Marine Invasions Research

Principal Investigator

Twitter Logo
Follow us on Twitter: @SERCinvasions


Biological invasions - the establishment of species beyond their historical range - are a major force of ecological and evolutionary change. Our lab aims to understand the patterns, processes, and consequences of invasions in marine ecosystems on local to global scales.  We have laboratories and staff on both coasts of North America, on Chesapeake Bay and San Francisco Bay (Tiburon Lab).  These bays are focal points for our long-term, intensive research, which spans Pacific and Atlantic shorelines of the Americas --- from polar to tropical latitudes. 

Most marine invasions result from human-mediated species transfers, which are often associated with commercial and recreational vessels. A major component of our research examines shipping, transportation, and trade dynamics for the United States with the National Ballast Information Clearinghouse (NBIC), a joint program with the U.S. Coast Guard that is based at SERC.  NBIC tracks the status and trends of ballast water delivery and management for the Nation.

Our research encompasses a wide range of projects, exploring the ecology and management of coastal marine ecosystems.  We focus primarily on invasion dynamics but also examine species interactions of both native and non-native species. Overall, we seek to: (1) characterize patterns of marine invasion across space, time, and taxonomic groups; (2) develop a mechanistic understanding of the processes that drive observed patterns; (3) advance predictive capability about the establishment, spread, and impacts of non-native species in marine ecosystems; (4) evaluate the efficacy of management strategies to limit the establishment and impact of invaders; and (5) understand the roles of species interactions, including predator-prey and host-parasite relationships, in marine communities. 

Further details on the various dimensions of our work are available below. 

Freshwater & Estuarine Ecologist: Invasion Ecology
Description: We currently seek applications to fill a research position to evaluate invasion dynamics by non-native species (NNS) in freshwater and estuarine ecosystems, including a strong focus on the US Great Lakes. The successful candidate will lead a team research project, to evaluate invasion history and establish field-based measures to detect NNS at selected sites. The first year of this project will focus on project design and synthesis of existing data on freshwater NNS, providing the baseline for a multi-year project.
Education / Experience / Requirements: PhD in Aquatic Biology, Ecology, Biogeography or related field. Candidates must have (a) a strong background in aquatic invertebrate ecology, (b) knowledge of statistics, sampling design, and data management, (c) field experience, and (d) a good working knowledge of taxonomy for aquatic organisms. Applicants must be organized, self-motivated, independent and pro-active. Strong communication skills and ability to work as part of a research team are required as is a proven talent to write reports and publications. Experience giving presentations to various audiences (e.g., scientific conferences, agencies, and the public) is required. Some travel will be required. US citizenship or current work visa will be required.
Location: The position is based at the Marine Invasion Research Lab, Smithsonian Environmental Research Center (SERC), Edgewater, Maryland, USA. SERC is a research center of the Smithsonian Institution, located on the western shore of Chesapeake Bay, approximately 5 miles south of Annapolis, 25 miles west of Washington D.C., and 40 miles south of Baltimore. The Marine Invasion Research Lab ( currently has a staff of approximately 35 biologists, who conduct research on coastal ecosystems throughout the country and overseas, in collaboration with researchers from a variety of other institutions. Some aspects of the current research project will occur in the US Great Lakes.
Salary: $70,000-80,000/year plus benefits
Duration: 1 year, with prospect of renewal (3-5 years)

To Apply: Please submit the following as one attached file (PDF preferred): cover letter describing research experience and interests, current CV, and contact information (names, phone numbers, and email addresses) for 3 references. In your letter, please highlight your specific experience relevant to this announcement. Position is open until filled. For full consideration, please submit application materials by 1 October 2019. Applications should be submitted electronically to Laura Falsone (, including job title in the subject line.
Start Date: Position to begin in late 2019. 

