Sacred groves are remnant forest patches preserved through cultural or religious practices, which may serve as refugia for biodiversity in fragmented landscapes ([14]; [120]; [37]). In Ghana, these sacred groves protect culturally significant trees, vegetation, and water bodies dedicated to deities or ancestral spirits ([102]) and as a result, local norms are used to enforce their protection via taboos, integrating spiritual and ecological values ([38]; [68]). Historically, sacred groves have been used as biodiversity conservation hubs ([102]; [67]; [69]; [133]), yet contemporary anthropogenic pressures such as encroachment, farming, and mining threaten their integrity ([91]; [26]; [98]; [16]). It is estimated that there are about 2000 - 3200 sacred groves in Ghana with close to 80% occurring in the southern half of the country ([52]; [99]; [24]). Generally, the main objective for establishing sacred groves in communities in Ghana is to protect forests surrounding environmentally sensitive areas. The size of sacred groves in Ghana ranges from hundreds of hectares of large forest (>100 ha) to small plots (<0.5 ha) containing single trees or few stones ([52]; [49]). Because of their perceived attachment to some deities or ancestral spirits, sacred groves are referred to in different communities, such as nananompow (ancestral grove or royal Mausoleum) ([2]), abosompow or asoneyeso (shrine), mpanyinpow (ancestral forest), and nsamanpow (burial grounds) by the Akans ([95]; [18]).

Sacred groves serve ecological and socio-cultural functions like preserving virgin forests, serving as a refuge for rare and endemic local biodiversity. They also serve as sources of herbs for medicinal, social and religious purposes ([17]; [40]; [105]). Because of the linkage between traditional beliefs and deities or ancestral spirits, disobedience or disregard for traditional laws (taboos) regarding the encroachments of sacred groves attract severe punishments for culprits. Such punishments include offering animals as sacrifice and the performance of traditional rites to appease the local deity to avoid ill-health, and deaths, although this is often ineffective in modern Ghana unlike centuries ago ([71]; [57]). Anthropogenic activities have been reported to have been a major cause of biodiversity loss in the world although the bulk of research in this area within sacred groves is mainly focused on botanical, Ethno-botanical or socio-cultural functions ([68]; [67]; [70]; [54]). Notwithstanding this general situation, there have been some studies on insect diversity assessment in sacred groves as reported by [91], [89], and [87].

The class Insecta contains some important groups with several characteristics that make them suitable for ecosystem health monitoring ([84]; [94]; [85]; [101]; [33]). They inhabit all habitat types and play major roles in the functioning and stability of both terrestrial and aquatic ecosystems ([3]). For instance, it has been reported in several studies that diversity and abundance of grasshoppers ([5]; [4]; [65]; [81]), butterflies ([114]; [73]; [58]; [100]) beetles ([90]; [32]; [83]; [78]), and ants ([32]; [134]; [77]) can be used as good indicators of ecosystem health. The most common features that make insect ideal for bioindication are their ubiquitous occurrence, high species richness, basic sedentary nature, sensitivity to environmental pollutants, easy and inexpensive sampling and well-described taxonomy for families and genera ([106]; [27]; [13]). In line with that, aquatic insects have been widely used for measuring health within freshwater ecosystems in the past few decades ([55]; [27]; [93]; [84]; [94]). Orders like Ephemeroptera, Plecoptera, and Trichoptera (EPT) are highly responsive to changes in water quality and as such have been used in bioassessment frameworks globally ([27]; [86]; [44]; [117]).

Recent evidence however suggests that the structure of aquatic insect communities is not solely shaped by pollution or land use, but also by intrinsic ecological factors such as seasonality and stream dynamics, such as stream size and physico-chemical parameters (water quality) of the stream ([64]; [96]; [103]). For instance, a study conducted at the University of Ghana and such similar studies elsewhere exploited the sensitivity of Odonata to changes in the freshwater ecosystem in generating baseline information about the current state of aquatic systems ([1]; [86]). Odonata diversity associated with freshwater bodies has further been exploited as a tool for predicting the potential future changes in habitat quality ([1]; [86]; [80]; [35]). While well-documented globally, seasonal multi-taxon assessments remain under-represented in West African sacred grove literature. Seasonal variation in tropical streams, particularly the shift between rainy and dry seasons, is known to cause profound changes in aquatic insect communities. Studies from Ghana and other tropical countries (e.g. [109]; [72]; [7]) consistently show peaks in abundance and diversity during the dry season, often due to concentration of individuals in residual pools and more stable water conditions. Similarly, stream dynamics affects habitat heterogeneity, with smaller streams often experiencing greater environmental variability and stronger community shifts ([79]; [29]; [110]).

