The Relationship between Population Density and Body Size of the Giant Mountain Crab Indochinamon bhumibol (Naiyanetr, 2001), an Endangered Species of Freshwater Crab from Northeastern Thailand (Potamoidea: Potamidae)

Round 1

Reviewer 1 Report

The primary freshwater crab is essential stone species in freshwater ecosystems. However, the current status of freshwater crab in the world are not optimistic, and the rate of threatened species is 32.2% in Thailand according to Cummberlidge et al 2009, such as the giant mountain crab Indochinamon Bhumibol is listed as Endangered in IUCN Red List. More attention is needed for biodiversity conservation and assessment of current status of these species. The article, ID diversity-1834901 focused on relationship between population density and body size of this endangered species from Loei Province, Thailand and provided the valuable updated data for this species. These data have potential for conservation management of this endangered freshwater crab and other related threatened freshwater crab species in Thailand.  

In general, the study is basically well conducted, the text is basically well written, the most of the images are generally good. However, many improvements are needed.

My major concerns:

1.   The current status of this species is endangered (EN) according to the IUCN Red List assessment more than ten years ago (Esser, L and Cumberlidge, N., 2008). This present study conducted local field investigations of this species. It is essential and necessary to provide an updated statements indicating the current population status of this endangered crab for improving conservation management.

2.   Experimental design,

The methods described and experimental design in the present study is basically sufficient. But morphological taxonomic identification, and genetic lineage diagnostic analyses are neglected.

3.   Methods,

Normality test for the sampling data analyses should be used before the independent sample t-test.

4.   Results,

My concern is that dose these populations among all sampling sites in PL and PR are the same species? 

 

Minor concerns:

1.   Introduction,

The distribution area of the giant mountain crab Indochinamon Bhumibol are needed to provide according to the updated literatures. My concern is that dose other congeneric species distributed in the same or adjacent area?

2.   Results,

Dose some morphological variations observed and detected in different populations?

3.   Figure and figure legend,

Figure 1, Main rivers in areas of sampling site should be shown in the map of Thailand, Loei Province.

Figure legend, The name of two areas sampled in figure 1 are not consistent with those listed in figure and text file. 

Author Response

Dear Reviewer,

We response to your point-by-point as follow:

The primary freshwater crab is essential stone species in freshwater ecosystems. However, the current status of freshwater crab in the world are not optimistic, and the rate of threatened species is 32.2% in Thailand according to Cummberlidge et al 2009, such as the giant mountain crab Indochinamon Bhumibol is listed as Endangered in IUCN Red List. More attention is needed for biodiversity conservation and assessment of current status of these species. The article, ID diversity-1834901 focused on relationship between population density and body size of this endangered species from Loei Province, Thailand and provided the valuable updated data for this species. These data have potential for conservation management of this endangered freshwater crab and other related threatened freshwater crab species in Thailand.

Response: Thank you for your positive comments.

 

In general, the study is basically well conducted, the text is basically well written, the most of the images are generally good. However, many improvements are needed.

My major concerns:

1. The current status of this species is endangered (EN) according to the IUCN Red List assessment more than ten years ago (Esser, L and Cumberlidge, N., 2008). This present study conducted local field investigations of this species. It is essential and necessary to provide an updated statements indicating the current population status of this endangered crab for improving conservation management.

Response: We added “The population size of I. bhumibol in PL and PR seems to be large with a strong cohort of reproductive and almost reproductive individuals, which is a positive criterion when assessing extinction risk. It was assessed as EN on the IUCN Red List due to threats from human-induced habitat loss/degradation and pollution, specifically agriculture and aquaculture, logging, and wood harvest [5]. To reassess this species in a less threatened category it would be necessary to address the status of these threats and demonstrate that they are no longer a problem” in line 446-452.

 

2. Experimental design,

The methods described and experimental design in the present study is basically sufficient. But morphological taxonomic identification, and genetic lineage diagnostic analyses are neglected.