Miller, A.W., Reynolds, A.C., Minton, M.S. 2019. A spherical falling film gas-liquid equilibrator for rapid and continuous measurements of CO2 and other trace gases. PLOS ONE (Online September 25, 2019)

Blakeslee, A.M.H., Haram, L.E., Altman, I., Kennedy, K., Ruiz, G.M., Miller, A.W. 2019. Founder effects and species introductions: A host versus parasite perspective. Evolutionary Applications. (Online September 14, 2019)

Schäfer, S., Monteiro, J., Castro, N., Rilov, G.,  and Canning-Clode, J. 2019. Cronius ruber (Lamarck, 1818) arrives to Madeira Island: a new
indication of the ongoing tropicalization of the northeastern Atlantic.
Marine Biodiversity (online August 31, 2019)

Jimenez, H., Chang, A.L., Ruiz, G.M., 2019. Soft-sediment community stability across years in San Francisco Bay. Estuarine, Coastal and Shelf Science. Volume 227, 31 October 2019, (online August 5, 2019)

Clark, M.S.,  Nieva, L.V.,  Hoffman, J.I.,  Davies, A.J.,  Trivedi, U.H., Turner, F., Ashton, G.V., and Peck, L.S., 2019.  Lack of long-term acclimation in Antarctic encrusting species suggests vulnerability to warming. Nature Communication 10 (online July 29, 2019)


September 25, 2019

Miller, A.W.Reynolds, A.C.Minton, M.S. 2019. A spherical falling film gas-liquid equilibrator for rapid and continuous measurements of CO2 and other trace gases. PLOS ONE

Use of gas-liquid equilibrators to measure trace gases such as CO2, methane, and radon in water bodies is widespread. Such measurements are critical for understanding a variety of water quality issues such as acidification due to elevated CO2 or other processes related ecosystem metabolism and function. However, because gas-liquid equilibrators rely on generating sufficient surface area for gas exchange between liquid and gas phases, most traditional equilibrators pass water through small orifices or interstitial spaces that rapidly clog in highly productive or turbid waters, conditions that are common in estuaries, coastal bays, and riverine systems. Likewise, in cold temperatures, such equilibrators are subject to freezing. Both situations lead to failure and limit utility, especially for long term, continuous environmental monitoring. Here we describe and test a gas-liquid equilibrator that relies on a continuous falling film of water over a spherical surface to drive gas exchange. Our results demonstrate that this design is accurate in its ability to equilibrate fully to aqueous CO2 concentrations, is functional across a wide range of gas concentrations, and has a response time that is comparable with other equilibrator designs. Because this equilibrator uses free flowing, falling water to produce a surface for gas exchange, our field trials have shown it to be very resistant to clogging and freezing, and therefore well suited to long term deployment in highly productive waters like estuaries where CO2 concentrations fluctuate hourly, daily, and seasonally. When generated across a spherical surface, the falling film is not adversely affected by tilting off vertical, conditions that are common on a ship, small vessel, or buoy.

September 14, 2019

Blakeslee, A.M.H., Haram, L.E., Altman, I., Kennedy, K., Ruiz, G.M.Miller, A.W. 2019. Founder effects and species introductions: A host versus parasite perspective. Evolutionary Applications. 

Species colonizations (both natural and anthropogenic) can be associated with genetic founder effects, where founding populations demonstrate significant genetic bottlenecks compared to native populations. Yet, many successfully established free‐living species exhibit little reduction in genetic diversity—possibly due to multiple founding events and/or high propagule pressure during introductions. Less clear, however, is whether parasites may show differential signatures to their free‐living  hosts. Parasites with indirect life cycles may particularly be more prone to founder effects (i.e., more genetically depauperate) because of inherently smaller founding populations and complex life cycles. We investigated this question in native (east coast) and introduced (west coast) North American populations of a host snail Tritia obsoleta (formerly Ilyanassa obsoleta, the eastern mudsnail) and four trematode parasite species that obligately infect it. We examined genetic diversity, gene flow, and population structure using two molecular markers (mitochondrial and nuclear) for the host and the parasites. In the host snail, we found little to no evidence of genetic founder effects, while the trematode parasites showed significantly lower genetic diversity in the introduced versus native ranges. Moreover, the parasite's final host influenced infection prevalence and genetic diversity: Trematode species that utilized fish as final hosts demonstrated lower parasite diversity and heightened founder effects in the introduced range than those trematodes using birds as final hosts. In addition, inter‐regional gene flow was strongest for comparisons that included the putative historical source region (mid‐Atlantic populations of the US east coast). Overall, our results broaden understanding of the role that colonization events (including recent anthropogenic introductions) have on genetic diversity in non‐native organisms by also evaluating less studied groups like parasites.

