Coastal Wetlands: Ecosystems Affected by Urbanization?
, Ramón Ahumada-Rudolph 3, Katia Sáez 4, Pablo Fierro 5 and Carolina Rojas 6Round 1
Reviewer 1 Report
Is the length of coastline correct = 83,850km? Line 77
Van Veen dredge capacity should be in m3 I believe. Line 145
I assume no analysis of nutrients or heavy metals was undertaken. I think this would have substantially aided the analysis and quantification of urban runoff and its impact.
A description and quantification (ha, %) of the contributing catchments (urban, natural state, land use, topography, geology etc) as well as rates of urbanisation (historic and likely forecast) for both sites is needed in my opinion.
The descriptor 'drastic' (Line 384) to describe the difference in fecal coliform contamination is not warranted. In terms of bacterial water quality the difference between 3,500 and 1,000 MPN is very little i.e < 1 log. In general I'm not sure that the bacterial water quality contribution adds value to this paper, as a fuller analysis of nutrients and heavy metals is needed to substantiate anthropogenic inputs. Also bacterial indicators are relevant to public health, much less so than environmental health - the thrust of this research.
Is there an argument that the marine influence is still (as of the time of the study) significantly great as to ameliorate the impacts of urbanisation as demonstrated between the two wetlands? Is it possible to project the health of the R-A wetland in years to come at the current rate of urbanisation/degradation?
Author Response
Reviewer N°1
Response to Reviewer 1 Comments
General comments
The manuscript (introduction, methods, results and discussion) was modified to address the comments. It is crucial to stress the importance of this assessment, the incorporation of which in future wetland protection plans can help mitigate the current degradation of these ecosystems and support territorial sustainability regarding urban land use, etc.
In Chile there is a lack of management and legislation regarding the determination of the environmental quality and status of wetlands such as that which exists in more developed countries, which has given rise to severe and sometimes irreparable social conflicts.
Therefore, having the ability to visualize and reflect the functioning of wetlands and the influence of urbanization on them in Chile is a major advance that will be very beneficial for future territorial management and environmental protection and restoration plans. We are very grateful for the opportunity to present the results of this investigation, the fruit of much effort and work, in your prestigious journal.
Introduction
Observations
- Is the length of coastline correct = 83,850km?
Answer 1. Not modified in L77: Chile is a coastal country with perhaps one of the longest coastlines in the world, with an approximate length of 83,850 km including the continental length and island territory. Thus, the figure is correct.
Materials and Methods
Observations
- Van Veen dredge capacity should be in m3 I believe. Line 145
Answer 2. Not modified in L145: using a Van Veen manual dredge (0.025 m2 capacity). The capacity is expressed in terms of the sampling area opening size of 250 cm2. This dredge is designed for the collection of sediment in freshwater and saltwater from soft or moderately hard bottoms such as sand, gravel or clay.
- I assume no analysis of nutrients or heavy metals was undertaken. I think this would have substantially aided the analysis and quantification of urban runoff and its impact.
Answer 3. Environmental factors such as organic matter and sediment grain size certainly affect heavy metal distribution. The high heavy metal levels in wetland sediment could be due to its large retention capacity. The dominant heavy metals in coastal wetlands are Zn, Cd, Cu, Ni, Cr and Pb, which could result primarily from human activities. It is also necessary to recognize their baseline; this would have made the results more robust, but unfortunately was not within the objectives of the work.
- A description and quantification (ha, %) of the contributing catchments (urban, natural state, land use, topography, geology etc) as well as rates of urbanisation (historic and likely forecast) for both sites is needed in my opinion.
Answer 4. Modified in L 116 and L130: The land uses of the watersheds of both wetlands were recalculated and added in Table 1.