Response: We added “The morphological characters; carapaces, chelipeds, walking legs, abdomen, chelae, third maxilla, mandibular pals, first gonopods (G1) and second gonopod (G2) were analyzed by using Chuensri [13], Ng and Naiyanetr [14] and Naruse et al [15]” in line 104-107. We do not analysis the genetic lineage diagnostic in this manuscript due to the characteristic of the crabs are distinctive when compared to other species.

 

3. Methods,

Normality test for the sampling data analyses should be used before the independent sample t-test.

Response: We re-analyses by tested Normality in all parameters “The abundance of I. bhumibol was compared between the two study sites (PL and PR) using a normalization and an independent sample t-test” in line 125-126.

 

4. Results,

My concern is that dose these populations among all sampling sites in PL and PR are the same species?

Response: Yes, they are the same species according to “Suthamrit, W.; Thaewnon-ngiw, B. Morphometry of mountain crabs (Crustacea: Decapoda: Brachyura: Potamidae) from Phetchabun Mountains Thailand. Interdiscip. Res. Rev. 2020. 15, 24-31.”

 

Minor concerns:

1. Introduction,

The distribution area of the giant mountain crab Indochinamon Bhumibol are needed to provide according to the updated literatures. My concern is that dose other congeneric species distributed in the same or adjacent area?

Response: We provided in line 43-45 as “It found in Phu Ruea District, Dan Sai District, Tha Li District, Phu Luang District, Pakchom District, Loei Province; Lomkao District, Phetchabun Province; Sang-khom District, Nong Khai Province; and Nayoong District, Udonthani [5]”.

 

2. Results,

Dose some morphological variations observed and detected in different populations?

Response: No, we did not find some morphological variations observed and detected in different populations.

 

3. Figure and figure legend,

Figure 1, Main rivers in areas of sampling site should be shown in the map of Thailand, Loei Province.

Response: We added main rivers in Figure 1.

 

Figure legend, The name of two areas sampled in figure 1 are not consistent with those listed in figure and text file.

Response: We changed Figure legend “Figure 1. Map of Thailand showing sampling site in Phuruea national park and Phuluang wildlife sanctuary, Loei Province: 1) Huay Tiew; 2) Huay Kawak; 3) Huay Sai khao; 4) Huay Phai; 5) Huay Toei; 6) Huay Nam-khan; 7) Huay Nam San; 8) Huay Nam Thop; 9) Huay Nam Khai; 10) Huay Nam Loei; 11) Huay Sak and 12) Huay Pla Ba. On the right side of this figure showed a sampling site that consists of 3 lines transect within 10 sampling plots in each line transect” to “Map of Thailand showing sampling site in Phu Luang Wildlife Sanctuary (PL) and Phu Ruea National Park (PR), Loei Province: 1) Huay Tiew; 2) Huay Kawak; 3) Huay Sai khao; 4) Huay Phai; 5) Huay Toei; 6) Huay Nam khan; 7) Huay Nam San; 8) Huay Nam Thop; 9) Huay Nam Khai; 10) Huay Nam Loei; 11) Huay Sak and 12) Huay Pla Ba. On the right side of this figure showed a sampling site that consists of 3 lines transect within 10 sampling plots in each line transect”.

 

Author Response File: Author Response.docx

Reviewer 2 Report

This is a relatively well written work but there are still quite a number of edits that need to be made almost in every paragraph, and I am assuming that the editorial staff will take care of these. The figures are good and all are relevant.

I have made a number of comments on the manuscript itself. Here are some additional thoughts.

One thing that could be added is the adult size range of this species – this can be done if you have a large sample of the population and a range of females – the carapace width at which the species transitions from a non-reproductive sub-adult to a reproductive adult can be inferred. This is called the pubertal moult and defines the size of the species (they are calling this a giant species and the largest known, so they should be able to define the adult size range, which is taxonomically important). It is necessary to quantify words such as giant, large, small, when it comes to species of freshwater crabs.

