Coastal pollution from the industrial park Quintero bay of central Chile: Effects on abundance, morphology, and development of the kelp Lessonia spicata (Phaeophyceae)

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, Horcón 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 Horcón registered high HMs concentration in the seawater and marine sediments exceeding the international permissible limits (e.g in seawater Cu 20-859 μg L-1; sediments Cu > 50,000 μg 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 μg L-1, respectively) and of As in marine sediments (20,895 μg 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.

Fig 1. Morphological features recording.

A) Lessonia spicata intertidal populations examined at Cachagua sampling site, B) view of a holdfast of L. spicata showing its length (L) and width (W), and C) illustration of the measurement of the longest blade (BL) in an individual of L. spicata.

Fig 2. Comparison of morphological features.

Average of A) abundance, B) holdfast area, and C) length of the longest blade of Lessonia spicata population from Cachagua, Horcón and Ventanas.

Fig 3. Comparison of size structure based on holdfast diameter.

Percentual presence of three categories: recruit and juvenile, young, and adult sporophyte of Lessonia spicata populations. Each bar corresponds to one of the locations in this study: Cachagua, Horcón and Ventanas.

Fig 4. Principal components analysis of morphological features and heavy metals concentration.

PCA includes abundance, holdfast area and blade length (Fig 2), plus the concentration of [As] and [Cu] in seawater (SW) and marine sediments (MS) (Tables 1 and 2).

Fig 5. Spore released.

Accumulated spores released by sori of Lessonia spicata (number of spores released mL^-1, average ± S.D (n = 5). Ca; Cachagua, Ho; Horcón, Ve; Ventanas. T; treatment.

Fig 6. Settlement.

Number of settled spores of Lessonia spicata per treatment showing SD (n = 15), at 48 and 120 h of exposure.

Fig 7. Gametophyte development.

Development from settled spores to undifferentiated gametophyte during 37 days of exposure to the treatments, showing SD (n = 15). The legend indicates the following life cycle stages: Spores (S), Spores with germ tube (G) and Undifferentiated gametophyte (U) (Fig 3A–3C). Ca; Cachagua, Ho; Horcón, Ve; Ventanas. T; treatment.

Fig 8. Sexual differentiation.

Development from undifferentiated gametophyte to sexual gametophytes during 25 days of exposure to treatment, showing SD (n = 13). The legend indicates the different stages: Undifferentiated gametophyte (U), Female gametophyte (FG) and Male gametophyte (MG) (S2C–S2E Fig). Ca; Cachagua, Ho; Horcón, Ve; Ventanas. T; treatment.

Fig 9. Fertility and sporophyte formation.

A) Trends in the percentage of fertility and sporophyte formation based on the number of female gametophytes, and B) percentage of sporophyte production. Ca; Cachagua, Ho; Horcón, Ve; Ventanas. T; treatment.