Lake Merritt Beneath the Surface Zoom presentation
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On June 3rd 2020 Damon Tighe did a Zoom presentation about some of the organisms that live in Lake Merritt and then did a brief Q&A at the end.
Things discussed in the video that are worth a deeper look:
1) iNaturalist Observations for Lake Merritt
2) STEM Education information at Lake Merritt
3) Katie Noonan’s posters
a) Oceanization of Lake Merritt
b) Citizen Science at Lake Merritt
4) Shark and Ray die off event - Bay Nature Article
5) Measure DD - www.waterfrontaction.org
One MAJOR CORRECTION: Slide that talks about the population boom between 1860 and 1870 in Oakland was off by an order of magnitude. 1860 was 1,543. In 1870 it was 10,500 based upon the census data. Big Thank to Gene for catching that in the talk.
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Some of the questions in chat we were not able to get to during the presentation are answered below:
Stacy : Do the sponges grow in a particular region of the lake or all over?
Sponges can be found all over Lake Merritt. The best place to look is for hard substrates that are in the water all of the time
joanne : are there Daphnia in the lake?
Daphnia are a freshwater species so we don’t see them in the brackish water system of Lake Merritt. However Daphnia may be observed in the fresh water inflows, but I have yet to find one
Joel : This is awesome. In the Q&A, I hope Damon can talk a bit about how he sets out to observe at Lake Merritt. Sounds like he is wading in the water. Where? And when he observes something, what is his approach to identification?
When I head out to look for things at Lake Merritt I usually bring a small dish to set rocks, seaweed, etc in which allows time for things to crawl off these substrates. I will usually start to identify organisms by first uploading to iNaturalist, looking at local observations fo the SF Bay and if I’m still getting no where I will use Light and Smith’s manual which is the classic West Coast Marine Biology taxonomy book
Richard : when can you start installing better habitat structures for the invertebrates, e.g. wetland and subsurface structures?
The idea of install habitat structures for invertebrates is interesting and would probably be best for a group like the Water Front Action group to go after. It is important to rember that Lake Merritt is a tidal lagoon so historically is mainly a silty bottom environment.
Sarah : For the Q&A: Are there guided natural history paddles on the lake for members of the public?
I am not aware of any Natural History paddling events at Lake Merritt at this time.
Anne : For Q&A at the end: Do ocean phenomena like El Nino and the Warm Blob have an influence on the lake’s ecosystem?
Warm water events in the ocean definitely do seem to effect Lake Merritt. I think the increase we had of sea hares a few years back was correlated with a warm ocean water event
nurit yael ehrenberg hellion : How deep is lake Merritt?
Lake Merritt is about 10 feet deep at its max
Brian : Could an octopus survive in Lake Merritt?
An Octopus could likel survive the summer months in the lake when salinity is similar to the bay
Judith : Do waterbirds eat any of these snails, mollusks, etc.
Part of the reason for the big diversity of waterbirds at Lake Merritt is this big diversity of invertebrates to eat
Stacy : So are the Hedgpeth’s sapsucker, sea lettuce eater etc nudibranchs? I thought he said they weren’t but they’re so much like them…
Hedgpeth’s sapsucker, the Sea Lettuce easter and even the Sea Hare aren’t in the Order Nudibranchia where the true nudibranchs are. They are in closely related but different Orders.
David : How do you take these photographs?
I usually collect the organism into a jar or discarded item I’ve found around the lake and then transport them back home where I photograph them in a white bowl or a black track I got from Trader Joes that once carried asparagus. The big trick is that I will also collect a bunch of Lake Merritt water that I’ll keep cool in the fridge and filter through a coffee filter to clean up all the little bits in it.
jonbp : How do urban runoff and phosphate pollution affect the lake fauna?
It effect the eutrificiation of the lake as the extra sources of nutrients allows for blooms of various microorganisms
Hilary : aren't sea nettles poisonous?
Only some have a sting that are dangerous
Katerina : we saw dead bat rays in Lake Merritt and lagoons in Alameda...is there an organisation we could/should contact about this?
The group to report any dead rays or sharks to is www.pelagic.org or you can call it in as well (831) 459-9346
Kristen! : Do you keep the sample sometimes to send to organizations?
I don’t keep samples on initial finds. If a researcher contacts me about a specific organisms that usually they have seen on iNaturalist I will work with them on doing proper collection of the orgnaismt