Conserving Biodiversity in a Human-Dominated World: Degradation of Marine Sessile Communities within a Protected Area with Conflicting Human Uses

Conservation research aims at understanding whether present protection schemes are adequate for the maintenance of ecosystems structure and function across time. We evaluated long-term variation in rocky reef communities by comparing sites surveyed in 1993 and again in 2008. This research took place in Tigullio Gulf, an emblematic case study where various conservation measures, including a marine protected area, have been implemented to manage multiple human uses. Contrary to our prediction that protection should have favored ecosystem stability, we found that communities subjected to conservation measures (especially within the marine protected area) exhibited the greatest variation toward architectural complexity loss. Between 1993 and 2008, chronic anthropogenic pressures (especially organic load) that had already altered unprotected sites in 1993 expanded their influence into protected areas. This expansion of human pressure likely explains our observed changes in the benthic communities. Our results suggest that adaptive ecosystem-based management (EBM), that is management taking into account human interactions, informed by continuous monitoring, is needed in order to attempt reversing the current trend towards less architecturally complex communities. Protected areas are not sufficient to stop ecosystem alteration by pressures coming from outside. Monitoring, and consequent management actions, should therefore extend to cover the relevant scales of those pressures.

保护生态学研究旨在探明当前的保护方案是否足以长期维持生态系统的结构与功能。本研究通过对比1993年与2008年两次调查的样点，评估了岩礁群落的长期动态变化。本研究的研究区域为提古利奥湾（Tigullio Gulf），这是一个极具代表性的案例研究区域，当地已实施包括海洋保护区（marine protected area）在内的多项保护措施，以管控多种人类活动。与我们的初始预测相悖——我们曾认为保护措施应有助于提升生态系统稳定性——但研究发现，受保护措施管控的群落（尤其是海洋保护区内的群落）在群落结构复杂度退化方面表现出最为显著的变化。1993年至2008年间，早在1993年就已对未受保护样点造成干扰的长期人为压力（尤其是有机负荷），其影响范围已扩张至保护区内。这种人为压力的扩张或可解释本研究观测到的底栖群落（benthic communities）的变化。研究结果表明，为扭转当前群落结构复杂度持续降低的趋势，亟需建立基于生态系统的适应性管理（EBM）模式——即兼顾人类活动交互影响、并以持续监测为支撑的管理方案。仅靠保护区已不足以阻挡外部压力对生态系统造成的破坏。因此，监测及后续的管理措施应覆盖这些压力作用的相关空间尺度。