Indentifiying plankton - a rollercoaster of knowledge

Back in 2022, I was just starting my journey into marine plankton exploration. I knew nothing at all, only being aware of tiny marine organisms through examining intertidal seaweed specimens under a microscope. A 2-day ‘Introduction to zooplankton identification’ course at the Marine Biological Association in Plymouth really jump-started my fascination and eagerness to learn all that I could about plankton. From that point on (with a new plankton net in hand), I was self-taught - scouring books, papers, and websites, and bugging others for information about the things I was looking at under the microscope (I’m enormously grateful to those people).

One of the first things I learnt was just how massive an umbrella term ‘plankton’ is. Well, that’s not entirely true. It seemed that I had to go through my own ‘Dunning-Kruger effect’ first! On the surface, plankton ID seemed pretty straightforward. Some books showed me pictures of things that looked like the things that I was seeing, and I assumed that those things were the same. Over time, I came to realise that there can actually be a lot of things that looked like the things I was seeing, and that I needed to take a step back and really deep-dive into some of these organisms to tease out the distinguishing features (and I’m still doing that today). It was easy to feel disheartened when I realised how much I didn’t know, but the love of these little organisms and the addiction of finding new things literally every time I looked kept me moving forward.

I learned lots about many of the taxa I was observing. Some groups were easy to find out about; others, not so much. When you’re looking at plankton overall, and not specialising in a particular group, you have to become a ‘jack of all trades,’ as it were. I came to understand that I needed to know what I needed to know, and the rest can wait for retirement.

But even then, there are areas of plankton ID that are best left to the specialised (for me anyway). I’ve come to accept that I will never know everything, to take the knowledge when I can get it, and let some of the harder stuff go (for now). For example, I did a deep dive into Bryozoa cyphonautes larvae and learned how to ID most of the species. Then I discovered Bryozoa coronate larvae, which appear to be a lot harder to ID, so I currently choose to leave the ID at ‘Bryozoa coronate larva’ when I come across one. It’s similar with gastropod larvae. I’m sure there must be a handful of people out there who can ID a gastropod veliger larvae to genus, or even species, but I’m not one of them, at least not yet, so I still record them as ‘Gastropoda veliger larvae’.

Whilst there is a lot of information out there about some taxa (copepods and diatoms appear to be well covered), there is still a lot we don’t know, especially about meroplankton (larvae of benthic stuff), and a lot of ID that can only be done with DNA. Taxonomy is also always being updated and changed as new information comes to light, which is exciting, but can be confusing for citizen scientists.

I’ve been studying local Norfolk plankton for over 3 years now, and whilst I’ve learned a lot, there are still massive gaps in my ID knowledge, and that’s OK. My records for any given sample have a mixed ID resolution, from Phylum for some taxa (Nematodes, for example), families for others (Polychaetes - but there are still a lot of examples filed under ‘Indet. Polychaeta larva’), up to species (I can spot over 50 diatom species at 20 paces, but my Chaetocros spp. need a lot of work!). There are taxa I still really struggle with, and have to ask for help from folks who know more than me (dinoflagellates, for example).

It’s tempting to want to know everything, right away - believe me, I’ve been there! But that can be exhausting, and when you rush, you can miss important bits of information. Saying that, I’m not sure that I would want to take my plankton journey in any other way. The mistakes I’ve made have been an important part of getting information to stick in my head. I’m so glad I never gave up, that I went through the painful moments of low confidence (I still do quite regularly), because I’m so proud of what I have learned - the fact that I can give a talk about plankton without looking at notes, that I can list lots of taxa without having to remind myself how to spell them, that I can help others to discover the wonders of plankton themselves - these are all things, that in my early days of plankton surveying, I never thought I would be able to do.