Fish Habitat Research Articles

Application of telemetry-based fish habitat models to predict spatial habitat availability and inform ecological restoration.

Conservation decisions surrounding which fish habitats managers choose to protect and restore are informed by fish habitat models. As acoustic telemetry has allowed for improvements in our ability to directly measure fish positions year-round, so too have there been opportunities to refine and apply fish habitat models. In an area with considerable anthropogenic disturbance, Hamilton Harbour in the Laurentian Great Lakes, we used telemetry-based fish habitat models to identify key habitat variables, compare habitat associations among seasons, and spatially identify the presence distribution of six fish species. Using environmental data and telemetry-based presence-absence from 2016 to 2022, random forest models were developed for each species across seasons. Habitat variables with the highest relative importance across species included fetch, water depth, and percentage cover of submerged aquatic vegetation. The presence probability of each species was spatially predicted for each season within Hamilton Harbour. Generally, species showed a spatial range expansion with greater presence probability in the fall and winter to include parts of the harbor further offshore, and a range contraction in the spring and summer toward the nearshore, sheltered areas, with summer having the most limited habitat availability. Greater habitat suitability was predicted in western Hamilton Harbour for the majority of species, whereas the east end was less suitable and may benefit from habitat restoration. These types of fish habitat models are highly flexible and can be used with a variety of data, not just telemetry, and should be considered as an additional tool for fish habitat and fisheries managers alike.

Evaluation of fish habitat suitability based on stream hydrodynamics and water quality using SWAT and HEC-RAS linked simulation

The objective of this study was to evaluate fish habitat suitability by simulating hydrodynamic and water quality factors using SWAT and HEC-RAS linked simulation considering time-series analysis. A 2.9 km reach of the Bokha stream was selected for the habitat evaluation of Zacco platypus, with hydrodynamic and water quality simulations performed using the SWAT and HEC-RAS linked approach. Based on simulated 10-year data, the aquatic habitat was assessed using the weighted usable area (WUA), and minimum ecological streamflow was proposed from continuous above threshold (CAT) analysis. High water temperature was identified as the most influential habitat indicator, with its impact being particularly pronounced in shallow streamflow areas during hot summer seasons. The time-series analysis identified a 28% threshold of WUA/WUAmax, equivalent to a streamflow of 0.48 m3/s, as the minimum ecological streamflow necessary to mitigate the impact of rising water temperatures. The proposed habitat modeling method, linking watershed-stream models, could serve as a useful tool for ecological stream management.

Are restoration plans missing the target? Land tenure and cyclone risks reshuffles priorities for mangrove restoration

Coastal wetlands, vital for fisheries habitats, have suffered extensive losses. Ecosystem restoration offers opportunities to improve fish catch and restore the valuable services these ecosystems provide. Successful restoration is dependent on choosing a site where restoration is feasible, which encompasses biophysical, social, governance, logistical, and resource factors. However, factors that influence feasibility such as land tenure (governance feasibility) and future climate risks (biophysical feasibility) are often overlooked in quantitative analyses of site selection. We ask how spatial priorities for restoration change when considering how feasibility is affected by land tenure, cyclone risk, and both factors together. Specifically, we analyzed a case‐study of mangrove restoration to improve fish catch in Queensland, where there is interest in restoring coastal habitats to support fish habitats. We found that the rank order of planning units by restoration feasibility was highly influenced by both land tenure and cyclones, with cyclones changing ranks with clustered regions along the coastline and land tenure variably changing ranks throughout. In planning units where fisheries benefit is expected to be high, but cyclone risk substantially reduces restoration feasibility, practitioners could consider strategically planting mangroves near established mangrove forest and selecting resilient species for restoration. Formalizing regulations for incentives to private land holders and amending legislation for easier permitting are additional suggestions for addressing land tenure challenges. Our study emphasizes the importance of systematic approaches to considering feasibility in spatial planning for restoration to minimize the risk of failure.

