Ocean warming undermines the recovery resilience of New England kelp forests following a fishery-induced trophic cascade

Ecological theory predicts that kelp forests structured by trophic cascades should experience a recovery and persistence of their foundation species when herbivores become rare. Yet, climate change may be altering the outcomes of top-down forcing in kelp forests, especially those located in regions that have rapidly warmed in recent decades, such as the Gulf of Maine. Here, using data collected annually from 30+ sites spanning >350 km of coastline, we explored the dynamics of Maine’s kelp forests in the ~20 years after a fishery-induced elimination of sea urchin herbivores. Although forests (dominated by Saccharina latissima and Laminaria digitata) had broadly returned to Maine in the late 20th century, we found that forests in northeast Maine have since experienced slow but significant declines in kelp, and forest persistence in the northeast was juxtaposed by a rapid, widespread collapse in the southwest. Forests collapsed in the southwest apparently because ocean warming has – dir..., Methods for: Quantifying kelp forest trajectories through time and space Associated files: DMR_benthicsurvey_algae_urchin_randomsites_alldepths_2001_2018.csv ; Rasher_Steneck_benthicsurvey_algae_urchin_allsites_alldepths_2016.csv ; Rasher_Steneck_benthicsurvey_algae_urchin_allsites_alldepths_2017.csv ; Rasher_Steneck_benthicsurvey_algae_urchin_allsites_alldepths_2018.csv To quantify changes in Maine’s kelp forests through time and space, we conducted in situ surveys (via SCUBA) of rocky reefs every year from 2001 to 2018 (via long-term monitoring by the Maine Department of Marine Resources; hereafter “ME-DMR”). From May to June of each year, ME-DMR divers visually surveyed up to 140 randomly selected sites, some of which were sheltered from waves and/or in rivers or estuarine environments and were subsequently excluded from our analysis (see below and associated code).  At each site, the diver began their survey at 15 m depth (mean lower low water, hereafter “MLLW”) and swam perpend..., , # Ocean warming undermines the recovery resilience of New England kelp forests following a fishery-induced trophic cascade [https://doi.org/10.5061/dryad.v9s4mw73q](https://doi.org/10.5061/dryad.v9s4mw73q) ## Description of the datasets and file structures Below, find the metadata for columns in each raw data file: ### DMR\_benthicsurvey\_algae\_urchin\_randomsites\_alldepths\_2001\_2018.csv * year - Integer for year. * date - Date in M/D/Y format. * site.number - Integer identifier for site. Numbers were reused between years, but do not correspond to the same sites. * region.code - Integer code of DMR management area. Does not match region. Not used in analyses. * region - Character identifier for name of region on the coast of Maine. * exposure.code - Integer identifier for 1-5 qualitative scale of total arc (in degrees) where a site was exposed to the open ocean. * coastal.code - Integer identifier for 1-5 qualitative scale of a site's coastal status. Exposed mainl...生态学理论预测，受营养级联（trophic cascades）调控的海带林（kelp forests）在草食性动物稀缺时，其建群种应能够实现恢复并维持种群存续。然而，气候变化或正在改变海带林的自上而下调控结果，尤其是近几十年来快速变暖的区域，例如缅因湾（Gulf of Maine）。本研究依托横跨超350千米海岸线的30余个年度监测位点数据，探究了缅因州海带林在渔业驱动下清除海胆草食类群后约20年间的动态变化。尽管以长海带（Saccharina latissima）和掌状海带（Laminaria digitata）为优势种的海带林已于20世纪后期在缅因州大范围恢复，但我们发现缅因州东北部的海带林近年来出现了缓慢却显著的种群衰退，而东北部林分的维持状况与西南部快速且大范围的林分崩塌形成鲜明对比。西南部海带林的崩塌显然与海洋变暖相关——[原文截断]，研究方法：量化海带林时空动态变化 关联文件： DMR_benthicsurvey_algae_urchin_randomsites_alldepths_2001_2018.csv； Rasher_Steneck_benthicsurvey_algae_urchin_allsites_alldepths_2016.csv； Rasher_Steneck_benthicsurvey_algae_urchin_allsites_alldepths_2017.csv； Rasher_Steneck_benthicsurvey_algae_urchin_allsites_alldepths_2018.csv 为量化缅因州海带林的时空变化，我们于2001年至2018年每年开展岩礁生境原位调查（in situ surveys）（借助SCUBA潜水）——数据源自缅因州海洋资源部（Maine Department of Marine Resources，以下简称"ME-DMR"）的长期监测项目。每年5月至6月，ME-DMR的潜水员会目视调查至多140个随机选取的位点，其中部分位点因受波浪遮蔽、位于河流或河口环境中而被排除在本研究分析之外（详见下文及关联代码）。在每个位点，潜水员从15米深度（平均最低低潮面，mean lower low water，以下简称"MLLW"）出发，沿垂直方向游动……[原文截断]，# 海洋变暖削弱新英格兰海带林经渔业驱动的营养级联后的恢复韧性 [https://doi.org/10.5061/dryad.v9s4mw73q] ## 数据集与文件结构说明 下文为各原始数据文件的列元数据： ### DMR_benthicsurvey_algae_urchin_randomsites_alldepths_2001_2018.csv * year：年份，整数型数据。 * date：日期，格式为M/D/Y。 * site.number：位点整数标识符，不同年份可重复使用编号，但不对应同一实地位点。 * region.code：DMR管理区域的整数代码，与实际地理区域不匹配，分析过程中未使用该字段。 * region：缅因州沿海区域名称的字符型标识符。 * exposure.code：位点暴露于公海的总弧度（度）的1-5级定性评分整数标识符。 * coastal.code：位点海岸状态的1-5级定性评分整数标识符，暴露性主岸……[原文截断]