Acropora cervicornis and Acropora palmata cultured on a low maintenance line nursery design in The Bahamas

Abstract

Acroporid corals are one of the most important corals in the Caribbean because of their role in building coral reefs. Unfortunately, Acropora corals have suffered a severe decline in the last 50 years thus prompting the development of many restoration practices, such as coral nurseries, to increase the abundance of these species. However, many coral nursery designs require constant visits and maintenance limiting restoration to more convenient sites. Additionally, most studies lack the details required for practitioners to make informed decisions about replicating nursery designs. Two line nurseries were monitored for three years in The Bahamas to assess the survival of corals, Acropora cervicornis and Acropora palmata, as well as evaluate the durability and cost effectiveness of the nursery design. Survivorship ranged from 70 to 97% with one location experiencing significantly higher survivorship. The initial year build-out cost was high for a nursery, $22.97 per coral, but each nursery was comprised of specific materials that could withstand high storm conditions. Some unique aspects of the design included the use of longline clips and large-diameter monofilament lines which allowed for easier adjustments and more vigorous cleaning. The design proved to be very durable with materials showing a life expectancy of five years or more. Additionally, the design was able to withstand multiple hurricanes and winter storm conditions with little to no damage. Only two maintenance visits a year were required reducing costs after construction. After three years, this nursery design showed promising durability of materials and survivorship of both Acropora cervicornis and Acropora palmata despite being serviced just twice a year.

Effectiveness of different nursery designs for the restoration of the threatened coral Acropora cervicornis in Culebra, Puerto Rico

“…Survivorship of fragments in both nurseries was relatively high (more than 90%), similar to other studies that compared survival between propagation structures, including floating units (Griffin et al, 2012;Maurer et al, 2022). Such high survival rates support the contention that floating structures are an appropriate approach to propagating corals for reef restoration activities.…”

“…An evaluation of nursery designs to select the best approach that enhances coral demographics while increasing cost-effectiveness (i.e., a higher number of corals produced) is essential to improve local restoration efforts. However, most studies measuring the demography of nursery-grown corals lack the details required for managers to make informed decisions about replicating nursery designs (Maurer et al, 2022). Details such as coral farms' productivity, material costs, labour hours, and equipment needed to install and maintain the propagation units are necessary to determine overall costeffectiveness.…”

Fish-based herbivory and the natural maintenance of algal fouling on coral nurseries used across the Great Barrier Reef

“…Coral nurseries naturally attract biofouling, which is widely documented to reduce coral growth and survivorship (McCook et al 2001;Bica and Solomonovich 2020). Fouling algae on nurseries worldwide is typically removed by hand with brushes (Henry et al 2021;Dehnert et al 2022;Maurer et al 2022), a practice yet to be commonly applied by CNP nursery operators on the GBR (Howlett et al 2021). This study tested the extent to which fish grazing on nurseries enabled 'natural' removal of algae, thereby reducing the manual maintenance efforts and associated time and labour costs for CNP tourism operators.…”

“…The challenge posed by algal competition has become a significant concern for restoration projects, leading to substantial investments in anti-fouling approaches, particularly through the application of coatings (Shafir et al 2009;Guest et al 2014;Roepke et al 2022). Despite these efforts, most coral nursery projects continue to rely on manual de-fouling performed by human labour (Johnson et al 2011;Hyde et al 2013;Maurer et al 2022). Though, nearly all efforts to minimize fouling beyond the natural maintenance performed by fish results in additional costs (Fitridge et al 2012).…”

“…Despite this array of designs and applications, all nurseries remain prone to fouling by several algal and invertebrate species (Frias-Torres et al 2015a), which can negatively affect the growth and survivorship of the corals they stock (Johnson et al 2011;Hyde et al 2013). Maintenance of nurseries to remove this unwanted fouling can introduce a significant cost to coral restoration initiatives (Johnson et al 2011;Hyde et al 2013;Maurer et al 2022).…”