Coastal pollution from the industrial park Quintero bay of central Chile: Effects on abundance, morphology, and development of the kelp Lessonia spicata (Phaeophyceae)
Authors: Andr√©s Meynard
Loretto Contreras-Porcia
Carolina Oyarzo-Miranda
Nicol√°s Latorre
Cristian Bulboa
Jorge Rivas
Journal: PLoS ONE (2020)
Discipline: Multidisciplinary
Keywords: Quintero Bay; pollution; Lessonia spicata; morphometric; population studies
Affiliations: Departamento de Ecolog√≠a y Biodiversidad, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile., Centro de Investigaci√≥n Marina Quintay (CIMARQ), Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile., Center of Applied Ecology and Sustainability (CAPES), Santiago, Chile., Programa de Doctorado Medicina de la Conservaci√≥n, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile.

Abstract:  The industrial park of Quintero Bay (QB) in the central coast of Chile was established in the 1960s, presents high levels of pollution due to the industrial activity, and it is known as one of the five Chilean "sacrifice zones". Lessonia spicata is the most important habitat-forming kelp species in the intertidal along the central and south shores of Chile, and currently there are no morphometric and population studies of L. spicata (or other seaweed species) nor studies about the effects of pollution on its development in QB and neighbouring sites. In this context, the aims of this study were (i) to register the abundance and morphological features of L. spicata populations from Ventanas, Horc√≥n and Cachagua (sites with different pollution histories and located only up to 40 km from the QB); ii) to determine the heavy metals (HMs) concentration in seawater and marine sediments; and (iii) to evaluate in vitro the effects of exposure to seawater from the three sampling sites on spore release and early developmental stages, up to the juvenile sporophyte. Results showed that the chronically exposed Ventanas kelp population had the smallest adult individuals in comparison with the other sites. Ventanas and Horc√≥n registered high HMs concentration in the seawater and marine sediments exceeding the international permissible limits (e.g in seawater Cu 20-859 Œºg L-1; sediments Cu &gt; 50,000 Œºg kg-1). Unexpectedly in Cachagua, a site often considered unpolluted, high concentrations of Cu and As were also registered in the seawater (859 and 1,484 Œºg L-1, respectively) and of As in marine sediments (20,895 Œºg kg-1). Exposure of gametophytes to the seawater from Ventanas resulted in a developmental delay compared to the other treatments; however, low sporophyte production was determined in all treatments. Our results indicate that QB, more notably Ventanas, induce highly negative effects on individual development, and consequently on seaweed populations, which suggest a long-term negative impact on the community structure of these marine zones. Furthermore, the high concentrations of HMs reported here at Cachagua suggest a recent expansion of pollution along the central coast of Chile, evidencing effects on the marine ecosystem health even on sites far from the pollution source. 

Retracted: No

PubPeer comments:
 Due to my interest in understanding more about the impact of industrial activities in coastal zones, a few weeks ago the article by Oyarzo-Miranda et al. attracted my attention. It is to date a fascinating piece of research and I would like to congratulate the authors for their work. However, I have a couple of doubts regarding several aspects that are at least eye-catching: The first is the statistical treatment of the data where the authors use a Mann-Whitney test to do their a posteriori analysis. In this sense the results that come out of the kruskall-wallis where the null hypothesis  the samples belong to the same population is rejected (in this case it would be that there are no differences in the treatments). In this sense the authors really do an interesting job, since the null hypothesis is rejected and the alternative is that they do not belong to the same population (i.e. the response to the treatment is different). However, what catches my attention is the use of the Mann Whitney test as a post-hoc test. This I believe is grossly erroneous and I think it may affect the conclusions presented in the paper. Since their conclusions are based on performing ordinary pair-wise rank sum (i.e. Wilcoxon or Mann-Whitney) tests. Consequently, two problems arise that make me slightly doubt the interpretation of the results: (a) the ranks used for the pair-wise rank sum tests are not the ranks used by the Kruskal-Wallis test. b) the rank sum tests do not use the pooled variance implied by the Kruskal-Wallis null hypothesis. Therefore, the results of the post-hoc test (which means that it is not a post-hoc test) selected cannot be applied if a Kruskal-Wallis was previously applied. In this sense, it would be logical to apply a Dunn s test or perhaps a Tukey test that would use the same rank sum. However, looking at the figures, I do not think that the results vary much, especially in those where there is a noticeable difference in the treatments. I think the authors should review the content, just in case. I tried to look for the data obtained in the manuscript but unfortunately they are not available. Only the p-value and the Chi2 obtained (Hint if the statistical result is a Chi2 then it cannot be more than 2 pair-wise samples). Regarding the analytical procedures, which in the case of sediments and water results in high values, the authors do not show concisely, not even in the supplementary material, any information about the quality controls used. This would further validate their results , the same for sediments where reference materials are not used to certify the correct treatment, as reported by Parra et al. in Table 2. This is more than important because the concentrations of metals reported in some cases are well above previous published values as cited by the authors in the text. In the same line of assuring the analytical quality of the same I do not see in the text and neither in the brief supplementary material reported the limits of detection, the limits of quantification, nor the values of blanks that are normally performed at the beginning every 5 or 6 samples measured to assure the quality in the measurements performed in the equipment. Regarding the results and discussion I miss some things like discussing in depth or at least suggesting the role of water mass movements to transport pollutants from the source to the other sampling zones (Horcu00f3n is a relatively short distance (less than 7 km coastline), which in the case of cachagua is somewhat greater (I used google earth to calculate it), . Especially taking into account that the nearest zone has lower values than the farthest one, suggesting a possible alternative source such as construction activities and or human settlement. Another part of the work that caught my attention is the rather dubious comparison of the values obtained in water, for example, where very high levels are clearly reported, which exceed EPA quality guidelines . But the comparison is perhaps a bit whimsical because in the same document in the footnotes it is mentioned that these levels must be corrected following a series of conversion factors and it is not mentioned if the samples were filtered through a 0.45 um filter as recommended, so there is no difference between the metal actually dissolved in the water and the metal sticked to particles. Which leads to an overstimation, following this asumption the EPAu00b4s guideline indicates and is specified relatively clearly in this document a very important factor to take into account is being ignored. So unfortunately the amount of Cu in this case but also of As in water could be significantly overestimated, even also several orders of magnitude. I recommend reading the following comprehensive review on the role of organic matter in the availability of metals which will probably add more clarity to the authors of the manuscript. In addition to the following article: Deruytter, D., Vandegehuchte, M. B., Garrevoet, J., De Laender, F., Vergucht, E., Delbeke, K.,u2026 Janssen, C. R. (2015). Salinity and dissolved organic carbon both affect copper toxicity in mussel larvae: Copper speciation or competition cannot explain everything. Environmental Toxicology and Chemistry, 34 (6), 1330-1336. doi: 10.1002 etc.2924 Finally, I suggest that the authors take into account some of the suggested corrections or at least clarify the doubts raised in a constructive spirit and make all the data available in the supplementary material. In these times for science, openness is more than necessary. ,