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Article

Identification of Critical and Tolerable Fish Habitat Requirements Based on Pre- and Post-Typhoon Data

by
Hung-Pin Chiu
,
Jian-Ping Suen
* and
Pin-Han Chen
Department of Hydraulic and Ocean Engineering, National Cheng Kung University, No. 1 University Road, Tainan 701, Taiwan
*
Author to whom correspondence should be addressed.
Water 2025, 17(3), 425; https://doi.org/10.3390/w17030425
Submission received: 25 December 2024 / Revised: 25 January 2025 / Accepted: 28 January 2025 / Published: 3 February 2025
(This article belongs to the Section Biodiversity and Functionality of Aquatic Ecosystems)
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Abstract

:
Catastrophic typhoons with heavy rainfall introduce massive flow and fine sediments into stream channels. In addition, the natural disturbances and engineering practices afterward may strongly alter the fish abundance and their environment. This study compared physical habitat parameters and fish abundance before and after two major typhoons using two sampling period datasets (November 2008–March 2009 and May 2011–March 2012). The study area was in the Cishan Stream, a tributary of the Gaoping River in southern Taiwan. This area experienced two strong typhoons (Morakot and Fanapi) between the two sampling periods, providing an opportunity to compare pre- and post-typhoon conditions. The collected species were Hemimyzon formosanus, Rhinogobius nantaiensis, Onychostoma alticorpus, Candidia barbata, Acrossocheilus paradoxus, and Spinibarbus hollandi. Our results show a decrease in substrate size, fish size, and fish weight after typhoons. The river channel transformed into an unstable condition after the heavy rains, as major habitat types in our sampling stations changed from riffles with coarse substrate to runs with fine substrate. The results of statistical tests indicate the different habitat requirements of three major fish species (H. formosanus, R. nantaiensis, and O. alticorpus) and can indicate whether species’ requirements change between the two sampling periods. Water depth and pebbles were critical habitat requirements for the adults of H. formosanus; water depth, pebbles, and sand were critical habitat requirements for the adults of R. nantaiensis; and flow velocity and standard deviation of flow velocity were critical requirements for the juveniles of O. alticorpus. Understanding habitat requirements can provide useful information for post-disaster restoration and contribute to eco-sensitive river engineering.

1. Introduction

Streams are subject to natural disturbances, such as floods and droughts, which are important elements in structuring stream communities [1,2,3,4]. Although these disturbances can differ in their degrees of influence, they significantly affect fish abundance and their habitats [3,4,5,6,7,8,9,10,11,12]. During droughts, reduced water levels can result in habitat fragmentation and a decrease in usable area. This can cause fish communities to leave preferred habitats and search for refuge habitat [13]. Severe drought may cause fish kills in intermittent streams due to reduced stream area [14,15]. Floods, which are caused by rains and typhoons, can affect fish behavior [16], fish assemblage structure [17], and fish abundance [18]. Swanson et al. [9] pointed out that geomorphology, riparian vegetation, and instream organisms would be negatively affected by typhoons and floods in a forested mountain stream. However, floods can also provide some positive effects on fish. Lojkásek et al. [19] found that the abundance of brown trout increased after floods because the composition of sediments affected the survival rate of spawned eggs after floods. These positive and negative influences are mainly based on the intensity of floods and their time of occurrence (pre- or post-spawning) [1,19,20].
The variation of many environmental factors directly or indirectly affects fish communities [21]. These factors include physical characteristics (e.g., velocity, depth, and substrate types) and chemical characteristics (e.g., dissolved oxygen, pH, and conductivity) of the river environment. However, for some species, a number of studies have demonstrated that some criteria of environmental factors may keep in a specific range, but others could vary in different environments [22,23,24]. Some fish species may strongly prefer some critical environmental factors, and some fish species accept some highly varied environmental factors.
Taiwan is located within the monsoon zone. Summer weather in Taiwan generally lasts from May to September. The influence of monsoons can be intense and occur over relatively short temporal scales compared to trade winds. Taiwan also experiences many tropical depressions and typhoons during the summer, which can lead to large amounts of rainfall, which results in increased flow and high sediment delivery. Additionally, human demands are continually increasing; therefore, landscapes are constantly changing. This can cause further disturbance of hillside soil that has already been weakened. It is noted that the frequency of disturbances such as landslides, debris flows, and floods after typhoons and rainfall events has increased since the Chi-Chi Earthquake in 1999. In recent years, Taiwan has experienced several typhoons that have caused floods, landslides, or debris flows that disturbed instream organism habitat and reduced fish abundance [4,7,10,12,25,26,27,28,29,30].
Recent efforts in Taiwan have strived to establish a positive relationship between humans and their environment, and this has included a focus on ecosystem recovery after natural or man-made disturbances. Many researchers have acknowledged the relationship between biology and habitat, including habitat diversity at different scales [31,32], the habitat suitability index of fish [33,34,35,36], and the relationships between hierarchical spatial frameworks and habitat [37,38,39]. However, less is known about the relationships between severe habitat modification and the preferred habitat for fish after typhoons.
The aims of this study were (1) to compare the differences in fish assemblage and microhabitat before and after typhoons, (2) explore the influences of different habitat requirements for the adults and juveniles of dominant fish species, and (3) apply habitat requirements to restoration and ecological engineering.

2. Materials and Methods

2.1. Area of Study

The study area is located in the upper part of the Cishan Stream, a major tributary of the Gaoping River, the largest river in southern Taiwan. Cishan Stream originates from Yushan Mountain at an altitude of 2700 m, and it flows through the Namaxia, Jiaxian, Shanlin, and Cishan Districts. Then, it converges with the Laonong Stream to form the Gaoping River. Generally, the study section is in a rural natural channel with fewer human modifications.
In August 2009, Typhoon Morakot brought more than 2500 mm of rain in three days [40]. The 24, 48, and 72 h durations of precipitation were estimated to exceed 2000-year recurrence frequencies. Furthermore, Typhoon Fanapi hit this area in September 2010. Both typhoons greatly affected river environments and resulted in impacts on most fish-suitable habitat areas.
Two stations were chosen for this study (Figure 1). The first, at Min-Chuan Bridge, included habitat types such as pools, riffles, glides, and runs before Typhoon Morakot [39]. The substrates were predominately boulders and cobble, and the fish species that lived there were mainly Hemimyzon formosanum, Onychostom alticorpus, Rhinogobius nantaiensis, Acrossocheilus paradoxus, and Candidia barbata. After typhoons, the range of substrate size broadened from gravels to boulders (Figure 2).
The habitat types at the second site, Holly Mt. Zion, were similar to that of Min-Chuan Bridge before Typhoon Morakot, and included pools, riffles, glides, and runs [39]; the substrates were dominated by cobble and pebbles. Fish assemblages included the same species as the first site. After typhoons, the dominant substrate ranged from sand to cobble (Figure 3).

2.2. Indicator Species

Each fish species has a preferred microhabitat which may include considerations of substrate, depth, and velocity [41,42,43,44]. This study focused on the habitat requirements of adults and juveniles H. formosanus, R. nantaiensis, and O. alticorpus before and after typhoons. These species were selected because they were the most abundant in the area.

2.2.1. H. formosanus

H. formosanus is a fish species native to the western and northern parts of Taiwan. It lives mainly in the midstream and upstream portions of the river. The environments where the H. formosanus was found were characterized by a high flow velocity, coarse substrate (pebbles and cobble) [45,46,47], and high dissolved oxygen. This study defines a standard length above 4.5 cm as adult fish and below 4.0 cm as juvenile fish [39,48].

