Symbiosis

Coral reefs worldwide are experiencing unprecedented and rapid declines. However, deeper, mesophotic coral ecosystems (MCEs; 30–150 m) may act as refuges for coral species, providing larvae to recolonize degraded shallow reefs. This study assessed the genetic connectivity of shallow and mesophotic Montastraea cavernosa populations on the Belize Barrier Reef and the community structure of their endosymbiotic algae (Family Symbiodiniaceae) across a fine-scale depth gradient (10, 16, 25, 35 m). Evaluation of nine polymorphic microsatellite markers demonstrated that relatively shallow (10 and 16 m) M. cavernosa populations were genetically distinct from relatively deep (25 and 35 m) populations. High throughput sequencing of ribosomal coding DNA from Symbiodiniaceae communities of M. cavernosa revealed differences in community structure across depth, with shallow-specialist and depth-generalist community profiles. This research provides important information for the management of distinct deep and adds to the body of research on the understudied MCEs of the Mesoamerican Reef.

A mutualistic symbiosis exists between the alga Sargassum spp. and two shrimp species, L. tenuicornis and L. fucorum. But little is known about how the shrimp locate their host alga. Both visual and chemical cues are potentially available. Visual cues would be presumably restricted at night but chemical cues are potentially available continuously. Additionally, a previous study has looked at both cue variables with results that are mixed. This current research elaborates on the previous study in an attempt to fully understand Sargassum shrimp chemoreception. A y-maze and four-chambered apparatus were used to test if the shrimp were able to detect Sargassum cues, conspecific cues, and Dimethylsulfoniopropionate (DMSP) cues. Neither shrimp species showed a strong directional response to any of the chemical cues, but the Sargassum and DMSP cues did cause more shrimp to exhibit searching behavior. Additionally, several differences in response between male and female shrimp were found for each cue. A weaker dilution of DMSP was tested in an attempt to determine sensitivity of L. fucorum shrimp to the chemical cue. This weaker dilution also caused L. fucorum to exhibit searching behavior, but the sensitivity to the cue was not found and further research is needed to fully answer this question. These results show the shrimp are able to detect chemical cues in their environment and help determine more accurately the role of chemoreception in initiating and maintaining this shrimp/algal association.

Cladonia perforata is an endangered lichen endemic to the Atlantic Coastal
Ridge, Lake Wales Ridge, Southwest Florida, and the North Gulf Coast of Florida. In all
but a single locality, C. perforata relies entirely on asexual reproduction through
fragmentation for reproduction, dispersal, and recruitment. This study suggests a positive
correlation between fragment size and survivability of fragments after one year. The
average thallus grew at a rate of 10.42% per year and younger branches of a thallus grew
at a quicker rate than older branches. Additionally, a review of thalli morphology
suggests C. perforata has a diverse form, and becomes more bifurcated as it increases in
size.