Investigation of anchor ice evolution in rivers and the impact of hydrometeorological conditions

The evolution of anchor ice during river freeze-up is known to significantly influence sediment transport, fish habitats, and river hydrology during winter. It may also lead to the formation of anchor ice dams and the generation of anchor ice waves that can cause flooding. Many of the previous field studies of anchor ice focused on the conditions leading to its formation and release, its crystal structure and properties, and the evaluation of its impacts. However, direct measurements of the temporal variation of anchor ice in rivers are rare, which has limited our understanding of this important and dynamic ice form. In this study, six anchor ice events were measured on two Canadian rivers using an underwater camera system, accompanied by comprehensive measurements of weather and hydraulic data and frazil ice concentrations. The temporal evolution of anchor ice was observed to occur in one of three stages: growth, stable, or decay. The direction (i.e., upward or downward) and trend of the net air–water heat flux reliably indicated the timing of these three stages. Anchor ice growth in the majority of events was through a combination of frazil accretion and in-situ crystal growth, resulting in event-averaged growth rates from 0.48 to 1.77 cm/h. Anchor ice grew solely through frazil accretion when snowfall occurred, with event-averaged growth rates from 1.64 to 3.53 cm/h. Anchor ice decay occurred through the thermal thinning of accumulations at an average decay rate of −0.48 to −2.52 cm/h. Anchor ice release was controlled by thermal factors and always occurred after the end of supercooling. Frazil accretion rates were estimated using measurements of anchor ice growth rates and suspended frazil concentrations and ranged from 2.6 × 10−3 to 6.0 × 10−3 m/s.

Strategic Siting of Hydroelectric Power Plants to Power Railway Operations with Renewable Energy

The present study explores the strategic siting of hydroelectric power plants, focusing on the Miyanaka Intake Dam (MID) and Shinano River Hydroelectric Power Station (SHP). Built in 1939 to support Tokyo’s railway electrification, these facilities demonstrate the complexities of balancing renewable energy production with ecological conservation. Despite the high costs and energy losses associated with transmitting power from the Sea of Japan side, the SHP has effectively powered Tokyo’s rail system for over 80 years, owing to advanced transmission technologies and the region’s abundant water resources. However, river-crossing structures such as dams disrupt fish migration and habitats, necessitating the implementation of fishways. The MID fishway, continually improved since its construction, emphasizes the importance of integrating ecological considerations into hydropower projects. Our findings highlight the higher power generation efficiency on the Sea of Japan side and stress the need for careful site selection to ensure sustainable hydroelectric power while preserving river ecosystems. In conclusion, hydropower sites should be chosen based on both environmental impacts and future development potential to maintain the ecological balance and support long-term renewable energy goals.

Hydrological connectivity and environment characteristics explain spatial variation in fish assemblages in a wet–dry tropical river

AbstractHydrological connectivity in river systems facilitates the movement of animals across riverine landscapes and influences fish habitat but is threatened by climate change and water resource developments. We studied fish assemblages across a large wet–dry tropical river system in northern Australia that is under consideration for new agricultural and water resource developments, which are expected to alter hydrological connectivity. We explored relationships between the environment and several biotic variables; fish taxonomic composition, species turnover, and species trait presence, quantifying how they were related to hydrological connectivity. Environmental dissimilarity of sites was influenced by hydrological connectivity variables, including flow, elevation, and river distance. Environment characteristics and hydrological connectivity together were important predictors of fish taxonomic composition. Fish species turnover was highest in headwater sites, and species presence absence was related to feeding and reproductive traits. Our results suggest that habitat specialists and species with reproductive traits that depend on hydrological connectivity, such as diadromous species, are most vulnerable to declines in relative abundance following a reduction in connectivity, which would lead to range contractions within catchments. Maintaining habitats that support taxonomically and functionally unique fish assemblages, such as wetlands and headwater streams, is important for maintaining biodiversity.

Enrichment characteristics of microplastics in Antarctic benthic and pelagic fish and krill near the Antarctic Peninsula

Global microplastic pollution has garnered widespread attention from researchers both domestically and internationally. However, compared to other regions worldwide, little is known about microplastic pollution in the marine ecosystems of the Antarctic region. This study investigated the abundance and characteristics of microplastics (MPs) in the gills and intestines of 15 species of Antarctic fish and Antarctic krill (Euphausia superba). The results indicate that the abundance of MPs in Antarctic fish and E. superba ranged from 0.625 to 2.0 items/individual and 0.17 to 0.27 items/individual, with mean abundances of 0.93 ± 0.96 items/individual and 0.23 ± 0.44 items/individual, respectively. Antarctic fish ingested significantly more MPs than E. superba. There was no significant difference in the abundance of MPs between the gills and intestines of Antarctic fish. However, the quantity of pellet-shaped MPs in the gills was significantly higher than in the intestines. The depth of fish habitat influenced the quantity and size of MPs in their bodies, with benthic fish ingesting significantly fewer MPs than pelagic fish. Pelagic fish ingested significantly more MPs sized 1–5 mm than benthic fish. Additionally, analysis of the characteristics of MPs revealed that fiber-shaped MPs were predominant in shape, with sizes generally smaller than 0.25 mm and 0.25–0.5 mm. The predominant colors of MPs were transparent, red, and black, while the main materials were polypropylene (PP), polystyrene (PS), polyamide (PA), and polyvinyl chloride (PVC). Compared to organisms from other regions, the levels of MPs in Antarctic fish and E. superba were relatively low. This study contributes to a better understanding of the extent of MP pollution in Antarctic fish and E. superba, aiding human efforts to mitigate its impact on the environment.

