Taheri Mehrshad, Grego Mateja, Riedel Bettina, Vincx Magda, Vanaverbeke Jan
Ghent University, Biology Department, Marine Biology Research Group, Krijgslaan 281, S8, 9000 Ghent, Belgium; Iranian National Institute for Oceanography and Atmospheric Science (INIOAS), 9, Etemadzadeh Avenue, West Fatemi Street, Tehran, Iran.
Marine Biology Station Piran, National Institute of Biology, Fornace 41, 6330 Piran, Slovenia.
Mar Environ Res. 2015 Sep;110:110-23. doi: 10.1016/j.marenvres.2015.08.004. Epub 2015 Aug 18.
The effect of short and long-term induced anoxia on a benthic nematode community and its potential for recovery after reoxygenation were investigated in an in situ experiment on a silty-sand bottom in the Gulf of Trieste, the northern Adriatic Sea. Anoxia was created artificially by three underwater benthic Plexiglas chambers at a depth of 24 m. Treatments lasted for 2, 23 and 307 days. Control samples (Normoxia) were taken on 3 (Normoxia 1) and 25 (Normoxia 2) August 2010 outside the chambers (4-5 m further). After opening the chambers, recovery cores were taken after 7 days (Anoxia 2D), 30 days (Anoxia 23D) and 90 days (Anoxia 307D). Our results revealed that short-term anoxia (Anoxia 2D) did not affect nematode total density and diversity, community structure and their vertical distribution in the sediment. However, total and vertical nematode density, species richness and diversity decreased at 23 days and decreased further at 307 days anoxia. Some nematode species like Metalinhomoeus effilatus, Paralinhomoeus caxinus and Terschellingia longicaudata even survived at 307 days anoxia treatment. Our results also demonstrated that nematode community exposed to 23 days anoxia did not recover after 30 days sediment reoxygenation but, a full recovery was observed after 90 days for nematode community exposed to 307 days anoxia. Feeding type contribution (functional aspect) of the nematode community also changed at the anoxia treatments and during the recovery process. This change was most drastic at the Anoxia 23D and 307D treatments. At both Normoxia and Anoxia 2D treatments, selective deposit feeders (1A), non-selective deposit feeders (1B) and epistrate (diatom) feeders (2A) nematodes were observed in the dominant nematode community. Epistrate feeders disappeared from in the Anoxia 23D treatment epistrate and also selective deposit feeders did not belong to the dominant nematode species in the Anoxia 307D treatment. After the recovery process, epistrate feeders and selective deposit feeding nematodes reappeared again amongst the dominant nematode species after 30 and 90 days of recovery, respectively.
在亚得里亚海北部的的里雅斯特湾粉砂质海底进行的一项原位实验中，研究了短期和长期诱导缺氧对底栖线虫群落的影响及其复氧后的恢复潜力。通过三个位于24米深处的水下底栖有机玻璃室人工制造缺氧环境。处理持续2、23和307天。对照样本（常氧）于2010年8月3日（常氧1）和25日（常氧2）在室外部（再往外4 - 5米）采集。打开室之后，在7天（缺氧2天）、30天（缺氧23天）和90天（缺氧307天）后采集恢复样本。我们的结果显示，短期缺氧（缺氧2天）并未影响线虫的总密度和多样性、群落结构及其在沉积物中的垂直分布。然而，在23天和307天缺氧时，线虫的总密度和垂直密度、物种丰富度和多样性下降。一些线虫物种，如纤细金属同形线虫、卡氏拟同形线虫和长尾特尔谢林线虫，甚至在307天的缺氧处理中存活下来。我们的结果还表明，经历23天缺氧的线虫群落在沉积物复氧30天后没有恢复，但经历307天缺氧的线虫群落在90天后观察到完全恢复。线虫群落的摄食类型贡献（功能方面）在缺氧处理和恢复过程中也发生了变化。这种变化在缺氧23天和307天处理时最为剧烈。在常氧和缺氧2天处理中，优势线虫群落中均观察到选择性沉积取食者（1A）、非选择性沉积取食者（1B）和表膜（硅藻）取食者（2A）线虫。在缺氧23天处理中，表膜取食者消失，在缺氧307天处理中，选择性沉积取食者也不属于优势线虫物种。恢复过程后，表膜取食者和选择性沉积取食线虫分别在恢复30天和90天后再次出现在优势线虫物种中。