Despite studies done in sacred groves in Ghana, there is no study in these streams that seeks to measure the effect of stream dynamics (e.g. stream size and water quality) on aquatic insect diversity and by extension, assess the stream health in the two sacred groves, Abiriw and Odumante, in Ghana. And so, this study could serve as a baseline study to kick start other studies that will lead to comprehensive studies on stream health within these two sacred to be used to inform conservation strategies in the same. In line with that this study investigates how seasonality and stream dynamics affected by anthropogenic activities interact to shape aquatic insect diversity within two sacred groves in Ghana as a measure of stream health within these sacred groves.

We hypothesized that seasonality and stream dynamics including localized disturbances, have a profound influence on aquatic insect diversity within Abiriw and Odumante sacred groves. This study contributes to the growing body of literature advocating for integrated ecological and cultural conservation of sacred groves using aquatic insect diversity as a bioindicator in measuring the health within aquatic ecosystems. Specifically, the study determined aquatic insect diversity in the two sacred groves, assessed the seasonal variation in insect communities and used the information to evaluate stream health within these sacred groves.

Our findings show the importance of environmental gradients, especially seasonality and stream dynamics in shaping aquatic insect communities within sacred groves. Although both streams examined in this study were subjected to varying

Figure 2. A Non-Metric Multidimensional Scaling (NMDS) ordination of the sampling sites (triangular and circular points) sampled within the study area, depicting insect assemblage structure within these sites. Sites categorized into same impacts fall within circles (NMDS, stress = 0.07).

degrees of impacts with Odumante more impacted compared to Abiriw, we inferred from the results that seasonal differences and stream dynamics were the main determining factors of aquatic invertebrate diversity within the sacred groves. Specifically, the high diversity recorded at Odumante shows that small streams with high to moderate anthropogenic impacts create an enabling environment for high insect diversity. This finding is consistent with published research ([116]; [8]; [28]).

Seasonal shifts, especially the transition between rainy season and dry season, and periods of high temperature cause distinct alterations in aquatic insect assemblages, as reported elsewhere ([122]; [124]; [47]; [12]). These hydrological cycles drive predictable ecological rhythms, influencing oxygen levels, substrate composition, current velocity, and nutrient flux, which in turn affect the recruitment, emergence, and mortality of different insect taxa. Our observation of higher abundance and richness in the dry season aligns with studies showing that low-flow periods offer stable microhabitats conducive to insect aggregation, predator proliferation, and resource retention ([64]; [23]).

Insect diversity may differ from one stream to another, probably in relation to differences in flow, oxygen concentration and other factors such as the accumulation of organic debris ([123]; [25]; [42]; [48]). Rainfall affects water levels and current strengths of aquatic insect habitats. For instance, net-spinning caddisflies and stoneflies suffer population reduction during heavy rains that could cause floods ([60]; [104]). The significantly higher insect abundance and diversity observed in the dry season support patterns observed in other tropical freshwater systems. Reduced flow during the dry season creates stable microhabitats that promote aggregation of aquatic insects, particularly collectors and predators. Also, the significantly lower DO levels in these streams may be an indication of oxygen stress affecting breeding sites in these streams during dry seasons although there is physical stability during same period ([115]; [45]; [59]). In contrast, the rainy season often brings heavy flow variability and turbidity, leading to displacement and reduced capture efficiency. These seasonal shifts influence beta diversity and community composition, a trend observed in similar studies elsewhere ([64]; [109]; [41]; [119]; [125]; [129]).