2.2.2. R. nantaiensis

R. nantaiensis is a native fish species that lives mainly in the Zengwun and Gaoping Rivers. Its preferred habitat is shallow water with coarse substrates (gravel and pebbles) [46]. This study defines a standard length above 4.6 cm as adult fish and below 4.5 cm as juvenile fish [49].

2.2.3. O. alticorpus

O. alticorpus is a native species. Its preferred habitat is characterized by a high flow and boulders [45]. A standard length above 20.0 cm is adult fish and below 20.0 cm is juvenile fish [50].

2.3. Fish Sampling

Pre-typhoon data were collected from November 2008 to March 2009. Post-typhoon data were collected in May, July, and December 2011 and in January, February, and March 2012. All post-typhoon data were collected after Typhoon Fanapi. In total, 104 and 126 grids were sampled using PAEDs (prepositioned areal electrofishing devices) [51] before and after typhoons, respectively. This study used the electrofishing devices with two 1 m sticks which frame a rectangular electrode with dimensions of 1 m × 1 m. After the placement of the electrofishing devices, the sample grids were not disturbed for at least eleven minutes [52]. After this acclimation time, the electrodes were charged for one minute, and the samplers used dip-nets to collect immobilized fish downstream of the rectangular electrode frames. The caught fish were identified, and their standard length and wet weight were recorded. Then, they were released to their original collection location. Before conducting this study, permission was obtained from the local community and the Agriculture and Marine Bureau of the Kaohsiung City Government.

2.4. Habitat Survey

Habitat survey data included water temperature, flow velocity (at 60% depth), water depth, substrate, pH, electrical conductivity (EC), salinity, dissolved oxygen (DO), and turbidity for each sample grid. The water depth and flow velocity were surveyed at nine points that they evenly chose in each sample grid, and then the average of the nine values was used to represent the water depth and flow velocity of the sample grid. A 1 m × 1 m plastic frame was used to determine the percentage of substrate composition by surface-visual method [53]. This frame was marked with one hundred grid cells, with each cell’s substrate size categorized as sand (<2 mm), gravel (2–64 mm), pebbles (64–256 mm), cobble (256–512 mm), and boulders (>512 mm).

2.5. Statistical Analyses and Habitat Requirement Types

Different species and life stages of fishes have different specific habitat requirements [21,54,55,56]. After extreme environmental changes, if fishes are still present in some specific range of habitat environments for some environmental factors, these factors are critical to them. Otherwise, some environmental factors may be tolerable to them because fishes can adjust themselves to the new habitat environment. Therefore, this study used the independent-sample t-test and Pearson’s correlation to denote critical and tolerable habitat requirements for adult and juvenile fish. Critical habitat requirements were defined as environmental factors that were similar between before and after typhoons. Because of the similarity of environmental factors, these environmental factors were critical habitat requirements that fish still can inhabit in the habitat after typhoons. Tolerable habitat requirements were considered environmental factors for which fish can tolerate some variation. First, each environmental factor was analyzed using an independent-sample t-test comparing the habitat use of fish species before and after typhoons. If this test detected a non-significant difference in fish habitat (i.e., p ≥ 0.05), then the factor was considered a critical habitat requirement. If it showed a significant difference (i.e., p < 0.05), these environmental factors that combined fish abundance were analyzed using Pearson’s correlation to determine tolerable habitat requirements. Two types of tolerable habitat requirements are defined in this study. A non-significant Pearson’s correlation (p ≥ 0.05) indicated neither positive nor negative correlation between fish abundance and environmental factors. If this was the case, then both periods (before and after typhoons) showed that the correlations between fish abundance and environmental factors were not significant. We interpreted this to mean that fish did not significantly correlate with this environmental factor in both periods as the first type of tolerable habitat environment. Furthermore, if there was a positive correlation before typhoons and no correlation after typhoons, it meant the fish changed from preferred to no correlation to this factor. The fish can be tolerant to the environmental changes. This environmental factor was considered as the second type of a tolerable habitat requirement. On the other hand, if there was a negative correlation before typhoons and no correlation after typhoons, it meant the fish changed from non-preferred to no correlation to this factor. We do not think it was a tolerable habitat requirement.

3. Results

3.1. Fish Data

Sampling efforts collected 1242 and 543 individuals before and after typhoons, respectively. H. formosanus, R. nantaiensis, and O. alticorpus were the dominant fish species in the study area, and they were captured with a total of 1101, 281, and 271 individuals, respectively. The most abundant fish species was H. formosanus, whose average standard lengths before and after typhoons were 4.7 cm and 3.8 cm at Min-Chuan Bridge, respectively; the average standard lengths before and after typhoons were 3.8 cm and 3.6 cm at Holly Mt. Zion, respectively; the average wet weights before and after typhoons were 2.3 g and 1.1 g at Min-Chuan Bridge, respectively; and the average wet weights before and after typhoons were both 1.1 g at Holly Mt. Zion (Table 1). The second abundant fish species was R. nantaiensis, whose average standard lengths before and after typhoons were 4.5 cm and 3.2 cm at Min-Chuan Bridge, respectively; the average standard lengths before and after typhoons were 4.6 cm and 3.5 cm at Holly Mt. Zion, respectively; the average wet weights before and after typhoons were 2.0 g and 1.0 g at Min-Chuan Bridge, respectively; and the average wet weights before and after typhoons were 2.4 g and 1.3 g at Holly Mt. Zion, respectively (Table 1). The third abundant fish species was O. alticorpus, whose average standard lengths before and after typhoons was 12.5 cm and 4.5 cm at Min-Chuan Bridge, respectively; the average standard lengths before and after typhoons were 6.3 cm and 5.7 cm at Holly Mt. Zion, respectively; the average wet weights before and after typhoons were 74.1 g and 3.6 g at Min-Chuan Bridge, respectively; the average wet weights before and after typhoons were 34.7 g and 5.6 g at Holly Mt. Zion, respectively (Table 1). A. paradoxus, C. barbata, and Spinibarbus hollandi were also collected in the study area, but the abundance of these species was too low, so they were omitted from further analyses (Table 1). All fish species are native to Taiwan.

3.2. Environmental Factors

Field efforts surveyed 104 microhabitat grids before the typhoons (62 at Min-Chuan Bridge and 42 at Holly Mt. Zion) and 126 grids after the typhoons (65 at Min-Chuan Bridge and 61 at Holly Mt. Zion). Each microhabitat was characterized by water temperature, water quality (EC, turbidity, salinity, DO, and pH), flow velocity, water depth, and substrate composition. Water temperature, EC, turbidity, sand, and gravel at both stations after typhoons were higher than before typhoons (Table 2). DO, pH, flow velocity, standard deviation of velocity, water depth, standard deviation of water depth, cobbles and boulders at both stations after typhoons were lower than before typhoons (Table 2). Salinity had no difference at both stations before and after typhoons (Table 2). Pebbles at Min-Chuan Bridge after typhoons were higher than before typhoons, but the result of pebbles was reversed at Holly Mt. Zion (Table 2).

