A monitoring and assessment project conducted during 2020-2022 allowed for evaluation of water quality and clam seed health in Florida shellfish hatcheries and nurseries. The following problem-solving guide utilizes information generated through this project (referred to as Clam Seed Project) to assist seed producers in understanding and alleviating seed mortality at their facilities.
Have you been experiencing slow growth, abnormalities, fouling, and/or mortalities of larvae, post-set and/or juveniles at your hatchery or nursery facility? This guide will take you through the steps, one-by-one, to determine possible causes and provide resources so you can make informed management decisions to improve seed health and increase production. Expand each tab below to address factors related to your production facility.
Have you measured the salinity and temperature of your culture water?
Other important parameters to measure are dissolved oxygen, pH, and alkalinity.
Great! Proceed to the next step.
Below is a list of resources for understanding basic water quality parameters.
These fact sheets identify basic water quality parameters and recommended values for aquaculture. If one of your parameters is out of range, troubleshooting procedures and comments are provided as an aid.
You may choose to invest in monitoring equipment to better understand water quality at your location. There are many options available to get you started. Check out the Equipment Vendor List and Video Resources to get started.
Have you tested your incoming source water for chemical composition? This can include testing for a full suite of ions, harmful metals, regulated inorganic chemicals (IOC), volatile organics (VOC), pesticides, and herbicides?
Acceptable values or recommended ranges for most of these parameters have not been established for shellfish aquaculture. The observed values measured at facilities participating in the Clam Seed Project during 2020-22 may serve as a reference for comparison to your water supply source or incoming tank water values. If one of your parameters is out of range, troubleshooting procedures and comments are provided as an aid.
These compounds have a high vapor pressure and low water solubility. Many are human-made chemicals used and produced in the manufacture of paints, pharmaceuticals, and refrigerants. Acceptable values or recommended ranges of volatile organics (VOC) have not been established for aquaculture. Water samples collected annually from facilities participating in the Clam Seed Project were analyzed for 80 VOCs. The observed values may serve as a reference to compare with your water supply source or incoming tank water values.
In year 1 (2020-21), nine of the 10 facilities had VOC values less than the reporting limits, which are the smallest amount or lowest concentration of a substance following established EPA analytical procedures. One facility had a recorded value of 25 ug/L for Tetrahydrofuran, which has a reporting limit of 20.0 ug/L. Tetrahydrofuran is used to make a variety of products, like plastics, rubbers, adhesives, and PVC pipes. Tetrahydrofuran is not expected to build up in tissues of fish or other wildlife. To learn more about Tetrahydrofuran, visit Minnesota’s Department of Health factsheet.
In year 2 (2021-22), nine of the 10 facilities had VOC values less than the reporting limits. One facility had recorded values of 51.4 ug/L for Acetone and 8.4 ug/L for Bromoform; reporting limits for these compounds are 30.0 ug/L and 1.0 ug/L, respectively. Acetone is a common industrial solvent used to clean surfaces, effectively removing dirt, grease, stains, waxes, resins, and paint from metals, PVC and other surfaces. To learn more about Acetone, visit the CDC factsheet. Bromoform is a colorless liquid with a chloroform-like odor. Bromoform can be used as a disinfectant and solvent for waxes, greases, and oils. To learn more about Bromoform, visit the EPA factsheet and CDC factsheet.
For a full list of VOCs analyzed by Midwest Laboratories, visit their online catalog and search for EPA 8260- Water Volatile Organics (VOC) package.
Acceptable values or recommended ranges of pesticides have not been established for aquaculture. Water samples collected in 2021-22 from nurseries participating in the Clam Seed Project following a mosquito control spraying event were analyzed for 20 pesticides. After contacting local mosquito control departments, Naled was determined to be the active ingredient sprayed near two of the nursery facilities. Both facilities had reported values less than the reporting limit of 1.0 ug/L for pesticides, which is the smallest amount or lowest concentration of a substance that can be determined following established EPA analytical procedures. Permethrin was the active ingredient sprayed near the other nursery facilities. Analytical labs contacted could not test water samples for this pesticide.
