclusion, while D. orbita has received research attention as a potential food product with nutritious value, ocean climate change may compromise its nutritional qualities and reduce sustainable harvests in the future. Furthermore, ocean climate change may have deleterious impacts on the longevity and reproductive potential of this important rocky shore predator. © 2017 Elsevier B.V. All rights reserved.
1. Introduction The combination of changing ecological landscapes and disturbance regimes associated with ocean warming and acidiﬁcation, as well as other stressors (e.g. pollution, ﬁshing pressure, species invasions) creates an uncertain future for nearshore marine environments and the important ﬁsheries that they support (Cooley et al., 2012). Ocean climate change is likely to inﬂuence ﬁsheries productivity and value, with potentially negative consequences for food security (Cooley et al., 2012; Lloret et al., 2015; Tirado et al., 2010) and ecosystem integrity (Ferrari et al., 2011; Kroeker et al., 2013; Manriquez et al., 2016). While the potential impacts of ocean climate change on ﬁsheries production have been well studied, almost no work has been done investigating the inﬂuence of ocean warming and acidiﬁcation on seafood quality (but see Anacleto et al., 2014 and Valles-Regino et al., 2015). The future production of high protein seafood is important to support ever growing ⁎ Corresponding author at: National Marine Science Centre, Southern Cross University, P.O. Box 4321, Coffs Harbour, NSW 2450, Australia. E-mail address: [email protected]
http://dx.doi.org/10.1016/j.jembe.2017.03.006 0022-0981/© 2017 Elsevier B.V. All rights reserved.
human populations with reduced agricultural capacity (Cooley et al., 2012; Doney et al., 2009). Proximate variables provide an overview of an animal's energetic resources (Berthelin et al., 2000; Pérez-Camacho et al., 2003) and nutritional value for human consumption, breaking down edible ﬂesh into its primary constituents; moisture, ash, protein, and lipid (Begum et al., 2012; Silva and Chamul, 2000; Souﬁa et al., 2014). Changes in the composition of these proximate variables may alter the reproductive potential (Marshall et al., 1999) and nutritive value of commercially important ﬁsheries species (Spitz et al., 2010). Thus, an assessment of proximate composition under future ocean conditions provides an opportunity to analyse the potential impacts on seafood quality and population sustainability. A previous study demonstrated that future ocean conditions can lead to a signiﬁcant decrease in total lipids and omega 3 and 6 polyunsaturated fatty acids in the edible ﬂesh of predatory marine whelks (Valles-Regino et al., 2015). In two species of bivalves, Anacleto et al. (2014) found that elevated temperature signiﬁcantly decreased the relative proportion of some fatty acids, but not protein. Seafood quality and safety can also depend on accumulation of trace elements, including essential minerals and heavy metals in the ﬂesh
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(Ab Lah et al., 2016), and environmental factors such a temperature and pH can inﬂuence the uptake of certain metal ions (Baines et al., 2006; López et al., 2010). Molluscs have been identiﬁed as one of the most sensitive phyla to ocean climate change (Byrne et al., 2013; Kroeker et al., 2013; Parker et al., 2013). Meanwhile, ﬁsheries are diversifying and expanding the breadth of targeted species (Kasperski and Holland, 2013; McClenachan et al., 2014; Witkin et al., 2015). While invertebrate ﬁsheries research focus over the past few decades has generally favoured typical bivalve molluscs, like oysters (Guo et al., 2016), some researchers are exploring underexploited gastropod species that provide potential new sources of protein (Ab Lah et al., 2016; Appukuttan and Philip, 1994; Noble et al., 2013; Woodcock and Benkendorff, 2008; Zarai et al., 2011). For example, gastropods in the family Muricidae represent an emerging ﬁsheries resource and comprise approximately 39% of the global gastropod harvest (FAO, 2015). However, the majority of Muricidae production is based on Rapana venosa in China (Castell, 2012), so muricid whelks are still considered to be under-represented in ﬁsheries and aquaculture on a global scale (FAO, 2014). Dicathais orbita (Muricidae) is a marine predatory whelk species (Neogastropoda) common in the temperate waters off the central and southern coasts of Australia and New Zealand (Woodcock and Benkendorff, 2008). This species has functional food potential, with high quality polyunsaturated fatty acids (Valles-Regino et al., 2015) and anticancer compounds (Benkendorff, 2013; Benkendorff et al., 2015) and have been investigated for their aquaculture potential (Noble et al., 2013; Woodcock and Benkendorff, 2008). Here, we evaluated the inﬂuence of ocean warming and acidiﬁcation on the nutritional properties and physiological health of D. orbita. We measured proximate response variables (lipid, moisture, ash and protein content), a stress indicator (glycogen content), trace elements, change in shell length and animal weight as well as feeding rate to establish the biochemical responses of D. orbita to future ocean change. It was hypothesised that D. orbita nutritional quality and physiological health would deteriorate under induced warming and acidiﬁcation stress.
Beach, New Zealand). Water pH was manipulated by bubbling CO2enriched air via a gas mixer (PEGAS 4000MF) through the CO2enriched header tanks, while the water in the current treatment header tanks was bubbled with ambient air. Each of the 12 header tanks supplied temperature and pH controlled water at 3 L·min−1 to a tray (860 × 650 × 96 mm) that housed twelve D. orbita. Animals were weighed (pan top balance to 0.01 g precision) and their maximum shell length was measured using callipers (1 mm precision) at the start and end of the experiment (analysed as percentage change). Whelks were acclimated in experimental conditions for one week before feeding trials commenced. Whelks were fed Sydney rock oysters (Saccostrea glomerata), which are a common prey item on local intertidal reefs. The whelks were initially fed a consistent number of oysters ranging 30–50 mm, with new oysters of similar size added daily to ensure whelk feeding rates were not inﬂuenced by food scarcity. Feeding rate was calculated as the mean number of oysters eaten per day per tray. Water pH, alkalinity, temperature and salinity readings were measured daily and used to calculate the partial pressure of CO2 (pCO2) using the CO2SYS program (Pierrot et al., 2006) with constants from Mehrbach et al. (1973) as adjusted by Dickson and Millero (1987). For the remainder of this publication, low pH conditions will be referred to as having elevated pCO2. 2.2. Sample preparation and proximate analyses of foot meat Whelks were dissected for proximate analysis according to Ab Lah et al. (2016). This was done to establish the percentage of whelk foot meat attributable to moisture (weight loss after drying at 40 °C), protein (Biuret protein assay), lipid (1:1 chloroform: methanol extract) and ash (incinerated in a mufﬂe furnace). One sample of foot meat (~0.35 g) was taken from three whelks per tray at random to create three physically homogenized replicates for each proximate response variable. All samples were frozen (−80 °C) for later use and were defrosted immediately prior to analysis.