3.3. Difference in Fish Habitat Environment

The difference in environmental factors comparing use before and after typhoons was displayed in Table 3, Table 4 and Table 5 for three dominant fish species. All of these environmental factors had significant difference for adults of H. formosanus before and after typhoons, with the exception of water depth and pebbles (Table 3). Water depth, sand, and pebbles had non-significant difference for the adults of R. nantaiensis before and after typhoons (Table 4). The results showed that only the mean and variability of flow velocity had non-significant difference for the juveniles of O. alticorpus before and after typhoons (Table 5). All of these environmental factors had significant difference for the juveniles of H. formosanus and R. nantaiensis before and after typhoons (Table 3 and Table 4). Consequently, most environmental factors resulted in great changes for three dominant fish species after typhoons.

3.4. Fish Abundance and Habitat Environments

Pearson’s correlation was used to analyze the correlations between fish abundance and environmental factors during pre- and post-typhoon periods. All correlations (r) and significance levels (p) are showed in Table 6, Table 7 and Table 8. During both periods, EC, the standard deviation of water depth, sand, and boulders had no correlations with the adults of H. formosanus, and turbidity, standard deviation of flow velocity gravel, and cobble had no correlations with the juvenile of H. formosanus (Table 6). Only DO had a positive correlation with the adults of H. formosanus before typhoons and no correlation after typhoons (Table 6). EC, turbidity, standard deviation of flow velocity, gravel, and cobble had no correlations with adults and juveniles of R. nantaiensis at both periods (Table 7). Furthermore, sand and boulders also had no correlations with the juvenile of R. nantaiensis at both periods (Table 7). Only flow velocity had a positive correlation with adults of R. nantaiensis before typhoons and no correlation after typhoons (Table 8). Only pebbles had a positive correlation with juvenile of H. formosanus and R. nantaiensis before typhoons and no correlation after typhoons (Table 6 and Table 7). All of these environmental factors had no correlations with the juvenile of O. alticorpus during both periods, with the exception of water depth, standard deviation of water depth, and boulders, which had positive correlations before typhoons and no correlations after typhoons (Table 8).

4. Discussion

4.1. Fish

Typhoons caused landslides and debris flow that decreased fish populations [10]. The abundance of H. formosanus and O. alticorpus decreased after typhoons (Table 1). Additionally, the length and weight of R. nantaiensis and O. alticorpus decreased at both stations after typhoons. The habitat types in the study area had been transformed into shallow riffles or runs by channel dredging and following-up sediment accumulation after typhoons [45]. H. formosanus preferred shallow water, which was expected to provide them with better refuge and food sources [34,46]. However, debris flow and landslides caused serious fatality of the fish species [4,10,12,28,29]. The abundance of R. nantaiensis slightly increased at both stations after typhoons, but the length and wet weight of R. nantaiensis decreased at the two stations (Table 1). Typhoon Morakot was a serious disturbance to the environments, so the habitats and organisms (fish and invertebrates) perhaps had not fully recovered in Cishan Stream. Fish fauna recovered to a pre-typhoon condition 14 months after Typhoon Herb in Cishan Stream [12], but the disturbance of Typhoon Morakot was greater than the disturbance of Typhoon Herb. R. nantaiensis prefers the substrate composition of gravel and pebbles [46]. In this study, the substrate environment almost changed from boulders and cobble to pebbles, gravel, and sand at both stations after typhoons (Table 2), making them more suitable for R. nantaiensis. In contrast, O. alticorpus prefers boulders [45], so their numbers have decreased due to the environmental change caused by typhoons. Finally, fewer adults of O. alticorpus were found in the study area.

4.2. Microhabitat

Stream habitats were destroyed by debris flow and landslides caused by typhoons [12]. Water temperature was higher after typhoons than before typhoons (Table 2). This was because the pre-typhoon samples were concentrated during the winter and spring when air temperatures were cooler. After typhoons, EC and turbidity were higher than before typhoons (Table 2) because riverbanks had been weakened, allowing for soil and sands to be eroded into the river. Furthermore, the upstream segments of the river were still undergoing construction to repair typhoon damage. This could further contribute to the increased turbidity and EC values. DO was lower after typhoons (Table 2) because the majority of the macrophytes, algae, and microorganisms were covered by the amount of sediments, decreasing the oxygen content [25]. Salinity and pH were the only characteristics that showed little difference before and after typhoons.
After typhoons, dredging was used in the stream to form a deep and narrow straightened main channel based on human safety and local structure. However, the channel after dredging resulted in the homogenization of stream habitats that affect habitat availability for aquatic organisms [57]. The results show that the mean flow velocity and mean water depth were generally higher before typhoons, with the exception of mean flow velocity at Min-Chuan Bridge (Table 2). Furthermore, the standard deviation of flow velocity and water depth were both higher before typhoons. It indicates that the flow velocity and water depth were more diverse before typhoons than after typhoons. Diverse habitat environments had a positive correlation with biodiversity [45,58,59].

4.3. Critical Habitat Requirements

Critical habitat requirements try to show that these environmental factors were critical to fish in survival after serious disturbances. They need to be kept similar no matter how the stream habitat environment has been changed. Water depth and pebbles were not significantly different before and after typhoons (Table 3). This illustrates that water depth and pebbles were critical to the survival of adults of H. formosanus after typhoons. Therefore, water depth and pebbles were critical habitat requirements for the adults of H. formosanus. In contrast, all factors were significantly different for the juveniles of H. formosanus, meaning that no factors were critical habitat requirements (Table 3). Sand, water depth, and pebbles were not significantly different for the adults of R. nantaiensis, so water depth, sand, and pebbles were critical to the adults of R. nantaiensis in survival after typhoons (Table 4). The result for the juveniles of R. nantaiensis was the same as for H. formosanus, meaning that there were no factors that were critical habitat requirements (Table 4). Chiu and Suen [45] used principal component analysis to examine the relationships between four fish species and thirteen environmental factors in the Cishan Stream, and they found that H. formosanus and R. nantaiensis had a noticeable correlation to water depth. Furthermore, H. formosanus preferred pebbles [45,46], and R. nantaiensis preferred pebbles and cobbles but avoided boulders [46]. Consequently, it is important to maintain water depth and substrate types for the adults of H. formosanus and R. nantaiensis after serious disturbances.
Flow velocity and the standard deviation of flow velocity were not significantly different for the juveniles of O. alticorpus (Table 5) before and after typhoons. Lyu and Suen [39] confirmed that O. alticorpus can adapt to less than 1.05 m/s when considering all life stages. In this study, the flow velocities were 0.57 m/s and 0.48 m/s before and after typhoons, respectively. Consequently, the flow velocity and variability of flow velocity were critical habitat requirements for the juveniles of O. alticorpus.