Additional resources:
Acceptable values or recommended ranges of herbicides have not been established for aquaculture. Water samples collected annually in 2020-22 from nurseries participating in the Clam Seed Project were analyzed for Glyphosate. All facilities had reported values less than the method detection limit of 10 ppb in both years. This limit is the smallest amount or lowest concentration of a substance that can be determined following established EPA analytical procedures. The observed values may serve as a reference for comparison to your facility’s incoming water supply source or tank water values. To learn more about Glyphosate, visit the EPA factsheet.
You may choose to invest in testing specific compounds in your source water to better understand water quality at your location. There are many analytical laboratories to choose from. Before testing for pesticides and herbicides, contact your local mosquito control or transportation departments to determine the active ingredient used for spraying and when the next spraying event may take place.
For the Clam Seed Project, Midwest Laboratories conducted analyses for the following:
Website: https://midwestlabs.com/contact-us. Visit their online catalog for more information.
For the Clam Seed Project, Waters Agricultural Lab conducted the herbicide analysis for Glyphosate.
Website: https://watersag.com/
Have you sampled your hatchery for potential problem areas that chronically harbor microbes (“hot spots”) using bacterial plating methods? Examples of “hot spots” include incoming water, larval tank water, maturation tank water, larvae, algae stock cultures, and air supply.
You may choose to perform your own bacterial plating or to send samples to a lab for analyses. This could help you determine your bacterial load and proportion of non-pathogenic and pathogenic Vibrio bacteria.
Resources to perform bacterial monitoring using plating methods at your facility:
Laboratories to send samples for bacteriology analyses:
Sampling, packing, and shipping instructions:
Prior to sampling, contact the lab to obtain specific instructions and submission forms and to ensure they can receive samples. Place samples of moribund (in terminal decline, but not dead) shellfish and/or culture waters in new ziplock or Whirl-Pak® bags and ship in a Styrofoam box with a frozen gel pack. Ship immediately after collecting samples via overnight courier during the first of the week. Shipping and analyses will be at the facility’s expense.
Hard clams have notably few infectious diseases compared to other bivalve mollusks and to date no problems due to infectious diseases have been observed in cultured clams from Florida waters.
Laboratories to send samples for histopathology analyses:
Sampling, packing, and shipping instructions:
Prior to sampling, contact the lab to obtain specific instructions and submission forms and to ensure they can receive samples. Place samples of shellfish in new zip lock or Whirl-Pak® bags and ship in a Styrofoam box with a frozen gel pack. Ship immediately after collecting samples via overnight courier during the first of the week. Shipping and analyses will be at the facility’s expense.
For Hatchery Operators:
For Nursery Operators:
Check out the Algal Culture Workshop Resources to get you started. Learn how much to feed and how to perform sterile inoculation techniques for algal cultures.
Additional resources include:
Great! Proceed to the next step.
The What Do Clams Eat pictorial guide was developed to assists shellfish growers in identifying potential food sources for hard clams, spatial and seasonal distribution of food, and whether the food is good (nutritious) or bad (noxious or harmful) for clams. The guide focuses on two regions of Florida – Suwannee Sound on the west coast, where clam leases in Dixie and Levy Counties are located, and Indian River Lagoon on the east coast, encompassing clam leases in Brevard and Indian River Counties.
You may choose to send a water sample to determine phytoplankton quality and quantity.
Contact:
Procedures:
Packing and Shipping Instructions:
Prior to sampling, contact the lab to obtain specific instructions and submission forms and to ensure they can receive samples. You may need to preserve water samples prior to shipment. Ship samples in a Styrofoam box with a frozen gel pack via an overnight courier during the first of the week to: Dr. Ed Phlips, University of Florida, Fisheries and Aquatic Sciences, 7922 NW 71st Street, Gainesville, FL 32653. Shipping and analyses will be at the facility’s expense.
Think about your routine management practices. Are there potential changes that could be made?
The University of Florida/IFAS in partnership with Florida Atlantic University, Harbor Branch Oceanographic Institute developed educational materials to assist molluscan shellfish seed producers in Florida with funding through the Florida Sea Grant College Program (R/LR-A-63).