We could draw direct inferences from our results that the increase in temperature of the streams during dry season could be because of the loss of shade cover coupled with the high solar radiation in the study areas, as reported elsewhere ([61]; [127]). Also, the little differences in the turbidity of the two sacred groves and in the different seasons may be an indication of minor anthropogenic disturbance or a reduction in water volumes especially in the dry season ([127]; [88]). Furthermore, the decline in DO in the streams, especially in the dry season, is an indication of environmental stress which can adversely affect aquatic insects ([97]; [92]). Further, the pH values recorded for this study show stable chemical and habitat conditions for aquatic life in both streams ([97]; [92]). Also, the largely secondary forests at the riparian areas of the Abiriw stream could have ensured relatively better water quality in that stream by offering protection from erosion through better shading, and a better natural filtration system ([124]; [88]). In contrast to Abiriw sacred grove, the Oduamante stream with highly intensive riparian agricultural activities can potentially contribute to increased water and nutrient runoff into the stream and thereby affecting the water quality as was observed in the reduced dissolved oxygen levels ([124]; [88]).

The dominance of Hemiptera is an indicator of low levels of dissolved oxygen, moderate pollution, high nutrients and some amount of habitat disturbance in these streams especially within the Odumate sacred grove. This is because Hemiptera is known to tolerate oxygen stressed aquatic environment better than most EPT taxa. This is due to their characteristic carriage of air bubbles under water and constant respiration at the water surface. Also, several studies have shown that Hemiptera are usually tolerant in moderately polluted environment ([20]; [43]; [97]; [126]).

The results of insect diversity during the rainy season contrast with other studies that showed that aquatic insect abundance in the rainy season is relatively higher compared to dry season in streams and rivers ([111]; [130]; [103]) but in support with results of other studies ([47]; [131]). This may be because most aquatic insects in the study area might have been displaced from their habitats due to increased flow rate and strong current that normally accompany rainfall in the study area as has been reported in earlier studies ([51]; [34]; [82]). Stream dynamics critically moderates insect community structure by mediating trade-offs between taxonomic richness and abundance ([123]; [64]; [75]). The NMDS for the two study areas were clearly distinct, especially in Odumante, supporting this analysis as was the result in other studies elsewhere ([118]; [132]).

Furthermore, the smaller Odumante stream exhibited higher family richness despite lower abundance, contrasting sharply with the larger Abiriw stream where greater water volume supported higher abundance but reduced diversity. This result probably emanates from environmental filtering processes at Abiriw, with an extensive catchment area, amplified diffuse pollution and sedimentation, reducing microhabitat heterogeneity which favours pollution-tolerant generalists ([29]; [31]); whereas at Odumante, constrained dimensions maintained heterogeneous microhabitats that buffered localized disturbances, enabling specialized guild persistence ([110]). Consequently, stream dynamics driven environmental heterogeneity increased directly might have shaped community outcomes explaining Odumante’s relatively higher richness and Shannon diversity versus Abiriw’s abundance-dominated assemblages. The river continuum concept which states that small streams such as the current study streams (1 - 3 Strahler stream order) are classified as headwaters which are heavily influenced by riparian vegetations by leaving allochthonous detritus and its shading effect ([123]; [42]) could also be used to explain this dynamic of high diversity at Odumante.

The riparian vegetation at Odumante sacred grove was found to have been highly impacted by human activities which have eventually affected the physicochemical characteristics of the water specifically the reduction of DO but might have led to increased allochthonous detritus and thereby providing more opportunities and support for higher diversity. This nonetheless was at the expense of high abundance which may be due to low oxygen levels that will eventually impact breeding sites and increased inter and intra-specific competition, leading to a reduction in individual populations and other such impacts especially during the dry season and may be a sign of relatively some level of pollution which ends up affecting the most sensitive groups like the EPT groups. This demonstrates how intrinsic stream dynamics and seasonal influence community structure in freshwater ecosystems.