August 31, 2019

Schäfer, S., Monteiro, J., Castro, N., Rilov, G.,  and Canning-Clode, J. 2019. Cronius ruber (Lamarck, 1818) arrives to Madeira Island: a new
indication of the ongoing tropicalization of the northeastern Atlantic. 
Marine Biodiversity. 

This manuscript reports the first sightings and collection of the swimming crab Cronius ruber (Lamarck, 1818) on the coast of Madeira Island, Portugal. After the recent record in the Canary Islands, this represents a further step northward on this species’ expansion in distribution in the eastern Atlantic. The crab was first spotted during underwater visual census surveys done by scuba diving in July 2018 and was repeatedly observed during the following months, in different locations on the south coast of Madeira. Analysis of temperature data from several geographic locations where C. ruber is present was performed to assess how thermal regimes and ongoing changes may influence this recent distribution shift. Current temperature trends in Madeira suggest that the arrival and establishment of C. ruber to Madeira might have been facilitated this thermophilic species, adding evidence for the ongoing tropicalization of this area. Finally, the current spread of C. ruber in both Canaries and Madeira island systems highlights the need for a long-term monitoring program targeting this and other non-indigenous species (NIS).

August 5, 2019

Jimenez, H., Chang, A.L., Ruiz, G.M., 2019. Soft-sediment community stability across years in San Francisco Bay. Estuarine, Coastal and Shelf Science. Volume 227, 31 October 2019, 

Macrobenthos is used commonly in disturbance-related studies of coastal ecosystems, including those that evaluate invasions by non-native species (NIS), but still little is known about temporal variation in community characteristics, especially in bays and estuaries. In this study we investigated inter-annual changes in the soft-sediment benthic communities of San Francisco Bay over a period of five years, evaluating the contribution of NIS vs. native species to community attributes (species richness, abundance) and the efficacy of sampling (percent richness detected for each NIS and native species). Benthic macrofauna were collected, identified, and quantified from 10 stations (48–50 replicate samples) per year across the high salinity region of the Bay. A total of 36,872 individuals belonging to 126 morphospecies were collected; 61 species were native, accounting for 22% of total abundance, and 31 species were NIS, which reached 74% of total abundance. The other 34 species were either cryptogenic or unresolved taxa. Soft-sediment communities were mainly comprised of amphipods (Ampelisca abdita, Sinocorophium heteroceratum, Monocorophium acherusicum), polychaetes (Sabaco elongatus, Euchone limnicola) and bivalves (Venerupis philippinarum). Community structure and composition were stable across years during the period of the study, despite a major marine heat wave and a record-breaking drought that raised average salinity levels for several years. The sampling was effective, especially for NIS, detecting a higher proportion (94–100%) of estimated richness for NIS compared to native species (74–89%) across the five year period, suggesting NIS were more evenly distributed in space and time and many native species occurred more patchily and less frequently.

July 29, 2019

Clark, M.S.,  Nieva, L.V.,  Hoffman, J.I.,  Davies, A.J.,  Trivedi, U.H., Turner, F., Ashton, G.V., and Peck, L.S., 2019.  Lack of long-term acclimation in Antarctic encrusting species suggests vulnerability to warming. Nature Communication 10, Article 3383

Marine encrusting communities play vital roles in benthic ecosystems and have major economic implications with regards to biofouling. However, their ability to persist under projected warming scenarios remains poorly understood and is difficult to study under realistic conditions. Here, using heated settlement panel technologies, we show that after 18 months Antarctic encrusting communities do not acclimate to either +1 °C or +2 °C above ambient temperatures. There is significant up-regulation of the cellular stress response in warmed animals, their upper lethal temperatures decline with increasing ambient temperature and population genetic analyses show little evidence of differential survival of genotypes with treatment. By contrast, biofilm bacterial communities show no significant differences in community structure with temperature. Thus, metazoan and bacterial responses differ dramatically, suggesting that ecosystem responses to future climate change are likely to be far more complex than previously anticipated.