2. Materials and method
2.3. Physiological health indicators from gills
2.1. Experimental set up
Gills were removed for glycogen analysis. These were dissected from three randomly selected whelks per tray, as above. Samples of gill tissue were frozen in liquid nitrogen to slow enzymatic activity and tissue degradation, and subsequently hand ground in 10 mL of 0.06 M perchloric acid (PCA) within a falcon tube using a Teﬂon masher for 3 min. Adjusting the method described in Krisman (1962), the homogenized samples were centrifuged at 4200 rpm for 2.5 min and 1 mL of the resultant supernatant was transferred into smaller vials for glycogen analysis. Glycogen was analysed following Krisman (1962) as described by Roberts et al. (2009). Glycogen concentration in the gill samples was then estimated from the linear regression equation of a standard curve using oyster glycogen Type II (Sigma-Aldrich) and adjusted for dilution to obtain the ﬁnal amount of glycogen as a percent of fresh weight.
To test the hypotheses that both ocean warming and acidiﬁcation will reduce the physiological health and nutritional value of Dicathais orbita, 144 adult whelks were divided into control and experimentally induced warming and acidiﬁcation treatments for 35 days at the National Marine Science Centre (NMSC) in Coffs Harbour, Australia (30° 16′3.70″S, 153° 8′15.31″E). The experiment utilised D. orbita (51–79 mm shell length) from rock platforms around the Coffs Harbour region and had a two-factor design with four treatments, each with three replicate trays (n = 3, current conditions representing our control, mean ± SD = 22.9 ± 0.5 °C and 378.6 ± 35.6 ppm; elevated temperature, 25.2 ± 0.6 °C and 382.2 ± 35.5 ppm; elevated CO2, 22.9 ± 0.5 °C and 749.9 ± 80.6 ppm and increased temperature and elevated CO2, 25.3 ± 0.6 °C and 763.0 ± 104.6 ppm), adapted from Provost et al. (2016). Current sea surface temperatures were based on average sea surface temperature (± SD) for the Coffs Harbour region during the time of the experiment (21.3 ± 1 °C, Navy Metoc (2015)). Current pH during the experimental period was expected to be ~8.1 (Poore et al., 2013). Future temperature and pH were based on the IPCC (2013) predictions for future oceanic conditions under climate change scenario RCP8.5; approximately +3 °C in water temperature and −0.3 pH units. The temperature and pH of seawater was controlled in twelve, 1100 L circular, ﬁbreglass, outdoor header tanks (1.35 m diameter × 0.9 m high). Sea water was pumped from the adjacent ocean into the NMSC ﬂow-through aquarium system and ﬁltered at 50 μm prior to entering header tanks at 3 L·min− 1. Water temperature in the header tanks was controlled using heater chiller units (Aquahort Ltd., Omana
2.4. Trace element analysis of foot meat For trace element analysis, 1 g samples of whelk foot tissue were submitted to the Environmental Analysis Laboratory (EAL), Southern Cross University (NATA Accreditation Number 14960). Fresh samples of D. orbita foot tissues were dissolved in a mixture of HNO3 (25%) and HCl (75%) (1:3, v/v) and subjected to hot-block (Hot-Block; Environmental Express, South Carolina, U.S.A) according to an acid digestion procedure (APHA, 2012). Elemental concentrations were analysed by inductively-coupled plasma mass spectrometry (ICPMS) using a NexION 300 D series ICP spectrometer with an ESI SC-FAST Auto Sampler (Perkin Elmer, Waltham, Massachusetts, U.S.A.).
