臺灣西南海域高屏海底峽谷深海多毛類分類多樣性及功能多樣性之分布

生物多樣性是現今環境變遷的一項重要指標，為探討在不同空間尺度下生物多樣性受到強烈環境變化的影響，本研究於2014至2015年底在高屏海底峽谷及其相鄰斜坡重複採集深海底棲多毛類，將生物樣本分類至屬或科，並測量其α-多樣性:包括分類多樣性(Taxonomic diversity)及功能多樣性(Functional diversity)，以及β-多樣性:包括群聚組成、物種致換(Turnover)及物種嵌套(Nestedness)的變化，探討不同層面之生物多樣性在強烈內潮擾動之高屏海底峽谷及相對穩定之大陸斜坡的變化。研究結果顯示，由於高屏峽谷強烈內潮的影響，該地區底流速度較快，沉積物侵蝕時間較長，因此多毛類群聚組成明顯與鄰近斜坡不同。此外由於峽谷強勁底流長時間侵蝕沉積物中較富有機質的細顆粒，因此不論是優勢、常見或是總多毛類分類群及功能群數量都因為食物缺乏及物理擾動而明顯減少。另外，在高屏峽谷及其相鄰斜坡的兩條穿越線中，多毛類β-多樣性主要由物種致換(Turnover)造成，此結果可歸因於由深度梯度造成之環境因子改變，使得適應能力較差之科屬被取代。但若比較峽谷及其相鄰斜坡的採樣，在600公尺以淺，物種嵌套(物種喪失，Nestedness)是影響β-多樣性的主要機制，然而在600公尺以深，物種致換則為影響β-多樣性的主要機制，其原因推測為接近峽谷頭物理擾動較強，造成多毛類區域性滅絕，然而遠離峽谷頭環境漸趨穩定，較適應擾動環境的多毛類則取代適性較差之科屬。總結來說，透過本研究我們更進一步了解在強烈物理擾動下，深海底棲分類多樣性、功能多樣性及群聚組成的變化及其影響機制。

關鍵字

多毛類；海底峽谷； α多樣性； β多樣性；分類多樣性；功能多樣性；物種置換；物種嵌套

並列摘要

In this study, we conducted a repeated sampling in the Gaoping submarine canyon (GPSC) and adjacent slope over a year to examine the effect of a physically dynamic and perturbed submarine canyon on the biodiversity of deep-sea polychaete assemblages. We compared the biodiversity at different spatial scales (i.e., α and β-diversity) and for the taxonomic (i.e., genus/family abundance) and functional attributes (i.e., functional traits). We showed that the taxon (genus/family) composition of polychaete in the GPSC was distinctly different from that on the adjacent slope. The total, common and dominant taxa, and functional groups were all depressed in the GPSC, presumably, due to habitat destruction by episodic turbidity currents and erosion and removal of the or-ganic-rich fine sediment by strong internal-tide-driven currents in the canyon. The higher taxon turnover (taxon replacement) than taxon nestedness (taxon loss) along the canyon and slope transects suggests that the environmental-selective differentiation (e.g., depth-related factors) were the key process determining the bathymetric variation of the polychaete assemblages. Between the GPSC and adjacent slope, the taxon nestedness was higher than the taxon turnover in the shallower sites (< 600 m) but the turnover was higher than the nestedness in the deeper sites (> 600m), suggesting a transition of the dominant mechanisms from “local extinction” to “environmental filtering” in shaping the variation of polychaete assemblages from the slope to the canyon. Overall, our study provides insights on how polychaetes taxonomic and functional diversity responded to the physical disturbance in the deep-sea, as well as improves the mechanistic under-standing of the interplays among multiple environmental drivers in shaping the deep-sea diversity.

並列關鍵字

Polychaetes ； Submarine canyon ； α-diversity ； β-diversity ； Taxonomic diversity ； Functional diversity ； Turnover ； Nestedness

參考文獻

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臺灣西南海域高屏海底峽谷深海多毛類分類多樣性及功能多樣性之分布

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