Discussion
Observations
- The descriptor 'drastic' (Line 384) to describe the difference in fecal coliform contamination is not warranted. In terms of bacterial water quality the difference between 3,500 and 1,000 MPN is very little i.e < 1 log. In general I'm not sure that the bacterial water quality contribution adds value to this paper, as a fuller analysis of nutrients and heavy metals is needed to substantiate anthropogenic inputs. Also bacterial indicators are relevant to public health, much less so than environmental health - the thrust of this research.
Answer 5. Modified L393- L396: Fecal coliform bacteria in wetland ecosystems have attracted special attention in environmental research due to the use of these microorganisms as indicators of fecal contamination and microbiological deterioration of water. Various comparisons of fecal indicator bacteria (FIB) in sediment and the water column have been reported, which have led to the conclusion that sediment is the dominant microorganism reservoir. Numerous authors have observed that FIB concentrations in sediment are several times higher than in the water column; for example, Van Donsel and Geldreich (1971) observed that sediment concentrations were from 100 to 1000 times greater than those in the overlying water in various aquatic environments. In the absence of turbulence and resuspension, sediment contributes very little bacteria load to surface water, unlike what occurs in the studied wetlands, where turbidity is high; therefore, the difference between 3500 and 1000 is significant, since despite not being an order of magnitude greater, this reveals that the associated sediment could contain even more fecal coliforms, which is environmentally concerning.
The fecal coliform levels reported in our analyses are consistent with the increase in urbanization around the water bodies, but also warn of their quality, as these wetlands are often used for water consumption, recreation, fishing, etc., which leads to a public health problem. In addition, this environmental quality indicator allows a more precise assessment of the environment to aid in the development of more precise environmental management plans for wetlands and the setting of limits for this parameter, which in Chile are not established, for the mitigation and restoration of degraded environments.
Observations
- Is there an argument that the marine influence is still (as of the time of the study) significantly great as to ameliorate the impacts of urbanisation as demonstrated between the two wetlands? Is it possible to project the health of the R-A wetland in years to come at the current rate of urbanisation/degradation?
Answer 6. It has been reported that the area of the Rocuant-Andalién decreased by 10% from 2004 to 2014 and that a decrease of up to 32% as a result of urbanization is expected. With such projections, it is unlikely that the environmental carrying capacity of an ecosystem that is so degraded will not be altered. In addition, considering the complexity of its functioning, it is very probable that the resilience of the wetland will be exceeded despite the marine influence. If we add the effects of the current drought in central Chile that began in 2007, which has significantly affected water availability, it is very likely that environmental pressure in this wetland will increase.
Author Response File: 
Author Response.docx
Reviewer 2 Report
I suggest the revision of the text for the correction of minor language errors.
Also, some of the graphs included within the article are not very well visible (fig. 5, 6 and 8) so I suggest using different colors/ bigger font size. The inscriptions in Fig 8 are overlapping so the graph is diffucult to read.
Author Response
Reviewer N°2
General comments
In Chile there is a lack of management and legislation regarding the determination of the environmental quality and status of wetlands such as that which exists in more developed countries, which has given rise to severe and sometimes irreparable social conflicts.
Therefore, having the ability to visualize and reflect the functioning of wetlands and the influence of urbanization on them in Chile is a major advance that will be very beneficial for future territorial management and environmental protection and restoration plans, and I am grateful for the opportunity to present the results of this investigation, the fruit of much effort and work, in your prestigious journal.
The text has been reviewed and minor language errors corrected.
Results
Observations
- Some of the graphs included within the article are not very well visible (fig. 5, 6 and 8) so I suggest using different colors/ bigger font size. The inscriptions in Fig 8 are overlapping so the graph is diffucult to read.
Answer 1. Modified. Some of the graphs were modified, for example, Figure 6, which had different font types. Unfortunately, Figures 5 and 8 did not change much because the R program presents the analysis in that form, at a low resolution. It is also important to consider that the font size is determined by the instructions given to the author by the journal.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
I appreciate the intent of this work and should you choose, there may be merit in outlining some recommendations for future research/investigations on this two wetlands e.g nutrient and heavy metal sampling.