4.4. Tolerable Habitat Requirements

Tolerable habitat requirements describe environmental factors for which fish can tolerate some variation. EC, turbidity, DO, standard deviation of water depth, sand, and boulders were tolerable habitat requirements for the adults of H. formosanus. Before typhoons, the adults of H. formosanus preferred a habitat with a high DO, but they did not exhibit any preference after typhoons (Table 6). The higher turbidity could lead to a decline in plankton [60], which produced low oxygen content [25]. However, the adults of H. formosanus reflected no correlation with DO after typhoons (Table 6). This suggests that this variation could be tolerable for the adults of H. formosanus. EC, the standard deviation of water depth, sand, and boulders were significantly different for the adults of H. formosanus (Table 3). However, the adults of H. formosanus reflected no correlation with EC, the standard deviation of water depth, sand, and boulders during pre-typhoon and post-typhoon periods, respectively (Table 6). Consequently, the variation in EC, standard deviation of water depth, sand, and boulders could be tolerable ranges for the adults of H. formosanus.
Tolerable habitat requirements, which include turbidity, the standard deviation of flow velocity, gravel, pebbles, and cobble for the juveniles of H. formosanus, were different from the requirements for adults. Although turbidity and the standard deviation of flow velocity had great changes after typhoons (Table 3), they did not affect fish preference before and after typhoons (Table 6). Before typhoons, the juveniles of H. formosanus preferred habitats with pebbles; there is no similar preference for the substrate composition of pebbles after typhoons (Table 6). This suggests that the juveniles of H. formosanus could tolerate such variations. H. formosanus avoids sandy substrate [46], so the variation of gravel and pebbles could be tolerable ranges for the juveniles of H. formosanus in this study.
EC, turbidity, flow velocity, standard deviation of flow velocity, gravel, and cobble were tolerable habitat requirements for adults of R. nantaiensis. After typhoons, EC, turbidity, and gravel increase greatly, and the standard deviation of flow velocity and cobble decrease (Table 4). However, all of these factors had no correlations with the adults of R. nantaiensis before and after typhoons, respectively (Table 7). Flow velocity has no correlation after typhoons, but it had a positive correlation before typhoons (Table 7). R. nantaiensis preferred higher velocity [46], but adults could be tolerable variations of flow velocity after typhoons.
All factors were tolerable habitat requirements for the juveniles of R. nantaiensis except DO, flow velocity, water depth, and standard deviation of water depth. All of these factors showed marked change after typhoons (Table 4), but they did not affect the preference of for juveniles (Table 7). R. nantaiensis preferred shallow water [45,46], but juveniles of R. nantaiensis had a negative correlation with water depth in this study after typhoons (Table 7). Juvenile fish had a limited swimming ability and range of motion [61,62], so they perhaps avoided too-low water depth to be predated. The abundance of juveniles after typhoons (n = 139) was more than that before typhoons (n = 60) based on sampling data. This suggests that the juveniles had a high tolerance for EC, turbidity, standard deviation of flow velocity, and substrates.
All factors were tolerable habitat requirements for the juveniles of O. alticorpus. EC, turbidity, DO, sand, gravel, pebbles, and cobbles do not have significant correlations with the juveniles of O. alticorpus before and after typhoons, respectively (Table 8). This illustrates that these environmental factors do not affect the fish assemblage during both periods. The water depth, standard deviation of water depth, and boulders had positive correlations before but no correlations after typhoons. This suggests that these environmental factors positively affect fish assemblage before typhoons and do not do so after typhoons. O. alticorpus preferred deep water [45,46], and this study observed similar findings for the juveniles of O. alticorpus before typhoons. However, although the juveniles had no correlation with water depth after typhoons, they can seemingly adapt to water depth. In this study, the range of water depth is mainly between 30 cm and 40 cm, which proves that juveniles can still adapt to such depths. Juveniles can tolerate the changes in substrates because they can adapt to diverse substrates [39].

4.5. Applications of Habitat Requirements for Restoration and Ecological Engineering

Habitat changes indeed affect fish assemblages after typhoons [12], but different environmental factors have different influences. Therefore, an important goal of this study was to provide this information for restoration. The definition of critical and tolerable habitat requirements can help in understanding critical environments and tolerable variability for juveniles and adults. When considering critical habitat requirements, a water depth of 33.16–35.03 cm and substrate with 23.90–32.60% pebbles were critical ranges for the adults of H. formosanus in survival; a water depth of 22.73–29.62 cm, substrate with 1.50–7.70% sand, and 32.30–46.90% pebbles were critical ranges for the adults of R. nantaiensis in survival; and a water velocity of 0.48–0.57 m/s with a standard deviation of 0.22–0.25 were critical ranges for the juveniles of O. alticorpus in survival (Table 9). This is valuable information for restoration design. Also, different life stages of different species may have different tolerable habitat requirements. This is especially relevant to the juveniles of O. alticorpus, which is more tolerable of habitat than any other species (Table 6, Table 7 and Table 8). However, the tolerance of O. alticorpus is still questionable because no adults were caught in this study. Overall, the application of this information to habitat suitability indices or consideration of tolerable habitat ranges in future restoration projects could allow for a better reflection of organisms’ needs.
In summary, this study compares environmental factors and fish assemblage before and after typhoons by exploring the habitat requirements of three dominant species, H. formosanus, R. nantaiensis, and O. alticorpus. Salinity and pH showed few changes, but electrical conductivity, turbidity, dissolved oxygen, water velocity, the standard deviation of water velocity, water depth, standard deviation of water depth, and substrate all showed notable changes after typhoons. The abundance of two dominant species (H. formosanus and O. alticorpus) decreased after typhoons, likely because of the increase in finer particles (sand and gravel) after typhoons. The standard length and wet weight of the collected fish also decreased after typhoons, except for the H. formosanus. Water depth and pebble substrate were critical habitat requirements for the adults of H. formosanus, making these two important factors for the restoration of the species. Water depth, sand, and pebbles were important factors for the adults of R. nantaiensis, while low flow velocity and variability of flow velocity were important factors for the juveniles of O. alticorpus. This critical and tolerable habitat requirement information could provide preferable ranges of environmental factors for restoration to create more suitable habitat environments for aquatic organisms. Our study shows how fish communities change after storms and identifies critical factors that influence fish distribution. It would be very important from a management standpoint to try to minimize impacts from floods and carefully restore streams with some nature-based solutions so that they can provide more suitable habitats for fish.

Author Contributions

Conceptualization, H.-P.C., J.-P.S. and P.-H.C.; methodology, H.-P.C., J.-P.S. and P.-H.C.; software, H.-P.C. and P.-H.C.; validation, H.-P.C. and J.-P.S.; formal analysis, H.-P.C. and P.-H.C.; investigation, H.-P.C., J.-P.S. and P.-H.C.; resources, H.-P.C., J.-P.S. and P.-H.C.; data curation, H.-P.C. and P.-H.C.; writing—original draft preparation, H.-P.C. and P.-H.C.; writing—review and editing, J.-P.S.; visualization, J.-P.S.; supervision, J.-P.S.; project administration, J.-P.S.; funding acquisition, J.-P.S. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the National Science and Technology Council, Taiwan, grant number NSC 102-2221-E-006-246-MY3.

Data Availability Statement

Data are available upon request.

