Current Lab Projects
The Seasonal Dynamics of Sandy Habitat Geomorphology and Epifaunal Associations on the Continental Shelf of Monterey Bay, California.
In many areas geomorphology drives species distribution and abundance. On the continental shelf, the sandy plains habitat comprises one of the largest habitats of the north-eastern Pacific and is of great importance to California’s largest commercial fisheries, Dungeness crab and market squid. Yet, large knowledge gaps remain and impede a clear understanding of the dynamics of the sandy substrate geomorphology as well as for understanding of what drives organismal distributions. This research will investigate how structural changes of the seafloor of the continental shelf (15-160 m depth) impact the biological habitat. Seasonal use of, acoustical methods (mulitbeam and side scan sonar) will be used to quantify geomorphological dynamics of the seafloor and video methods gathered via remotely operated vehicle will be used to quantify associated epifaunal species densities. The results of this research will not only fill needed knowledge gaps for the scientific community but, it will also provide timely information to coastal marine resource managers and policy makers. Funding for this project is provided by the National Science Foundation.
Acoustic bathymetric profile of the Monterey Harbor shale beds (left photo) and aggregation of market squid (right photo) along continental shelf sandy habitat.
The Value of Habitat Diversity in Marine Reserves: Spiny Lobster and Sheephead Use of the Intertidal Zone at the Santa Catalina Island MPA.
A guiding principle in the design of marine protected areas is that a diversity of habitats must be included to provide the complete range of ecosystem services for exploited species. This is especially true of species that use different habitats at different times in their reproductive cycles. In this study we propose to use a long term data set on intertidal habitat composition and demography of sheephead and spiny lobster in the Santa Catalina Island MPA. This set of data is unique in that it contains information on intertidal habit composition and demographic information for spiny lobsters and sheephead in the years preceding the establishment of the MPA, the year the MPA was established and in the years following the establishment of the MPA. As part of this project we will collect two additional years of survey data which will then be analyzed in a Before After Control Impact Paired Series (BACIPS) analysis. Our project can provide researchers and managers with strong quantitative information on the impact of the Catalina MPA on key demographic features of in populations of spiny lobster and sheephead. This project will also provide insight into the importance of incorporating intertidal habitat into the design of MPAs that target these two species in Southern California. Funding for this project is provided by the USC Sea Grant Program and the California Ocean Protection Council.
Time lapse photographs of the intertidal turf community at Catalina Island showing A) diurnal foraging activity by fish at sunset, B) after sunset lobsters, C) maximum high tide with foraging lobsters reaching peak densities, D) receding tide with most of the lobsters having left the site.
Spatial Realism in the Mussel Bed Disturbance Paradigm
As part of a collaboration with California State University, Los Angeles and the University of California at Los Angeles our lab group is participating in a project to enhance our understanding of how disturbance structures natural communities. Our understanding of how physical disturbance shapes the structure of populations and communities owes much to field studies of wave-generated gap formation in mussel beds. Prior studies depict mussel beds as a non-equilibrium system, in which disturbance is spatially unpredictable, generating a random patchwork of mussel cover and gaps. The proposed work would test assumptions and predictions of an alternative view – that disturbance shows predictable landscape patterns that depend not merely on spatial distribution of external forcing (wave stress) but also on biological processes determining the structure of the aggregation. Specifically, spatially varying mussel productivity (recruitment and growth), physiological stress, and predation interact to produce landscape patterns in the structure of the mussel cover. Certain regions of the mussel bed develop as mono-layers attached directly to the rock, resisting disturbance. Other regions develop in multi-layered configurations that when very deep force superficial mussels to attach solely to adjacent mussels instead of the rock surface, and cause interior mussels to only weakly attach to either rock or one another, favoring propagating disturbances. Therefore, spatial patterns of gap formation and recovery emerge from a unified landscape process.
Field work emphasizes construction of a detailed GIS database using geospatial sampling methods applied to mussel bed sites in Barkley Sound, British Columbia. GIS data layers for each site will include wave force, topography (tidal height, slope, and aspect), mussel size structure, mussel bed thickness, differentiation of layering, and size-specific attachment strengths stratified by layer. GIS interpolations and regression analyses will used to first examine assumptions of the hypothetical landscape process and then test specific predictions regarding spatial patterns in the occurrence of disturbance and recovery. Finally, controlled field experiments will test the key proposition that different mussel bed structures cause different resistance to, extent of, and recovery from disturbance. Funding for this project is being provided by the National Science Foundation.
Wave exposed shoreline in British Columbia, Canada (left photo). Mussel bed demonstrating signs of storm driven gap formationwithin in the bed (right photo).
Geomorphic Controls over Littoral Communities in California
It has been suggested that the distribution of many species, and structure of many habitats, is constrained initially by broad scale variability in coastal geomorphology and geology. Thus the spatial characteristics of rock types can be an important determinant of the types of organisms that can settle, grow, and survive in a given location. A faulted rock substratum creates crevasses that can be colonized by marine organisms such as abalone. Harder, weather resistant rocks form promontories that can affect local circulation, the locations of coastal upwelling centers and ultimately the formation of the large intertidal communities that occupy these headlands. At scales below which ecologists traditionally study these systems, the microscopic scale, rock micro-textures can also effect the benthic community that emerges in a single location. For instance, rocks can be rugose and hard at the microscale but appear to be smooth and friable when observed at larger scales. Consequently, the controls that rocks can exert on intertidal ecologic processes such as recruitment, growth and survival vary with varying sizes and types of organisms and with the spatial scale at which rock-organism interactions occur. Hence a strong geological habitat/species relationship may exist across multiple spatial scales and these relationships are strongly dependent on the scale of observation. As part of a collaboration with Moss Landing Marine Lab we are developing high resolution, three dimensional models of intertidal communities in California that can be used to quantitatively assess the relationship between geomorphology and community structure in the rocky intertidal. This project will result in the development of new interdisciplinary methodological approaches and tools to study California’s coastal environments. Funding for this project is provided by the California State University Council on Ocean Affairs Science and Technology.
