Data_Sheet_3_Sandy Beach Macrofauna of Yucatán State (Mexico) and Oil Industry Development in the Gulf of Mexico: First Approach for Detecting Environmental Impacts.docx

The biodiversity of the coastal ecosystems in the Gulf of Mexico is threatened by anthropogenic activities of various kinds. The predominant portion of the land-sea margin in the State of Yucatán consists of exposed sandy beaches. This ecosystem is threatened by several activities that vary in spatial scales, at a local: cargo/fishing ports, touristic facilities, maritime traffic, and domestic pollution; and at a larger scale: the forthcoming development of the oil industry. In the absence of information about the biodiversity of the beaches of Yucatán, we implement the Marine Biodiversity Observation Network (MBON) Pole to Pole sampling protocol to (1) Quantify the spatial patterns of diversity of macrofauna along the beaches; (2) quantify current levels of pollution by hydrocarbons (aromatic and aliphatic); (3) estimate sampling effort for future environmental impact assessments. During November 2018, six localities along the coastline of Yucatán State were sampled following a spatial hierarchical design that included three sites at each locality, and 9–18 core samples in the intertidal strata of each site. As a result, 31 species of invertebrates were registered. The patterns of distribution and abundance of species showed that there was a base community structure along the entire coast dominated by four species. In general, the density of species was relatively low (2–4 species/0.01 m3) and the density of individuals was high (20–200 ind./0.01 m3). The beta diversity was higher between localities with good environmental health, but the estimated alpha diversities did not show a pattern regarding the health of the coast. Lastly, the overall number of species reported suggest that gamma diversity of the macrofauna in the beaches of Yucatán is within the highest known worldwide. Levels of hydrocarbons detected in this study are exceptionally low compared to those reported for other coastal areas of the Gulf of Mexico and are several orders of magnitude lower than those considered as lower-threshold values for marine sediments. The biological and chemical patterns reported here indicated that it is an appropriate moment to start long-term monitoring. The sampling design we suggest is based on statistical precision and internationally recognized protocols for assessment of marine diversity on sandy beaches.

墨西哥湾沿岸生态系统的生物多样性正受到各类人类活动的威胁。尤卡坦州的海陆交界带主体为裸露沙滩。该生态系统面临多种空间尺度各异的威胁：局部尺度包括货运/渔港、旅游设施、海上交通及生活污染；更大尺度则涉及即将开展的石油工业开发。鉴于尤卡坦州海滩的生物多样性信息仍存在空白，本研究采用海洋生物多样性观测网络（Marine Biodiversity Observation Network, MBON）的"极到极"采样方案，旨在达成三个目标：(1) 量化大型底栖动物沿海岸的多样性空间分布格局；(2) 定量评估当前烃类（芳香烃与脂肪烃）污染水平；(3) 为未来环境影响评价估算采样工作量。2018年11月，研究团队按照空间分层设计，对尤卡坦州海岸线沿线的6个采样点开展了采样——每个采样点设置3个样地，每个样地的潮间带区段采集9~18个岩心样本。本次研究共记录到31种无脊椎动物。物种分布与丰度模式显示，整条海岸带存在以4个物种为优势类群的基础群落结构。总体而言，物种密度相对较低（2~4种/0.01 m³），而个体密度较高（20~200 只/0.01 m³）。环境健康状况良好的采样点间的β多样性更高，但估算得到的α多样性并未呈现与海岸健康状况相关的分布格局。最后，本次记录的物种总数表明，尤卡坦州海滩大型底栖动物的γ多样性处于全球已知较高水平。本研究检测到的烃类含量相较于墨西哥湾其他沿海区域极低，较海洋沉积物污染下限阈值低数个数量级。本研究报道的生物学与化学特征表明，当前是启动长期监测的适宜时机。本研究提出的采样设计基于统计精度要求，并遵循国际公认的沙滩海洋生物多样性评估方案。