R.D. Tate et al. / Journal of Experimental Marine Biology and Ecology 493 (2017) 7–13
2.5. Statistical analyses Hypotheses were tested using multivariate and univariate permutational analyses of variance (PERMANOVA, Anderson (2001)). Similarity matrices were created using Euclidean distance, and 9999 permutations were run for each analysis. Two-factor PERMANOVAs were used to test hypotheses about the inﬂuence of ocean warming and acidiﬁcation on proximate variables and glycogen. Pairwise tests were used to establish patterns among means for response variables with a signiﬁcant interaction between temperature and pCO2. A third factor, ‘tray’ was nested in the interaction of temperature and pCO2 for shell growth and animal weight analyses. The Monte Carlo method was applied to estimate pvalues for pair-wise tests with b 100 permutations. Trace element data were normalised to the same scale and shell length data was transformed using a log (x + 1) function prior to analysis. Both animal weight and shell length were analysed on the percentage change. The outputs of PERMANOVA analyses can be found in Supplementary Tables S1–S6. Supplementary Table S7 provides mean (± SD) values for water chemistry data. 3. Results 3.1. Survival, growth and consumption No Dicathais orbita died during the experiment, and these animals grew an average of 0.03 ± 1.21% in shell length and lost an average of 2.25 ± 4.43% in wet weight, although there was no signiﬁcant variation between treatments and the control, nor was a tray effect detected (see Supplementary Table S1). Neither ocean acidiﬁcation nor ocean warming had a signiﬁcant impact on the consumption rate of oysters, although, on average D. orbita ate more often under elevated temperature and elevated pCO2 (Fig. 1, Supplementary Table S2). 3.2. Proximate analyses of foot meat Protein content was signiﬁcantly affected by an interaction between ocean warming and acidiﬁcation (Fig. 2A). Elevated temperatures signiﬁcantly reduced average protein content under current pCO2 exposure (pair-wise, p b 0.05, mean change 54%), and elevated pCO2 exposure at 22 °C resulted in a similar reduction in average protein content (pair-wise, p b 0.05, mean change 45%). Moisture content was signiﬁcantly altered by an interaction between ocean warming and acidiﬁcation (Fig. 2B). Average moisture content signiﬁcantly increased in response to elevated temperatures under both current pCO2 exposure
(pair-wise, p b 0.01, mean change 14%) and elevated pCO2 exposure (pair-wise, p b 0.001, mean change 13%). D. orbita foot meat contained signiﬁcantly greater average moisture content resulting from elevated pCO2 at 22 °C (pair-wise, p b 0.05, mean change 6%), but not at 25 °C (pair-wise, p N 0.05). Both elevated temperature (mean change 20%) and pCO2 (mean change 17%) signiﬁcantly reduced the average lipid content and no interaction was detected by PERMANOVA (Fig. 2C). Ash content was not signiﬁcantly affected by either warming or acidiﬁcation, nor was there an interaction between these factors (Table 1). PERMANOVA outputs can be found in Supplementary Table S3. 3.3. Physiological health indicators from gills Elevated temperature signiﬁcantly reduced average glycogen content (mean change 35%, Fig. 2D). Elevated pCO2 had no impact on glycogen content (Supplementary Table S3). 3.4. Trace element analyses of foot meat 3.4.1. Macronutrients Neither calcium nor magnesium content was signiﬁcantly inﬂuenced by elevated temperature or pCO2 (Table 1). A signiﬁcant mean reduction of 8% in potassium content resulted at elevated temperatures (Table 1). Average sodium content signiﬁcantly increased in response to elevated temperatures (mean change 102%, Table 1). Elevated temperature signiﬁcantly reduced average sulfur content (mean change 7%, Table 1). Phosphorus content was signiﬁcantly reduced by elevated temperatures (mean change 11%, Table 1). See Supplementary Table S4 for PERMANOVA results. 3.4.2. Micronutrients There was a signiﬁcant increase in average boron content at elevated temperatures equating to a mean increase of 51% (Table 1). Manganese content was affected by a signiﬁcant interaction between temperature and pCO2, although pair-wise tests were not powerful enough to establish signiﬁcant difference among treatments (Table 1). Nevertheless, there is a trend towards an increase in average manganese content at 25 °C under current pCO2 conditions, whereas under future pCO2 conditions average manganese content is elevated at 22 °C, but not 25 °C (Table 1). There was no signiﬁcant change to selenium, zinc or acid soluble silicon content (Table 1). Supplementary Table S5 provides PERMANOVA analyses of micronutrients. 3.4.3. Heavy metals There was a signiﬁcant increase in average copper content by 211% of the ambient controls as a result of elevated temperatures (Table 1). Average lead content under current conditions was 7 ± 3 mg/kg, which experienced a signiﬁcant mean decrease of 66% as a result of elevated pCO2 (Table 1). Silver, arsenic, cadmium and mercury content showed no signiﬁcant differences (Table 1). Total arsenic content averaged 226 ± 32 mg/kg overall. See Supplementary Table S6 for further information regarding PERMANOVA results. 4. Discussion
Fig. 1. Mean number of oysters eaten per day per treatment and control by D. orbita (±SD).
Predatory rocky shore invertebrates, such as Muricidae molluscs can be important predators, as well as providing a source of food for human consumption. Many communities around the world rely heavily on marine sources of protein (Cooley et al., 2012) and the pressures on associated ﬁsheries will intensify as human population growth continues (Lloret et al., 2015). As well as increased harvesting pressure, valuable ﬁsheries species are also subject to chemical contaminants (Lloret et al., 2015) and ocean acidiﬁcation and warming (Tirado et al., 2010). It is, therefore, important that we understand how ocean climate change will impact the energetic reserves and nutritional quality of seafood and attempt to identify potentially robust species. In this regard,
R.D. Tate et al. / Journal of Experimental Marine Biology and Ecology 493 (2017) 7–13
Fig. 2. Mean percentage (±SD) that each proximate variable contributed to D. orbita foot meat, where blue and non-lined bars represent the current temperature and low pCO2 controls, respectively, and red and lined bars represent the experimentally elevated temperature and high pCO2 treatments, respectively. Statistical results as detected by PERMANOVA (n = 3, pair-wise tests where interactions were detected) are described in Section 3.2.
