Sharks, oceans and stormwater – what’s the connection?

Storm drain exit pipe- showing all the debris that came from the road. Everything that goes into the drain, goes into the streams and lakes, and then into the ocean. There is no treatment.
Storm drain exit pipe- showing all the debris that came from the road. Everything that goes into the drain, goes into the streams and lakes, and then into the ocean. There is no treatment.

I’m heading to @CMOS-CGU 2016 conference in New Brunswick tomorrow.

 

I’ll present citizen science work from last summer’s urban streams exploration.

What does this have to do with oceans and eOceans?
 
Let me explain. 
 
I teach fish ecology field school at Dalhousie University in the summers. Here, we explore lakes and coastal marine ecosystems by snorkelling. This helps me to better understand the data collected by scuba divers that are reported to eShark and eOceans.
 
Last year, I added another course on Urban Freshwater Systems to compliment the fish ecology course. We investigated 9 streams that connect to the ocean – exploring how urbanization affects freshwater, and downstream coastal ecosystems. Many marine fish use freshwater streams and lakes to grow or spawn (see catadromous and anadromous fish), so this is relevant to ocean science. 
 
We found that biodiversity was much lower where stormwater is dumped straight from parking lots and streets into the streams and lakes. Pollution, like hydrocarbons from cars, kills the most sensitive invertebrate species and only those tolerant species, like blackfly larvae and leaches, survive. It also kills juvenile fish and affects spawning fish.
 
This is really important in Nova Scotia where barriers (like dams & culverts) are being removed, and fish ladders are being built to help oceanic fishes move upstream to their spawning and growing grounds – Gaspereau, Eel, salmon etc.
 
If we expend these resources (one recently installed fish ladder cost $4 million) and get the fish upstream to spawn, but their juveniles and prey (benthic invertebrates) are killed by stormwater pollution then the benefits are very limited.
 
One study, for example, found that 95% of juvenile fish had fatal deformities when exposed to stormwater from a highway – their hearts, brains and bodies didn’t function. Holding the water for a few hours, or running it through a soil column, allowed for bacterial breakdown of the pollutants, and drastically reduced deformities to <5%.
 
In our investigation, we found that one industrial site – a big box store complex that installed novel infrastructure that held rainwater back, cooled it down and cleaned up the contaminants by running it through soil before releasing to the stream showed signs of being equal to, and surpassing the biodiversity of the cleanest streams we could find. Really? More diversity next to big box stores then in a forest? Really! 
 
This could be an important finding that shows that development doesn’t necessarily have to come at the cost of biodiversity and ecosystem health if done right. 
 
We need to get another year of data before we can publish it, but this initial study is insightful. 
 
And the connection to sharks?
 
Not in Nova Scotia, but likely in other areas with coastal sharks. See this news story about sharks that died in California as a result of flooding. Taking a watershed approach to terrestrial conservation would mean that water moving downstream would be slower, carrying less debris, and less pollution to estuaries and coastal ecosystems where many sharks, including juvenile sharks, call home. It might also be carrying more fish – important prey items for sharks. 

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