Re-examining Temporal and Spatial Variation of Benthic Invertebrate Biodiversity in Lake Maurepas, Louisiana, USA, Forty Years Later

Lake Maurepas, an oligohaline embayment in southeastern Louisiana, USA, lies on the westernmost edge of the socio-ecologically important Lake Pontchartrain Basin, a region with a history of hydraulic fossil shell dredging and water pollution. Relative to the nearby Lake Pontchartrain, our knowledge of the invertebrate community in Lake Maurepas is limited. The most recent record of benthic invertebrate community data was collected between 1983 and 1984. We aim to establish an updated baseline dataset on the spatial and temporal variability of the invertebrate community within Lake Maurepas, and compare our findings with those from 1984, using the same petite ponar grab dredging methodology. While species richness is similar between the two sampling projects, we observed higher species abundance and a distinct species composition in 2024 than in 1984. We observe temporal patterns in 2024 invertebrate species abundance and community composition, which are driven by oligochaetes, midge larvae, Helobdella leeches, and Probythinella mud snails, whereas the 1984 study showed no comparable seasonal trends. Contrary to the 1984 study, saltwater species were rarely collected in 2024. Our findings provide baseline information on invertebrate diversity and abundance in Lake Maurepas, describe changes that have occurred over the last 40 years, and identify potential bioindicator species, which is important considering anthropogenic impacts on the lake.美国路易斯安那州东南部的莫尔帕斯湖（Lake Maurepas）是一处寡盐水湾（oligohaline embayment），地处具有社会生态重要性的庞恰特雷恩湖流域（Lake Pontchartrain Basin）最西端，该区域曾开展过水力化石贝壳疏浚作业，且存在水污染历史。相较于邻近的庞恰特雷恩湖，学界对莫尔帕斯湖无脊椎动物群落的认知仍较为有限。该湖底栖无脊椎动物群落数据的最新记录采集于1983至1984年间。本研究旨在基于统一的小型波纳采泥器（petite ponar grab dredging）疏浚采样方法，构建莫尔帕斯湖无脊椎动物群落时空分布变异的最新基准数据集，并将本次研究结果与1984年的观测数据进行对比。尽管两次采样项目的物种丰富度相近，但2024年观测到的物种丰度更高，且物种组成与1984年存在显著差异。2024年的无脊椎动物物种丰度及群落组成呈现出时间动态特征，该特征由寡毛类（oligochaetes）、摇蚊幼虫（midge larvae）、Helobdella属水蛭（Helobdella leeches）以及Probythinella属泥螺（Probythinella mud snails）主导；而1984年的研究未观测到类似的季节变化趋势。与1984年的研究结果相反，2024年的采样中几乎未采集到盐水生境物种。本研究结果为莫尔帕斯湖无脊椎动物多样性与丰度提供了基准数据，阐明了该湖近40年来发生的群落变化，并筛选出潜在的生物指示物种，考虑到人类活动对该湖的影响，这一发现具有重要意义。