In science there are many jargon words that have off-putting names but are rather simple and understandable once someone pulls you aside and explains it. Connectivity is also one of these jargon words but it is actually not that hard to understand once someone takes the time to tell you what it means. Like most things in science, connectivity is best explained in an analogy and not a definition.
It might be a little easier to think of connectivity in terms of people in cities instead of groups of fish in a salt marsh or a reef. In urban environments, a lot people travel into the city from the surrounding suburbs to work every day. In this way, cities and their surrounding suburbs are connected and therefore typically have high levels of connectivity. Because cities and suburbs share a lot of same people and have high connectivity, what happens in the city likely has an impact on the surrounding suburbs.
In addition to everyone’s favorite time, the daily commute (shout out to the brave souls on the 405), a large number of people travel from city to city via planes, trains or automobiles. This number of people is much less than the number of people that make a daily commute from the suburbs into major urban areas. In this way, different cities still experience connectivity with each other, but are less connected than cities and their surrounding suburbs. Following along still?
Fish move around to different places just like people. It is important to understand why fish move and where they are moving to and which environments they are connected. Are fish leaving an area because there isn’t enough food? Are they leaving because there is enough food but are being outcompeted for space? Connectivity through movements between habitats can help us understand these questions and help us grasp what makes good environments for fish. In my Master’s work, I used connectivity to understand how well we have rebuilt (aka restored) salt marshes work as habitat for fishes in Southern California. So far, things are looking good; fish seem to like the homes we built for them.
Apart from being important for restoration, understanding the connectivity helps us manage the threats fish face including pollution, fishing pressure, and habitat loss. Did this fish I am eating use contaminated habitat? Is the whale population that brings in tourism dollars effectively protected? Is habitat restoration or designating no take reserves increasing the number of fish in fishable areas? Is this fish I caught today the same fish I caught somewhere else? These are all connectivity questions that fish tracking has a role in answering.
However, answering these connectivity questions can be tough, expensive, and require long, long hours, as I am sure many of my friend’s blog posts here will touch on. Arrays managed by one project team or person can only be so effective and cover so much area. Many times, the limits on arrays cause the loss of really cool large-scale connectivity stories. For example, fish tagged from my Masters moved extremely far distances to areas far from where I had receivers. For example, one small young shovelnose guitarfish traveled 40 km from the small protected estuary I worked in all the way to Santa Monica Pier, one of the most heavily visited and fished piers in southern California. This is really far distance for a relatively small fish to travel and it would have had to move through a variety of different habitats and risk being eaten to make it to Santa Monica Pier.
How did I know about this cool large distance movement? Well, it wouldn’t of been possible had another project not of been there and shared the data with me. So basically, this totally awesome finding was by a stroke of luck! The idea of all the potential lost data on long-term movements stuck with me for years after: how many large scale connectivity stories were we missing simply because the small size of the arrays? Are researchers and research managers really getting the full-picture?
And this my dear friends is why SCATTN is so important: using partnerships to better understand these large-scale connectivity questions that have eluded us for so long. Only by using each other’s arrays and sharing data, will the large scale movements of so many species be understood. This is especially important for my work at the Channel Islands National Marine Sanctuary as a lot of the environmental protections we implement are by setting aside certain habitats, which includes things like marine protected areas. However, if we know that a number of fish move beyond the boundaries of these protected areas or experience high connectivity with a site just outside a protected area, then we as managers need to adjust where protections are. By scientists working together, we can start to document these large-scalemovements to paint a better picture of connectivity for resource managers, which will hopefully end in a healthier ocean of all.
*. For definitions of these jargon science words please see the science jargon translator available on the SCATTN website
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Ryan is former member of the CSULB Shark Lab and his master's focused on the movements of juvenile estuary fishes and sharks. He currently is a PhD student at UCSB and working as a Research Operations Specialist at the Channel Islands National Marine Sanctuary.