our novel study clearly shows that ocean warming and acidiﬁcation will likely reduce the nutritional quality and physiological health of D. orbita. In particular, the protein content of the foot meat of D. orbita declined by approximately 45% as a result of an interaction between ocean warming and acidiﬁcation. Concurrently, moisture content significantly increased in response to these two factors. As a model for other molluscan species sought after for human consumption, the reduced protein content per kilogram would drastically reduce the quality of the meat, while driving up the need for either greater harvests or faster/larger aquaculture production, potentially impacting sustainable supply. The additional reduction in growth rates of many molluscs may compound this reduction in nutritional quality with reduced
meat yield (Doney et al., 2009). Furthermore, as the accumulation of protein stores in the body tissue of molluscs provides energy for growth and gametogenesis (Moussa et al., 2014; Racotta et al., 1998; Rodriguez-Astudillo et al., 2005), the substantial reduction in tissue protein under future ocean conditions could lead to reduced fecundity. If these changes are more general across other seafood taxa, the reduction in seafood quality in response to ocean warming and acidiﬁcation will inﬂuence the capacity of wild ﬁsheries to support future human populations. Lipids are functionally important for reproduction, particularly the production of eggs in molluscs (Napolitano et al., 1992), but are also beneﬁcial for human health. Consistent with a previous study on
Table 1 The percentage of the proximate composition of D. orbita foot meat attributable to inorganic matter (mean percentage ash ± SD) and broken into its constituent trace elements (mean mg/kg ± SD). Statistically signiﬁcant differences among experimental factors in PERMANOVA analyses are noted. Trace element Inorganic content Macronutrients (mg/kg)
Heavy metals (mg/kg)
Ash (% of foot meat) Potassium Sodium Sulfur Phosphorus Calcium Magnesium Boron Manganese Selenium Zinc Silicon (acid soluble) Copper Lead Silver Arsenic Cadmium Mercury
22 °C (low pCO2)
25 °C (low pCO2)
22 °C (high pCO2)
25 °C (high pCO2)
Temp × pCO2
2.4 ± 0.2 9975.7 ± 371.0 11,347.3 ± 1630.6 17,715.7 ± 980.7 4888.0 ± 171.9 3381.7 ± 1926.2 6414.7 ± 1191.3 6.7 ± 0.6 7.2 ± 0.4 2.5 ± 0.4 105.2 ± 63.9 48.3 ± 16.3 12.7 ± 1.7 7.3 ± 3.0 6.6 ± 3.0 219.0 ± 50.1 0.3 ± 0.2 0.1 ± b0.1
2.3 ± 0.1 9253.0 ± 542.5 30,102.0 ± 7806.6 16,742.7 ± 915.7 4129.0 ± 301.8 2687.7 ± 322.8 6716.3 ± 388.3 10.3 ± 1.0 9.9 ± 2.7 3.1 ± 2.7 81.0 ± 5.0 195.0 ± 128.4 89.4 ± 42.5 2.5 ± 2.7 4.1 ± 0.6 259.7 ± 50.1 0.3 ± 0.2 0.2 ± 0.1
2.3 ± 0.1 10,194.0 ± 257.2 17,017.3 ± 1591.9 17,594.7 ± 564.6 4661.3 ± 236.5 4749.0 ± 4414.1 5440.0 ± 1076.6 6.5 ± 0.3 9.9 ± 2.8 3.1 ± 1.0 75.4 ± 2.5 140.7 ± 111.5 37.1 ± 5.9 1.5 ± 0.6 4.3 ± 2.2 240.0 ± 69.6 0.3 ± 0.1 0.2 ± b0.1
2.3 ± 0.1 9220.3 ± 696.0 27,095.0 ± 6313.7 16,207.7 ± 1037.6 4358.3 ± 257.9 2629.7 ± 655.5 5979.3 ± 317.9 9.6 ± 1.3 6.2 ± 0.7 1.6 ± 0.2 78.2 ± 2.7 207.3 ± 92.6 65.1 ± 9.0 1.8 ± 0.8 2.5 ± 1.0 185.0 ± 19.7 0.1 ± b0.1 0.2 ± 0.1
ns b0.05 b0.01 b0.05 b0.01 ns ns b0.01 ns ns ns ns b0.001 ns ns ns ns ns
ns ns ns ns ns ns ns ns ns ns ns ns ns b0.05 ns ns ns ns
ns ns ns ns ns ns ns ns b0.05 ns ns ns ns ns ns ns ns ns
R.D. Tate et al. / Journal of Experimental Marine Biology and Ecology 493 (2017) 7–13
D. orbita (Valles-Regino et al., 2015), in current conditions the foot meat contained substantial concentrations of lipids (~6% lipid). The lipid content signiﬁcantly decreased in response to elevated temperature and pCO2, but was nevertheless still high relative to other muricid whelks, which have been shown to contain between 1 and 2% lipid content (Ramesh and Ayyakkannu, 1992; Souﬁa et al., 2014; Vasconcelos et al., 2009). The foot meat lipid proﬁle of D. orbita is dominated by polyunsaturated fatty acids (PUFAs), particularly Omega-3 PUFAs (Valles-Regino et al., 2015). These PUFAs are considered beneﬁcial for humans as they provide essential fatty acids, carry fat-soluble vitamins, reduce the risk of heart disease, have anti-inﬂammatory properties and aid in suppressing abnormal heart beats and promoting efﬁcient blood circulation, among other beneﬁts (Simopoulos, 1991; Simopoulos, 2008; Swanson et al., 2012). Similar to many of the response variables we measured, there was a reduction in the proportion of Omega-3 PUFAs in D. orbita ﬂesh after exposure to elevated water temperature (Valles-Regino et al., 2015). Overall, the loss of lipid content reported here, combined with the alterations in the fatty acid proﬁle (VallesRegino et al., 2015), in response to ocean warming reduces the nutritional value of D. orbita for human consumption, and may impact their fecundity, egg production and overall ﬁtness. The proportional increase in moisture in whelk ﬂesh was likely linked to the loss of lipid, and protein content under elevated temperatures, as well as the increased sodium content. Elevated sodium levels have implications for osmoregulation and homeostasis (Voisin and Bourque, 2002), and may increase blood pressure (He and MacGregor, 2002). In contrast, the decrease in potassium content may impact the intracellular ion balance and further impede acid-base regulatory ability (Zarai et al., 2011) of D. orbita, thus contributing to stress. High water temperature reduced glycogen content in the gills of D. orbita. This is likely to be related to the higher metabolic rates of molluscs under elevated temperature requiring more energy for respiration (Miller et al., 2015). As the storage form of glucose, glycogen levels indicate the energy available in a particular structure (Lau and Leung, 2004). Relatively higher glycogen levels are likely to be found in structures allocated to costly metabolic functions such as respiration and reproduction (Lau and Leung, 2004; Santini and Chelazzi, 1995). Glycogen can be a useful biomarker for its sensitivity to a range of stressors (Lagadic et al., 1994; Lucas and Beninger, 1985), and a number of studies have found a signiﬁcant decline in molluscan