The title should be changed: from: “Relationship between population density and body size of giant mountain crab (Indochinamon bhumibol), endangered species of freshwater crab from Loei Province, Thailand” to “The relationship between population density and body size of the giant mountain crab Indochinamon bhumibol (Naiyanetr, 2001), an endangered species of freshwater crab from northern Thailand (Potamoidea: Potamidae)”.

The population size of this species (previously listed as unknown) seems to be large with a strong cohort of reproductive and almost reproductive individuals, which is a positive criterion when assessing extinction risk. It was assessed as EN on the IUCN Red List due to threats from human-induced habitat loss/degradation and pollution, specifically agriculture and aquaculture, logging, and wood harvest. To reassess this species in a less threatened category it would be necessary to address the current status of these threats and demonstrate that they are not longer a problem.

Comments for author File: Comments.pdf

Author Response

Dear Reviewer

Thank you for your kindness review. We provide a point-by-point response as follow:

This is a relatively well written work but there are still quite a number of edits that need to be made almost in every paragraph, and I am assuming that the editorial staff will take care of these. The figures are good and all are relevant.

Response: Response: Thank you for your positive comments.

 

I have made a number of comments on the manuscript itself. Here are some additional thoughts.

One thing that could be added is the adult size range of this species – this can be done if you have a large sample of the population and a range of females – the carapace width at which the species transitions from a non-reproductive sub-adult to a reproductive adult can be inferred. This is called the pubertal moult and defines the size of the species (they are calling this a giant species and the largest known, so they should be able to define the adult size range, which is taxonomically important).

Response: We added the adults size range in the Table 3, 4 and 5.

 

It is necessary to quantify words such as giant, large, small, when it comes to species of freshwater crabs.

Response: We added “The minimum – maximum weight, carapace width and carapace lenght of the giant crabs were 31.6-98.2 g., 4.2-6.5 cm. and 3.2-5 cm.; large were 12.1-72.2 g., 3.1-6.3 cm. and 2.4-4.8 cm.; and small were 9.4-4.9 g., 2.9-4.8 cm. and 2.3-3.7 cm. [5]” in line 40-43.

 

The title should be changed: from: “Relationship between population density and body size of giant mountain crab (Indochinamon bhumibol), endangered species of freshwater crab from Loei Province, Thailand” to “The relationship between population density and body size of the giant mountain crab Indochinamon bhumibol (Naiyanetr, 2001), an endangered species of freshwater crab from northern Thailand (Potamoidea: Potamidae)”.

Response: We changed the title to “The relationship between population density and body size of the giant mountain crab Indochinamon bhumibol (Naiyanetr, 2001), an endangered species of freshwater crab from north-eastern Thailand (Potamoidea: Potamidae)”

 

The population size of this species (previously listed as unknown) seems to be large with a strong cohort of reproductive and almost reproductive individuals, which is a positive criterion when assessing extinction risk. It was assessed as EN on the IUCN Red List due to threats from human-induced habitat loss/degradation and pollution, specifically agriculture and aquaculture, logging, and wood harvest. To reassess this species in a less threatened category it would be necessary to address the current status of these threats and demonstrate that they are not longer a problem.

Response: We added “The population size of I. bhumibol in PL and PR seems to be large with a strong cohort of reproductive and almost reproductive individuals, which is a positive criterion when assessing extinction risk. It was assessed as EN on the IUCN Red List due to threats from human-induced habitat loss/degradation and pollution, specifically agriculture and aquaculture, logging, and wood harvest [5]. To reassess this species in a less threatened category it would be necessary to address the status of these threats and demonstrate that they are no longer a problem” in line 444-450.

 

peer-review-20892971.v1.pdf

 

Line 33: Currently this family is referred to as the Gecarcinucidae

Response: Line 37: We changed “Parathelphusidae” to “Gecarcinucidae”.