Utility of artificial river reef structures to enhance fish habitat below a hydropeaking dam

Utility of artificial river reef structures to enhance fish habitat below a hydropeaking dam

Radiotelemetry reveals the dependence of inland tern breeding and foraging habitats on ADCP-identified sediment aggradation reaches in lowland rivers

The largest rivers in developed countries have usually been turned into waterways by straightening them and removing large bedforms hampering navigation. For river restoration and their sustainable management it is important to know how large bedforms support biodiversity, whether they could be protected and what potential conflicts in river management they can pose. We have addressed these questions by studying the role of large bedforms in supporting populations of two inland tern species Sternula albifrons and Sterna hirundo. We spatially analysed the behaviour of these two species with reference to the bedform structure mapped over a long semi-natural reach of the River Wisła (Vistula) (S. Poland). The results show that radiotagged terns breed on islands within the aggradation reaches, foraging in the adjacent shallows inhabited by populations of small fish. For Little Terns, the more complex the water line of emergent forms, the greater their foraging intensity. The islands do not pose any flood risk to human settlements. The whole geofeature forms an integral habitat for fish and birds; it is maintained by its geographic settings and so is stable over long periods of time (over 200 years). Protection of such habitats is thus feasible.

Evaluation of acoustic environmental effects and improvement method of ecological fish-nest bricks in the Yangtze River Basin: A model-based case study

With the rapid development of the Yangtze River Basin, the issue of underwater noise pollution has become increasingly severe, which has adversely affected aquatic creatures, particularly fish. Ecological fish-nest bricks (EFNBs), a new type of eco-friendly revetment, can provide a favorable habitat for fish. However, its effects on the acoustic environment remain unclear. The finite element numerical simulation method of acoustic-structure coupling is adopted to explore the acoustic environment of EFNBs, analyzing the impact of sound source frequency (within 300 Hz), structural forms, and arrangement of these bricks on the internal sound pressure level. The sound pressure level distribution of A-EFNBs were also analyzed at a distance of 0–0.5 m from the opening. A method of acoustic environment improvement is proposed, which utilizes porous polyurethane sponge (PPS) sound-absorbing material to establish a conducive acoustic environment for fish in EFNBs. The study results indicate that at low frequencies of sound source (f ≤ 150 Hz), the sound pressure level within EFNBs slightly decreases compared to the adjacent areas without EFNBs. The sound pressure level variation within the bricks increases with sound source frequency. The peak sound pressure increases with the number of openings. Interval arrangements can in general decrease sound pressure by less than 20 dB. At higher frequencies(f＞200 Hz), the sound pressure level at the opening of the A-EFNBs tends to increase. However, the PPS sound-absorbing material substantially reduces the sound pressure level by 15 –55 dB, rendering it an effective method for improving the acoustic environment for fish. The PPS sound-absorbing material is more suitable for habitat improvement of black carp (Mylopharyngodon piceus) and grass carp (Ctenopharyngodon idellus) with relatively low hearing thresholds among the four famous Chinese carps. The research findings can serve as a reference for designing and implementing river ecological restoration projects.