tissue glycogen content as a result of different stressors (Ansaldo et al., 2006; Duquesne et al., 2004; Hummel et al., 1996; Leung and Furness, 2001). For example, Li et al. (2007) found a signiﬁcant drop in mantle glycogen in response to heat stress in oysters (Crassostrea gigas). Furthermore, in oysters that had recently spawned, there was a three-fold reduction in glycogen and no recovery after 10 days in oysters subjected to heat stress (Li et al., 2007). If the glycogen reserves in other vital organs respond to elevated temperatures in a similar manner to the glycogen in D. orbita gills, reproductive success, ﬁtness and survival may be compromised under future climate change scenarios. Under current conditions the copper content of D. orbita foot meat was well below the allowable limits for safe consumption by humans. However, elevated temperature resulted in a large increase in copper content to 89.4 ± 42.5 mg/kg, beyond the 70 mg/kg maximum considered safe in molluscs (NSW Health Department, 2001). In contrast, the average lead content (7.3 ± 3.0 mg/kg) was above the limits for safe human consumption (2 mg/kg lead in molluscs, see Abbott et al. (2003) and ComLaw (2015)) in whelks held under current conditions, likely the result of anthropogenic land uses in and around the study area. The total arsenic in whelk ﬂesh was also high (219.0 ± 50.1 mg/kg), although the dangerous inorganic component is only considered to be approximately 1% of the total arsenic in marine invertebrates, including molluscs (Fabris et al., 2006; Sloth et al., 2005). Nevertheless, this metric still indicates that the levels of arsenic in D. orbita under current conditions are above the safe limits for human consumption (1 mg/kg inorganic arsenic, Abbott et al. (2003) and
ComLaw (2015)). However, people would have to regularly consume large amounts of D. orbita to experience toxicity, and heavy metal bioaccumulation is site-speciﬁc depending on local industry (Kılıç and Belivermiş, 2013; Scherz and Kirchhoff, 2006). While arsenic levels stayed high in all treatments, there was a signiﬁcant drop in lead content of D. orbita foot meat as a result of ocean acidiﬁcation. These complex results suggest the inﬂuence of bioaccumulated metal in marine gastropods will be challenging to predict in future ocean climates. Although survival and growth showed no signiﬁcant changes, this experiment only covered a 35 day period, which may not be long enough for any physiological deterioration to physically manifest. It is possible that prolonged exposure to future ocean conditions impacts the performance of D. orbita. Elevated temperature (Miller et al., 2015) and elevated pCO2 (Cummings et al., 2011; Pörtner et al., 2004), have been shown to increase metabolic rates, and concurrently energy demand, to cope with the stress (Brown et al., 2004; Li et al., 2007; Miller et al., 2015). Initially, rapid glycogenesis may explain the observed drop in lipid and glycogen content in D. orbita tissue in order to meet this demand under elevated temperature stress. However, the chronic exposure to both elevated temperatures and pCO2 may also result in tissue catabolism, perhaps explaining the reduction in protein content as a result of these stressors interacting with one another. Pörtner et al. (1998) examined the impact of elevated pCO2 on the marine invertebrate, Sipunclulus nudus, in part concluding that metabolic depression related to hypercapnia increased the catabolism of proteins and amino acids. Furthermore, chronic elevated pCO2 exposure may reduce protein synthesis. Overall, ocean acidiﬁcation and warming resulted in a clear deterioration in nutritional quality and in particular protein content, which may impact the value of whelk ﬁsheries in the future. There are also clear physiological deteriorations in D. orbita tissue that may reﬂect the impact of chronic, multiple stressors on reserves for growth, survival and reproduction, suggesting that ocean climate change may have greater ecological consequences. While we have only examined these effects in one species, if these patterns are mirrored by other harvested marine molluscs, it may have signiﬁcant consequences for value of molluscs in future food production. Certainly, this study highlights the need for further research into the nutritional consequences of ocean climate change on seafood quality across broader taxonomic groups, as this may have signiﬁcant consequences for effective ﬁsheries proﬁtability and production in coming decades. Supplementary data to this article can be found online at http://dx. doi.org/10.1016/j.jembe.2017.03.006.
Acknowledgements We thank Euan Provost, Jamie David, Lauren Hall, Kris Cooling, Alexia Graba-Landry, Amanda Beasley, Melinda Coleman and Adele Bennett for their help with practical work. Sample processing was undertaken with guidance from Roselyn Valles-Regino, Bijayalakshmi Nongmaithem and Ajit Ngangbam. [BK] References Ab Lah, R., Smith, J., Savins, D., Dowell, A., Bucher, D., Benkendorff, K., 2016. Investigation of nutritional properties of three species of marine turban snails for human consumption. Food Sci. Nutr. 5:14–30. http://dx.doi.org/10.1002/fsn3.360. Abbott, P., Baines, J., Fox, P., Graf, L., Kelly, L., Stanley, G., Tomaska, L., 2003. Review of the regulations for contaminants and natural toxicants. Food Control 14, 383–389. Anacleto, P., Maulvault, A.L., Bandarra, N.M., Repolho, T., Nunes, M.L., Rosa, R., Marques, A., 2014. Effect of warming on protein, glycogen and fatty acid content of native and invasive clams. Food Res. Int. 64, 439–445. Anderson, M.J., 2001. Permutation tests for univariate or multivariate analysis of variance and regression. Can. J. Fish. Aquat. Sci. 58, 626–639. Ansaldo, M., Nahabedian, D.E., Holmes-Brown, E., Agote, M., Ansay, C.V., Guerrero, N.R.V., Wider, E.A., 2006. Potential use of glycogen level as biomarker of chemical stress in Biomphalaria glabrata. Toxicology 224, 119–127. APHA, 2012. In: American Public Health Association (Ed.), Standard Methods for the Examination of Water and Wastewater. APHA, Washington, D.C.
