Preprint volume - SIBM
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Preprint volume - SIBM

Preprint volume - SIBM Preprint volume - SIBM

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Pre-print Volume - Posters Topic 2: MARINE ORGANISMS AND ECOSYSTEMS AS MODEL SYSTEMS include animal components. To assess differences in sea urchin density, a PERMANOVA analysis including Species (fixed, 2 levels: P. lividus and A. lixula), Year (fixed, 4 levels: ’06,’07,’08,’09) Protection (fixed, 2 levels A, C) and Site (random, 2 levels) factor was performed, while the PERMANOVA of benthic assemblage cover included Year, Protection and Site factor. A Zone A 1 B Zone A C Zone 1 Km Fig. 1 – Sampling sites at the MPA “Isola di Ustica”: A1, A2, C1 and C2. Siti di campionamento nell’AMP “Isola di Ustica”: A1, A2, C1 and C2. 2 41 st S.I.B.M. CONGRESS Rapallo (GE), 7-11 June 2010 127 N Ustica Island C 2 Results – Density of both sea urchin populations was lower in 2009 than in 2006. P. lividus and A. lixula densities ranged between 4±0.5 ind./m 2 and 3.35±0.3 ind./m 2 , respectively, in 2006 and 0.5±0.1 ind./m 2 and 0.6±0.0 ind./m 2 in 2009. During this decrement of both sea urchins, a benthic algae shift from Corallinales (barren state) to erect macroalgae was observed. PERMANOVA showed only an important interaction between “Year x Site” terms of both sea urchin density and benthic assemblage. For every site, Pair-Wise tests confirmed the important effect Year on the studied variables. Conclusions – No protection effect on sea urchin abundance was detected. P. lividus and A. lixula showed a strong decrement within both take and no-take zones. Multiple natural control factors (like low sea urchin recruitment and natural predation) may have provoked the drop of sea urchins abundance. This change in sea urchin abundances likely promoted the flourishing of erect macroalgae in the upper infralittoral of Ustica MPA. These results offer new tips of reflection for a simple cascade trophic model in Mediterranean rocky infralittoral systems. References BONAVIRI C., FERNANDEZ T.V., BADALAMENTI F., GIANGUZZA P., DI LORENZO M., RIGGIO S. (2009) - Fish versus starfish predation in controlling sea urchins populations in Mediterranean rocky shores. Mar. Ecol. Progr. Ser., 382: 129-138. GIANGUZZA P., CHIANTORE M., BONAVIRI C., CATTANEO-VIETTI R., VIELMINI I., RIGGIO S. (2006) - The effects of recreational Paracentrotus lividus fishing on distribution patterns of sea urchins at Ustica Island MPA (Western Mediterranean, Italy). Fish. Res., 81: 37– 44. STENECK R.S., DETHIER M.N. (1994) - A functional group approach to the structure of algal dominated communities. Oikos, 69: 476-498. C 1

Pre-print Volume - Posters Topic 2: MARINE ORGANISMS AND ECOSYSTEMS AS MODEL SYSTEMS A. CHRACHRI 1 , A.R. TAYLOR 1,2 , G.L. WHEELER 1,3 , H. GODDARD 1 , C. BROWNLEE 1 1 The Marine Biological Association, the Laboratory, Citadel Hill, Plymouth PL1 2PB, UK. aacc@mba.ac.uk 2 University of North Carolina Wilmington, USA. 3 PML, Plymouth, UK. A VOLTAGE GATED H + -CONDUCTANCE UNDERLYING PH HOMEOSTASIS AND CALCIFICATION IN COCCOLITHOPHORIDS IL VOLTAGGIO “GATED” PER IL FLUSSO DI MEMBRANA DI IONI H+ COME BASE DELL’OMEOSTASI DEL PH DELLA CALCIFICAZIONE NEI COCCOLITOFORIDI Abstract – Intracellular precipitation of calcite in calcifying coccolithophorid such as Coccolithus pelagicus generate large amounts of H + load in cytosol. Therefore, these cells have a requirement for an efficient high capacity mechanism for H + excursion. In many animal tissues, it has been demonstrated that voltage-gated proton (H + ) channels play an important role in cellular defense against acidic stress. In this report, we have characterized a similar voltage dependent proton conductance in the calcifying coccolithophorid, Coccolithus pelagicus, using patch-clamp technique. We have also demonstrated that in voltage-clamp mode, depolarization of these cells from a holding potential of -50 mV to +70 mV caused an increase in pHi that was accompanied by a sizeable outward conductance. These findings are consistent with the existence of a conductive H + (equivalent) pathway. Key-words: coccolithophorid, Coccolithus pelagicus, patch-clamp technique, voltage-gated proton (H + ) channels, pH. Introduction - Coccolithophorids are photosynthetic marine microalgae that form extensive blooms in the surface waters of the world’s oceans and are considered to be the most significant producer of calcite on earth. It has been shown that in Coccolithus pelagicus calcification occurs in a specialized centrally located intracellular compartment, the coccolith vesicle, which is derived from the Golgi (Taylor et al., 2007). The process of intracellular calcification requires efficient and energetically cost-effective ion transport to the coccolith vesicle as well as intracellular homeostasis of both Ca 2+ and H + . Materials and methods – Whole cell patch clamp recordings were conducted at 20 o C. In some experiments, decalcified cells were either loaded with 300 μM BCECF free acid in the patch clamp pipette. Changes in intracellular pHi were monitored using a Zeiss 510 confocal microscope. Results - Using the patch clamp technique, we characterized a conductance that is activated by depolarisation more positive than the equilibrium potential for H + . Tail current analysis revealed that the conductance reversed positively to EK + and ECl - , and closest to EH + . These data show that the biophysical characteristics of the outward conductance in C. pelagicus are consistent with those described for animal H + channels and led us to hypothesize a role in rapid H + efflux during pH homeostasis. Simultaneous patch clamp and pH imaging demonstrated that in cells that were clamped at voltages more negative of EH + no change in pHi was observed in response to sub-threshold depolarization, whereas significant reversible cytoplasmic alkalinisation 41 st S.I.B.M. CONGRESS Rapallo (GE), 7-11 June 2010 128

