Marine Invasions Research

Principal Investigator

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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. 

Cartlton, J.T., Keith, I, and Ruiz, G.M. 2019. Assessing marine bioinvasions in the Galápagos Islands: implications for conservation biology and marine protected areas.  Aquatic Invasions 14(1). 1–20pp. (Online March 28, 2019)

Ramalhosaa, P., Gestoso, I., Duarte, B., Caçador, I., and Canning-Clodeb, J. 2019. Metal pollution affects both native and non-indigenous biofouling recruitment in a subtropical island system. Marine Pollution Bulletin 141: 373–386. (Online March 6, 2019)

Newcomer, K., Flenniken, M.M., Carlton, J.T. 2019. Home and away and home again: discovery of a native reproductive strategy of the globally invading sea anemone Diadumene lineata (Verrill, 1869) in a satellite population. Biological Invasions. 1-7pp. (Online March 1, 2019)

Simkanin, C., Carlton, J.T., Steves, B., Fofonoff, P., Nelson, J., Clarke Murray, C., and Ruiz, G.M. 2019. Exploring establishment potential after long-distance dispersal: a test using marine debris species. Global Ecology and Biogeography. DOI: 10.1111/geb.12878 (Online January 29, 2019)

Cheng, B.S., Ruiz, G.S., Altieri, A.H., Torchin, M.E. 2018. The biogeography of invasion in tropical and temperate seagrass beds: Testing interactive effects of predation and propagule pressure. Biodiversity Research. (Online December 11, 2018)


March 28, 2019

Cartlton, J.T., Keith, I, and Ruiz, G.M. 2019. Assessing marine bioinvasions in the Galápagos Islands: implications for conservation biology and marine protected areas.  Aquatic Invasions 14(1). 1–20pp. 

The Galápagos Islands are recognized for their unique biota and are one of the world’s largest marine protected areas. While invasions by non-indigenous species are common and recognized as a significant conservation threat in terrestrial habitats of the Archipelago, little is known about the magnitude of invasions in its coastal marine waters. Based upon recent field surveys, available literature, and analysis of the biogeographic status of previously reported taxa, we report 53 nonindigenous species of marine invertebrates in the Galápagos Islands. Forty-eight (90.6%) of these species are newly reported or newly recognized as introduced, a nearly ten-fold increase from the five species previously recognized as nonindigenous. Of these 48 species, 30 (62.5%) were newly discovered in surveys commenced in 2015. Ascidians (11 species), bryozoans (10), polychaetes (9), and hydroids (8) account for 38 (71.7%) of the introduced species. Our analyses further detected 33 cryptogenic invertebrate and algal species and one littoral vascular plant. Most taxonomic groups remain to be assessed for the presence of non-indigenous species. Importantly, the recent field surveys were restricted predominantly to one habitat (harbor biofouling) on two islands, further suggesting that introduced species richness for the Galápagos Islands may be considerably higher. Most of the introduced species treated here were likely brought to the Galápagos by ships. While we presume that most if not all of the many thousands of vessels arriving in the Galápagos Islands since the 1500s had marine animals and plants attached to their hulls, we hypothesize that the general absence in the Islands of extensive shoreline structures (in the form of wharves, docks, pilings, and buoys) until the last half of the 20th century may have constrained extensive colonization by fouling species. The proliferation of shoreline structures may have both provided expanded habitat for non-indigenous species that had earlier colonized natural substrates, as well as having facilitated a 20th and 21st century wave of new invasions in the Galápagos Islands. Our results represent the greatest reported increase in the recognition of the number of invasions for any tropical marine environment in the world. This work suggests that the number and potential ecological impacts of nonindigenous species in tropical marine and maritime habitats may be substantially underestimated in other regions of the world. Our study demonstrates that tropical marine invasions deserve significant attention, not only in a biogeographical, historical, and ecological context, but also from a management perspective, especially in the Galápagos and other high-value conservation areas.

March 6, 2019

Ramalhosaa, P., Gestoso, I., Duarte, B., Caçador, I., and Canning-Clodeb, J. 2019. Metal pollution affects both native and non-indigenous biofouling recruitment in a subtropical island system. Marine Pollution Bulletin 141: 373–386. 

Hull fouling has been a driving force behind the development of most modern marine antifouling coatings that mainly contain copper based biocides to inhibit growth of fouling organisms. Despite these efforts, several nonindigenous species continue to be transferred via hull-fouling worldwide. In this study we designed a disturbance gradient with three commercial antifouling paints applied to PVC settling plates with different concentrations of copper oxide and allowed colonization of fouling communities in four marinas located at the Madeira Archipelago (NE Atlantic). Overall, the antifouling treatments were effective in decreasing the diversity of fouling communities and spatial variability across marinas was observed. Increasing exposure to metal pollutants decreases both species cover and total diversity, independently of their native or NIS condition. However, evidences found suggest that long-term effects of copper based antifouling coatings can be modulated by metalresistant species allowing a secondary substrate for the epibiosis of other species to establish.

