Holding time or fixative formulation has no obvious effect on histology of Porites evermanni and Montipora capitata

Area of Science:

• Marine Biology
• Histology
• Coral Reef Ecology

Background:

• Coral sample collection for histologic examination involves a holding period in seawater before fixation.
• This pre-fixation period may impact the interpretation of morphologic changes.
• Understanding these effects is crucial for accurate histologic analysis in coral research.

Purpose of the Study:

• To evaluate the impact of pre-fixation holding times in seawater on the microscopic morphology of two coral species.
• To determine if fixation medium (raw vs. artificial seawater) influences morphologic preservation.
• To identify any significant changes in coral tissue morphology related to holding duration.

Main Methods:

• Microscopic morphology of *Porites evermanni* and *Montipora capitata* was assessed.
• Samples were held in seawater for 0-120 minutes prior to fixation.
• Fixation was performed using Z-Fix formulated with either raw or artificial seawater.
• Statistical analysis, including false discovery rate correction, was employed.

Main Results:

• No evident adverse effects on overall microscopic morphology were observed across treatments.
• A statistically significant increase in the degree of mucosity of basal body walls was associated with holding time.
• This finding emerged after 88 statistical comparisons and accounting for the false discovery rate.

Conclusions:

• Pre-fixation holding of coral samples in seawater for up to 120 minutes does not generally affect their microscopic morphology.
• An increase in basal body wall mucosity is a potential artifact of prolonged holding times.
• These findings inform best practices for coral sample collection and processing for histologic studies.