Geology topics

Kristopher G. Benson

Publications and source records attributed to Kristopher G. Benson.

2 recordsLinked to original sources

USGS2026

Mesophotic octocoral larval settlement preferences and behaviors

Introduction Lab-based coral reproduction is advancing restoration efforts to support coral populations injured by the 2010 Deepwater Horizon oil spill. Objectives This study aimed to answer foundational questions concerning coral spawning and larval settlement that need to be resolved for these mesophotic and deep-sea coral species before restoration efforts can be scaled up. Methods From 2021 to 2023, fragments of the mesophotic octocorals Swiftia exserta and Thesea nivea were collected from the continental shelf offshore from Texas to Florida and transported to a federal facility in Florida. Multiyear spawning allowed for in-depth analysis of spawning periodicity, egg development, larval behavior, settlement rate, and substrate preference. In addition, we determined the likelihood of successful development and survival during early stages of development. Results Fertilization rates remained high throughout spawning periods of both species, with S. exserta spawning during a 1-month period and T. nivea continuing to spawn year-round. Larvae from both corals significantly preferred tiles seeded with crustose coralline algae, and there were species-specific preferences in substrate material. Additionally, larval survival or mortality was typically evident within a few days when in the presence of settlement substrates. In the absence of substrates, we observed larvae surviving for up to 2 months without settling. Conclusions This work answers critical questions to inform the long-term logistical planning for eventual out-planting of these species. Further, it highlights avenues that could accelerate future restoration-based reproduction efforts into unexplored mesophotic and deep species.

Alabama, Louisiana, Mississippi, Texas↗

USGS2025

Spawning and larval development of the mesophotic octocoral Swiftia exserta in aquaria

The 2010 Deepwater Horizon oil spill injured mesophotic and deep-sea environments over a vast area. In order to restore mesophotic and deep-sea coral species impacted by the spill, information on fundamental ecosystem processes such as reproduction is needed. During expeditions in 2021 and 2022, fragments of the mesophotic octocoral Swiftia exserta were collected from the northern Gulf of Mexico and transported to aquaria at federal facilities in South Carolina, Florida, and Texas. In fall of 2021 and 2022, several of these fragments spawned in captivity, providing an opportunity to learn about their reproduction and inform future restoration activities. Broadcast spawning occurred on 19 and 20 October, 2021, and on 20 days from 29 September to 7 November, 2022. These spawning events permitted detailed observations of spawning behavior and timing, and yielded over 2,400 oocytes. Individual spawns were preceded by a distinctive “spawning posture” in the polyps, lasting between five minutes and two hours, and may have been cued by light. Swiftia exserta larvae settled and developed at comparable rates to other broadcast spawning octocorals, becoming swimming planulae by three days post spawn (dps) and starting to settle by 14 dps. These observations represent the first such records for S. exserta and, more broadly, for any mesophotic coral in the Gulf of Mexico, providing important insights for the restoration of these species. This investigation lays the foundation for future work to explore the influences of seasonal environmental variables, such as light and temperature, on spawning and reproductive seasonality in this species.

Marine Biology↗