# Clearance rates of sand-burrowed and laterally pressed unburrowed Pismo clam Tivela stultorum (Mawe 1823) in a laboratory open-flow system

## TL;DR

Researchers validated a new way to keep Pismo clams healthy in the lab without sediment, measuring their feeding rates under different conditions.

## Contribution

This is the first study to provide physiological data for Pismo clam husbandry protocols in a controlled lab setting.

## Key findings

- Clams remained healthy for 40 days regardless of burrowing condition.
- Clearance rates increased with flow up to 1000 ml/min and plateaued afterward.
- Microalgal concentrations above 200 cells/µl reduced maximal clearance rates.

## Abstract

Pismo clam extraction is currently banned in Mexico to help the recovery of natural populations. Thus, the primary objective of this study was to gain insight on its basic biology and husbandry protocols. Growth and clearance rate (CR) of sand-burrowed and sediment-free, laterally pressed adult Pismo clams were quantified in the laboratory as a function of burrowing condition, flow, temperature, and microalgal concentration using open-flow chambers. After 40 days, clams remained healthy regardless of burrowing condition and showed a hyperbolic CR response pattern to increased flow, with CR directly proportional to flows lower than 1000 ml min−1. Maximal asymptotic CR values (300 to 400 ml min−1 org−1) were observed from 1000 to 2000 ml min−1. No significant CR differences were observed between burrowed and laterally pressed clams, yet microalgal concentration effects were detected, with constant maximal CRs of ∼250 ml min−1 in the range of 50 to 200 cells µl−1 and decline at higher concentrations. Maintenance protocols of laterally pressed organisms were validated in the laboratory with both weight and CR data. To our knowledge, this is the first study providing whole-body physiological data translated into effective husbandry protocols for Pismo clams. This approach represents a fresh perspective to traditional research areas, opening the possibility for continued experimentation under controlled conditions.

Summary: A novel method for maintaining healthy sediment-free Pismo clams, Tivela stultorum, in the laboratory was validated with whole-body physiological data under various environmental conditions.