Acknowledgments

The authors gratefully acknowledge the support for this research provided in part by the National Science Council, Taiwan, under grant number NSC 102-2221-E-006-246-MY3. We also thank Pey-Yi Lee’s comments and suggestions, and the field assistance of NCKU Ecological Water Resources Management Lab members. Electrofishing was approved by the Agriculture Council, Taiwan, and fish handling followed the regulation of the animal care and ethics committee.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Fritz, K.M.; Tripe, J.A.; Guy, C.S. Recovery of Three Fish Species to Flood and Seasonal Drying in a Tallgrass Prairie Stream. Trans. Kans. Acad. Sci. 2002, 105, 209–218. [Google Scholar] [CrossRef]
  2. Poff, N.L.; Ward, J.V. Implications of Streamflow Variability and Predictability for Lotic Community Structure: A Regional Analysis of Streamflow Patterns. Can. J. Fish. Aquat. Sci. 1989, 46, 1805–1818. [Google Scholar] [CrossRef]
  3. Resh, V.H.; Brown, A.V.; Covich, A.P.; Gurtz, M.E.; Li, H.W.; Minshall, G.W.; Reice, S.R.; Sheldon, A.L.; Wallace, J.B.; Wissmar, R. The Role of Disturbance in Stream Ecology. J. N. Am. Benthol. Soc. 1988, 7, 433–455. [Google Scholar] [CrossRef]
  4. Roghair, C.N.; Dolloff, C.A.; Underwood, M.K. Response of a Brook Trout Population and Instream Habitat to a Catastrophic Flood and Debris Flow. Trans. Am. Fish. Soc. 2002, 131, 718–730. [Google Scholar] [CrossRef]
  5. Carline, R.F.; McCullough, B.J. Effects of Floods on Brook Trout Populations in the Monongahela National Forest, West Virginia. Trans. Am. Fish. Soc. 2003, 132, 1014–1020. [Google Scholar] [CrossRef]
  6. Chuang, L.C.; Shieh, B.S.; Liu, C.C.; Lin, Y.S.; Liang, S.H. Effects of Typhoon Disturbance on the Abundances of Two Mid-Water Fish Species in a Mountain Stream of Northern Taiwan. Zool. Stud. 2008, 47, 564–573. [Google Scholar]
  7. Han, C.C.; Tew, K.S.; Fang, L.S. Spatial and Temporal Variations of Two Cyprinids in a Subtropical Mountain Reserve—A Result of Habitat Disturbance. Ecol. Freshw. Fish 2007, 16, 395–403. [Google Scholar] [CrossRef]
  8. Matthews, W.J. Fish Faunal Structure in an Ozark Stream: Stability, Persistence and Catastrophic Flood. Copeia 1986, 1986, 388–397. [Google Scholar] [CrossRef]
  9. Swanson, F.J.; Johnson, S.L.; Gregory, S.V.; Acker, S.A. Flood Disturbance in a Forested Mountain Landscape: Interactions of Land Use and Floods. BioScience 1998, 48, 681–689. [Google Scholar] [CrossRef]
  10. Sato, T. Dramatic Decline in Population Abundance of Salvelinus leucomaenis after a Severe Flood and Debris Flow in a High Gradient Stream. J. Fish Biol. 2006, 69, 1849–1854. [Google Scholar] [CrossRef]
  11. Suen, J.P.; Eheart, J.W.; Herricks, E.E.; Chang, F.J. Evaluating the Potential Impact of Reservoir Operation on Fish Communities. J. Water Resour. Plan. Manag. 2009, 135, 475–483. [Google Scholar] [CrossRef]
  12. Tew, K.S.; Han, C.C.; Chou, W.R.; Fang, L.S. Habitat and Fish Fauna Structure in a Subtropical Mountain Stream in Taiwan before and after a Catastrophic Typhoon. Environ. Biol. Fish. 2002, 65, 457–462. [Google Scholar]
  13. Davey, A.J.H.; Kelly, D.J.; Biggs, B.J.F. Refuge-Use Strategies of Stream Fishes in Response to Extreme Low Flows. J. Fish Biol. 2006, 69, 1047–1059. [Google Scholar] [CrossRef]
  14. Arthington, A.H.; Olden, J.D.; Balcombe, S.R.; Thoms, M.C. Multi-Scale Environmental Factors Explain Fish Losses and Refuge Quality in Drying Waterholes of Cooper Creek, an Australian Arid-zone River. Mar. Freshwater Res. 2010, 61, 842–856. [Google Scholar] [CrossRef]
  15. Davey, A.J.H.; Kelly, D.J. Fish Community Responses to Drying Disturbances in an Intermittent Stream: A Landscape Perspective. Freshw. Biol. 2007, 52, 1719–1733. [Google Scholar] [CrossRef]
  16. Fitzsimons, M.J.; Nishimoto, R.T. Use of Fish Behavior in Assessing the Effects of Hurricane Iniki on the Hawaiian Island of Kaua’i. Environ. Biol. Fish. 1995, 43, 39–50. [Google Scholar] [CrossRef]
  17. Power, M.E.; Matthews, W.J.; Stewart, A.J. Grazing Minnows, Piscivorous Bass and Stream Algae: Dynamics of a Strong Interaction. Ecology 1985, 66, 1448–1456. [Google Scholar] [CrossRef]
  18. Collins, J.P.; Young, C.; Howell, J.; Minckley, W.L. Impact of Flooding in a Sonoran Desert Stream, Including Elimination of an Endangered Fish Population (Poeciliopsis o. occidentalis, Poeciliidae). Southwest. Nat. 1981, 26, 415–423. [Google Scholar] [CrossRef]
  19. Lojkásek, B.; Lusk, S.; Halačka, K.; Lusková, V.; Drozd, P. The Impact of the Extreme Floods in July 1997 on the Ichthyocenosis of the Oder Catchment Area (Czech Republic). Hydrobiologia 2005, 548, 11–22. [Google Scholar] [CrossRef]
  20. Jowett, I.G.; Richardson, J. Effects of a Severe Flood on Instream Habitat and Trout Populations in Seven New Zealand Rivers. N. Z. J. Mar. Freshw. Res. 1989, 23, 11–17. [Google Scholar] [CrossRef]
  21. Moyle, P.B.; Vondracek, B. Persistence and Structure of the Fish Assemblage in a Small California Stream. Ecology 1985, 66, 1–13. [Google Scholar] [CrossRef]
  22. Freeman, M.C.; Bowen, Z.H.; Crance, J.H. Transferability of Habitat Suitability Criteria for Fishes in Warmwater Streams. N. Am. J. Fish. Manag 1997, 17, 20–31. [Google Scholar] [CrossRef]
  23. Glozier, N.E.; Culp, J.M.; Scrimgeour, G.J. Transferability of Habitat Suitability Curves for a Benthic Minnow, Rhinichthys cataractae. J. Freshw. Ecol. 1997, 12, 379–393. [Google Scholar] [CrossRef]
  24. Thomas, J.A.; Bovee, K.D. Application and Testing of a Procedure to Evaluate Transferability of Habitat Suitability Criteria. Regul. Rivers Res. Manage. 1993, 8, 285–294. [Google Scholar] [CrossRef]
  25. Abujanra, F.; Agostinho, A.A.; Hahn, N.S. Effects of the Flood Regime on the Body Condition of Fish of Different Trophic Guilds in the Upper Paraná River Floodplain, Brazil. Braz. J. Biol. 2009, 69, 469–479. [Google Scholar] [CrossRef]
  26. Burkholder, J.; Eggleston, D.; Glasgow, H.; Brownie, C.; Reed, R.; Janowitz, G.; Posey, M.; Melia, G.; Kinder, C.; Corbett, R.; et al. Comparative Impacts of Two Major Hurricane Seasons on the Neuse River and western Pamlico Sound Ecosystems. Proc. Natl. Acad. Sci. USA 2004, 101, 9291–9296. [Google Scholar] [CrossRef]
