Community development in seagrasses

For my work assessing patterns of recruitment on Calvert Island, I’m using a variety of devices to attract larval settlers and mobile adult forms of invertebrates. The devices I use in eelgrass (Zostera marina) habitats target different organisms, including those that are mobile and sessile as adults. The video below shows the installation of artificial seagrass on an array that also contains two settlement plates, and a small kitchen scrubby pad. This artificial seagrass is meant to represent the real thing in shape and texture. However, it provides a uniform substrate that we can use to look at how the communities that grow on the surfaces on eelgrass leaves differ across meadows and as you move from the edge to the interior of the meadow.

Video by Derek VanMaanen and Zach Montieth. Thanks for installing these ASUs! And, thank you, Krystal Bachen, for making them. Emily Adamczyk, thank you for the inspiring design. Finally, thank you, Minako Ito, for bringing the materials for these from Japan and kindly leaving them for us to use!

Invertebrate recruitment and gearing up for Seagrass BioBlitz 2018

In late May 2018, I traveled to Calvert Island for my monthly visit. I’ve been going up since February this year, one week each month, and during my time on the island I observe patterns of settlement and recruitment of marine invertebrates. I work across habitats — eelgrass, kelp, rocky shore — and across gradients of water flow and wave exposure. I measure rates of recruitment on a variety of devices: PVC plates, wooden scrub brushes, kitchen scrubby pads. Small animals either settle on my devices from planktonic larvae or they crawl or swim from nearby benthic habitats.

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Types of settlement devices (photo credit: Kyle Hall, Derek Van Manaanen)

This work is inspired by the diverse and heterogeneous landscape of Central British Columbia, which contains hundreds of islands separated from mainland areas by glacially-carved and now-flooded fjords and channels. This work also follows directly from last summer’s BioBlitz (intensive biodiversity survey) put on by the Hakai Institute and Smithsonian MarineGEO. In three weeks, we observed nearly a third of the known invertebrate fauna characteristic of the region that stretches from northern California to the Aleutian Islands, roughly 1,000 species. One thing that struck us ecologists, taxonomists, and natural historians was the high rates of recruitment that we saw in high invertebrate abundance with dominance of younger age classes. What makes this place so diverse and plentiful? Tackling this question is one of my goals for my postdoctoral fellowship with the Hakai Institute.

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credit: Amanda Bemis, Gustav Paulay, Leslie Harris, Josh Silberg

At the end of June 2018, I’ll be running another BioBlitz, this time focusing on seagrass, the habitat we sampled least last year but know is essential for providing shelter and foraging grounds for a variety of fish and shellfish. Seagrass habitats also happen to be natural laboratories for ecological work at University of British Columbia (Mary O’Connor and Laura Parfrey labs) that investigates the structure and dynamics of meta-communities. This work will benefit from increased taxonomic resolution of the flora and fauna associated with seagrass. One of the goals of this year’s BioBlitz is to generate an exhaustive field guide to the algae and invertebrates that can be found in seagrass habitats around Calvert Island.

With my recruitment work in eelgrass (Zostera marina) I’m  starting to add to our growing species list of seagrass fauna. I’ve been identifying, photographing, and preserving specimens to help connect the smaller life stages of animals (larvae or juveniles) to their adult counterparts. Here’s a sampling of some of the organisms I’ve been finding.

 

 

I think my favorite creatures right now, though, are echinoderms. I’ve been finding lots of urchin and cucumber juveniles that are very small, only 1-3mm large, and I presume that they recently settled out of the plankton onto my brushes and scrubby pads. Here are some echino-treats for all the enthusiasts out there

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I’m also finding lots of tiny organisms that I am unable to identify. Luckily, we have a great team of experts joining us next month to work on these tiny organisms, including harpacticoid copepods, diatoms, protists, flatworms, and mud dragons! Here’s a short video to give you a sense of just how many copepods and diatoms I find in some of my samples:

 

Okay, that’s it for now. We’ll have some coverage of the seagrass BioBlitz through Hakai Magazine, and I will try to contribute more observations to the blog in the coming weeks and months.

 

UPDATE: I zoomed in on the shot of the hydroids and saw one of them budding off a medusa!

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