Load spike protection for Django Channels
Theres a lot of things you cant to do about DDOS..however there are some neat 'tricks' depending on how much resources you have at your disposal, and how much somebody wants to take you offline.
Are you offering a total public service that requires direct connection to the resource you are trying to protect?
If so, you just going to need to 'soak up' DDOS with the resources you have, by scaling up and out... or even elastic... either way it's going to cost you money!
or make it harder for the attacker to consume your resources. There are number of methods to do this. 
If you service requires some kind of authentication, then separate your authentication services from the resource you are trying to protect.
Many applications, the authentication and 'service' run on the same hardware. thats a DOS waiting to happen.
Only let fully authenticated users access the resources you are trying to protect with dynamic firewall filtering rules. If your authenticated then gate to the resources opens (with a restricted QOS in place) ! If your a well known, long term trusted users, then access the resource at full bore.
Have a way of auditing users resource behaviour (network,memory,cpu) , if you see particular accounts using bizarre amounts, ban them, or impose a limit, finally leading to a firewall drop policy of their traffic. 
Work with an ISP that can has systems in place that can drop traffic to your specification at the ISP border.... OVH are your best bet. an ISP that exposes filter and traffic dropping as an API, i wish they existed... basically moving you firewall filtering rules to the AS border... niiiiice! (fantasy)
It won't stop DDOS, but will give you a few tools to keep resources wasted a consumption by attackers to a manageable level. DDOS have to turn to your authentication servers... (possible), or compromise many user accounts.... at already authenticated users will still have access :-)
If your DDOS are consuming all your ISP bandwidth, thats a harder problem, move to a larger ISP! or move ISP's... :-). Hide you main resource, allow it to be move dynamically, keep on the move! :-). 
Break the problem into pieces... apply DDOS controls on the smaller pieces. :-)
I've tried a most general answer, but there are a lot a of depends, each DDOS mitigation requires a bit of Skin, not tin approach.. Really you need a anti-ddos ninja on your team. ;-)
Take a look at distributed protocols.... DP's maybe the answer for DDOS. 
Have fun.
Is there anything specific that can be done to help make a Django Channels server less susceptible to light or accidental DDoS attack or general load increase from websocket/HTTP clients? Since Channels is not truly asynchronous (still workers behind the scenes), I feel like it would be quite easy to take down a Channels-based website - even with fairly simple hardware. I'm currently building an application on Django Channels and will run some tests later to see how it holds up.
Is there some form of throttling built in to Daphne? Should I implement some application-level throttling? This would still be slow since a worker still handles the throttled request, but the request can be much faster. Is there anything else I can do to attempt to thwart these attacks? 
One thought I had was to always ensure there are workers designated for specific channels - that way, if the websocket channel gets overloaded, HTTP will still respond.
Edit: I'm well aware that low-level DDoS protection is an ideal solution, and I understand how DDoS attacks work. What I'm looking for is a solution built in to channels that can help handle an increased load like that. Perhaps the ability for Daphne to scale up a channel and scale down another to compensate, or a throttling method that can reduce the weight per request after a certain point. 
I'm looking for a daphne/channels specific answer - general answers about DDoS or general load handling are not what I'm looking for - there are lots of other questions on SO about that.
I could also control throttling based on who's logged in and who is not - a throttle for users who are not logged in could help.
Edit again: Please read the whole question! I am not looking for general DDoS mitigation advice or explanations of low-level approaches. I'm wondering if Daphne has support for something like:

Throttling
Dynamic worker assignment based on queue size
Middleware to provide priority to authenticated requests

Or something of that nature. I am also going to reach out to the Channels community directly on this as SO might not be the best place for this question.