scholarly journals Biological Control of Salvinia molesta (D.S. Mitchell) Drives Aquatic Ecosystem Recovery

Diversity ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 204
Author(s):  
Samuel N. Motitsoe ◽  
Julie A. Coetzee ◽  
Jaclyn M. Hill ◽  
Martin P. Hill
Keyword(s):  
Biological Control ◽  
Ecological Impacts ◽  
Control Treatment ◽  
Macroinvertebrate Communities ◽  
Salvinia Molesta ◽  
Ecosystem Recovery ◽  
Epilithic Algae ◽  
Aquatic Macroinvertebrate ◽  
Introduced Range ◽  
Aquatic Macroinvertebrate Communities

Salvinia molesta D.S. Mitchell (Salviniaceae) is a damaging free-floating invasive alien macrophyte native to South America. The biological control programme against S. molesta by the weevil Cyrtobagous salviniae Calder and Sands (Erirhinidae) has been successful in controlling S. molesta infestations in the introduced range, however, there is some debate as to how biological control success is measured. This study measured the response of epilithic algae and aquatic macroinvertebrate communities in a S. molesta-dominated state and subsequently where the weed had been cleared by biological control, as a proxy for ecosystem recovery in a before–after control–impact mesocosm experiment. The restored treatment (S. molesta and C. salviniae) demonstrated epilithic algae and aquatic macroinvertebrate recovery during the “after” biological control phase, defined as similar to the control treatment. Comparatively, the impacted treatment (100% S. molesta) showed a drastic decline in biodiversity and shifts in community assemblages. We conclude that the biological control effort by C. salviniae facilitated biodiversity recovery of the impacted treatment. Furthermore, epilithic algae and aquatic macroinvertebrate communities were reliable biological indicators for measuring ecological impacts of invasion and ecosystem recovery following biological control, and thus represent potential tools for evaluating biological control success and ecological restoration.

scholarly journals Composition and Structure of Aquatic Macroinvertebrate Communities in Mining Areas Streams (Côte d’Ivoire, West Africa)

2020 ◽  
Vol 3 (1) ◽  
pp. 15
Author(s):  
Ouattara Dongui Seniva ◽  
Tape Logboh David ◽  
Edia Oi Edia
Keyword(s):  
Ammonium Phosphate ◽  
Aquatic Environments ◽  
Ecological Indices ◽  
Macroinvertebrate Communities ◽  
Aquatic Macroinvertebrate ◽  
Whitney Test ◽  
Mining Areas ◽  
Mann Whitney Test ◽  
Composition And Structure ◽  
Aquatic Macroinvertebrate Communities

The existence of mining areas for decades could potentially affect aquatic environments and human health. This study allowed assessing the effects of mining activities on streams in three mining areas (Hiré, Lauzoua and Tortiya). Macroinvertebrates were collected on eight campaigns at eight stations using a hand-net, an Ekman grab and surber net. Environmental variables were recorded also. In this study the conductivity values were higher in the locality of Hiré. It was between 154.2 μS / cm (Tchindégri station) and 1753 μS / cm (Tributary Gbloh station). The highest temperature values were recorded in the stations of Tortiya locality (24 o C: Bou 2; 33.1 o C: Bou 1). A total of 184 taxa distributed among nine classes, 20 orders, 80 families and comprising 14 401 individuals were recorded. Insecta were the most diversified class in macroinvertebrate community (84% of taxa collected, eight orders and 59 families). Ecological indices (Shannon Weiner, rarefied richness, Pielou’s evenness) were significantly low at Lauzoua (N'Téko station) and Hiré (Tributary Gbloh station) (Mann- Whitney test, P <0.05). Ecological indices showed no significant variation between the stations of the locality of Tortiya. The PCA had grouped the stations into four clusters. Conductivity, ammonium, phosphate, nitrites, and nitrates were significantly higher (Mann- Whitney test, P < 0.05) in cluster I (Tributary Gbloh station) Compared to other clusters. Eight taxa (Limnius sp., Liberonautes chaperi, Gordius sp., Phyllogomphus sp., Orectogyrus sp., Bezzia sp., Adenophlebiodes, Parasedodes sp.) were specific to Tchindégri station (Hiré) and six taxa (Naucoris sp., Amphiops sp., Hydrobius sp., Pseudobagous longulus, Culicinae and Gomphus sp.) were associated to the Bou 1 and Bou 2 stations (Tortiya).

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