When is the best time to sample aquatic macroinvertebrates in ponds for biodiversity assessment?

Freshwater macroinvertebrates along the Nigeria-Cameroon border enhance the conservation value of the lower Guinea forest biodiversity hotspot

In Nigeria and tropical Africa, the bias towards the protection of natural sites on account of terrestrial biodiversity or their resultant ecosystem services has led to a considerably low number of freshwater conservation studies in the region. To close this gap, six lotic freshwater systems in three different natural sites (Obudu Mountains, Agbokim Waterfalls, and Cross River National Park) along the Cameroon border of Nigeria were evaluated for the biodiversity of macroinvertebrates and some aspects of water quality in December 2021 and March 2022. Among other macroinvertebrate-related indices, the community conservation index (CCI), which considers the presence of threatened, rare, and notable species, was used for the conservation evaluation of the freshwater systems. The Ephemeroptera-Plecoptera-Trichoptera (EPT) species were notably rich at the sites, with over 12 species each at the Afundu Stream, Kwa River, Cataract Stream, and Agbokim River. All of the sites had a very high conservation value, according to the CCI, which was greater than 20. Some Obudu sites (Grotto and Becheve streams), despite having fewer EPT taxa, had higher CCI than the Kwa or Agbokim River. This was due to the presence of the endangered damselflies (Africocypha centripunctata and Allocnemis vicki) at the Obudu sites and a rare mayfly species in Nigeria (Tricorythus tinctus), which was reported at Agbokim and Kwa Rivers. The presence of a notable damselfly genus (Pentaphlebia) at the Afundu stream of the Obudu Mountains also raises some hope that the critically endangered damselfly (Pentaphlebia gamblesi), whose adult was last seen in 1973, could still be alive at the site. Canonical Correspondence Analysis revealed that the proportion of scrapers had a strong association with high BOD and EC in Agbokim River, while the Becheve and Grotto streams which had high vegetal cover was positively associated with shredders. Also, increasing DO in Afundu Stream, Kwa River and Cataract Stream was positively associated with EPT richness. This study revealed that more freshwater ecological studies need to be conducted at isolated natural sites and protected areas in Africa. Findings from such studies have implications for preserving freshwater ecosystems of high conservation value from the various threats that characterize the Anthropocene.

Land Use Influencing the Distribution of Pesticides in Surface Water: The Case of the Ma River and Its Tributaries in Thanh Hoa Province, Vietnam

Pesticide residues are regularly found in surface water, which could be dangerous for freshwater ecosystems and biodiversity. Pesticides may enter waters through a variety of pathways, but runoff from irrigation or precipitation has the highest quantities. Previous studies analyzing the pesticides pollution or ecological risks of pesticides focused on few regions (e.g., European and United States), whereas analysis of pesticide pollution in Southeast Asia and especially in Vietnam is limited. This study presents an investigation of banned pesticides used across the range of land use in catchments of the Ma river and its tributaries in Thanh Hoa province, Vietnam. Applying principal component analysis (PCA), we investigated the relationship between specific pesticides and land use. Besides, cluster analysis (CA), the method of aggregating monitoring locations, was applied in this study to find spatial pattern of pesticides pollution. Due to their persistence and remobilization during floods and runoff, all ten banned pesticides-eight insecticides (aldrin/dieldrin, BHC, chlordane, endrin, heptachlor, lindane, malathion, and parathion) and two herbicides (paraquat, and 2,4D)-still remain in surface water and are not presumably influenced by the fraction of land use area in the catchments. Clustering results revealed that banned pesticides still occur in some areas. Site TH08 close to Le Mon industrial zone and TH18 in Thanh Hoa city have higher concentrations of banned pesticides than other sites due to their highly toxic and long-time existence in the environment. Overall, our study provides approach to investigate pesticides in surface water for a province in Vietnam that may be used for future ecotoxicological studies to enhance risk assessment for stream ecosystems.

Survived the Glaciations, Will They Survive the Fish? Allochthonous Ichthyofauna and Alpine Endemic Newts: A Road Map for a Conservation Strategy

The Calabrian Alpine newt (Ichthyosaura alpestris inexpectata) is a glacial relict with small and extremely localised populations in the Catena Costiera (Calabria, Southern Italy) and is considered to be "Endangered" by the Italian IUCN assessment. Climate-induced habitat loss and recent fish introductions in three lakes of the Special Area of Conservation (SAC) Laghi di Fagnano threaten the subspecies' survival in the core of its restricted range. Considering these challenges, understanding the distribution and abundance of this newt is crucial. We surveyed the spatially clustered wetlands in the SAC and neighbouring areas. First, we provide the updated distribution of this subspecies, highlighting fish-invaded and fishless sites historically known to host Calabrian Alpine newt populations and two new breeding sites that have been recently colonised. Then, we provide a rough estimate of the abundance, body size and body condition of breeding adults and habitat characteristics in fish-invaded and fishless ponds. We did not detect Calabrian Alpine newts at two historically known sites now invaded by fish. Our results indicate a reduction in occupied sites and small-size populations. These observations highlight the need for future strategies, such as fish removal, the creation of alternative breeding habitats and captive breeding, to preserve this endemic taxon.