 

Line 36: assessed by the International Union for the Conservation of Nature (IUCN) Red List as an endangered (EN) species

Response: Line 43-47: We changed “It is endemic to Loei Province and listed as endangered species…” to “It found in Phu Ruea District, Dan Sai District, Tha Li District, Phu Luang District, Pak-chom District, Loei Province; Lomkao District, Phetchabun Province; Sang-khom District, Nong Khai Province; and Nayoong District, Udonthani [5]. and assessed by tThe Interna-tional Union for the Conservation of Nature (IUCN) Red List assessed this species as an-listed as endangered (EN) species [56]”

 

Line 37-38: and because it is threatened by habitat destruction and pollution

Response: Line 47-48: We changed “because its occurrence is restricted to mountain streams in the north-eastern part of Thailand” to “and because it is threatened by habitat destruction and pollution”.

 

Line 49: does this mean that there is already a conservation plan being implemented for the EN species? If so explain how the plan would be adjusted in the light of the findings of this study. If not, suggest how such a plan could be formulated.

Response: Line 63: We changed “adjusted conservation action plan” to “suggest how such a plan could be formulated”.

 

Line 81: delete this

Response: Line 95: We deleted “each month”.

 

Line 83-84: You need to make it clear that you are sampling mountain streams, and that your transects are positioned in the stream (rather than on the forest floor)

Response: Line 97-99: We changed “At each sampling site, a 1 x 1 m plot was demarcated every 5 m along the transect to collect crabs” to “At each sampling site, a 1 x 1 m plot was demarcated every 5 m along the transect in the mountain streams to collect crabs”.

 

Line 91-92: Please explain how age was determined by the shape of the abdomen for both sexes. Where are the results of this - I cannot find them?

Response: We added “The morphological characters; carapaces, chelipeds, walking legs, abdomen, chelae, third maxilla, mandibular pals, first gonopods (G1) and second gonopod (G2) were analyzed by using Chuensri [13], Ng and Naiyanetr [14] and Naruse et al. [15]” in line 102-105.

 

Line 203: Is this population size difference because PL is a much larger area than PR, or might there be other reasons for this apparent difference (if it is a real difference, given that it was not statistically supported)?anyway)?

Response: It is not. The statistic is not significant.

 

Line 293-296: delete

Response: We deleted “Authors should discuss the results and how they can be interpreted from the perspective of previous studies and of the working hypotheses. The findings and their implications should be discussed in the broadest context possible. Future research directions may also be highlighted”

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

I appreciate the authors’ responses to my comments on the ms, ID diversity-1834901. However, some improvement is still needed.

 

My concerns,

1.     According to authors’ response, the giant mountain crab Indochinamon Bhumibol is found in Phu Ruea District, Dan Sai District, Tha Li District, Phu Luang District, Pakchom District, Loei Province; Lomkao District, Phetchabun Province; Sang-khom District, Nong Khai Province; and Nayoong District, Udonthani. My concern is why only two areas, Phu Ruea District and Phu Luang District of Loei Province were selected for this study? It is necessary to explain, since they are not consistent to that was proposed in title “northeastern Thailand”. 

2.     Whether other freshwater crab species (congeneric or not) are distributed in or near the area, Phu Luang Wildlife Sanctuary (PL) and Phu Ruea National Park (PR), Loei Province. Since my question is not responded in authors’ response.

Except for this mountain crab, my concern is how many freshwater crabs distributed in these two Wildlife Sanctuary / National Park? And interspecific competition can’t be ignored in discussions.  

3.     Figure 2.

 

Scale bars should be provided in figure 2, (a) to (d). And the background and the figure “male’s gonopod” in (d) are not standard. In addition, high-definition images are needed.

Author Response

Dear Reviewer 1

 

We would like to send the response to reviewer Comments and Suggestions for Authors for your consideration.