  27. Cheal, A.; Coleman, G.; Delean, S.; Miller, I.; Osborne, K.; Sweatman, H. Responses of Coral and Fish Assemblages to a Severe But Short-Lived Tropical Cyclone on the Great Barrier Reef, Australia. Coral Reefs 2002, 21, 131–142. [Google Scholar] [CrossRef]
  28. Cover, M.R.; de la Fuente, J.A.; Resh, V.H. Catastrophic Disturbances in Headwater Streams: The Long-Term Ecological Effects of Debris Flows and Debris Floods in the Klamath Mountains, Northern California. Can. J. Fish. Aquat. Sci. 2010, 67, 1596–1610. [Google Scholar] [CrossRef]
  29. Lamberti, G.A.; Gregory, S.V.; Ashkenas, L.R.; Wildman, R.C.; Moore, K.M. Stream Ecosystem Recovery Following a Catastrophic Debris Flow. Can. J. Fish. Aquat. Sci. 1991, 48, 196–208. [Google Scholar] [CrossRef]
  30. Paerl, H.W.; Bales, J.D.; Ausley, L.W.; Buzzelli, C.P.; Crowder, L.B.; Eby, L.A.; Fear, J.M.; Go, M.; Peierls, B.L.; Richardson, T.L.; et al. Ecosystem Impacts of Three Sequential Hurricanes (Dennis, Floyd and Irene) on the United States’ Largest Lagoonal Estuary, Pamlico Sound, NC. Proc. Natl Acad. Sci. USA 2001, 98, 5655–5660. [Google Scholar] [CrossRef]
  31. Newson, M.D.; Harper, D.M.; Padmore, C.L.; Kemp, J.L.; Vogel, B. A Cost-Effective Approach for Linking Habitats, Flow Types and Species Requirements. Aquat. Conserv. Mar. Freshw. Ecosyst. 1998, 8, 431–446. [Google Scholar] [CrossRef]
  32. Schwartz, J.S.; Herricks, E.E. Fish Use of Ecohydraulic-Based Mesohabitat Units in a Low-Gradient Illinois Stream: Implications for Stream Restoration. Aquat. Conserv. Mar. Freshw. Ecosyst. 2008, 18, 852–866. [Google Scholar] [CrossRef]
  33. Linduska, J.P. Bottom Type as a Factor Influencing the Local Distribution of Mayfly Nymphs. Can. Entomol. 1942, 74, 26–30. [Google Scholar] [CrossRef]
  34. Lee, P.Y.; Suen, J.P. Comparing Habitat Suitability Indices (HSIs) Based on Abundance and Occurrence Data. N. Am. J. Fish. Manag. 2013, 33, 89–96. [Google Scholar] [CrossRef]
  35. Lee, P.Y.; Suen, J.P. Dependency and Independency among Fish Density and Electivity Indices in a Stream Fish Assemblage. Environ. Biol. Fish. 2014, 97, 111–119. [Google Scholar] [CrossRef]
  36. Raleigh, R.F.; Zuckerman, L.D.; Nelson, P.C. Habitat Suitability Index Models and Instream Flow Suitability Curves: Brown Trout; Biological Report 82(10.124); U.S. Fish and Wildlife Service: Washington, DC, USA, 1986. [Google Scholar]
  37. Frissell, C.A.; Liss, W.J.; Warren, C.E.; Hurley, M.D. A Hierarchical Framework for Stream Habitat Classification: Viewing Streams in a Watershed Context. Environ. Manag. 1986, 10, 199–214. [Google Scholar] [CrossRef]
  38. Harvey, G.L.; Clifford, N.J.; Gurnell, A.M. Towards an Ecologically Meaningful classification of the Flow Biotope for River Inventory, Rehabilitation, Design and Aappraisal Purposes. J. Environ. Manag. 2008, 88, 638–650. [Google Scholar] [CrossRef]
  39. Lyu, Y.S.; Suen, J.P. Relationship between Fish Habitat Diversity and Hierarchical Spatial Framework and Its Application in River Restoration. TW J. Biodivers. 2010, 12, 43–60. [Google Scholar]
  40. Teng, T.Y.; Huang, J.C.; Lee, T.Y.; Chen, Y.C.; Jan, M.Y.; Liu, C.C. Investigating Sediment Dynamics in a Landslide-Dominated Catchment by Modeling Landslide Area and Fluvial Sediment Export. Water 2020, 12, 2907. [Google Scholar] [CrossRef]
  41. Hazelton, P.D.; Grossman, G.D. Turbidity, Velocity and Interspecific Interactions Affect Foraging Behaviour of Study Rosyside Dace (Clinostomus funduloides) and Yellowfin Shinners (Notropis lutippinis). Ecol. Freshw. Fish 2009, 18, 427–436. [Google Scholar] [CrossRef]
  42. Kanno, Y.; Schmidt, C.U.; Cook, S.B.; Mattingly, H.T. Variation in Microhabitat Use of the Threatened Spotfin Chub (Erimonax monachus) among Stream Sites and Seasons. Ecol. Freshw. Fish 2012, 21, 363–374. [Google Scholar] [CrossRef]
  43. Labonne, J.; Allouche, S.; Gaudin, P. Use of a Generalized Linear Model to Test Habitat Preferences: The Example of Zingel Asper, an Endemic Endangered Percid of the River Rhône. Freshw. Biol. 2003, 48, 687–697. [Google Scholar] [CrossRef]
  44. Midway, S.R.; Kwak, T.J.; Aday, D.D. Habitat Suitability of the Carolina Madtom, an Imperiled, Endemic Stream Fish. Trans. Am. Fish. Soc. 2010, 139, 325–338. [Google Scholar] [CrossRef]
  45. Chiu, H.P.; Suen, J.P. The Importance of Providing Multiple-Channel Sections in Dredging Activities to Improve Fish Habitat Environments. Water 2016, 8, 36. [Google Scholar] [CrossRef]
  46. Lee, P.Y.; Suen, J.P. Niche Partitioning of Fish Assemblages in a Mountain Stream with Frequent Natural Disturbances—An Examination of Microhabitat in Riffle Areas. Ecol. Freshw. Fish 2012, 21, 255–265. [Google Scholar] [CrossRef]
  47. Lu, Y.S.; Suen, J.P. Intraspecific and Interspecific Variations in Habitat Usage by Hemimyzon formosanus and Sinogastromyzon nantaiensis in Riffle Areas of a Mountain Stream. Water 2023, 15, 3959. [Google Scholar] [CrossRef]
  48. Chen, I.S.; Fang, L.S. The Freshwater and Estuarine Fishes of Taiwan; National Museum of Marine Biology and Aquarium: Pingtung County, Taiwan, 1999. [Google Scholar]
  49. He, D.J.; Li, S.H.; Lin, R.S.; Yu, S.L.; Jhuang, M.D.; Jhou, W.J. A Study of Biotic Indicators and Habitat Suitability Curves; Water Resources Planning Institute, Water Resources Agency, Ministry of Economic Affairs: Taichung City, Taiwan, 2012. [Google Scholar]
  50. Fang, L.S.; Han, C.C.; Chen, I.S. The Biology of an Endangered and Endemic Cyprinid, Varicorhinus alticorpus of Taiwan; National Museum of Marine Biology and Aquarium: Kaohsiung City, Taiwan, 1995. [Google Scholar]
  51. Schwartz, J.S.; Herricks, E.E. Use of Prepositioned Areal Electrofishing Devices with Rod Electrodes in Small Streams. N. Am. J. Fish. Manag. 2004, 24, 1330–1340. [Google Scholar] [CrossRef]
  52. Bain, M.B.; Finn, J.T.; Booke, H.E. A Quantitative Method for Sampling Riverine Microhabitats by Electrofishing. N. Am. J. Fish. Manag. 1985, 5, 489–493. [Google Scholar] [CrossRef]
