人類活動對岩岸潮間帶附著生物的影響

The effects of human activities on the populations of attached organisms in intertidal rocky shore

李宗翰(Tsung-Han Lee)

指導教授 ： 李美慧

國立臺灣大學/理學院/地理環境資源學研究所/碩士(2011年)

https://doi.org/10.6342/NTU.2011.02744

摘要

本研究試圖了解人造結構物對附著生物的影響，亦探討遊客踩踏行為對潮間帶岩岸附著生物的衝擊。選定北海岸後厝漁港及麟山鼻漁港，於2010年9月、12月及2011年3月、6月，對港內海堤、港外消波塊與周圍天然岩塊三種不同結構物上進行附著生物調查，並輔以2010年12月及2011年3月、6月水質調查結果與生物調查結果進行討論。另於三芝區淺水灣的潮間帶進行遊客踩踏模擬實驗，選取安山岩及藻礁岩石平台各十處，每處平台設置三個樣方，分別施予不同強度的踩踏 (每個月0下、125下、500下)，從2010年6月到11月每個月初進行踩踏，月末進行生物調查，停止踩踏後仍於2010年12月、2011年2月及5月觀察生物相的恢復狀況。應用生物相似性分析 (Bray-Curtis similarity)、非度量多維空間尺度 (n-MDS)、變異數分析 (ANOVA)、主成份分析 (principal component analysis)、相關分析 (correlation coefficient)、 BIO-EVN等方法，比較各站點生物群聚結構及水質狀況的時空變異；亦使用物種優勢度 (Simpson Index)、物種歧異度 (Shannon-Wiener’s index of species diversity) 與物種均勻度 (Pielou’s index of evenness) 等指數，瞭解踩踏後生物群聚之變動狀況。
附著生物調查發現，消波塊上的生物群聚狀況與天然岩塊較相近，港內海堤上生物總豐度則較其他兩種棲地低。消波塊雖然生物群聚狀況類似天然岩塊，但在生物生長季時，天然岩塊上的生物豐度高於消波塊生物豐度；同時也發現，水質環境因結構物的設置產生改變，影響附著生物的豐度。此外，不論在哪種結構物上，無陰影遮蔽的棲地生物豐度較高，尤其是帽貝類、綠藻類等生物，紅藻類則為陰影處的優勢生物。
從踩踏實驗結果得知，不論在安山岩或藻礁，受踩踏樣方之物種優勢度較控制組高，而物種歧異度與均勻度則較控制組低。每個月踩踏500下之樣方在實驗進行三個月後，出現各種生物豐度皆較控制組低的情況。附著動物受踩踏後數量立即減少，但停止踩踏後即恢復；紅藻類則是踩踏兩到三個月後才受影響，但停止踩踏實驗後六個月仍難恢復。人類踩踏海岸岩石，除了直接使生物消失，也間接干擾了原有的潮間帶生態系，如經踩踏後紅藻類難恢復的情況下，與之存在空間競爭關係的石蓴 (Ulva lactuca) 覆蓋率增加，導致施予踩踏之樣方，在停止踩踏後石蓴的覆蓋率反而較控制組高，進而影響潮間帶生物組成及關係。
未來政府在增設基礎建設並吸引觀光客的同時，應有適當的管理規劃。設置港區結構物時，可增加混凝土建物表面的溝紋與孔隙，模擬天然棲地狀態，且避免設置後出現光照不足或水體環境封閉的狀況。春夏季則需對北海岸潮間帶進行遊客數量管制，使遊客享受海岸自然景觀與生態之美的同時，也能保護此處潮間帶生態系，達到政府推動生態永續利用的目標。

關鍵字

岩岸潮間帶 ； 人工結構物 ； 附著生物 ； 人類踩踏 ； 生物多樣性

並列摘要

The aim of this study is to investigate effects of artificial structures and human trampling on attached organisms in intertidal rocky shore. The intertidal attached organisms on breakwaters, seawalls and natural rocky shores were studied in Linshanbi and Houcuo Harbour, North coast of Taiwan. To assess the generality of patterns through four seasons, natural and artificial habitats were sampled at September 2010, December 2010, March 2011 and June 2011. We also measured several seawater parameters at each sampling site at December 2010, March 2011 and June 2011. Furthermore, we selected two types of rocky intertidal platforms, andesite rock and algal reef, in the Qianshui Bay near Houcuo Harbour. There are ten rocks for each rock type and three quadrats with different trampling treatments on each rock. The trampling treatments were used 0, 125 and 500 footsteps per 100cm2 per month on different quadrats for each rock from June 2010 to November 2010. Observations were made on attached organisms at the end of each month during trampling treatment as well as 1, 3 and 6 months after the last of trampling treatment. The data were analysed by Bray-Curtis similarity, non-metric multi-dimensional scaling (n-MDS), ANOVA, principal component analysis, correlation coefficient and BIO-EVN, in order to test the temporal and spatial variations of the attached organisms and seawater parameters. Biodiversity Index, such as species dominance (Simpson Index), species diversity (Shannon-Wiener’s index of species diversity) and species evenness (Pielou’s evenness) were calculated to study changes in assemblages after tampling.
There are two main findings. First, attached organism assemblages on seawalls were largely distinct from those on breakwaters or natural rocky shores. There were lower abundance of species at seawalls than breakwaters and natural rocky shores. The attached organism assemblages at breakwaters were similar to natural rocky shores, but the abundance of species at natural rocky shores were higher than breakwaters during the growing season of attached organisms. Besides, changes in the seawater environment produced by the establishment of artificial structures will affect the abundance of attached organisms. In addition, no matter what kind of structures, green algae and invertebrates had greater abundance on unshaded surface, while red algae had greater cover on shaded seawalls.
Second, trampling experiment shows that there were higher species dominance and lower species diversity and evenness at experimental quadrats after trampling treatment. All kinds of organisms reduced to 50% of control values at 500 footsteps per month after three months of trampling treatment. Attached animals declined immediately after trampling started, but they recovered at the end of trampling treatments. By contrast, red algae were resistant to trampling effects in first three months of trampling, but they couldn’t recover after the experiment. Thus it can be seen, human trampling will cause both direct and indirect effects on intertidal ecosystem. For example, percentage cover of sea lettuce (Ulva lactuca) increased after trampling because red algae are difficult to recover from trampling treatments, which compete for settlement space with sea lettuce. As a result, the percentage cover of sea lettuce at experimental quadrats were higher than control values after trampling.

並列關鍵字

intertidal rocky shore ； artificial structures ； attached organisms ； human trampling ； biodiversity

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