Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK.
Proc Biol Sci. 2012 Sep 7;279(1742):3393-400. doi: 10.1098/rspb.2012.0313. Epub 2012 Jun 13.
Historic baselines are important in developing our understanding of ecosystems in the face of rapid global change. While a number of studies have sought to determine changes in extent of exploited habitats over historic timescales, few have quantified such changes prior to late twentieth century baselines. Here, we present, to our knowledge, the first ever large-scale quantitative assessment of the extent and biomass of marine habitat-forming species over a 100-year time frame. We examined records of wild native oyster abundance in the United States from a historic, yet already exploited, baseline between 1878 and 1935 (predominantly 1885-1915), and a current baseline between 1968 and 2010 (predominantly 2000-2010). We quantified the extent of oyster grounds in 39 estuaries historically and 51 estuaries from recent times. Data from 24 estuaries allowed comparison of historic to present extent and biomass. We found evidence for a 64 per cent decline in the spatial extent of oyster habitat and an 88 per cent decline in oyster biomass over time. The difference between these two numbers illustrates that current areal extent measures may be masking significant loss of habitat through degradation.
历史基线对于在快速的全球变化背景下了解生态系统至关重要。尽管有许多研究试图确定在历史时期内受人类活动影响的栖息地范围的变化，但很少有研究能够量化 20 世纪后期基线之前的这种变化。在这里，我们展示了，据我们所知，首次对 100 年来海洋生境形成物种的范围和生物量进行的大规模定量评估。我们研究了美国历史上（已开发）但仍处于基线期的野生本地牡蛎丰度记录，该基线期在 1878 年至 1935 年之间（主要在 1885 年至 1915 年之间），以及最近的基线期在 1968 年至 2010 年之间（主要在 2000 年至 2010 年之间）。我们量化了 39 个历史时期和 51 个现代时期河口的牡蛎场范围。来自 24 个河口的数据允许对历史和现在的范围和生物量进行比较。我们发现，牡蛎栖息地的空间范围在时间上减少了 64%，牡蛎生物量减少了 88%。这两个数字之间的差异表明，当前的面积测量可能掩盖了通过退化导致的栖息地的重大损失。
