watershed

So far as we can tell, there is at least one species that has not been impacted by the recent fire event:  the humpback whales.  These wonderful creatures have been moving up and down the coastline: playing, feeding and TALKING!  For several weeks now, their noisy grazing along the kelp beds has produced unusual sounds that drift up through the fog.  It is as if they are right below us, but we can’t spot them.  And the sounds become even spookier in the moonlight at night.

 

How could these sea creatures be impacted by the fire event?  This connection of the land and sea occurs in at least one place, and that is where the streams flow into the ocean.  All of the land area that feeds water into this outlet is called a Watershed.  As water flows over the land area, it picks up nutrients, sediment and pollutants, and transports them to the outlet.  All of these things can affect the ecological processes along the way, and at the mouth of the watershed.

 

Just recently, we heard from the BAER and SEAT teams that they are going to take a look at the “drainages” along the Big Sur coast.  They are analyzing the land to try to make a determination of how rainfall will move over these “watersheds” and what the impact will be along the way.  It isn’t a coincidence that scientists are interested in these watersheds.  Even before the fires, several scientists came to the Reserve to begin discussions on a collaborative study of the Big Creek watershed.  Melissa Foley, a graduate student at UCSC basing her field work out of Big Creek Reserve, is studying the connections between terrestrial and marine ecosystems along the central California coast. She is particularly interested in where nutrients come from that are used by giant kelp and other organisms living in kelp forests. Melissa has been measuring the nutrients that come from the ocean (i.e. upwelling, decomposition of plankton) compared to nutrients that come from the land (i.e. watershed output of sediment). She has been sampling kelp and other organisms close to and far away from various creeks along the Big Sur coast to determine their isotopic signature, which reveals the origin of nutrients and food sources.

 

What Melissa is finding is that kelp forests far from creeks get the vast majority of their nutrients from ocean sources, whereas kelp forests adjacent to creeks incorporate both ocean-based nutrients and nutrients delivered from adjacent watersheds. However, as you would suspect, terrestrial nutrients are more important during the rainy season, when more of them are washed to the ocean. So while there is a background of ocean-based uptake along the coast in general, kelp forests that are situated next to watersheds show a pulsating pattern of uptake from the land. While it may seem to make intuitive sense, this type of direct connection between terrestrial and marine ecosystems has not been thoroughly investigated before and adds exciting detail to our understanding of the coastline as a whole. Melissa is now proposing to look at this winter’s impending runoff from burned and unburned watersheds to see if the relationship between these adjacent systems changes drastically after a large-scale wildfire. It will be very interesting to see how the fires affect the kelp forest.

 

We’re hoping that Melissa’s work can provide the springboard for more research on land-sea linkages. We recently held a workshop at the Reserve that included Steve Lindley and Dave Rundio from NOAA’s Southwest Fisheries Science Center in Santa Cruz; Jonathan Moore, a UCSC freshwater ecologist; and Tim Tinker, a long-time UCSC sea otter researcher. Lindley and Rundio have been studying the steelhead (as reported earlier in the RoundUp) in Big Creek for the past four years and have detailed data on stream invertebrates, water quality and flow. Tinker has been studying movement, diet and infectious diseases in sea otters from Monterey Bay to Santa Barbara. During the workshop, various intriguing questions came up: What infectious diseases affecting sea otters are running off from the land? Does that differ between urban and rural areas? Do insect larvae that filter water in the streams impact what is being delivered to the oceans? How much influence is there in the other direction, from the sea to the watershed, via deposition of seaweed onto beaches and creeks, returning steelhead or even seabirds feeding upstream? In nature there’s almost never a one-way street.

 

This workshop was just one example of the Reserve’s mission; to provide a venue for the expansion of our knowledge of the natural world by culturing collaborative research. As a result of our workshop, the participants were eager to write proposals, start collecting data and answer these questions. Using the data Melissa, Steve and Dave have gathered, we’re hoping Jon Moore will get some graduate students to work at Big Creek and Tim Tinker will have a team doing otter surveys in the area this Fall. So, you may see folks with binoculars and datasheets, who look like biologists, sitting along the coast this coming year. Stop and ask them about their sea otter research, and see if they can tell what the humpbacks are talking about!

 

Mark Readdie and Terry Hallock