Back to: Seeding

Once resubmerged in seawater, the sori will release spores continuously for the next hour or so. Within the first five minutes, you should begin taking samples of the spore solution and observing them under the microscope. 

Using a pipette, collect a small amount of your spore solution, and place a drop onto a special microscope slide called a hemocytometer. A hemocytometer is a microscope slide that was originally designed for counting blood cells but works great for a visual count of any type of cell—and in this case, spores! When you look under the microscope at the hemocytometer, you will see a gridded pattern. Over that grid, you will (hopefully!) see spores swimming around. Spores should be visible under 100x magnification. This first look will give you an initial idea of how many spores are being released. Keep taking samples every five minutes until you feel like there isn’t an increase in spore density. 

There are two methods to count your spores using the hemocytometer. On closer inspection of the hemocytometer, you will notice that there are nine gridded sections. One method of counting is using all four corners and then taking the average of your counts. This is typically used when the spore density is low, and because it takes into account the average of the entire slide, the value can be considered a bit more accurate. 

The second method is used when there is a high spore density, and you will just count the number of spores swimming in the center grid. Spores can move pretty quickly, and if there are hundreds swimming around, it can be easy to lose track of your value. Some people like to use a handheld clicker to help keep track of their count, and it is always helpful to get several people to do a count and then take the average of what everyone gets. 

We generally recommend that you only count the spores that are actually swimming, because those are considered the healthiest and have the best chance of settling onto the seed string. However, if seeding bull kelp, there is growing evidence that non-motile spores can still successfully settle¹. The video below shows sugar kelp spores swimming around on a hemocytometer.

Once you have your final spore count number, multiply it by 10,000; this converts the value from the number of spores in the area of the slide to a volume of spores per mL. A count of 1 spore means a density of 10,000 spores per 1 mL. This tells you how many spores are in each milliliter of your spore solution. 

You will want to keep taking samples from your spore solution every 10 minutes or so, and once you notice the number of spores you count under the microscope starts to level off, you will know that the tissue has hit its peak release, and it is ready to start introducing that spore solution to your spools. The spores are only motile for 1-2 hours, so around the 45-50 minute mark, you will want to make your final observations to give yourself time to seed all of your spools.  

¹ Pulaski, B. and Konar, B. 2021. Direct release of embryonic sporophytes from adult Nereocystis luetkeana (Laminariales, Ochrophyta) in a high latitude estuary. Algae. 36(2): 147 – 154. https://doi.org/10.4490/algae.2021.36.5.10