Abstract The theory of island biogeography was tested in Nicaraguan volcanic crater lakes, colonized by fish from the older and larger source Nicaraguan Great Lakes. Spearman correlations of ranked molecular phylogenetic diversity in the Midas cichlid species complex ( Amphilophus cf. citrinellus ) were significant ( p ≤ 0.05) or marginally significant (0.05 < p ≤ 0.10) with diversity with crater lake age in three of four data sets tested. Correlations were noted with deepwater area, the product of littoral area and age, and with the product of horizontal and vertical barriers between the crater lakes and the nearest source lakes divided by the product of littoral area and age. By treating the Midas cichlid species complex as a single taxon, ranked fish taxon richness in each lake correlated significantly with lake age, littoral area, and with the product of age and littoral area. These results support the concept that littoral area and lake age may be factors in the colonization of volcanic crater lakes from the source lakes, and the amount of deep water in a lake as well as lake age may be important factors in speciation in the Midas cichlid species complex. Seven species from the crater lakes have been classified as Critically Endangered by the IUCN.

Abstract It is a great importance of finding the cost-effective strategy of treating chromite ore processing residue (COPR). Cr(Ⅵ), presented in aqueous media, could easily be reduced, adsorption and removed from water body through a proper treatment, but Cr(Ⅵ), incorporated in COPR, could not, due to its characteristic inherent to COPR. In general, the reduction and adsorption of Cr(Ⅵ) could take place at a low pH, the COPR, however, has a high acid neutralizing capacity, so that a great deal of the inorganic acid would be required to maintain its pH at low value. In this work, a series of treatment trials, comprised of the production of chromate from COPR by leaching process, the subsequent detoxification and in-situ stabilisation of post-leached COPR (plCOPR) were conducted. After column extracting process using the seawater, Cr(Ⅵ)-containing leachate of 600~800 mg/L is led to the ion exchange columns, charged with the anion exchange resin, to adsorb the Cr(Ⅵ) until the effluent contains Cr(Ⅵ) of 5 mg/L. The Cr(Ⅵ) loaded ion exchange column was eluted by NaOH solution and the maximum concentration of Cr(Ⅵ) in the elution was 43.1 g/L. Afterward, plCOPR was mixed with sodium sulfide and iron sulfide+lime as a reductant and a stabiliser, respectively, and the mixture was discharged directly from the mixer and piled on a certain area. After 360 d of curing, Cr(VI) concentration in the leachate from the toxicity characteristic leaching procedure (TCLP) was arrived at 1.2 mg/L, below the regulatory limit disposal standard (HJ/T 301-2007, 3 mg/L).

Abstract Macrophytes are key components of aquatic ecosystems including wetlands that have considerable ecological importance. The role of macrophytes is closely linked to their structural attributes like species composition and abundance. Therefore, this study aimed to assess macrophyte species composition, abundance and diversity of six hydrogeologically connected wetlands in the upper Abbay River basin, Ethiopia. The studied wetlands (Gudera, Geray, Zindib, Kurt Bahir, Infranz and Wonjeta) are found in west Gojjam administrative zone, Amhara region, Ethiopia. Two cross-sectional surveys were conducted at the end of September 2021 and February 2022. Quadrat sampling technique was employed to collect macrophyte samples following protocols for sampling aquatic macrophytes in freshwater wetlands. A total of 41 species of macrophytes belonging to 16 families were identified across the wetlands. The wetlands were dominated by emergent macrophytes, with the Poaceae and Cyperaceae families being particularly abundant. The physicochemical water quality status, water level fluctuations and level of human interventions might be the reason for the variation in the macrophytes composition, abundance and diversity across the wetlands. The low macrophyte diversity index value and the presence of pollution-tolerant taxa such as Pistia stratiotes and Azolla africana indicate an overall ecological degradation of the wetlands. Therefore, this study highlights the potential role of macrophyte monitoring to identify anthropogenic pollution. Application of appropriate land use planning and the development of macrophyte based multimetric indices are recommended for their sustainable management.