The major aquatic insect orders of Ephemeroptera, Plecoptera and Trichoptera which are very sensitive to pollutants were poorly represented at both sacred groves in both seasons. This may be an indication of the poor water quality of the streams, including oxygen stress as reported by ([9]; [53]; [22]). Also, the dominance of Diptera, Hemiptera and Coleoptera in both sacred groves, was a confirmation that these insect orders were the most described and largest in relations to other insect orders and they can inhabit almost every habitat in the aquatic environment in this case in the two sacred groves in agreement with other studies ([11]; [76]; [10]).

Furthermore, this study showed that the persistence of Odonata especially Libellulidae on the aquatic landscape was heavily influenced by structures within the environment, mostly biosphere such as shade cover ([112]; [128]; [62]) and land use type ([107]; [30]) and micro-climate ([83]; [53]). [1], [39], and [36], point out that the degree of shadiness seems to be a principal cue for Odonates to select a forest habitat, but the forest type (species composition) as well as the age of the forest bordering running water sites is of little influence for the Odonata assemblages as long as the required cover is present. These conditions were normally depicted in Abiriw.

Studies have shown that EPT are very sensitive to pollution within aquatic ecosystems. For instance, studies have reported that they are very sensitive to sediment, heavy metals, eutrophication pesticides, etc. pollution ([6]; [22]) within the aquatic ecosystem. In general, these studies have shown that low diversity and abundance of EPT is an indication of pollution by high nutrient levels or reduced dissolved oxygen in the water body. The result of our study aligns with these findings and further confirmation that these streams might be polluted or have low dissolved oxygen levels. The low levels of EPT may also be due to chemical runoff from nearby agricultural fields, and the loss of forest cover and land-use change in the riparian environment especially at Odumante as reported in [6], [22] and [44]. The low levels of EPT coupled with the dominance of Diptera in our studies are an indicator of declining macroinvertebrate diversity within these streams ([53]; [22]; [117]).

Overall, the study demonstrates that seasonal variation, spatial location, and stream dynamics specifically environmental stress like low oxygen in the stream especially during dry season and pollution from agricultural fields significantly influence aquatic insect diversity and abundance in the study areas especially at Odumante sacred grove. These findings underscore the ecological importance of preserving both sites, especially during the dry season when aquatic insect communities are more diverse and abundant. The study further showed that both Odumante and Abiriw sacred groves harbour a high number of aquatic insects. The traditional norms and taboos which were previously used to deter people from encroaching in the sacred groves appeared to have been relaxed, resulting in encroachment and pollution of the streams.

Odumante sacred grove had a higher insect diversity compared to Abiriw sacred grove even though Odumante was more fragmented. One major contributory factor to the low insect diversity at Odumante was human impact stemming from the surrounding villages along the upper reaches of the stream to the sacred grove. It is also concluded from this study that aquatic insects prefer impacted environment especially for streams in sacred groves classified under first-order or low-order (1 to 2) in the Strahler stream order system because according to the river continuum concept such streams are classified as headwaters and are heavily influenced by riparian vegetations by increasing shading and allochthonous detritus which further gives rise to more resources and increased heterogenous environment. The low abundance of EPT shows that the stream dynamics such as dissolve oxygen is low and pollution from runoff from agricultural fields is increasing. The EPT diversity in this study can therefore be used as surrogate organisms to conclude on the stream dynamics that the stream is moderately to severely impacted. We recommend that there should be reduced human activities to slow human impact in these streams in these sacred groves to improve aquatic insect biodiversity conservation.

The authors would like to express their most sincere thanks to the Department of Animal of Animal Biology and Conservation Science of University of Ghana for their support for this research. The authors would also like to acknowledge the leadership and local community for granting them access to the two sacred groves.

Data will be made available on request.

This research was self-funded by the authors.

Victor Parry: Conceptualization, Writing of manuscript, Data collection and analysis; Roger, Sigismund Andersen: Conceptualization, Data collection and analysis and identification of insect groups, Samuel Adu-Acheampong: Data processing, Writing of manuscript, Review & editing of manuscript, Mukundi Mukundamago: Writing of manuscript, Review & editing of manuscript, Emmanuel Robert Blankson: Writing of manuscript, Review & editing of manuscript, Rosina Kyerematen; Conceptualization, Writing review & editing of manuscript and Supervision.