 

Best regards,

 

Rattanawat Chaiyarat,

 

Round 2

I appreciate the authors’ responses to my comments on the ms, ID diversity-1834901. However, some improvement is still needed.

Response Thank you for your comments for improvement.

 

My concerns,

1. According to authors’ response, the giant mountain crab Indochinamon Bhumibol is found in Phu Ruea District, Dan Sai District, Tha Li District, Phu Luang District, Pakchom District, Loei Province; Lomkao District, Phetchabun Province; Sang-khom District, Nong Khai Province; and Nayoong District, Udonthani. My concern is why only two areas, Phu Ruea District and Phu Luang District of Loei Province were selected for this study? It is necessary to explain, since they are not consistent to that was proposed in title “northeastern Thailand”.

      Response      1. All areas are licated in north-eastern Thailand.

2. We explain as “It found in Phu Ruea District, Dan Sai District, Tha Li District, Phu Luang District, Pakchom District, Loei Province; Lomkao District, Phetchabun Province; Sang-khom District, Nong Khai Province; and Nayoong District, Udonthani Province, north-eastern Thailand [5]. The International Union for the Conservation of Nature (IUCN) Red List assessed this species as an endangered (EN) species [6] and because it is threatened by habitat destruction and pollution. Although the habitats of freshwater crabs in tropical regions are diverse and include rivers, streams, waterfalls, wetlands, karsts, and caves. This species is highly limited in its distribution and is mostly found in the waterfalls and stream channels of mountain forests [7]. According to previous studies, water pollution, hunting, habitat destruction in the form of deforestation and increasing agriculture are threats to freshwater crabs in Asia. A previous study of freshwater crab in Thailand emphasized taxonomy and diversity aspects [4, 5, 8-11], but information is lacking on population size, abundance, trends, and ecology of giant mountain crabs. This study aimed to investigate the relationship between population density and body size of I. bhumibol in Phu Luang Wildlife Sanctuary (PL) and Phu Ruea National Park (PR), Loei Province as they are head watershed of Loie Province. Furthermore, holotype and paratype of I. bhumibol were collected in PL [4]. The findings of this study may enhance the knowledge of the population dynamics and body size patterns of this endemic species to north-eastern Thailand, which could lead to suggest how such a plan could be formulated and area management strategy to protect it from imminent extinction” in line 40-59.
3. Whether other freshwater crab species (congeneric or not) are distributed in or near the area, Phu Luang Wildlife Sanctuary (PL) and Phu Ruea National Park (PR), Loei Province. Since my question is not responded in authors’ response.

Response According to previous publication of Suthamrit et al. (2020) [5] Indochinamon bhumibol, Iomon nanand Vietopotamon phuluangnense are freshwater crabs (Potamidae) found in Na Haew Distric, Nong Hin District, Phu Luang District, Wang Saphung District and Phu Kradueng Distric, Loei, Province.

 

Except for this mountain crab, my concern is how many freshwater crabs distributed in these two Wildlife Sanctuary / National Park? And interspecific competition can’t be ignored in discussions.

Response We added “According to Suthamrit et al. [5], I. bhumibol, were found in same areas with Iomon nanand Vietopotamon phuluangnense (Potamidae) such as Na Haew Distric, Nong Hin District, Phu Luang District, Wang Saphung District and Phu Kradueng Distric, Loei, Province. But they were never captured at the same site due to I. bhumibol occurring at high elevation, while Iomon nan and Vietopotamon phuluangnensewere found at lower elevation as freshwater crabs from highland of Zimbabwe that coexistence in different flowing environment of water [30]” in Discussion line 343-349.

 

3. Figure 2.

Scale bars should be provided in figure 2, (a) to (d). And the background and the figure “male’s gonopod” in (d) are not standard. In addition, high-definition images are needed.

Response We Change Figure 2 as you comment.

Author Response File: Author Response.docx