water Article
The Effects of Depth-Related Environmental Factors on Traits in Acropora cervicornis Raised in Nurseries Claudia Patricia Ruiz-Diaz 1, * , Carlos Toledo-Hernández 1, *, Juan Luis Sánchez-González 1,2 and Brenda Betancourt 3 1 2 3
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Citation: Ruiz-Diaz, C.P.; Toledo-Hernández, C.; Sánchez-González, J.L.; Betancourt, B. The Effects of Depth-Related
Sociedad Ambiente Marino (SAM), San Juan 00931-2158, Puerto Rico; juan.sanchez2@upr.edu Department of Biology, University of Puerto Rico, San Juan 00931-3360, Puerto Rico Department of Statistics, University of Florida, Gainesville, FL 118545, USA; bbetancourt@ufl.edu Correspondence: claudiapatriciaruiz@gmail.com (C.P.R.-D.); cgth0918@gmail.com (C.T.-H.)
Abstract: Populations of Acropora cervicornis, one of the most important reef-building corals in the Caribbean, have been declining due to human activities and global climate change. This has prompted the development of strategies such as coral farms, aimed at improving the long-term viability of this coral across its geographical range. This study focuses on comprehending how seawater temperature (ST), and light levels (LL) affect the survival and growth of A. cervicornis fragments collected from three reefs in Culebra, Puerto Rico. These individuals were fragmented into three pieces of the similar sizes and placed in farms at 5, 8, and 12 m depth. The fragments, ST and LL were monitored for 11 months. Results show that fragments from shallow farms exhibit significantly higher mortalities when compared to the other two depths. Yet, growth at shallow farms was nearly 24% higher than at the other two depths. Corals grew fastest during winter, when temperature and LL were lowest, regardless of the water depth. Fragment mortality and growth origin were also influenced by reef origin. We conclude that under the current conditions, shallow farms may offer a slight advantage over deep ones provided the higher growth rate at shallow farms and the high fragment survival at all depths. Keywords: restauration; coral farm; Acropora cervicornis; sea temperature; light levels
Environmental Factors on Traits in Acropora cervicornis Raised in Nurseries. Water 2022, 14, 212. https://doi.org/10.3390/w14020212 Academic Editor: Kevin B. Strychar Received: 9 December 2021 Accepted: 7 January 2022 Published: 12 January 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).
1. Introduction The degradation of Caribbean coral reefs has reached unprecedented rates. It is estimated that nearly 80% of the Caribbean reefs have been lost, while the remaining 20% are seriously threatened [1–3]. The scientific community’s consensus for the observed declines points towards human-related activities such as extensive sedimentation and nitrification [4,5], the unsustainable exploitation of shellfish and fish resources [6]; and more recently, the increase in seawater temperature, ocean acidification, light levels, and coral diseases [7–12]. These factors, acting alone or synergistically, have diminished the natural capacity of corals to recover [13,14]. The significant reduction in the staghorn coral Acropora cervicornis in its natural habitat is, perhaps, the best example of the current situation of reef-building corals in the Caribbean. Historically, A. cervicornis was one of the most dominant and essential reef-builder coral species in the Caribbean [15]. Its broad vertical distribution, i.e., from a 1 to 30 m depth [16], high branching rates, and impressive asexual proliferation due to branch fragmentation [17] allowed this species to dominate vast areas of the reefscape. These so-called “thickets” also provided the necessary structural complexity to sustain a high diversity of fishes, invertebrates, algae, and microbial organisms [18–20]. However, during the 1980s and 1990s, over 90% of A. cervicornis populations throughout the Caribbean basin died to disease outbreaks and temperature-associated bleaching [4,10,12,21]. Furthermore, during the following decades, the effects of coastal-water
Water 2022, 14, 212. https://doi.org/10.3390/w14020212
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