Laboratory of Biomonitoring of the Environment LR01 ES14, University of Carthage, Faculty of Sciences of Bizerte, Zarzouna 7021, Tunisia.
Department of Biology, College of Sciences, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia.
Braz J Biol. 2021 May 10;82:e247073. doi: 10.1590/1519-6984.247073. eCollection 2021.
In Northern Tunisia, seasonal streams, called wadi, are characterized by extreme hydrological and thermal conditions. These freshwater systems have very particular features as a result of their strong irregularity of flow due to limited precipitation runoff regime, leading to strong seasonal hydrologic fluctuations. The current study focused on the spatio-temporal distribution of chironomids in 28 sampling sites spread across the Northern Tunisia. By emplying PERMANOVA, the results indicated a significant spatio-temporal variation along various environmental gradients. The main abiotic factors responsible for noted differences in the spatial distribution of chironomids in wadi were the conductivity and temperature, closely followed by altitude, pH, salinity, talweg slope and dissolved oxygen, identified as such by employing distance-based linear models' procedure. The Distance-based redundancy analysis ordination showed two main groups: the first clustered the Bizerte sites, which were characterized by high water conductivity, sodium concentration and salinity. The second main group comprised sites from the Tell zone and was characterized by low temperatures, neutral pH, low conductivity and nutrients content. The subfamily TANYPODIINAE (e.g., Prochladius sp., Prochladius choerus (Meigen, 1804) and Macropelopia sp.) was the dominant group at Tell zone, whereas species such as Diamesa starmachi (Kownacki et Kownacha, 1970) and Potthastia gaedii (Meigen, 1838) were found only in Tell Wadis. In contrast, chironomid species such as Diamesa starmachi (Kownacki et Kownacha, 1970), Potthastia gaedii (Meigen, 1838), Procladius choreus (Meigen, 1804) were specific for Tell Mountain. Cap Bon wadis region was dominated by genus Cladotanytarsus sp. The results of this survey liked the taxonomic composition of chironomid assemblages to the variation of hydromorphological and physic-chemical gradients across the northern Tunisia wadis.
在突尼斯北部，季节性溪流（称为 wadi）的水文和热条件非常极端。这些淡水系统具有非常特殊的特征，因为它们的流量非常不规则，这是由于有限的降水径流量导致的，导致强烈的季节性水文波动。本研究集中于在突尼斯北部的 28 个采样点上研究摇蚊的时空分布。通过 PERMANOVA，结果表明，各种环境梯度存在显著的时空变化。导致 wadi 中摇蚊空间分布差异的主要非生物因素是电导率和温度，紧随其后的是海拔、pH 值、盐度、河谷坡度和溶解氧，这是通过距离线性模型过程确定的。基于距离的冗余分析排序显示了两个主要组：第一组聚类了 Bizerte 站点，其特点是高水导率、钠浓度和盐度。第二个主要组由 Tell 区的站点组成，其特点是低温、中性 pH 值、低电导率和养分含量。TANYPODIINAE 亚科（例如，Prochladius sp.、Prochladius choerus (Meigen, 1804) 和 Macropelopia sp.）是 Tell 区的优势群体，而 Diamesa starmachi (Kownacki et Kownacha, 1970) 和 Potthastia gaedii (Meigen, 1838) 等物种仅在 Tell Wadis 中发现。相比之下，Diamesa starmachi (Kownacki et Kownacha, 1970)、Potthastia gaedii (Meigen, 1838)、Procladius choreus (Meigen, 1804) 等摇蚊物种是 Tell 山特有的。Cap Bon wadis 地区以 Cladotanytarsus sp. 属为主。这项调查的结果表明，摇蚊组合的分类组成与突尼斯北部 wadi 的水形态和物理化学梯度的变化有关。