  53. Platts, W.S.; Megahan, W.F.; Minshall, G.W. Methods for Evaluating Stream, Riparian, and Biotic Conditions; US Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station: Ogden, UT, USA, 1983. [Google Scholar]
  54. Koster, W.J. Some Phases of the Life History and Relationships of the Cyprinid, Clinostomus elongatus (Kirtland). Copeia 1939, 1939, 201–208. [Google Scholar] [CrossRef]
  55. McKee, P.M.; Parker, B.J. The Distribution, Biology, and Status of the Fishes Campostoma anomalum, Clinostomus elongatus, Notropis photogenis (Cyprinidae), and Fundulus notatus (Cyprinodontidae) in Canada. Can. J. Zool. 1982, 60, 1347–1358. [Google Scholar] [CrossRef]
  56. Van Liefferinge, C.; Seeuws, P.; Meire, P.; Verheyen, R.F. Microhabitat Use and Preferences of the Endangered Cottus gobio in the River Voer, Belgium. J. Fish Biol. 2005, 67, 897–909. [Google Scholar] [CrossRef]
  57. Gualdoni, C.M.; Boccolini, M.F.; Oberto, A.M.; Principe, R.E.; Raffaini, G.B.; del Carmen Corigliano, M. Potential Habitats versus Functional Habitats in a Lowland Braided River (Córdoba, Argentina). Ann. Limnol. Int. J. Lim. 2009, 45, 69–78. [Google Scholar] [CrossRef]
  58. Castella, E.; Richardot-Coulet, M.; Roux, C.; Richoux, P. Aquatic Macroinvertebrate Assemblages of Two Contrasting Floodplains: The Rhǒne and Ain rivers, France. Regul. Rivers Res. Manag. 1991, 6, 289–300. [Google Scholar] [CrossRef]
  59. Obrdlik, P.; Garcia-Lozano, L.C. Spatio-Temporal Distribution of Macrozoobenthos Abundance in the Upper Rhine Alluvial Floodplain. Arch. Hydrobiol. 1992, 124, 205–224. [Google Scholar] [CrossRef]
  60. Kasangaki, A.; Chapman, L.J.; Balirwa, J. Land Use and the Ecology of Benthic Macroinvertebrate Assemblages of High-Altitude Rainforest Streams in Uganda. Freshw. Biol. 2008, 53, 681–697. [Google Scholar] [CrossRef]
  61. Wieser, W. Developmental and Metabolic Constraints of the Scope for Activity in Young Rainbow Trout (Salmo gairdneri). J. Exp. Biol. 1985, 118, 133–142. [Google Scholar] [CrossRef]
  62. Wolter, C.; Arlinghaus, R. Navigation Impacts on Freshwater Fish Assemblages: The Ecological Relevance of Swimming Performance. Rev. Fish Biol. Fish. 2003, 13, 63–89. [Google Scholar] [CrossRef]
Water 17 00425 g001
Figure 1. The surveyed stations in Cishan Stream.
Figure 1. The surveyed stations in Cishan Stream.
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Figure 2. The physical habitat (a) before and (b) after typhoons at the Min-Chuan Bridge.
Figure 2. The physical habitat (a) before and (b) after typhoons at the Min-Chuan Bridge.
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Figure 3. The physical habitat (a) before and (b) after typhoons at Holly Mt. Zion.
Figure 3. The physical habitat (a) before and (b) after typhoons at Holly Mt. Zion.
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Table 1. Abundance, mean standard length (cm), and weight (g) for each species before and after typhoons.
Table 1. Abundance, mean standard length (cm), and weight (g) for each species before and after typhoons.
StationSpeciesAbundanceStandard Length (cm)Weight (g)
BeforeAfterBeforeAfterBeforeAfter
Min-Chuan BridgeA. paradoxus20106.43.513.41.7
C. barbata475.24.53.12.2
S. hollandi010.05.90.03.6
O. alticorpus1402312.54.574.13.6
H. formosanus3841774.73.82.31.1
R. nantaiensis57784.53.22.01.0
Holly Mt. ZionA. paradoxus5593.44.31.32.7
C. barbata2032.53.20.41.3
S. hollandi020.023.80.0277.5
O. alticorpus10266.35.734.75.6
H. formosanus3891513.83.61.01.0
R. nantaiensis71754.63.52.41.3
Table 2. Environmental factors of stations before and after typhoons. All values are the means. SD is the standard deviation.
Table 2. Environmental factors of stations before and after typhoons. All values are the means. SD is the standard deviation.
Environmental FactorMin-Chuan BridgeHolly Mt. Zion
BeforeAfterBeforeAfter
Water temperature (°C)18.5621.1320.0423.17
EC (μS/cm)331.49428.12359.33442.99
Turbidity (NTU)1.3846.783.57103.91
Salinity (ppt)0.20.20.20.2
DO (mg/L)9.298.418.957.96
pH8.148.128.088.07
Flow velocity (m/s)0.790.770.720.46
SD of flow velocity (m/s)0.320.240.250.16
Water depth (cm)37.9232.6736.7528.37
SD of water depth (cm)12.495.969.936.79
Sand (<2 mm)1%10%4%14%
Gravel (2–64 mm)5%42%7%37%
Pebbles (64–256 mm)20%30%53%25%
Cobble (256–512 mm)37%12%19%15%
Boulders (>512 mm)37%6%17%9%
Table 3. The mean of each environmental factor before and after typhoons for H. formosanus. SD is the standard deviation. Numbers in bold mean that the factor is a critical habitat requirement factor.
Table 3. The mean of each environmental factor before and after typhoons for H. formosanus. SD is the standard deviation. Numbers in bold mean that the factor is a critical habitat requirement factor.
Environmental FactorAdultJuvenile
MeanpMeanp
BeforeAfterBeforeAfter
EC (μS/cm)339.9446.10.00352.2412.60.00
Turbidity (NTU)1.5531.360.002.1580.000.00
DO (mg/L)9.398.160.009.028.540.00
Flow velocity (m/s)0.950.840.010.930.800.00
SD of flow velocity (m/s)0.350.270.000.310.230.00
Water depth (cm)33.1635.030.4631.0327.550.00
SD of water depth (cm)12.137.010.009.485.110.00
Sand (%)1.03.60.011.43.10.00
Gravel (%)3.434.30.004.841.90.00
Pebbles (%)23.932.60.0652.633.30.00
Cobble (%)37.119.40.0026.315.60.00
Boulders (%)34.59.70.0014.86.10.00
Table 4. The mean of each environmental factor before and after typhoons for R. nantaiensis. SD is the standard deviation. Numbers in bold mean that the factor is a critical habitat requirement factor.
Table 4. The mean of each environmental factor before and after typhoons for R. nantaiensis. SD is the standard deviation. Numbers in bold mean that the factor is a critical habitat requirement factor.
Environmental FactorAdultJuvenile
MeanpMeanp
BeforeAfterBeforeAfter
EC (μS/cm)345.6454.70.00337.8432.80.00
Turbidity (NTU)2.7984.710.002.9975.710.00
DO (mg/L)8.997.540.008.738.130.00
Flow velocity (m/s)0.850.490.000.800.520.00
SD of flow velocity (m/s)0.290.180.000.290.200.00
Water depth (cm)29.6222.730.0533.4226.290.00
SD of water depth (cm)8.826.150.029.366.510.00