Individual mangrove trees provide alternative reef fish habitat on backreefs

Mangrove trees occur in a variety of geomorphic and sedimentary settings. Yet, studies investigating their role as habitat providers often focus on the most common biophysical types, such as deltaic, estuarine, open coast or lagoonal mangroves on soft sediments, disregarding less typical environments. Here, we investigated the influence of individual mangrove trees growing on a consolidated backreef system (Laucala Bay, Fiji) on habitat use by reef fishes. Combining field surveys and an experiment, we quantified the extent to which reef mangrove trees serve as habitat for solitary or shoaling reef fishes. Using mangrove tree mimics, we disentangled effects attributable to the physical structure of trees from those related to their bio-chemical properties. We found that fish numbers were 3.7 times higher within close proximity to the mangrove trees than at control sites and correlated significantly with root system perimeter. The roots of larger trees sheltered aggregations of juveniles and adults at incoming and high tides. Mangrove trees and mimics attracted fishes alike. We show that mangrove trees on backreefs provide habitat for shoaling and adult reef fishes in addition to serving as nursery areas, an ecosystem service otherwise lacking on backreef areas with low structural complexity.

Understanding the dynamics of fish spawning phenology and habitat in a changing ecosystem using a long-term ichthyoplankton monitoring dataset

As ecosystems change, understanding the consequences for fish population dynamics and habitat use is essential for resource management. Using white perch ( Morone americana) survey data on early life stages collected during a long-term ichthyoplankton monitoring program in the Hudson River (New York, USA), an ecosystem under immense pressure from climate change, ecological shifts, and anthropogenic activities, we evaluated the drivers of changes in egg abundance and spawning habitat between 1980 and 2017. Results indicated that egg abundance is associated nonlinearly with temperature, conductivity, discharge, depth, location, and the week of year. We also found that egg abundance has declined within the river over time. Additionally, shifts in hotspots of spawning activity were identified, including evidence that the lower extent of spawning habitat has moved upriver since 1980. This study indicates that the dynamics of white perch early life histories and spawning habitat are changing. It also highlights the utility of a long-term monitoring program for broadening our understanding of fish ecology in the age of big data in changing ecosystems.

Otolith microchemistry identifies shallow, intertidal-dominated estuaries as important nurseries for sand flounder in New Zealand

Estuaries provide critical habitat, food, and refuge for juvenile fish. Elemental concentrations in otoliths can retrospectively identify estuarine nursery habitats that contribute disproportionately to adult populations, providing valuable information for fisheries and coastal ecosystems. The present study aimed to (1) compare elemental signatures of juvenile (age 0+) sand flounder Rhombosolea plebeia otoliths collected from 9 estuaries in east Otago, New Zealand, and (2) assess the application of otolith microchemistry for identifying the nursery habitats contributing to adult (age 1+) sand flounder from the coastal shelf population. Otoliths from juvenile flounder were collected in November 2020, and adults of the same cohort were collected in the winter/spring of 2022. Laser ablation inductively coupled plasma mass spectrometry quantified 12 element concentrations within the post-settlement region of juvenile and adult otoliths using depth-profiling and ablation transects, respectively. Significant differences in post-settlement elemental concentrations were detected among estuaries. Juvenile and adult sand flounder were classified to their nursery origin using canonical analysis of principal coordinates. Grouping estuaries by the New Zealand Estuary Trophic Index classification scheme improved the overall juvenile classification accuracy from 56.7% (51/90) to 82.2% (74/90). Adult sand flounder (n = 78) were classified to have originated from shallow intertidal dominated estuaries (62%), followed by Otago Harbour (32%) and shallow, short residence time river and tidal river with adjoining lagoon estuaries (6%). The results highlight how otolith microchemistry can provide information on the use of critical estuarine nursery habitats for a commercially important species.

Modelling the distribution of fish habitat type and habitat diversity in natural rivers

Analyzing the spatial distribution and habitat diversity of river habitats not only helps us understand river ecology and guides effective management, but also informs efforts to create suitable habitats for fish and restore environmental diversity. Henceforth, we developed a Two-Dimensional Habitat Diversity Construction Model to predict and analyze the variation and spatial distribution of fish habitat types under the normal (for both dry and wet seasons) and flood flows (for different return periods). Shannon and Simpson Index, and Habitat Diversity Index (HDI) were used to assess the habitat diversity under normal and flood flow conditions. The simulation results showed that under normal flow, fish habitat distribution is along the channel while under flood flow it is more on the banks. Under average annual flow and high flow during the rainy season, 4.4 % and 20.51 % of water-covered areas, respectively, lack suitable habitats. For flood flows with return periods of 2 years and 100 years, 55.6 % and 73.36 % of water-covered areas do not support any habitat types. Regardless of the flow type, the model can reasonably evaluate the spatial distribution and habitat diversity of various habitat types in the river. Findings from this study will assist in conserving existing fish habitats, and in introducing missing/lacking habitats. In addition, it could provide a reference for creating ecological habitats for fish in rivers and restoring habitat diversity.

