Demystifying Cassiopea species identity in the Florida Keys: Cassiopea xamachana and Cassiopea andromeda coexist in shallow waters

Abstract

The phylogeny of the Upside-Down Jellyfish (Cassiopea spp.) has been revised multiple times in its history. This is especially true in the Florida Keys, where much of the Cassiopea stock for research and aquarium trade in the United States are collected. In August 2021, we collected 55 Cassiopea medusae at eight shallow water sites throughout the Florida Keys and sequenced COI, 16S, and 28S genes. Mitochondrial genes demonstrate that the shallow waters in Florida are inhabited by both Cassiopea xamachana and a non-native Cassiopea andromeda lineage, identified in multispecies assemblages at least thrice. While C. xamachana were present at all sites, the C. andromeda-mitotype individuals were present at only a minority of sites. While we cannot confirm hybridization or lack thereof between the C. xamanchana and C. andromeda lineages, these previously unknown multispecies assemblages are a likely root cause for the confusing and disputed COI-based species identities of Cassiopea in the Florida Keys. This also serves as a cautionary note to all Cassiopea researchers to barcode their individuals regardless of the location in which they were collected.

Blue appendages and temperature acclimation increase survival during acute heat stress in the upside-down jellyfish,Cassiopea xamachana

“…These corals have phenotypic differences consistent with local adaptation of thermal performance (Palumbi et al, 2014). Similarly, either the temperature or the duration of daily maximum temperature in the Atlantic site may not be sufficient to induce increased thermal tolerance (either via acclimation or local adaptation).While our COI data revealed that all animals used in this study are C. xamanchana, (consistent with sequencing results from (Muffett & Miglietta, 2023)), our data is unable to resolve population-level differences or test for local adaptation. Thus, it is possible that Cassiopea sampled from both sites represent the same population and are thus robust to stable and fluctuating temperatures.…”

“…Given the morphological variation and potential for cryptic species among Cassiopea sp ., (Muffett & Miglietta, 2023) the species identity of collected animals was confirmed. DNA isolated from medusae used for the 2022 acute heat stress experiment was used to amplify the COI gene for sequencing.…”

Bacterial communities ofCassiopeain the Florida Keys share major bacterial taxa with coral microbiomes

“…A total of 55 medusae were collected by wading in eight sites along the length of the Florida Keys in late August 2021 over eight days (see Table 1 for a list of sites). Species identification for each individual is reported in Muffett & Miglietta 2023 and summarized in Supplementary Table S1. At each site, coordinates, temperature, time of day, depth, salinity, and pH were recorded (Table 1).…”

“…One internal swab was placed in DESS, the other in ethanol, as with external swabs. A section of bell tissue was then collected and placed in ethanol for mitochondrial species confirmation (see Muffett & Miglietta 2023). The size of each medusa was taken, and individual medusae were photographed.…”