Sand (%)1.57.70.071.817.10.00
Gravel (%)5.746.90.006.136.40.00
Pebbles (%)46.932.30.1544.926.70.00
Cobble (%)27.76.60.0027.59.60.00
Boulders (%)18.36.40.0219.710.20.02
Table 5. The mean of each environmental factor before and after typhoons for O. alticorpus. SD is the standard deviation. Numbers in bold mean that the factor is a critical habitat requirement factor.
Table 5. The mean of each environmental factor before and after typhoons for O. alticorpus. SD is the standard deviation. Numbers in bold mean that the factor is a critical habitat requirement factor.
Environmental FactorJuvenile
Meanp
BeforeAfter
EC (μS/cm)348.71443.200.00
Turbidity (NTU)2.2481.440.00
DO (mg/L)9.118.150.00
Flow velocity (m/s)0.570.480.10
SD of flow velocity (m/s)0.220.250.42
Water depth (cm)47.4932.760.00
SD of water depth (cm)13.326.150.00
Sand (%)3.318.70.00
Gravel (%)8.851.00.00
Pebbles (%)25.415.50.02
Cobble (%)24.110.90.01
Boulders (%)38.43.90.00
Table 6. Correlations between fish abundance and environmental factors before and after typhoons for H. formosanus. * = significantly different at p < 0.05 level; ** = significantly different at p < 0.01 level. SD is the standard deviation. Numbers in bold mean that the factor is a tolerable habitat requirement factor.
Table 6. Correlations between fish abundance and environmental factors before and after typhoons for H. formosanus. * = significantly different at p < 0.05 level; ** = significantly different at p < 0.01 level. SD is the standard deviation. Numbers in bold mean that the factor is a tolerable habitat requirement factor.
Environmental FactorAdultJuvenile
BeforeAfterBeforeAfter
rprprprp
EC (μS/cm)−0.2160.050.0850.340.304 **0.01−0.256 **0.00
Turbidity (NTU)−0.215 *0.03−0.1570.08−0.0340.730.0290.75
DO (mg/L)0.248 *0.01−0.0170.85−0.1430.150.250 **0.01
Flow velocity (m/s)0.436 **0.000.249 **0.010.374 **0.000.292 **0.00
SD of flow velocity (m/s)0.367 **0.000.246 **0.010.1040.290.1280.16
Water depth (cm)————−0.257 **0.01−0.1340.13
SD of water depth (cm)0.1020.300.0670.46−0.304 **0.00−0.178 *0.05
Sand (%)−0.1850.06−0.1460.10−0.1190.23−0.223 *0.01
Gravel (%)−0.202 *0.04−0.0590.51−0.0950.340.0450.62
Pebbles (%)————0.546 **0.000.1440.11
Cobble (%)0.208 *0.030.176 *0.05−0.1330.180.0860.34
Boulders (%)0.1380.160.0680.45−0.335 **0.00−0.0510.57
Table 7. Correlations between fish abundance and environmental factors before and after typhoons for R. nantaiensis. * = significantly different at p < 0.05 level; ** = significantly different at p < 0.01 level. SD is the standard deviation. Numbers in bold mean that the factor is tolerable habitat requirement factor.
Table 7. Correlations between fish abundance and environmental factors before and after typhoons for R. nantaiensis. * = significantly different at p < 0.05 level; ** = significantly different at p < 0.01 level. SD is the standard deviation. Numbers in bold mean that the factor is tolerable habitat requirement factor.
Environmental FactorAdultJuvenile
BeforeAfterBeforeAfter
rprprprp
EC (μS/cm)0.1290.250.1190.18−0.0620.58−0.0320.72
Turbidity (NTU)0.1620.100.0290.750.1620.100.0080.93
DO (mg/L)−0.1660.09−0.250 **0.01−0.320 **0.00−0.0510.57
Flow velocity (m/s)0.203 *0.04−0.1140.210.0570.57−0.186 *0.04
SD of flow velocity (m/s)0.0060.95−0.0470.61−0.0290.770.0050.96
Water depth (cm)————−0.1180.23−0.217 *0.02
SD of water depth (cm)−0.404 **0.00−0.0170.85−0.235 *0.020.0250.78
Sand (%)————−0.0510.610.1530.09
Gravel (%)−0.0500.620.1060.24−0.0160.87−0.0540.55
Pebbles (%)————0.199 *0.04−0.0160.86
Cobble (%)−0.0680.49−0.1030.25−0.0550.58−0.1260.16
Boulders (%)−0.250 *0.01−0.0220.81−0.1520.120.1150.20
Table 8. Correlations between fish abundance and environmental factors before and after typhoons for juvenile of O. alticorpus. * = significantly different at p < 0.05 level; ** = significantly different at p < 0.01 level. SD is the standard deviation. Numbers in bold mean that the factor is tolerable habitat requirement factor.
Table 8. Correlations between fish abundance and environmental factors before and after typhoons for juvenile of O. alticorpus. * = significantly different at p < 0.05 level; ** = significantly different at p < 0.01 level. SD is the standard deviation. Numbers in bold mean that the factor is tolerable habitat requirement factor.
Environmental FactorBeforeAfter
rprp
EC (μS/cm)0.1810.100.0420.64
Turbidity (NTU)−0.0050.960.0170.85
DO (mg/L)−0.0320.75−0.0140.88
Water depth (cm)0.357 **0.000.0460.61
SD of water depth (cm)0.255 **0.01−0.0150.87
Sand (%)0.1250.200.0810.37
Gravel (%)0.1760.080.1280.15
Pebbles (%)−0.1790.07−0.1240.17
Cobble (%)−0.1390.16−0.0120.90
Boulders (%)0.193 *0.05−0.0640.48
Table 9. Critical environments for each species. SD is the standard deviation.
Table 9. Critical environments for each species. SD is the standard deviation.
Mean
BeforeAfter
Adult of H. formosanus
Water depth (cm)33.1635.03
Pebbles (%)23.9032.60
Adult of R. nantaiensis
Water depth (cm)29.6222.73
Sand (%)1.507.70
Pebbles (%)46.9032.30
Juvenile of O. alticorpus
Flow velocity (m/s)0.570.48
SD of flow velocity (m/s)0.220.25
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MDPI and ACS Style

Chiu, H.-P.; Suen, J.-P.; Chen, P.-H. Identification of Critical and Tolerable Fish Habitat Requirements Based on Pre- and Post-Typhoon Data. Water 2025, 17, 425. https://doi.org/10.3390/w17030425

AMA Style

Chiu H-P, Suen J-P, Chen P-H. Identification of Critical and Tolerable Fish Habitat Requirements Based on Pre- and Post-Typhoon Data. Water. 2025; 17(3):425. https://doi.org/10.3390/w17030425

Chicago/Turabian Style

Chiu, Hung-Pin, Jian-Ping Suen, and Pin-Han Chen. 2025. "Identification of Critical and Tolerable Fish Habitat Requirements Based on Pre- and Post-Typhoon Data" Water 17, no. 3: 425. https://doi.org/10.3390/w17030425

APA Style

Chiu, H.-P., Suen, J.-P., & Chen, P.-H. (2025). Identification of Critical and Tolerable Fish Habitat Requirements Based on Pre- and Post-Typhoon Data. Water, 17(3), 425. https://doi.org/10.3390/w17030425

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