Impacts of wastewater treatment plants on benthic macroinvertebrate communities in summer and winter

Treated effluent from municipal wastewater treatment plants (WWTPs) is a major source of contamination that can impact population size, community structure, and biodiversity of aquatic organisms. However, because the majority of field research occurs during warmer periods of the year, the impacts of wastewater effluent on aquatic communities during winter has largely been neglected. In this study, we assessed the impacts of wastewater effluent on aquatic benthic macroinvertebrate (benthos) communities along the effluent gradients of two WWTPs discharging into Hamilton Harbour, Canada, during summer and winter using artificial substrates incubated for 8 weeks. At the larger of the two plants, benthic macroinvertebrate abundance was higher and diversity was lower at sites downstream of the outfall compared to upstream sites in both seasons. Whereas at the smaller plant, the opposite was observed, abundance increased and diversity decreased with distance from the outfall in both seasons. While the impacts of wastewater on benthic communities were largely similar between seasons, we did detect several general seasonal trends - family diversity of macroinvertebrates was lower during winter at both WWTPs and total abundance was also lower during winter, but only significantly so at the smaller WWTP. Further, benthic macroinvertebrate community composition differed significantly along the effluent gradients, with sites closest and farthest from the outfall being the most dissimilar. Our contrasting results between the WWTPs demonstrate that plants, with different treatment capabilities and effluent-receiving environments (industrial/urban versus wetland), can dictate how wastewater effluent impacts benthic macroinvertebrate communities.

The determinant factors for macroinvertebrate assemblages in a recreational river in Negeri Sembilan, Malaysia

The determinant factors for macroinvertebrate assemblages in river ecosystems are varied and are unique and specific to the type of macroinvertebrate family. This study aims to assess the determinant factors for macroinvertebrate assemblages in a recreational river. The study was conducted on the Ulu Bendul River, Negeri Sembilan, Malaysia. A total of ten sampling stations were selected. The research methodology included (1) water quality measurement, (2) habitat characterization, and (3) macroinvertebrate identification and distribution analysis. The statistical analysis used in this study was canonical correspondence analysis (CCA) to represent the relationship between the environmental factors and macroinvertebrate assemblages in the recreational river. This study found that most of the families of macroinvertebrates were very dependent on the temperature, DO, NH₃-N, type of riverbed, etc. All of these factors are important for the survival of the particular type of macroinvertebrate, plus they are also important for selecting egg-laying areas and providing suitable conditions for the larvae to grow. This study advises that improved landscape design for watershed management be implemented in order to enhance water quality and physical habitats, and hence the protection and recovery of the macroinvertebrate biodiversity.

Pond Acoustic Sampling Scheme: A draft protocol for rapid acoustic data collection in small waterbodies

Freshwater conservation is vital to the maintenance of global biodiversity. Ponds are a critical, yet often under-recognized, part of this, contributing to overall ecosystem functioning and diversity. They provide habitats for a range of aquatic, terrestrial, and amphibious life, often including rare and declining species.Effective, rapid, and accessible survey methods are needed to enable evidence-based conservation action, but freshwater taxa are often viewed as "difficult"-and few specialist surveyors are available. Datasets on ponds are therefore limited in their spatiotemporal coverage.With the advent of new recording technologies, acoustic survey methods are becoming increasingly available to researchers, citizen scientists, and conservation practitioners. They can be an effective and noninvasive approach for gathering data on target species, assemblages, and environmental variables. However, freshwater applications are lagging behind those in terrestrial and marine spheres, and as an emergent method, research studies have employed a multitude of different sampling protocols.We propose the Pond Acoustic Sampling Scheme (PASS), a simple protocol to allow a standardized minimal sample to be collected rapidly from small waterbodies, alongside environmental and methodological metadata. This sampling scheme can be incorporated into a variety of survey designs and is intended to allow access to a wide range of participants, without requiring complicated or prohibitively expensive equipment.Adoption of this sampling protocol would enable consistent sound recordings to be gathered by researchers and conservation organizations, and allow the development of landscape-scale surveys, data sharing, and collaboration within an expanding freshwater ecoacoustic community-rather than individual approaches that produce incompatible datasets. The compilation of standardized data would improve the prospects for effective research into the soundscapes of small waterbodies and aid freshwater conservation efforts.

