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. 2021 May 6;18(9):4928.
doi: 10.3390/ijerph18094928.

Harmful Algal Blooms in Aquaculture Systems in Ngerengere Catchment, Morogoro, Tanzania: Stakeholder's Experiences and Perception

Offoro Neema Kimambo  1   2 , Jabulani Ray Gumbo  3 , Hector Chikoore  4 , Titus Alfred Makudali Msagati  5
Affiliations

Harmful Algal Blooms in Aquaculture Systems in Ngerengere Catchment, Morogoro, Tanzania: Stakeholder's Experiences and Perception

Offoro Neema Kimambo et al. Int J Environ Res Public Health. .

Abstract

The aquaculture sector has experienced fast growth as a result of livelihood diversification initiatives among small-scale farmers in Tanzania. Regrettably, the dynamics of harmful algal blooms (HABs) have been overlooked despite the noticeable forcing of climate variability, the interaction between social-economic activities, and domestic water supply reservoirs. This study aimed at surveying the occurrence, experiences, and perceptions of HABs in aquaculture systems from stakeholders in the Ngerengere catchment, Morogoro, Tanzania. A cross-sectional survey focus group discussion (FDG), key informant interviews, and anecdotal observation were adopted. A convenient and purposive sample population was drawn from pond owners, registered water users, and government officials in the catchment. For data analysis, descriptive statistics and constant comparison were performed. Most respondents (95%) were able to recognize the image of blooms displayed. Approximately 70% of the respondents agreed that water quality has deteriorated over time, and blooms occur during the dry season. Further, 60% of the respondents agreed that water pollution is a serious problem attributed to sources other than industrial discharge. There was no consensus regarding the health impacts associated with HABs. Raising awareness on HABs is of paramount importance as it will provide the basis for the development of HABs management framework and health risk assessment.

Keywords: Morogoro; Ngerengere catchment; aquaculture systems; cyanobacteria; harmful algal blooms; stakeholder perceptions; water pollutions.

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Conflict of interest statement

The authors declare that they have no conflict of interest.

Figures

Figure 1
Figure 1
Study area map (adapted with permission from Kimambo et al. [33]).
Figure 2
Figure 2
Gender (A) and marital status (B) descriptive plots for all the respondents.
Figure 3
Figure 3
Descriptive plots for number of years respondents stayed in the study area (A) and education level (B).
Figure 4
Figure 4
Descriptive plots for occupation (A) and how informed the respondents are about water problems in the Ngerengere catchment (B).
Figure 5
Figure 5
Descriptive plots of water problems (A) and quality over time (B).
Figure 6
Figure 6
Ranks (response in %) for the reasons of poor water quality in the study area.
Figure 7
Figure 7
Ranks for the major threats as perceived by the respondents.
Figure 8
Figure 8
Descriptive plots for harmful algal blooms (HABs) recognition (A), how regular do blooms occur (B), idea/aware on HABs (C) and the idea/aware of HABs health effects (D).
Figure 9
Figure 9
Aspects tested in recognition of HABs formation and their course in water. (A): Sometimes I see a noticeable discharge from industries; (B): Sometimes I see clear crystal water(C): Sometimes I see algal blooms with limited clarity and odour apparent (D): Sometimes we document history of discharge.
Figure 10
Figure 10
Ranks on whether sometimes an object sees the severity of algal blooms and dead fish.
Figure 11
Figure 11
The conventional methods for HABs control.
Figure 12
Figure 12
Visible foam-like algae as observed at Konga, Kidangawa (A), Greenish colorations as observed at Kingolwira fishponds (B); next to it is red algae (C), and finally mat-like algae as observed at Konga, Kidangawa (D). Specific location, i.e., latitude and longitudes, in the brackets (photos by the author during the survey).
See this image and copyright information in PMC

References

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