R.D. Tate et al. / Journal of Experimental Marine Biology and Ecology 493 (2017) 7–13
Appukuttan, K.K., Philip, M.B., 1994. Gastropods - an emerging resource in the by-catch of shrimp trawlers at Sakthikulangara - Neendakara area. Seaf. Export. J. 25, 5–18. Baines, S.B., Fisher, N.S., Kinney, E.L., 2006. Effects of temperature on uptake of aqueous metals by blue mussels Mytilus edulis from Arctic and temperate waters. Mar. Ecol. Prog. Ser. 308, 117–128. Begum, M., Akter, T., Minar, M.H., 2012. Analysis of the proximate composition of domesticated stock of pangas (Pangasianodon hypophthalamus) in laboratory condition. J. Environ. Sci. and Nat. Resour. 5, 69–74. Benkendorff, K., 2013. Natural product research in the Australian marine invertebrate Dicathais orbita. Mar. Drugs 11, 1370–1398. Benkendorff, K., Rudd, D., Nongmaithem, B.D., Liu, L., Young, F., Edwards, V., Avila, C., Abbott, C.A., 2015. Are the traditional medical uses of Muricidae molluscs substantiated by their pharmacological properties and bioactive compounds? Mar. Drugs 13, 5237–5275. Berthelin, C., Kellner, K., Mathieu, M., 2000. Storage metabolism in the Paciﬁc oyster (Crassostrea gigas) in relation to summer mortalities and reproductive cycle (West Coast of France). Comp. Biochem. Physiol. B: Biochem. Mol. Biol. 125, 359–369. Brown, J.H., Gillooly, J.F., Allen, A.P., Savage, V.M., West, G.B., 2004. Toward a metabolic theory of ecology. Ecology 85, 1771–1789. Byrne, M., Foo, S., Soars, N.A., Wolfe, K.D.L., Nguyen, H.D., Hardy, N., Dworjanyn, S.A., 2013. Ocean warming will mitigate the effects of acidiﬁcation on calcifying sea urchin larvae (Heliocidaris tuberculata) from the Australian global warming hot spot. J. Exp. Mar. Biol. Ecol. 448, 250–257. Castell, L., 2012. Gastropod molluscs. In: Lucas, J.S., Southgate, P.C. (Eds.), Aquaculture: Farming Aquatic Animals and Plants, second ed. Wiley-Blackwell, Chichester, West Sussex, pp. 567–581. ComLaw, 2015. In: Australia and New Zealand Food Standards (Ed.), Standard 1.4.1 - Contaminants and Natural Toxicants. Commonwealth of Australia, Australia. Cooley, S.R., Lucey, N., Kite-Powell, H., Doney, S.C., 2012. Nutrition and income from molluscs today imply vulnerability to ocean acidiﬁcation tomorrow. Fish Fish. 13, 182–215. Cummings, V., Hewitt, J., Van Rooyen, A., Currie, K., Beard, S., Thrush, S., Norkko, J., Barr, N., Heath, P., Halliday, N.J., Sedcole, R., Gomez, A., McGraw, C., Metcalf, V., 2011. Ocean acidiﬁcation at high latitudes: potential effects on functioning of the Antarctic bivalve Laternula elliptica. PLoS One 6 (1), e16069. Dickson, A., Millero, F., 1987. A comparison of the equilibrium constants for the dissociation of carbonic acid in seawater media. Deep Sea Res. Part A 34, 1733–1743. Doney, S.C., Fabry, V.J., Feely, R.A., Kleypas, J.A., 2009. Ocean acidiﬁcation: the other CO2 problem. Annu. Rev. Mar. Sci. 1, 169–192. Duquesne, S., Liess, M., Bird, D.J., 2004. Sub-lethal effects of metal exposure: physiological and behavioural responses of the estuarine bivalve Macoma balthica. Mar. Environ. Res. 58, 245–250. Fabris, G., Turoczy, N.J., Stagnitti, F., 2006. Trace metal concentrations in edible tissue of snapper, ﬂathead, lobster, and abalone from coastal waters of Victoria, Australia. Ecotoxicol. Environ. Saf. 63, 286–292. FAO, 2014. In: FAO Fisheries and Aquaculture Department (Ed.), The State of World Fisheries and Aquaculture. Food and Agriculture Organisation of the United Nations, Rome online. FAO, 2015. In: FAO Fisheries and Aquaculture Department (Ed.), Fishery and Aquaculture Statistics. Global Capture Production 1950–2013 (FishstatJ). Food and Agriculture Organization of the United Nations, Rome online. Ferrari, M.C., McCormick, M.I., Munday, P.L., Meekan, M.G., Dixson, D.L., Lonnstedt, O., Chivers, D.P., 2011. Putting prey and predator into the CO2 equation-qualitative and quantitative effects of ocean acidiﬁcation on predator-prey interactions. Ecol. Lett. 14, 1143–1148. Guo, L., Xu, F., Feng, Z., Zhang, G., 2016. A bibliometric analysis of oyster research from 1991 to 2014. Aquac. Int. 24, 327–344. He, F.J., MacGregor, G.A., 2002. Effect of modest salt reduction on blood pressure: a metaanalysis of randomized trials. Implications for public health. J. Hum. Hypertens. 16, 761–770. Hummel, H., Amiard-Triquet, C., Bachelet, G., Desprez, M., Marchand, J., Sylvand, B., Amiard, J.C., Rybarczyk, H., Bogaards, R.H., Sinke, J., De Wit, Y., De Wolf, L., 1996. Sensitivity to stress of the estuarine bivalve Macoma balthica from areas between The Netherlands and its southern limits (Gironde). J. Sea Res. 35, 315–321. IPCC, 2013. IPCC summary for policy makers. In: Stocker, T.F., Qin, D., Plattner, G.-K., Tignor, M., Allen, S.K., Boschung, J., Nauels, A., Xia, Y., Bex, V., Midgley, P.M. (Eds.), Climate Change 2013: The Physical Science Basis. Contribution of Working Group 1 to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, UK and New York, USA. Kasperski, S., Holland, D.S., 2013. Income diversiﬁcation and risk for ﬁshermen. Proc. Natl. Acad. Sci. 110, 2076–2081. Kılıç, Ö., Belivermiş, M., 2013. Spatial and seasonal distribution of trace metal concentrations in mussel (Mytilus galloprovincialis) and sediment of bosphorus and golden horn. Bull. Environ. Contam. Toxicol. 91, 402–408. Krisman, C.R., 1962. A method for the colorimetric estimation of glycogen with iodine. Anal. Biochem. 4, 17–23. Kroeker, K.J., Kordas, R.L., Crim, R., Hendriks, I.E., Ramajo, L., Singh, G.S., Duarte, C.M., Gattuso, J.P., 2013. Impacts of ocean acidiﬁcation on marine organisms: quantifying sensitivities and interaction with warming. Glob. Chang. Biol. 19, 1884–1896. Lagadic, L., Caquet, T., Ramade, F., 1994. The role of biomarkers in environmental assessment (5). Invertebrate populations and communities. Ecotoxicology 3, 193–208. Lau, D.C.P., Leung, K.M.Y., 2004. Feeding physiology of the carnivorous gastropod Thais clavigera (Kuster): do they eat “soup”? J. Exp. Mar. Biol. Ecol. 312, 43–66. Leung, K.M.Y., Furness, R.W., 2001. Survival, growth, metallothionein and glycogen levels of Nucella lapillus (L.) exposed to sub-chronic cadmium stress: the inﬂuence of nutritional state and prey type. Mar. Environ. Res. 52, 173–194.
