カリフォルニア南部のケルプ森林の生態系において,上から下へと強い統制が行われている
Benjamin S Halpern1, Karl Cottenie, Bernardo R Broitman
1National Center for Ecological Analysis and Synthesis, 735 State Street, Santa Barbara, CA 93101, USA. halpern@nceas.ucsb.edu
まとめ
捕食者による上から下へのコントロールは,下から上への栄養コントロールよりも,海洋の食物網に大きな影響を与えます. 捕食者の豊富さを理解することは,海藻の森のような沿岸の生態系を管理するための鍵です.
科学分野:
- 海洋生態学 海洋生態学とは
- フードウェブのダイナミクス
- 生態系管理とは,生態系の管理です.
背景:
- 人為的な栄養素の投入と捕食者の除去は,海洋生態系を変化させている.
- トップダウン対ボトムアップのコントロールの相対的な重要性については,海洋食物網では依然として議論されている.
研究 の 目的:
- ケルプ森林の食物網のダイナミクスにおけるトップダウンとボトムアップのコントロールの相対的な役割を調査する.
- 肉食動物がより低いトロフィックレベルに豊富に存在する影響を定量化するために.
主な方法:
- カリフォルニア・チャネル諸島のケルプ林の46種の種数に関する多年にわたる大規模なデータセットを利用した.
- ボトムアップの影響を評価するために,衛星から得られた一次生産データを統合した.
- トップダウン対ボトムアップ因子で説明される豊かさの変動を分析しました.
主要な成果:
- トップダウンコントロールは,ボトムアップコントロールと比較して,ボトムとミッドトロフィックレベルの多さに7〜10倍の多様性を説明しました.
- 捕食者の多さに直接的・間接的な種レベルでの反応は,上から下の制御の重要なメカニズムでした.
- ケルプの森の生態系には,上から下への規制が強く見られます.
結論:
- 捕食者の多量と上から下への影響は,海洋食物網構造の重要な要因であり,特にケルプの森です.
- 漁業規制などの上から下への影響に焦点を当てた管理戦略は,沿岸の海洋生態系の健康にとって極めて重要です.
関連する概念動画
Keystone Species
Measures of species biodiversity, such as richness (i.e., the number of species present) and evenness (i.e., their relative abundance), describe an ecological community’s structure. Many factors affect community structure, including abiotic factors (e.g., sunlight and nutrients), disturbances (e.g., fire or flood), species interactions (e.g., predation or competition), and chance events (e.g., foreign species invasion). Certain species—such as keystone species—also play a pivotal role in the...
Freshwater Microbial Ecology
Freshwater systems such as streams, rivers, and lakes exhibit distinct physical and biological characteristics that influence their microbial communities. These environments are broadly categorized into lotic systems—those with flowing waters like streams and most rivers—and lentic systems, which include still or slow-moving waters such as lakes, ponds, and marshes.In lentic systems, phytoplankton drive primary production, generating autochthonous organic carbon. In contrast, lotic systems...
Marine Microbial Ecology
Marine microbial ecosystems are shaped by distinct physicochemical limits, including high salinity, low nutrient availability, and fluctuating oxygen levels. These conditions favor smaller microbial cell sizes, which maximize their surface-to-volume ratio for efficient nutrient uptake.Microbial activity and community composition are closely linked to biogeochemical cycles, particularly in dynamic environments like estuaries, where halotolerant microbes thrive in response to variable salinity...
Primary Production
The total amount of energy acquired by primary producers in an ecosystem is called gross primary production (GPP). However, of this energy, producers use some for metabolic processes, and some is lost as heat, decreasing the amount of energy available to the next trophic level. The remaining usable amount of energy is called the net primary productivity (NPP). In terrestrial ecosystems, NPP is driven by climate, while light penetration and nutrient availability drive NPP in aquatic ecosystems.
Deep Sea Microbial Ecology
The deep ocean and its underlying sediments represent vast, largely unexplored microbial habitats that extend far beyond the sunlit photic zone. The photic (euphotic) zone typically spans the upper ~100–200 meters of pelagic waters in the open ocean, but its depth varies geographically and seasonally, where sufficient light supports photosynthetic life. Below this lies the deep sea, spanning roughly 1000–6000 meters (bathypelagic to abyssal zones), with deeper hadal trenches extending beyond...
Osmoregulation in Fishes
When cells are placed in a hypotonic (low-salt) fluid, they can swell and burst. Meanwhile, cells in a hypertonic solution—with a higher salt concentration—can shrivel and die. How do fish cells avoid these gruesome fates in hypotonic freshwater or hypertonic seawater environments?