Year-round sampling of the fish community in a boreal lake: differences between summer and winter influence estimates of species composition, catch, and fish size.

Boreal lakes experience pronounced seasonal variation in abiotic factors, especially light, temperature, and oxygen. A deep boreal humic lake was sampled year-round to test putative changes in total fish catch, species composition, catch-per-unit-effort (CPUE), habitat use, fish size, and condition. Monthly sampling was conducted in Lake Pääjärvi, southern Finland, during one full year in 2020-2021 as well as in March and August 2021 and 2022. The fish community was dominated by cyprinid species in all months, but the percentage of percid fish caught increased during the warm summer period. Most fish were caught in littoral habitats and the highest catches occurred in summer, but some species (e.g., ruffe, Gymnocephalus cernua, and pikeperch, Sander lucioperca) remained abundant in the winter catch. The body size of fish was larger in the winter catch, while condition factor was higher in summer for most species. Fish species proportions in total catch, CPUE, and average size of fish were closest to the annual mean values in September, which may be used as the optimal period to monitor fish communities of similar deep boreal lakes. Our findings highlight the need for year-round research to reveal the impacts of rising temperatures and diminishing ice-covered periods in fish communities and lake food webs.

First Record of Snakehead Gudgeon (Ophiocara porocephala) in Sorong, West Papua, Indonesia

Aims: As reported this paper, the new record of O. porocephala has helped to improved the knowledge of the species as it extends the distribution range. Study Design: Short Communication. Place and Duration of Study: This research was conducted from September to November 2021. Sampling was carried out in the Tampa Garam mangrove forest swamp located in Tampa Garam Village, Maldum Mes Distric, Sorong City. Methodology: The morphology of fishes has been the primary source of information for taxonomic and evolutionary studies. There were numerous characters available for morphological study. Results: O. porocephala had a horizontally and terminally wide mouth with a large enough distance from the posterior area of ​​the eye. O. porocephala had ideal eye spacing with small eyelids and large corneas, two dorsal fins and an anal fin each with a distance of 1 and 22mm between the dorsal fins, the anterior dorsal consists of spines fins, while the posterior was weak fins. Fish habitat was found in mangrove areas or in estuarine areas with a salinity of 11 ppt, small fish lived in shallow areas while larger fish lived in deeper areas. The brightness of the air when the fish were isolated was 100%. Oxygen levels at 4 mg/l. O. Porocephala obtained during the study, consisting of gender is 1 female and unidenified. Meanwhile, the fish size in the class 10,9-225,39 cm and gonad weight is 2,62 of female fish with categorie gonad maturity is 3. Conclusion: Based on the results of research, fish that live in mangrove areas are carnivorous, with large fish species having a total length of 18,4 cm and small fish less than 10 cm, further research needs to be carryout base on the feed habit and maturity of this fish.

Anchor chains—A simple low‐cost device to assist passage of small‐bodied mass fish

AbstractAttention has been placed on a variety of barriers that hinder fish passage in modern times. The most prevalent fish barriers were culverts which have negatively impacted waterway connectivity and fish habitats. For small‐bodied mass fish, high barrel velocities and turbulence have reduced fish swimming performance because of their weak swimming capabilities. In the present study, physical testing was conducted under controlled flow conditions to assess the extent and magnitude of turbulence characteristics, secondary flow and low‐velocity zones in a 0.5‐m‐wide box culvert barrel. Two cases were investigated; a reference case consisting of a smooth rectangular channel and a low‐cost design solution to improve upstream fish migration consisting of a single galvanized anchor chain fitted within a smooth rectangular channel. The single anchor chain was positioned towards one corner of the channel to induce asymmetric flow, reducing overall energy losses and enhancing the existing low‐velocity zone in the adjacent channel corner. The anchor chain induced a strong turbulent flow motion away from the anchor chain, characterized by higher Reynolds stress and turbulent kinetic energy, along with a distinct channel flow asymmetry. Conversely, the low‐velocity zone, between the anchor chain and the bottom channel corner, was significantly expanded with reduced longitudinal mean velocities and turbulent scales. Whilst the anchor chain link contributed to some complex localized wake flow, the anchor chain also influenced the distributions of normal turbulent stresses (v'z2 – v'y2), which in turn influenced the location of secondary flow cells. This secondary flow redirected low momentum fluid into the low‐velocity zones, setting the conditions for the favorable upstream passage of small‐bodied mass fish species.