Three dimensional geospatial models of the rocky intertidal at Point Lobos State Reserve in Central California. The image on the left depicts topographic complexity in the intertidal while the image on the right is the topographic model with a photo mosaic of the intertidal community rendered to the topography.
Development of Scale Dependent Survey Methods for Monitoring Species Diversity and Abundance in Coastal Marine Communities
General landscape ecology theory suggests the factors that affect species distribution and abundance at the scale of a few meters may not necessarily relate to species distribution and abundance at larger spatial scales. Our lab is currently developing survey methods that can be used to estimate scale dependency in the relationship between environmental factors and patterns of species distribution and abundance in rocky intertidal communities. The data collected by members of our lab will then be used to develop GIS and statistical models that will provide estimates as to how strongly physical and biological processes structure intertidal marine communities at regional and local scales. The development of such models can then be used to help guide the design of environmental monitoring surveys aimed at tracking the relationship between the environment and marine species at multiple spatial scales. This work is currently being conducted at Point Lobos State Reserve and is funded by the Foundation of CSU Monterey Bay.
Geospatial field sampling with Total Station laser surveyor at Point Lobos State Marine Reserve.
Development of Ecosystem Based Management Strategies for Long Island Sound
Our lab participated in a comprehensive review of the last 20 years of marine and watershed research in Long Island Sound as part of an effort to advance an ecosystem based approach in this large urban estuary. The results of this work resulted in the publication of the first comprehensive Long Island Sound Research Synthesis Volume. Funding for this project wass provided by Connecticut and New York Sea Grant.
Yarish, C., Swanson, L.,Tedesco, M., Latimer, J. Stacey, P. and Garza, C. Eds. 2014. Long Island Sound: Prospects for an Urban Sea, XXII, 899 pp. Springer, New York, New York. (Publication Link)
Tedesco, M., Swanson, L., Stacey, P., Latimer, J., Yarish, C., and Garza, C. 2014. Synthesis for Management. In: Long Island Sound: Prospects for an Urban Sea, XXII,Yarish, C., Swanson, L.,Tedesco, M., Latimer, J. Stacey, P. and Garza, C. Eds. pp:481-539. Springer, New York, New York. (Publication Link)
Landscape Based Mechanisms of Boundary Formation in Rocky Intertidal Communities
As part of a long term collaboration in British Columbia, Canada with the Center For Environmental Analysis at California State University, Los Angeles and the California Institute of Technology our lab is investigating the interaction between landscape driven physical and biological processes that drive boundary formation in the mussel Mytilus californianus, a prominent member of rocky intertidal communities in the Pacific Northwest. Classic ecological theory views the distributional limit of M. californianus as an equilibrium process whereby the predatory sea star Pisaster ochraceus maintains the lower distributional boundary of the mussel in the intertidal by foraging on mussels that fall within the upper limits of the sea stars foraging range. Our experimental studies suggest that this interaction may be a nonequlibrium process that is in part related to the interaction between the physical landscape, physical forcing factors and the ability of Pisaster to forage in different physical environments. This work will be expanded to include studies of how the interactions between physical and biological processes help shape the three dimensional structure of intertidal communities. This work will help to further quantify the biological and physical mechanisms that drive boundary formation in marine species that inhabit coastal communities.
The lower distributional limit of Mytilus californianus before (left photograph) and one year after (right photograph) an experimentally induced increase in the abundance of Pisaster ochraceus. After one year the lower boundary of the mussel bed has demonstrated a significant upward recession.
Robles, C.D., Desharnais, R.A., Garza, C., Donahue, M.J. and Martinez, C.A. 2009. Complex equilibria in the maintenance of boundaries: experiments with mussel beds. Ecology, 90 (4): 985-995. (Publication Link)
Robles, C.D, Garza, C., Desharnais, R.A. and Donahue, M.J. 2010. Landscape patterns in boundary intensity: A case study of mussel beds. Landscape Ecology, 25 (5): 745-759. (Publication Link)
The Impact of the Asian Shore Crab on Intertidal Communities in Long Island Sound
As part of a collaborative effort with Fairfield University and the Northeast Fisheries Science Center of the National Oceanic and Atmospheric Administration our lab has recently completed a study looking at the impact of foraging by the invasive Asian Shore Crab, Hemigrapsus sanguineus, on populations of the blue mussel, Mytilus edulis. Our study suggests that Hemigrapsus can cause a 30% decrease in survivorship in populations of this conspicuous member of the Long Island Sound shoreline. When measured in conjunction with natural background mortality of this mussel the additional mortality imposed by Hemigrapsus can potentially reduce the ability of this economically and ecologically important organism to filter the waters in Long Island Sound. The ongoing loss of this essential ecosystem service may thus contribute to the severe hypoxic events that are often observed in Long Island Sound.
Brousseau, D. J., Goldberg, R. and Garza, C. 2014. Impact of predation by the invasive crab Hemigrapsus sanguineus on juvenille blue mussel survival in Western Long Island Sound, U.S.A. Northeastern Naturalist, 21 (1): 119-133. (Publication Link)