I'm pleased to announce the publication of a new collaborative paper in PLOS One:  Lee et al. (2021) Variable host responses mediate host preference in marine flatworm−snail symbioses (Link). In this paper, we investigated how the effects of a symbiotic marine flatworm vary amongst different tropical snail hosts in Panama. We found that the impacts of flatworms can vary from negative to neutral (or even possibly slightly positive) depending on snail host species.   Likewise, we found snails that tended to be more negatively affected by flatworms also exhibited a more vigorous rejection response during worm inoculations.  This work was initially conducted while [the recently graduated] Dr. Lee was an undergraduate student. (Congrats to the new Dr. Lee!)

The Davidson lab is continuing to advance research, even amidst the pandemic. Sarah has nearly finalized a working flume to test how water velocity may impact algae fragmentation. Jessica continues to analyze her data investigating how wood borers altered structural complexity of woody debris. New graduate students Rebecca and Carla are hard at work researching ideas for their projects.  Carla, members of the Kneitel lab, and I are also continuing to sample for aquatic invertebrates and invasive species through the Bushy Lake Restoration Project (pics below). While we suffered a few puncture holes in the inflatable kayak on our most recent trip, we were still able to finish the sampling before the kayak sank. Nothing like some frigid lake water to wake you up on an early Sunday morning. Finally, Cass (with help from Catlinh) are continuing to conduct a meta-analysis to better understand the varying impacts of invasive nutria (a burrowing aquatic rodent). 

Sacramento State students --- please see the flyer below for information on our COAST undergraduate research program! You can earn up to $500 towards a marine/watershed research project in collaboration with a faculty mentor.  Due: Oct 31, 2020. PDF copy of this flyer: 

Members of the Davidson Lab are collaborating with an interdisciplinary team of scientists from Sacramento State and other organizations (led by Dr. Michelle Stevens, Environmental Studies) to help develop a restoration plan for Bushy Lake. Bushy Lake is a small urban-influenced lake off the American River Parkway in Sacramento. While this lake suffers from urban-related disturbances (water quality, invasive species, debris), a wide variety of wildlife use this urban lake as habitat (see pictures below from Dr. Jamie Kneitel). Thus, this site has the potential of becoming a key refuge for threatened native species, such as western pond turtles and various waterfowl.

​The Davidson and Kneitel Labs at Sacramento State are currently conducting preliminary sampling to assess the abundances of invasive and native aquatic invertebrates. Once we finalize our sampling and survey design, we will conduct longer term sampling to better characterize the aquatic community and food web dynamics over time. Ultimately, this information will help us understand the aquatic food web at Bushy Lake and determine what additional control or management options may be necessary to restore this lake for native species. For more information see the Bushy Lake Restoration project website.

Updates: Despite the global pandemic, the Davidson lab moves forward with what research can be done from the safe confines of our homes and computers. Sarah Albright continues to develop and test a device to measure the tensile force of different algae in her garage. By examining the tensile force, she can test the biomechanical properties of different algae species and sizes.  Ultimately, we hope we can infer how algae species and size may influence fragmentation, a method that some invasive algae use to disperse and propagate. Ethan Roberts (now recently graduated!) has moved onto a job with the state where he helps to monitor and control invasive weeds. We're sad to see him go, but happy to hear of his successes. He continues to analyze and write up his research on the environmental effects of isopod burrows. Davidson has been hard at work analyzing and writing up research from his mangrove research on introduced Hawaii mangroves and project examining the biogeography of invasive shipworm borers.  We're all looking forward to returning to the field next season (hopefully) when the infection risk gets low enough. Until then, we'll isolate, keep working on our computer-based projects, and keep wearing our masks. 

Leaf detective:
Good news: I am happy to announce a new paper published in Science Activities called "Leaf detective: using evidence of damage on mangrove leaves to measure the effects of different herbivores."  In this lesson, elementary students examine real mangrove leaves (digitized) to infer which organism(s) caused the damage they observe.  They practice making a scientific question, collect data, graph, and then make a conclusion based on scientific evidence. This lesson represents several years of work and testing in both Sacramento and Hawaii elementary classrooms.  My Hawaii collaborators and I are happy that we can share this lesson idea with K-6 teachers. Please email me for a copy, if you do not have access through the link above. And teachers are welcome to contact me if you wish to discuss ideas on how to adapt it to an online learning environment. 

I hope everyone stays safe and vigilant. Wearing a mask saves lives! 

