A Journey in the kelp

Dr Jesse van der Grient

It has been wintertime, but does that mean our zooplankton nets are empty? Not at all, we had some surprises indeed! Over this time, we had many pieces of kelp turning up in our nets. Now, when they are big, this is not a real problem, although we need to make sure their animals are not counted as zooplankton (while they go for a ride, they could not possibly hope to be zooplankton!) However, with all the storms we have had lately, the kelp pieces are not necessarily big anymore. No indeed, they have turned into confetti! This makes sampling interesting, and hard. Mainly because we are looking for fish larvae which are now turning up in the water column – try find the fish larvae in the photo! We also had the privilege of having the amazing help of a FICS student to help sort and count many of our zooplankton samples.

Surprising catches in the zooplankton nets. We caught many a piece of kelp, including big ones (top, you can see various kelp-associated amphipods and isopods in the tray too), but it becomes more challenging when these pieces look more like confetti (bottom). A beautiful surprise was a siphonophore (right), a gelatinous carnivorous colonial animal
It does make you wonder about these effects on zooplankton (imagine having to dodge all those pieces floating around while looking for your food!) and the frequency of these occurrences. We collected over 200 fish larvae and photographed them all to support Rhian’s thesis on the zooplankton of the Falkland Islands. Besides the amazing zooplankton animals, we saw some bigger ones, too.
The Falkland cetaceans deserve a supervision award - they are constantly visiting our boat while we are working, to much delight of the researchers.
Megan Shapiro holding the camera in place to observe the mysterious seafloor (left). The camera is ready for when we are on station (right).
A long-expected video survey
Besides looking at the water column, this time the project also looked at the seafloor (for a change). With the help of Megan Shapiro, we went out with a camera to video the seafloor north of Kidney Island, at depths between 30-50 m. Our aims were to see what is there, and to find squid eggs in the deep. Our Patagonian squid is a little unusual for a loliginid squid – other species of loliginid squid attach their egg masses on rocky seafloor, while ours attach them to kelp. However, there has not been a systematic survey in the Falkland waters to check whether the squid solely lay eggs in kelp or use other substrates as well. If our squid also attach their eggs to rocks in deeper waters, then there is an unrecognised flexibility in the population regarding egg-laying behaviour. Further, it would mean that the spawning area of the squid might be much larger than the kelp forests. Deeper waters are colder, so if our kelp forests warm, which has influence on the squid egg development, the squid may prefer the deeper colder waters. We did indeed find egg masses in deeper waters (around 50 m depth) attached to rocks! It might be more widespread, but now the question is why and when do the squid decide to change? Hopefully future work will answer some of these questions.
The window on the squid physiology
How do squid egg masses respond to coastal warming? Well, the physiology experiments are up and running again, and with some initial setbacks, the data are starting to look very interesting. Warming results in higher respiration rates, which can be distinguished from the increase in respiration rates as the squidlings develop from embryo to tiny hatchling. Why focus on respiration? Respiration is a measure for energy consumption – higher respiration rates mean more energy is needed. As a developing baby squid, you have a limited food supply (in the form of the yolk sac). This supports their growth but is also important in the first few days of hatching (in case they cannot find food immediately, they have a “packed lunch”). If the hatchlings require more energy during development, they may have less lunch left upon hatching, meaning that the first few days as hatchlings could be more challenging. They could also be smaller – this has been demonstrated in other squid species, and we will check this once our hatchlings are there. Less “packed lunch” and/or being smaller will make this life stage of the squid more challenging, which could have implications later in terms of how many squid can make it to adulthood. If it will be the case or not, we do not know yet, but we are making progress in this puzzle.

Squid egg masses collected on the RV Jack Sollis (left) are ready for the physiology experiment (top middle). Measuring the effects of warming on squid egg respiration help us understand some potential effects of climate change (right). Hatchling squid are small, but even smaller in warmer water conditions (bottom middle)
A food-web unmasked
The implications for changing in squid development for the wider marine food web and fisheries can be tested in ecosystem models. We are making progress with the Falkland model. The static part (a snapshot as it were) of the energy flows is finished, showing some unexpected biomass predictions for deep pelagic (think deeper than 200 m deep) fishes, and gelatinous zooplankton (jellyfish, comb jellies, siphonophores, arrowworms, etc.). We are currently working on the dynamic part, so we can investigate effects over time. We can run some future scenarios as well, but we are focusing on calibration – that is, can the model reproduce historical biomass trends? If it can do that, we can have a little more faith in the future predictions.

None of the fantastic work/adventures described above would have been possible without the tremendous help of all our partners, and I am grateful for the opportunities they provide. Thank you to FIFCA, FIG, FIFD, SMSG, OSU, and BAS for their continued support.


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Stanley Cottage
Falkland Islands
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