March 1, 2019

Newcomer, K.Flenniken, M.M., Carlton, J.T. 2019. Home and away and home again: discovery of a native reproductive strategy of the globally invading sea anemone Diadumene lineata (Verrill, 1869) in a satellite population. Biological Invasions. 1-7pp 

Reproductive strategies, whether sexual or asexual, are critical aspects of introduction success and spread for non-indigenous species. The Western Pacific Diadumene lineata (Verrill, 1869), the world’s most widely distributed sea anemone due to numerous introductions, is believed to reproduce only by asexual means outside of its home range. Over the past 100 years, no populations with both males and females have been reported to co-occur outside of its native Japan. We report the first discovery of sympatric reproductive male (sperm-bearing) and female (egg-bearing) D. lineata in Coos Bay, Oregon, USA, confirmed by histological analysis. Given that only single gender introduced populations have been reported elsewhere, the presence of both genders in this US Pacific Northwest bay may be linked to high and continuous propagule pressure resulting from a history of intensive lumber and timber shipping directly between Japan and Coos Bay. Novel modern-day introductions of this species, in which reproductive traits previously only associated with native populations are manifested, could influence the future invasion success and spread of this species.

January 29, 2019

Simkanin, C., Carlton, J.T., Steves, B., Fofonoff, P., Nelson, J., Clarke Murray, C., and Ruiz, G.M. 2019. Exploring establishment potential after long-distance dispersal: a test using marine debris species. Global Ecology and Biogeography. DOI: 10.1111/geb.12878 

Aim: On 11 March 2011, the Great East Japan Earthquake triggered a massive tsunami that resulted in the largest known rafting event in recorded history. By spring 2012, marine debris began washing ashore along the Pacific coast of the United States and Canada with a wide range of Asian coastal species attached. We used this unique dataset, where the source region, date of dislodgment and landing location are known, to assess the potential for species invasions by transoceanic rafting on marine debris.

Location: Northeast Pacific from 20 to 60°N.

Time period: Current.

Major taxa studied: Forty‐eight invertebrate and algal species recorded on Japanese tsunami marine debris (JTMD).

Methods: We developed maximum entropy (MaxEnt) species distribution models for 48 species recorded on JTMD to predict establishment potential along the Pacific coast from 20 to 60°N. Models were compared within the context of historical marine introductions from Japan to this region to validate the emergence of marine debris as a novel vector for species transfer.

Results: Overall, 27% (13 species) landed with debris at locations with suitable environmental conditions for establishment and survival, indicating that these species may be able to establish new populations or introduce greater genetic diversity to already established non‐native populations. A further 21 species have an environmental match to areas where tsunami debris likely landed, but was not extensively sampled. Nearly 100 Japanese marine species previously invaded the northeastern Pacific, demonstrating this region’s environmental suitability for rafting Japanese biota. Historical invasions from Japan are highest in California and largely known from bays and harbours.

Main conclusions: Marine debris is a novel and growing vector for non‐native species introduction. By utilizing a unique dataset of JTMD species, our predictive models show capacity for new transoceanic invasions and can focus monitoring priorities to detect successful long‐distance dispersal across the world’s oceans.

December 11, 2018

Cheng, B.S., Ruiz, G.S., Altieri, A.H., Torchin, M.E. 2018. The biogeography of invasion in tropical and temperate seagrass beds: Testing interactive effects of predation and propagule pressure. Biodiversity Research.

Recent work has documented latitudinal gradients of biotic resistance, revealing diminished invasion success in the tropics as compared to the temperate zone. However, no studies have explored the biogeography of biotic resistance simultaneously with propagule pressure, which can greatly influence invasion dynamics and covary with latitude.

9–41° latitude, north‐western Atlantic seagrass beds.

We conducted field experiments to test the interactive effects of propagule pressure (experimentally placed recruits) and biotic resistance (predation) on invader performance in temperate and tropical seagrass beds. For these experiments, we used marine invertebrate propagules from bryozoans (Bugula neritina) and tunicates (Didemnum spp.). We also quantified natural recruitment with and without exposure to predators.

Surprisingly, predation substantially reduced invader survival at almost all latitudes. Overall, invaders experienced 15%–27% survival with predation as opposed to 75%–87% survival without predation. These patterns did not change when we increased local scale propagule pressure of Bugula by over 2‐fold. However, predation had no effect on invader survival in Florida, where natural recruitment was up to 500‐fold greater than other sites. We also measured substantial in situ recruitment of Bugula onto bare experimental surfaces that was not diminished with exposure to predators at mid‐latitudes, suggesting a regional scale predator swamping effect.

Contrary to recent findings of latitudinal variation in biotic resistance, we found that predation strongly reduced invader success in both temperate and tropical seagrass beds. However, our results also indicate that propagule pressure (natural recruitment) can influence invasion at the regional scale to overwhelm native communities. Our data suggest that predation and propagule pressure act at varying spatial scales to affect biogeographic patterns of invasion. The importance of latitudinal variation in these interactions is largely untested but deserves attention given that globalization will continue to facilitate opportunities for invasion.

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).