Environmental influences on the Indo–Pacific octocoral<i>Isis hippuris</i>Linnaeus 1758 (Alcyonacea: Isididae): genetic fixation or phenotypic plasticity?

Rowley, Sonia J.; Pochon, Xavier; Watling, Les

doi:10.7717/peerj.1128

Cited by 16 publications

(7 citation statements)

References 80 publications

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“…Previous studies have also found correlations between depth and growth rates of corals (Thresher, 2009). In shallow water, octocoral community composition and morphology follow environmental gradients of water quality, light intensity, and water movement (Kim et al, 2004;Gori et al, 2011;Rowley et al, 2015;Velásquez and Sánchez, 2015;Shoham and Benayahu, 2017). Although little is known about the effects of depthrelated environmental gradients on deep-sea octocorals (Quattrini et al, 2015), differences in growth rates may be due to food limitation, as the quality and availability of surface-derived food tend to decrease with depth (Suess, 1980).…”

Section: Discussionmentioning

confidence: 99%

In situ growth of deep-sea octocorals after the Deepwater Horizon oil spill

Girard

Cruz

Glickman

et al. 2019

Elementa: Science of the Anthropocene

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Although the role of deep-sea corals in supporting biodiversity is well accepted, their ability to recover from anthropogenic impacts is still poorly understood. An important component of recovery is the capacity of corals to grow back after damage. Here we used data collected as part of an image-based long-term monitoring program that started in the aftermath of the Deepwater Horizon oil spill to develop a non-destructive method to measure in situ growth rates of Paramuricea spp. corals and characterize the impact of the spill on growth. About 200 individual coral colonies were imaged every year between 2011 and 2017 at five sites (three that were impacted by the spill and two that were not). Images were then used to test different methods for measuring growth. The most effective method was employed to estimate baseline growth rates, characterize growth patterns, estimate the age of every colony, and determine the effects of impact and coral size on growth. Overall growth rates were variable but low, with average annual growth rates per site ranging from 0.14 to 2.5 cm/year/colony. Based on coral size and growth rates, some colonies are estimated to be over two thousand years old. While coral size did not have an influence on growth, the initial level of total impact in 2011 had a significant positive effect on the proportion of new growth after 2014. However, growth was not sufficient to compensate for branch loss at one of the impacted sites where corals are expected to take an average of 50 years to grow back to their original size. The non-destructive method we developed could be used to estimate the in situ growth rates on any planar octocoral, and would be particularly useful to follow the recovery of corals after impact or assess the effectiveness of Marine Protected Areas.

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Section: Discussionmentioning

confidence: 99%

In situ growth of deep-sea octocorals after the Deepwater Horizon oil spill

Girard

Cruz

Glickman

et al. 2019

Elementa: Science of the Anthropocene

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“…This may be the result of changes in resource allocation as colonies grow (Heino and Kaitala, 1999), or colonial compensation for decreasing particle capture rates as colony sizes increase (McFadden, 1986), thus having fewer polyps and reducing intracolonial competition and the cost of excess vegetative growth. This may also explain why P. resedaeformis colonies show a high degree of morphometric plasticity as this is believed to dampen the effect of intraspecific competition (Hoogenboom et al, 2008) and increase adaptability to environmental heterogeneity (Stearns, 1989;Shaish et al, 2007;Rowley et al, 2015). The relationship between total branch length and height was unable to be obtained for P. resedaeformis colonies and will be necessary to acquire and combine with published growth rates in future work.…”

Section: Discussionmentioning

confidence: 99%

Individual and Population Level Variation in the Reproductive Potential of Deep-Sea Corals From Different Regions Within the Gulf of Maine

