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首页> 外文期刊>Journal of Experimental Marine Biology and Ecology >Density dependent effects of an infaunal suspension-feeding bivalve (Austrovenus stutchburyi) on sandflat nutrient fluxes and microphytobenthic productivity
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Density dependent effects of an infaunal suspension-feeding bivalve (Austrovenus stutchburyi) on sandflat nutrient fluxes and microphytobenthic productivity

机译：饲喂混悬液的双壳类双壳虫（Austrovenus stutchburyi）对沙地养分通量和底栖植物生产力的密度依赖性影响

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摘要

We examined in situ the density dependent effects of an infaunal suspension-feeding bivalve, Austrovenus stutchburyi (hereafter Austrovenus) on sandflat nutrient fluxes and microphytobenthic (MPB) production. Nine experimental plots (0.64 m~(-2)) were established at two locations separated by 300 m. Ambient fauna was left intact and Austrovenus added to plots creating a density range from 20 to 2000 ind. m~(-2). Three weeks later, light and dark benthic chambers (area = 0.114 m~(-2)) were deployed to measure MPB production and nutrient fluxes. Austrovenus density was positively correlated with organic content and porosity but did not affect other sediment properties (grain size, pigment content) or resident macrofauna. In dark chambers there was a net influx of oxygen (O_2) into the sediments which increased with Austrovenus density (from - 0.45 to -1.21 mmol m~(-2) h~(-1)) whereas in light chambers there was a net efflux from the sediments which decreased with density (from 0.90 to 0.31 mmol m~(-2) h~(-1)). Significant (p<0.01) multiple linear regression models explained respectively 42% and 72% of the variability in the dark and light chamber O_2 fluxes with Austrovenus density as the most important predictor variable. When the effects of significant co-variables (light intensity, grain size) were accounted for, the negative relationship between O_2 flux and Austrovenus density was less steep in light chambers (ANCOVA p< 0.001) suggesting a stimulation of MPB production at higher densities. Estimates of gross MPB primary production indicated a 30% increase in rates of carbon fixation with Austrovenus density (from 36 to 48 mg C m~(-2) h~(-1)). Ammonium (NH_4~+) was released from the sediments in both light and dark chambers and increased with Austrovenus density by a factor of 5.9-6.9×. Multiple linear regression models were significant for light and dark chambers (p< 0.001; r~2 86-87%) with Austrovenus again as the most important variable influencing fluxes. ANCOVA results (p< 0.001) indicated that in dark chambers NH_4~+ efflux increased with Austrovenus density at a rate 1.76x greater than in light chambers. These results indicate that the greater efflux of NH_4~+ at high densities was being trapped by photosynthesising MPB at the sediment-water interface supporting higher rates of primary production. Our results suggest that a reduction in Austrovenus density will lower nutrient fluxes potentially influencing system productivity by reducing MPB production.
机译：我们就地检查了饲喂混悬液的双壳贝类（Austrovenus stutchburyi，以下简称Austrovenus）对沙地养分通量和微底栖动物（MPB）产量的密度依赖性影响。在相距300 m的两个位置上建立了9个实验区（0.64 m〜（-2））。保持环境动物完整无缺，在地块上增加奥氏菌，使密度范围从20到2000 ind。 m〜（-2）。三周后，部署明暗底栖室（面积= 0.114 m〜（-2））来测量MPB的产生和养分通量。奥氏体密度与有机物含量和孔隙率呈正相关，但不影响其他沉积物特性（粒度，色素含量）或常驻大型动物群。在暗室中，有氧气（O_2）净流入沉积物中，并随着奥氏体密度的增加而增加（从-0.45到-1.21 mmol m〜（-2）h〜（-1）），而在暗室中，则有净流入。沉积物的外排量随密度的降低而降低（从0.90降至0.31 mmol m〜（-2）h〜（-1））。显着（p <0.01）的多元线性回归模型分别解释了以奥氏体密度为最重要的预测变量的暗室和明室O_2通量的42％和72％的变异性。当考虑到重要的协变量（光强度，晶粒尺寸）的影响时，在光室中O_2通量与奥氏体密度之间的负相关关系不那么陡峭（ANCOVA p <0.001），表明在较高密度下刺激了MPB的产生。 MPB初级生产总值的估算表明，碳固定率随奥古斯丁密度的增加（从36 mg C m〜（-2）h〜（-1）增加到30％）。铵（NH_4〜+）在明暗室中均从沉积物中释放出来，并随奥氏体密度的增加而增加5.9-6.9倍。多重线性回归模型对于明室和暗室均具有显着性（p <0.001； r〜2 86-87％），而Austrovenus仍是影响通量的最重要变量。 ANCOVA结果（p <0.001）表明，在暗室中，NH_4〜+外排量随奥氏体密度的增加比在暗室中高1.76倍。这些结果表明，光合作用MPB在沉积物-水界面处捕获了高密度NH_4〜+较大的外流，从而支持了较高的初产率。我们的结果表明，降低奥氏体密度会降低养分通量，从而可能通过降低MPB产量而影响系统生产力。

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