Li, Y., Qin, J.G., Abbott, C.A., Li, X., Benkendorff, K., 2007. Synergistic impacts of heat shock and spawning on the physiology and immune health of Crassostrea gigas: an explanation for summer mortality in Paciﬁc oysters. Am. J. Phys. Regul. Integr. Comp. Phys. 293, R2353–R2362. Lloret, J., Rätz, H.-J., Lleonart, J., Demestre, M., 2015. Challenging the links between seafood and human health in the context of global change. J. Mar. Biol. Assoc. U. K. 96, 29–42. López, I.R., Kalman, J., Vale, C., Blasco, J., 2010. Inﬂuence of sediment acidiﬁcation on the bioaccumulation of metals in Ruditapes philippinarum. Environ. Sci. Pollut. Res. 17, 1519–1528. Lucas, A., Beninger, P.G., 1985. The use of physiological condition indices in marine bivalve aquaculture. Aquaculture 44, 187–200. Manriquez, P.H., Jara, M.E., Seguel, M.E., Torres, R., Alarcon, E., Lee, M.R., 2016. Ocean acidiﬁcation and increased temperature have both positive and negative effects on early ontogenetic traits of a rocky shore keystone predator species. PLoS One 11, e0151920. Marshall, C.T., Yaragina, N.A., Lambert, Y., Kjesbu, O.S., 1999. Total lipid energy as a proxy for total egg production by ﬁsh stocks. Nature 402, 288–290. McClenachan, L., Neal, B.P., Al-Abdulrazzak, D., Witkin, T., Fisher, K., Kittinger, J.N., 2014. Do community supported ﬁsheries (CSFs) improve sustainability? Fish. Res. 157, 62–69. Mehrbach, C., Culberson, C.H., Hawley, J.E., Pytkowicz, R.M., 1973. Measurement of the apparent dissociation constants of carbonic acid in seawater at atmospheric pressure. Limnol. Oceanogr. 18, 897–907. Miller, L.P., Allen, B.J., King, F.A., Chilin, D.R., Reynoso, V.M., Denny, M.W., 2015. Warm microhabitats drive both increased respiration and growth rates of intertidal consumers. Mar. Ecol. Prog. Ser. 522, 127–143. Moussa, R.M., ElSalhia, M., Khalifa, A., 2014. Energy storage and allocation of pearl oyster Pinctada radiata (Leach, 1814) in relation to timing of pearl seeding. Int. J. Biol. Biol. Sci. 3, 53–66. Napolitano, G.E., MacDonald, B.A., Thompson, R.J., Ackman, R.G., 1992. Lipid composition of eggs and adductor muscle in giant scallops (Placopecten magellanicus) from different habitats. Mar. Biol. 113, 71–76. Navy Metoc, 2015. Coastal Sea Surface Temperatures (Accessed 24/5/2015 from http:// www.metoc.gov.au/products/data/aussst.php). Noble, W.J., Benkendorff, K., Harris, J.O., 2013. Growth, settlement and survival of Dicathais orbita (Neogastropoda, Mollusca) larvae in response to temperature, diet and settlement cues. Aquac. Res. 46, 1455–1468. NSW Health Department, 2001. In: Department, N.H (Ed.), Metal Contamination of Major NSW Fish Species Available for Human Consumption. Better Health Centre - Publications Warehouse, Locked Mail Bag 5003, Gladesville, NSW 2111. Parker, L., Ross, P., Connor, W., Pörtner, H., Scanes, E., Wright, J., 2013. Predicting the response of molluscs to the impact of ocean acidiﬁcation. Biology 2, 651. Pérez-Camacho, A., Delgado, M., Fernández-Reiriz, M.J., Labarta, U., 2003. Energy balance, gonad development and biochemical composition in the clam Ruditapes decussatus. Mar. Ecol. Prog. Ser. 145, 133–145. Pierrot, D., Lewis, E., Wallace, D.W.R., 2006. MS Excel program developed for CO2 system calculations. ORNL/CDIAC-105a. Carbon Dioxide Information Analysis Centre, Oak Ridge National Laboratory, US Department of Energy, Oak Ridge, TN. Poore, A.G., Graba-Landry, A., Favret, M., Sheppard Brennand, H., Byrne, M., Dworjanyn, S.A., 2013. Direct and indirect effects of ocean acidiﬁcation and warming on a marine plant-herbivore interaction. Oecologia 173, 1113–1124. Pörtner, H.O., Reipschläger, A., Heisler, N., 1998. Acid-base regulation, metabolism and energetics in Sipunculus nudus as a function of ambient carbon dioxide level. J. Exp. Biol. 201, 43–55. Pörtner, H.O., Langenbuch, M., Reipschläger, A., 2004. Biological impact of elevated ocean CO2 concentrations: lessons from animal physiology and earth history. J. Oceanogr. 