Bioassessment of the ecological integrity of freshwater ecosystems using aquatic macroinvertebrates: the case of Sable Island National Park Reserve, Canada

Due to ubiquitous distribution of taxa, relatively low-cost and efficient sampling procedure, and known responses to environmental gradients, macroinvertebrate indicators are often a central component of biological monitoring of freshwater resources. This study examined establishing a baseline reference of benthic macroinvertebrate indicators in a biomonitoring approach as a means for monitoring the freshwater ponds of Sable Island National Park Reserve (SINPR), Canada. We compared water quality parameters monitored from 2015 to 2019 to a biomonitoring approach deployed in May, June, and August of 2019. A total of 27 taxa were recorded from the 30,226 specimens collected, with highest abundances of Corixidae, Amphipoda, Oligochaeta, and chironomid species Polypedilum bicrenatum. We found significant variability of community structure between different months of sampling (p = 0.001) and between ponds (p < 0.0001). A high correlation was found between dissolved organic carbon, sulfate, and the diversity of macroinvertebrate indicators, while conductivity, ammonia, and calcium were found to be correlated with species richness. While we found that water chemistry parameters exhibited spatial and temporal differences, the diversity of macroinvertebrate indicators is likely to be a more resilient metric for comparison between ponds. Further, our findings demonstrate that biomonitoring can be effective in systems with a low number of small, shallow, freshwater pond ecosystems. As our study deployed a high-resolution identification of biological indicators, we were able to establish a baseline reference for future monitoring as well as identify specific associations between pond water quality and biological assemblages that can be used as a context for the management of SINPR's freshwater resources. Continued monitoring of these ecosystems in future years will help to understand long-term environmental changes on the island.

Contribution of artificial waterbodies to biodiversity: A glass half empty or half full?

Artificial ponds are increasingly created for the services they provide to humans. While they have the potential to offer habitats for freshwater biodiversity, their contribution to regional diversity has hardly been quantified. In this study, we assess the relative contribution of five types of artificial ponds to regional biodiversity of five different regions, studying amphibians, water beetles and freshwater snails. This biodiversity is also compared with that observed in natural ponds from three of the investigated regions. Our results indicate that artificial ponds host, on average, about 50% of the regional pool of lentic species. When compared to natural ponds, the artificial ponds always supported a substantially lower alpha richness (54% of the natural pond richness). The invertebrate communities presented high values of beta diversity and were represented by a restricted set of widely distributed species, and by numerous rare species. There were discrepancies among the taxonomic groups: overall, amphibians benefited most from the presence of artificial ponds, since 65% of the regional lentic species pools for this group was found in artificial ponds, whereas 43% and 42% was observed in the case of beetles and snails, respectively. However, each invertebrate group was promptly the most benefited animal group in a single pond type. Therefore, artificial pond types were complementary among them in terms of contribution to regional diversity of the three animal groups. Based on these results, we forecast that future human-dominated landscapes in which most ponds are artificial will be particularly impoverished in terms of freshwater biodiversity, underlining the need to conserve existing natural ponds and to create new "near-natural" ponds. However, if properly designed and managed, artificial ponds could make a substantial contribution to support freshwater biodiversity at a regional scale. Furthermore, the number and diversity of artificial ponds must be high in each considered landscape.

Assessing the impact of the threatened crucian carp (Carassius carassius) on pond invertebrate diversity: A comparison of conventional and molecular tools

Fishes stocked for recreation and angling can damage freshwater habitats and negatively impact biodiversity. The pond-associated crucian carp (Carassius carassius) is rare across Europe and is stocked for conservation management in England, but its impacts on pond biota are understudied. Freshwater invertebrates contribute substantially to aquatic biodiversity, encompassing many rare and endemic species, but their small size and high abundance complicate their assessment. Practitioners have employed sweep-netting and kick-sampling with microscopy (morphotaxonomy), but specimen size/quality and experience can bias identification. DNA and environmental DNA (eDNA) metabarcoding offer alternative means of invertebrate assessment. We compared invertebrate diversity in ponds (N = 18) with and without crucian carp using morphotaxonomic identification, DNA metabarcoding and eDNA metabarcoding. Five 2 L water samples and 3 min sweep-net samples were collected at each pond. Inventories produced by morphotaxonomic identification of netted samples, DNA metabarcoding of bulk tissue samples and eDNA metabarcoding of water samples were compared. Alpha diversity was greatest with DNA or eDNA metabarcoding, depending on whether standard or unbiased methods were considered. DNA metabarcoding reflected morphotaxonomic identification, whereas eDNA metabarcoding produced markedly different communities. These complementary tools should be combined for comprehensive invertebrate assessment. Crucian carp presence minimally reduced alpha diversity in ponds, but positively influenced beta diversity through taxon turnover (i.e., ponds with crucian carp contained different invertebrates to fishless ponds). Crucian carp presence contributes to landscape-scale invertebrate diversity, supporting continued conservation management in England. Our results show that molecular tools can enhance freshwater invertebrate assessment and facilitate development of more accurate and ecologically effective pond management strategies.