Congratulations to Ethan Roberts who won 2nd place at the CSUS Spring Symposium for his talk: "Burrows created by an ecosystem engineer improve survivorship of intertidal invertebrates".  Congrats also to Sarah Albright, who successfully completed her Advancement to MS candidacy.  Other lab members are also working diligently, such as Jessica Nichols who is analyzing mounds of field data, and Jenna Grossman who is helping Sarah with algae fragmentation studies and beginning to design her own project. 

In other news, I am honored to receive the university's Outstanding Teaching Award for the college of NSM. I appreciate the support of my colleagues and students! I do love teaching as much as I love research. I am continuing to analyze data exploring how herbivory varies in introduced and native mangroves and collaborating with a Hawaii elementary school teacher and a former post doc adviser to develop curriculum for K-6 teachers using mangroves as a model system. 

Finally, back in January my wife and I traveled to the Galapagos Islands! It was an amazing trip and I'd recommend every biologist and nature lover to visit some time. It is one of the few places that felt pristine with a diversity of huge tree-like cactus, giant tortoises, strange tropical penguins, and an unparalleled wealth of marine life...including of course, my favorite: the beautiful Sally lightfoot crab.  We have still to fully sort through over 1000 photos we took...but here are a few samples. Enjoy! 

This summer lab member Sarah Albright spent every other weekend searching for native and non-native algae throughout San Francisco Bay. As preliminary research for her Master’s thesis, Sarah is creating a list of algae species residing in the Bay, and their current range. Some algae were found everywhere (such as Mastocarpus and Ulva), while others were only found in a few locations (such as at Oakland Port, where she found Codium fragile and Sargassum muticum).

​This Summer, the Council of Oceanic Affairs, Science, and Technology (COAST) hosted undergraduate student internships at several of the 29 National Estuarine Research Reserves across the United States. Lab member Ethan Roberts spent his Summer interning with Jeff Crooks at the Tijuana River National Estuarine Research Reserve (TRNERR), where he helped analyze historical data and update species identification guides. The goal of his internship project was to make the job of identifying cryptic species easier by pointing out key features and making direct visual comparisons, so he took to creating illustrations with pencil and colored pencil. 

Ethan’s work is also novel in that it accounts for species not seen in San Diego previously. For example, some salt marsh habitats at TRNERR are now home to the Princely fiddler crab, Uca princeps, a large tropical visitor not found in any modern field guides (below). As global climate change continues, taking a second look over dated species guides and implementing visual tools may become important parts of doing good science. 

Contributor: Ethan Roberts

COAST offers internships and other research opportunities for undergraduate and graduate students at Sacramento State and beyond! See here for details. ​​

Finally, Ethan Roberts won 1st place at the Sacramento State Student Research & Creative Activity Spring Symposium. Ethan presented his updated results in his talk: "It's not the heat, it's the humidity: burrow
microhabitats created by a boring crustacean ameliorate stressful conditions in the intertidal." He received a small cash prize will be going on to to present his talk in a CSU-wide competition at CSU Fullerton later next month. Congrats to Ethan for his hard work! 

​The newest paper from the Davidson lab has been published in Ecology Letters: 

Davidson TM, Altieri AH, Ruiz GM, Torchin ME. (2018) Bioerosion in a changing world: a conceptual framework. Ecology letters 21: 422–438 - Link


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This review and synthesis paper examines how the process of bioerosion, the breakdown of hard substrata by organisms, affects the structure and biodiversity in ecosystems and the socioeconomics of human systems. Then it predicts how this process is exacerbated or mitigated by human impacts. Many different organisms from bacteria to elephants bioerode substrata and this widespread process occurs all over the world from the deep ocean to the tallest mountains. For example, bioeroders, such as sea urchins, breakdown coral reef or rock to create pits to live in, erosive crabs and rodents create burrows in marsh banks and levees, while others such as lichens may dissolve and grow into stone used in monuments and statues. Thus, this process can have large scale (and sometimes destructive) impacts to ecosystems and human-made infrastructure (such as docks and buildings).

Several human impacts, such as climate change, introductions of invasive species, and nutrient pollution are affecting bioerosion, which in turn can influence how these changes alter ecosystems and human infrastructure.  However, these interactions are complex and interactive, and in many cases, we still do not have a strong understanding of how these human changes will influence bioerosion and future communities. Future work is needed to fully understand how bioerosion will be altered in an increasingly human-dominated world.