Abstract Forests are essential not only for their ecological roles but also as invaluable natural resources supporting biodiversity, climate regulation, and human livelihoods. In Mediterranean regions, pine-tree forests are particularly susceptible to intense wildfires, which pose significant challenges to containment and long-term forest health. This study focuses on the pine-tree forests of North Euboea, examining their embedded energy, natural regenerative capacity, and sustainable management approaches. Key aspects investigated include the forest’s contributions to biomass and resin productivity, the social and economic impacts of wildfire events, and the role of managed grazing as a proactive tool in fire prevention and forest stewardship. Our analysis highlights the potential benefits of grazing as a strategic measure to manage forest biomass levels, thereby reducing the fuel load and lowering the intensity of possible future fires. Grazing is also shown to support broader access across the forest landscape, allowing firefighting forces to respond more effectively in case of a fire outbreak. By utilizing grazing to maintain forest ecosystems beyond just the periphery, this approach can enhance both ecological resilience and community cohesion in regions vulnerable to forest fires. The study underscores the need for integrated management practices that balance forest use with conservation, leveraging grazing as a means to sustain the health and accessibility of Mediterranean pine-tree forests.

Abstract Natural resource conservation is vital for maintaining ecosystems that support biodiversity, regulate climate, and provide essential resources for human well-being. As ecosystems face growing pressures from deforestation, pollution, and climate change, remote sensing has become a key tool for monitoring and protecting these environments. Through satellite imagery, LiDAR, and aerial photography, remote sensing offers detailed insights into land cover changes, habitat degradation, and forest health, enabling data-driven conservation strategies. Mangroves play a crucial role in natural resource conservation by protecting coastlines from erosion, reducing the impacts of storms, and providing habitat for diverse marine species. They also act as significant carbon sinks, helping to mitigate climate change while supporting fisheries and local livelihoods. Specifically, for mangroves, remote sensing plays a critical role in assessing ecosystem health, species composition, and disturbances like illegal logging and coastal erosion, supporting effective conservation and restoration efforts to ensure their sustainability. The study of mangroves in the Gulf of Khambhat, Gujarat, emphasizes the critical role of mangrove ecosystems in biodiversity conservation, coastal protection. Leveraging remote sensing techniques such as microwave (ALOS PALSAR-2-L band with 25 m resolution) and optical (multi-spectral) (Sentinel-2 MSI with 10m resolution), the research integrates the mangrove and non-mangrove delineation, change detection to offer insights into natural resource conservation of mangroves and Above Ground Biomass (AGB) estimation. In this study the area of mangroves obtained is 94.94 km 2 from L-band SAR data (25 m resolution and 2020), 98.55 km 2 from Optical data (10m resolution and 2020) while the Forest Survey of India Report (2021) illustrate 101.53 km 2 mangrove area at Gulf of Khambhat, India. The accuracy of the area of mangroves obtained from remote sensing is 93.50 % from L-band SAR) and 97.06 % from Optical data (Sentinel-2 MSI) with respect to area reported in Forest Survey of India Report (2021). These results are crucial for loss and recovery monitoring of mangrove forest, to enable targeted conservation efforts. This study offers a comprehensive approach to conserving natural resources by enhancing the accuracy of biomass mapping and ecosystem monitoring, ensuring effective conservation strategies for the biodiversity-rich mangrove regions of the Gulf of Khambhat.

Abstract Mudskippers are amphibious fishes that can voluntarily leave the water and spend a considerable amount of time on the mudflats and are considered to have high ecological value in the mudflat environment. The present study was conducted in Cox’s Bazar coast to identify the mudskipper species. This study also points out the challenges in the field and provides possible recommendations. The mudskippers were collected from Rezu Khal, Inani, Patuartek, Imamer Dail, Monkhali, Shaplapur, Naf Jetty, Keari Ghat, and Shaporir Dwip during December 2023 to February 2024 by using cast net, thela jhal, scoop net and hand picking. Most of the samples were collected during low tide. A total of 15 mudskippers were recorded in this study and most of the species belong to the genus Periophthalmus (8 species) followed by Boleophthalmus (2 species), Periophthalmodon (2 species), Pseudapocryptes (1 species), Parapocryptes (1 species), and Apocryptodon (1 species). Boleophthalmus boddarti was found commonly distributed in all the stations, which is considered edible by a few coastal people and the Rohingya community. The size of this species is considerably bigger than the other recorded species and it can be farmed. Further, an extensive survey is needed to be undertaken in the other parts of Bangladesh coast to document more species and identify the species richness. It can be a possible component of the blue economy.