Spatiotemporal dynamics and forecasting of ecological security pattern under the consideration of protecting habitat: a case study of the Poyang Lake ecoregion

ABSTRACT The continuous expansion and development of anthropogenic activities pose considerable threats to the habitats of myriad species. Therefore, exploring how to protect and optimize species’ habitats to achieve harmony between humans and nature is particularly important. As a paradise for wildlife, Poyang Lake is the habitat and breeding ground for birds, fish, and other aquatic organisms. In this study, adopting a multi-level perspective of ‘point-line-area’, we had an appliance for habitat conservation by constructing an ecological security pattern (ESP) in the Poyang Lake Ecoregion (PYLE). We produced land use and land cover from 2000 to 2040 using the random forest and cellular automata-Markov model. Combining morphological spatial pattern analysis, landscape pattern index, and Linkage Mapper, we constructed a long-term ESP in the PYLE considering habitat protection. The spatiotemporal dynamics of ESP were compared and analyzed. The results show that PYLE's rapid economic development led to extensive urban growth, encroaching on surrounding bare land, which could undermine local species’ survival. Based on PYLE's predicted ESP in 2040, we propose an optimized ‘one area, two zones, and multiple points’ scheme to prioritize habitat protection. This comprehensive study provides innovative ideas and novel insights for future research and policy formulation in habitat protection.

Same streams in a different forest? Investigations of forest harvest legacies and future trajectories across 30 years of stream habitat monitoring on the Tongass National Forest, Alaska.

The effects of timber harvest practices and climate change have altered forest ecosystems in southeast Alaska. However, quantification of patterns and trends in stream habitats associated with these forests is limited owing to a paucity of data available in remote watersheds. Here, we analyzed a 30-year dataset from southeast Alaska's Tongass National Forest to understand how these factors shape stream habitats. First, we examined differences between broad management classes (i.e., harvested and non-harvested) that have been used to guide stream channel restoration goals. Second, we assessed associations between intrinsic landscape characteristics, watershed management, and timber harvest legacies on aquatic habitat metrics. And third, we examined trends in stream habitat metrics over the duration of the dataset to anticipate future management challenges for these systems. Small effect sizes for some harvest-related predictors suggest that some stream habitat metrics, such as pool densities, are less responsive than others, and management practices such as protecting riparian buffers as well as post-harvest restoration may help conserve fish habitats. Large wood densities increased with time since harvest at sites harvested >50 years ago, indicating that multiple decades of post-harvest forest regrowth may contribute large wood to streams (possibly alder), but that it is not enough time for old-growth trees (e.g., spruce, Picea, or hemlock, Tsuga,), classified as key wood, to develop and be delivered to streams. The declining trend in key wood (i.e., the largest size class of wood) regardless of management history may reflect that pre-harvest legacy old-growth trees are declining along streams, with low replacement. The introduction of wood to maintain complex stream habitats may fill this gap until riparian stands again contribute structural key wood to streams. Trend analyses indicate an increasing spatial extent of undercut banks that may also be influenced by shifting hydrologic regimes under climate change.

Climate change can disproportionately reduce habitats of stream fishes with restricted ranges in southern South America

Freshwater fishes are among the most threatened taxa worldwide owing to changes in land use, species introductions, and climate change. Although more than half of the freshwater fishes in the Chilean Mediterranean ecoregion are considered vulnerable or endangered, still little is known about their biogeography. Fishes of the family Perciliidae are endemic of this region and ideal cases to study potential implications of global warming given their endangered conservation status, small size, restricted range, and limited dispersal capacity in fragmented habitats. Here, we model the spatial distribution of habitats for Percilia irwini and P. gillissi under current (1970–2000) and future (2050–2080) climatic scenarios (SSP245, SSP585). We implement maximum entropy (MaxEnt) models adapted for stream networks using high-resolution datasets of selected geophysical and climatic variables. At present, both species inhabit relatively low-quality habitats. In the future (SSP585), suitable habitats for P. irwini are predicted to be reduced drastically (99%) with potential local extirpations in its northern range. Similarly, up to 62% of suitable habitats for P. gillissi would also be reduced in the future. Our study provides insights about assessing future threats and vulnerability of endemic, endangered, range-restricted, and small-bodied freshwater species in this region and elsewhere.