Species distributions are at the core of all ecological and evolutionary processes. Despite recognition that accelerating invasions are radically changing fundamental ecological processes, we currently lack the data for a broad scale understanding of these  patterns, emergent properties, and practical implications across both spatial and temporal scales. We are collecting quality occurrence data and using these data to understand patterns and mechanisms of invasion, and making these data publicly available for broader application by the public.

Our Projects

The impacts of introduced species pose significant challenges for conservation and restoration because they undermine a desired outcome for target species or habitats. In addition, some invasions impose significant economic costs through loss of agriculture, forestry, and fisheries products, and others, including mosquito-borne viruses and toxic algal blooms, have severe human health effects. Detailed analysis of several high-profile species invasions have highlighted the types and potential magnitude of invasion impacts that exist, however, the effect of most non-native species and the full scope of impacts from invasions remains poorly understood. To address this gap, we use a variety of approaches to characterize and test the ecological, evolutionary, and social effects of non-native species across diverse ecosystems.  This work advances understanding of how the Earth’s ecosystems function and also serve to inform resource management and conservation strategies.

Our Projects

Biological invasions provide opportunities to examine how species and ecosystems respond to new arrivals, and how species adapt to new environmental conditions. These types of “natural experiments” provide new insights into many biological processes, especially early in the colonization process, that are not possible with native communities.  We examine invasion ecology at the population, community, and ecosystem level across a diverse range of habitats and organisms, both to advance basic science and inform management and conservation strategies.

Our Projects

Managing biological invasions is a worldwide endeavor that aims to (a) prevent the human-caused spread of species, (b) control and remove unwanted species, and (c) reduce negative impacts to society and the environment. We are evaluating the efficacy and consequences of invasion management strategies and policies in coastal estuaries and marine systems.  Our work is often done in collaboration with local, state, federal and international partners and used actively to inform current management and policy decisions.

Our Projects

We study the dynamic interactions between society, trade, transport, and species in a variety of ways. These include modeling transport networks and biotic exchange, evaluating business model forecasts and their effects on trade routes and species distributions, and assessments of organism transfers across major corridors between oceans and continents.

Our Projects

Understanding how modes of human transportation affect the environment, and biological invasions in particular, is complicated and involves many components including both human and natural history. Human history because most invasions result from human-aided species transfers and invasion patterns often reflect human movements and transportation systems. Natural history because species identifications and their life history characteristics are paramount to knowing which species are non-native and how they have likely been introduced. We work to address these complexities and strive to understand the dynamics of species transport in marine systems. 

Our Projects

Balanced predation and competition are key to the health of any ecosystem. We are examining predation and competition rates in several environments including in the Rhode River near SERC where we study native species in nearshore environments and in introduced fouling communities on the Atlantic and Pacific coasts.  

Our Projects

Communities are constantly being shaped by human activities, activates that can affect hydrology, climate, chemical inputs, species richness (number of species that make up the community), as well as habitat quantity and quality. Our research focuses on how biological invasions change the marine and estuarine communities they invade and how recipient communities protect themselves from invasion. The following highlights a few of our recent projects exploring community changes resulting from nonnative species introductions.

Our Projects

Laravel tunicates

Propagule Pressure in Marine Habitats

We are examining the complex, dynamic interactions between parasites and their hosts, including both the evolutionary and ecological mechanisms that influence these interactions. Our research includes a wide variety of hosts (e.g., seagrasses, bivalves, crustaceans) and parasites (e.g., protists, bacteria, crustaceans).