60, 705–718. Provost, E.J., Kelaher, B.P., Dworjanyn, S.A., Russell, B.D., Connell, S.D., Ghedini, G., Gillanders, B.M., Figueira, W., Coleman, M.A., 2016. Climate-driven disparities among ecological interactions threaten kelp forest persistence. Glob. Chang. Biol. 23, 353–361. Racotta, I.S., Ramirez, J.L., Avila, S., Ibarra, A.M., 1998. Biochemical composition of gonad and muscle in the catarina scallop, Argopecten ventricosus, after reproductive conditioning under two feeding systems. Aquaculture 163, 111–122. Ramesh, M.X., Ayyakkannu, K., 1992. Nutritive Value of Chicoreus ramosus: A Status Report. 10. Phuket Marine Biological Centre Species Publication, p. 14. Roberts, M., Carragher, J., Benkendorff, K., 2009. Rock Lobster Post Harvest Subprogram: Determining Flesh Quality Attributes of Under-valued Large Southern Rocklobsters. FRDC Final ReportFisheries Research and Development Corporation and South Australian Research and Development Corporation, Aquatic Sciences. Rodriguez-Astudillo, S., Villalejo-Fuerte, M., Garcia-Dominguez, F., Guerrero-Caballero, R., 2005. Biochemical composition and its relationship with the gonadal index of the black oyster Hyotissa hyotis (Linnaeus, 1758) at Espiritu Santo Guld of California. J. Shellﬁsh Res. 24, 975–978. Santini, G., Chelazzi, G., 1995. Glycogen content and rates of depletion in two limpets with different foraging regimes. Comp. Biochem. Physiol. A Physiol. 111, 271–277. Scherz, H., Kirchhoff, E., 2006. Trace elements in foods: zinc contents of raw foods–a comparison of data originating from different geographical regions of the world. J. Food Compos. Anal. 19, 420–433. Silva, J.L., Chamul, R.S., 2000. Composition of marine and freshwater ﬁnﬁsh and shellﬁsh species and their products. In: Martin, R.E., Carter, E.P., Flick, G.L.J., Davis, L.M. (Eds.), Marine and Freshwater Products Handbook. Technomic Publishing Company, Inc., 851 New Holland Avenue, Lancaster, Pennsylvania 17604 U.S.A. Simopoulos, A.P., 1991. Omega-3 fatty acids in health and disease and in growth and development. Am. J. Clin. Nutr. 54, 438–463. Simopoulos, A.P., 2008. The importance of the omega-6/omega-3 fatty acid ratio in cardiovascular disease and other chronic diseases. Exp. Biol. Med. 233, 674–688.
R.D. Tate et al. / Journal of Experimental Marine Biology and Ecology 493 (2017) 7–13 Sloth, J.J., Larsen, E.H., Julshamn, K., 2005. Survey of inorganic arsenic in marine animals and marine certiﬁed reference materials by anion exchange high-performance liquid chromatography−inductively coupled plasma mass spectrometry. J. Agric. Food Chem. 53, 6011–6018. Souﬁa, C.E., Hazem, B.M., Olfa, B., Naceur, A., Mohamed, E.A., Naziha, M., 2014. Comparative study of nutritional values of edible viscera mediterranean mollusks gastropods Hexaplex trunculus and Bolinus brandaris. Hypobranchial glands inhibit human glioblastoma U87 tumor cells adhesion and proliferation. Int. J. Basic Appl. Sci. 3, 307–316. Spitz, J., Mourocq, E., Schoen, V., Ridoux, V., 2010. Proximate composition and energy content of forage species from the Bay of Biscay: high- or low-quality food? ICES J. Mar. Sci. 67, 909–915. Swanson, D., Block, R., Mousa, S.A., 2012. Omega-3 fatty acids EPA and DHA: health beneﬁts throughout life. Adv. Nutr. 3, 1–7. Tirado, M.C., Clarke, R., Jaykus, L.A., McQuatters-Gollop, A., Frank, J.M., 2010. Climate change and food safety: a review. Food Res. Int. 43, 1745–1765.
Valles-Regino, R., Tate, R., Kelaher, B., Savins, D., Dowell, A., Benkendorff, K., 2015. Ocean warming and CO2-induced acidiﬁcation impact the lipid content of a marine predatory gastropod. Mar. Drugs 13, 6019. Vasconcelos, P., Gaspar, M.B., Castro, M., Nunes, M.L., 2009. Inﬂuence of growth and reproductive cycle on the meat yield and proximate composition of Hexaplex trunculus (Gastropoda: Muricidae). J. Mar. Biol. Assoc. U. K. 89, 1223–1231. Voisin, D.L., Bourque, C.W., 2002. Integration of sodium and osmosensory signals in vasopressin neurons. Trends Neurosci. 25, 199–205. Witkin, T., Dissanayake, S.T.M., McClenachan, L., 2015. Opportunities and barriers for ﬁsheries diversiﬁcation: consumer choice in New England. Fish. Res. 168, 56–62. Woodcock, S.H., Benkendorff, K., 2008. The impact of diet on the growth and proximate composition of juvenile whelks, Dicathais orbita (Gastropoda: Mollusca). Aquaculture 276, 162–170. Zarai, Z., Frikha, F., Balti, R., Miled, N., Gargouri, Y., Mejdoub, H., 2011. Nutrient composition of the marine snail (Hexaplex trunculus) from the Tunisian Mediterranean coasts. J. Sci. Food Agric. 91, 1265–1270.