Pre-print Volume - Posters<br />

Topic 2: MARINE ORGANISMS AND ECOSYSTEMS AS MODEL SYSTEMS<br />

include animal components. To assess differences in sea urchin density, a<br />

PERMANOVA analysis including Species (fixed, 2 levels: P. lividus and A. lixula),<br />

Year (fixed, 4 levels: ’06,’07,’08,’09) Protection (fixed, 2 levels A, C) and Site<br />

(random, 2 levels) factor was performed, while the PERMANOVA of benthic<br />

assemblage cover included Year, Protection and Site factor.<br />

A Zone<br />

A 1<br />

B Zone<br />

A<br />

C Zone<br />

1 Km<br />

Fig. 1 – Sampling sites at the MPA “Isola di Ustica”: A1, A2, C1 and C2. Siti di campionamento nell’AMP “Isola di Ustica”: A1, A2, C1 and C2. 2<br />

41 st S.I.B.M. CONGRESS Rapallo (GE), 7-11 June 2010<br />

127<br />

N<br />

Ustica Island<br />

C 2<br />

Results – Density of both sea urchin populations was lower in 2009 than in 2006. P.<br />

lividus and A. lixula densities ranged between 4±0.5 ind./m 2 and 3.35±0.3 ind./m 2 ,<br />

respectively, in 2006 and 0.5±0.1 ind./m 2 and 0.6±0.0 ind./m 2 in 2009. During this<br />

decrement of both sea urchins, a benthic algae shift from Corallinales (barren state) to<br />

erect macroalgae was observed. PERMANOVA showed only an important interaction<br />

between “Year x Site” terms of both sea urchin density and benthic assemblage. For<br />

every site, Pair-Wise tests confirmed the important effect Year on the studied variables.<br />

Conclusions – No protection effect on sea urchin abundance was detected. P. lividus<br />

and A. lixula showed a strong decrement within both take and no-take zones. Multiple<br />

natural control factors (like low sea urchin recruitment and natural predation) may<br />

have provoked the drop of sea urchins abundance. This change in sea urchin<br />

abundances likely promoted the flourishing of erect macroalgae in the upper<br />

infralittoral of Ustica MPA. These results offer new tips of reflection for a simple<br />

cascade trophic model in Mediterranean rocky infralittoral systems.<br />

References<br />

BONAVIRI C., FERNANDEZ T.V., BADALAMENTI F., GIANGUZZA P., DI LORENZO M.,<br />

RIGGIO S. (2009) - Fish versus starfish predation in controlling sea urchins populations in<br />

Mediterranean rocky shores. Mar. Ecol. Progr. Ser., 382: 129-138.<br />

GIANGUZZA P., CHIANTORE M., BONAVIRI C., CATTANEO-VIETTI R., VIELMINI I.,<br />

RIGGIO S. (2006) - The effects of recreational Paracentrotus lividus fishing on distribution<br />

patterns of sea urchins at Ustica Island MPA (Western Mediterranean, Italy). Fish. Res., 81: 37–<br />

44.<br />

STENECK R.S., DETHIER M.N. (1994) - A functional group approach to the structure of algal<br />

dominated communities. Oikos, 69: 476-498.<br />

C 1

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