2019

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Deep-sea corals are of conservation concern in the North Atlantic due to prolonged disturbances associated with the exploitation of natural resources and a changing environment. As a result, two research cruises in the Gulf of Maine region during 2014 and 2017 collected samples of two locally dominant coral species, Primnoa resedaeformis and Paramuricea placomus, at six locations to investigate reproductive ecology. Remotely operated vehicles (ROVs) were used to collect specimens that were examined via paraffin histology, and coincident video surveys were used to determine size class distributions. Both species were identified as gonochoristic, and sampled locations exhibited dissimilarities in spermatocyst development and oocyte size except for those in close geographic proximity. Fecundities exhibited substantial ranges across sample locations and average oocyte sizes (±SD) were 140 ± 117 µm for P. resedaeformis and 64 ± 46 µm for P. placomus. In addition, colony size distributions were also significantly different across sampling locations. Notably, the Outer Schoodic Ridge sample location, with larger colony and oocyte sizes, was identified as a potential key source population of reproductive material in the Gulf of Maine. These data were used to calculate differences in reproductive potential based on relationships between colony morphology and reproductive output using height as a predictive proxy. Furthermore, calculated age at first reproduction, 7.6-19.8 years for P. resedaeformis and 20.7-37 years for P. placomus, which may be dependent on sex of the colony, provides a metric for estimating the amount of time these coral habitats will take to recover. This investigation, in response to historical population impacts and environmental change, links reproductive and morphometric relationships to inform population scale reproductive models, while also establishing an understanding of regional scale gametogenic variability within the Gulf of Maine region.

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“…Separation of species using these characters can be subjective, as the complex morphologies of both colonies and sclerites are rarely quantified [1, 14]. There is also a potential contribution of environmental plasticity to the morphological variation observed, as has been documented in other octocorals [59, 92, 93].…”

Section: Introductionmentioning

confidence: 99%

A next generation approach to species delimitation reveals the role of hybridization in a cryptic species complex of corals

et al. 2019

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Background Our ability to investigate processes shaping the evolutionary diversification of corals (Cnidaria: Anthozoa) is limited by a lack of understanding of species boundaries. Discerning species of corals has been challenging due to a multitude of factors, including homoplasious and plastic morphological characters and the use of molecular markers that are either not informative or have not completely sorted. Hybridization can also blur species boundaries by leading to incongruence between morphology and genetics. We used traditional DNA barcoding and restriction-site associated DNA sequencing combined with coalescence-based and allele-frequency methods to elucidate species boundaries and simultaneously examine the potential role of hybridization in a speciose genus of octocoral, Sinularia. Results Species delimitations using two widely used DNA barcode markers, mtMutS and 28S rDNA, were incongruent with one another and with the morphospecies identifications. When mtMutS and 28S were concatenated, a 0.3% genetic distance threshold delimited the majority of morphospecies. In contrast, 12 of the 15 examined morphospecies formed well-supported monophyletic clades in both concatenated RAxML phylogenies and SNAPP species trees of > 6000 RADSeq loci. DAPC and Structure analyses also supported morphospecies assignments, but indicated the potential for two additional cryptic species. Three morphologically distinct species pairs could not, however, be distinguished genetically. ABBA-BABA tests demonstrated significant admixture between some of those species, suggesting that hybridization may confound species delimitation in Sinularia. Conclusions A genomic approach can help to guide species delimitation while simultaneously elucidating the processes generating coral diversity. Results support the hypothesis that hybridization is an important mechanism in the evolution of Anthozoa, including octocorals, and future research should examine the contribution of this mechanism in generating diversity across the coral tree of life. Electronic supplementary material The online version of this article (10.1186/s12862-019-1427-y) contains supplementary material, which is available to authorized users.

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Environmental influences on the Indo–Pacific octocoralIsis hippurisLinnaeus 1758 (Alcyonacea: Isididae): genetic fixation or phenotypic plasticity?

Cited by 16 publications

References 80 publications

In situ growth of deep-sea octocorals after the Deepwater Horizon oil spill

In situ growth of deep-sea octocorals after the Deepwater Horizon oil spill

Individual and Population Level Variation in the Reproductive Potential of Deep-Sea Corals From Different Regions Within the Gulf of Maine

A next generation approach to species delimitation reveals the role of hybridization in a cryptic species complex of corals

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