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Seasonal Growth of the Purple Sea Urchin Heliocidaris crassispina Revealed by Sequential Fluorochrome Tagging.

ABSTRACT: Many studies have applied fluorochrome tagging to examine the growth of animals with calcified skeletons, but most of them have used only a single tag to determine the annual growth rate. We used sequential fluorochrome tagging to study the seasonal growth of the purple sea urchin Heliocidaris crassispina in Hong Kong waters from February 2012 to February 2013. Sea urchins ranging from 18.9 to 42.7 mm in test diameter had a yearly growth from 0.6 to 13.0 mm. During that year, the sea urchins grew from 0.6 to 5.0 mm in test diameter during the first six months, and from 0.4 to 10.2 mm in test diameter in the second six months. The seasonal differences in growth were confirmed using the von Bertalanffy model. The growth was clear for young sea urchins, especially for individuals less than 5 years old, but was not evident for sea urchins older than 7 years. The seasonal differences in growth were probably related to the reproductive cycle and the seasonal differences in environmental conditions. Our empirical results provide the first evidence of seasonal changes in growth for H. crassispina, demonstrating the usefulness of sequential fluorochrome tagging in studying the growth of sea urchins in the field. We also identify the problem of low recovery of tagged individuals and provide recommendations to improve the tagging procedure.

SUBMITTER: Suarez JDU

PROVIDER: S-EPMC8662310 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:In this research we present a transcriptomics analysis of the physiological response of a marine calcifier, Strongylocentrotus purpuratus, to ocean acidification, a decline in ocean pH that results from the absorption of anthropogenic carbon dioxide (CO2). Larvae were raised from fertilization to prism stage in seawater with elevated CO2 conditions based upon IPCC emissions scenario B1 (540ppm CO2) and A1FI (1020ppm CO2). Adult S. purpuratus were collected using SCUBA from Goleta Pier (Goleta,CA, USA) and maintained in flowing seawater tables at 15-16°C. Spawning was induced by coelomic injection of 0.5M KCl following standard methods (Strathmann 1987). Eggs were collected from 3 females and separately fertilized by sperm from a single male (i.e. all larvae were full or half-siblings). Each of the three replicate cultures were divided in three (nine cultures total) and held in 10L flow-through containers filled with seawater aerated through a side arm with commercially manufactured air containing three different pCO2: 380ppm CO2 (present day atmospheric CO2 level, pH 8.01 ± 0.01), 540ppm CO2, an optimistic atmospheric CO2 concentration predicted by the Intergovernmental Panel on Climate Change for 2100 (B1 scenario, pH 7.96 ± 0.01) and 1020ppm CO2 (A1FI scenario, pH 7.88 ± 0.01). Larvae were cultured at 15°C until prism stage (40h post-fertilization). At the 40 hour time point, a sample of 60,000 larvae was removed from each of the 9 cultures in the 380, 540 and 1020 ppm treatments and stored in 1 mL Trizol at -80 ºC for later RNA analysis. The larval cDNA sample from each replicate 540ppm CO2 culture was competitively hybridized against the 380ppm CO2 control culture from the same replicate female. Similarly, the larval cDNA sample from each replicate 1020ppm CO2 culture was competitively hybridized against the 380ppm CO2 control culture from the same replicate female. Using dye swaps of technical replicates, treatment effects could be estimated independently of dye effects.

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Seasonal Growth of the Purple Sea Urchin Heliocidaris crassispina Revealed by Sequential Fluorochrome Tagging.

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