Marine Invasions Research

Principal Investigator

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. 

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

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).   

Canning-Clode, Joao and Carlton, James T. 2017. Refining and expanding global climate change scenarios in the sea: Poleward creep complexities, range termini, and setbacks and surges. Diversity and Distributions, http://dx.doi.org/10.1111/ddi.12551

Carney, K.J., M.S. Minton, K.K. Holzer, A.W. Miller, L.D. McCann, G.M. Ruiz. 2017. Evaluating the combined effects of ballast water management and trade dynamics on transfers of marine organisms by ships. Published March 20, 2017 https://doi.org/10.1371/journal.pone.0172468

Moser, C.S., T.P. Wier, M.R. First, J.F. Grant, S.C. Riley, S.H Robbins-Wamsley, M.N. Tamburri, G.M. Ruiz, A.W. Miller, and L.A. Drake. 2017. Quantifying the extent of niche areas in the global fleet of commercial ships: the potential for “super-hot spots” of biofouling.  Biological Invasions. Online March 2, 2017. doi:10.1007/s10530-017-1386-4

Simkanin, C, I.C., Davidson, T.W. Therriault, G. Jamieson, J.F. Dower. 2017. Manipulating propagule pressure to test the invasibility of subtidal marine habitats. Biological Invasions. Online Feb 20, 2017

Davidson, I.C., M.S. Minton, K.J. Carney, A.W. Miller, and G.M. Ruiz. 2017. Pioneering patterns of ballast treatment in the emerging era of marine vector management. Marine Policy. Online,  Volume 78, April 2017, Pages 158–162.


Abstracts

 

March 2017

Canning-Clode, Joao and Carlton, James T. 2017. Refining and expanding global climate change scenarios in the sea: Poleward creep complexities, range termini, and setbacks and surges. Diversity and Distributions, http://dx.doi.org/10.1111/ddi.12551

Abstract

Aim
Invasion dynamics are sensitive to global-scale changes. New marine invasions have been recorded in dramatically increasing numbers along the world's coasts, due, in part, to the global warming of the oceans and the ability of many successful invasive marine species to tolerate a broader thermal range than native species. As a response to ocean warming, a poleward movement of numerous species has been observed in many biogeographic regions. Our aim was to explore several poorly recognized and thus rarely studied aspects of ocean climate change scenarios in order to advance our understanding of finer-grained aspects of poleward movements.

Methods
Three scenarios are investigated in our framework: (1) the existence of networks of complex intraregional origins, routes and destinations of poleward-moving species, (2) the existence of impenetrable termini where no further expansion is possible, linked to potential outflow corridors, and (3) the interplay of a warming ocean with aperiodic cold episodes.

Results
Poleward advances consist of distinct regional networks of origins, routes and destinations, largely undefined in most areas, linked in turn to the potential existence of endpoints where no further expansion may be possible without escape routes and/or human-mediated assistance. The interaction of aperiodic cooling periods may result in temporary setbacks or rate reductions in range expansions.

Main conclusions
The recognition of potentially complex origin-route-destination networks may significantly advance our predictive capacity of both future invasions and range expansions and potential impacts. Thus, specific focus on high-profile donor region species pools linked to established vector routes may yield far more robust management scenarios than currently in place. While it is probable that the frequency of climate-mediated surges (inevitable warming) and setbacks (cooling periods) of species invasions will increase over time, the net outcome is likely to be positive, resulting in an inexorable poleward expansion of thousands of species.

Carney, K.J., M.S. Minton, K.K. Holzer, A.W. Miller, L.D. McCann, G.M. Ruiz. 2017. Evaluating the combined effects of ballast water management and trade dynamics on transfers of marine organisms by ships. Published March 20, 2017 https://doi.org/10.1371/journal.pone.0172468

Abstract:

Global trade by merchant ships is a leading mechanism for the unintentional transfer of marine organisms, including non-indigenous species, to bays and estuaries worldwide. To reduce the likelihood of new invasions, ships are increasingly being required to manage their ballast water (BW) prior to discharge in coastal waters. In the United States, most overseas arrivals have been required to manage BW discharge since 2004, primarily through ballast water exchange (BWE), which flushes out ballast tanks in the open ocean (>200 miles from shore). Studies have found BWE to generally reduce the abundance of organisms, and the amount of water exchanged has been estimated at 96–100%. Despite its widespread use, the overall effect of this management strategy on net propagule supply through time has not been explored. Here, temporal changes in zooplankton concentrations and the volume of BW discharged in Chesapeake Bay, U.S. were evaluated, comparing pre-management era and post-management era time periods. Chesapeake Bay is a large port system that receives extensive BW discharge, especially from bulk cargo vessels (bulkers) that export coal overseas. For bulkers arriving from overseas, mean zooplankton concentrations of total and coastal indicator taxa in BW did not decline between pre- (1993–2000) and post management (2012–2013) eras, when controlling for season and sampling method. Moreover, bulkers discharged 21 million tonnes (82% of total for Chesapeake Bay) of overseas BW in 2013, representing a 374% increase in volume when compared to 2005. The combination of BW discharge volume and zooplankton concentration data indicates that (a) net propagule supply by bulkers has increased since BWE began in Chesapeake Bay; and (b) changes in vessel behaviour and trade have contributed strongly to this outcome. Specifically, the coal-driven increase in BW discharge volume from 2005–2013, concurrent with the onset of BWE regulations, worked to counteract intended results from BW management. A long-term analysis of bulker arrivals (1994–2013) reveals a 20-year minimum in arrival numbers in 2000, just when the implementation of BWE began. This study underscores the need to consider shifts in trade patterns, in order to advance and evaluate effective management strategies for biological invasions.

Moser, C.S., T.P. Wier, M.R. First, J.F. Grant, S.C. Riley, S.H Robbins-Wamsley, M.N. Tamburri, G.M. Ruiz, A.W. Miller, and L.A. Drake. 2017. Quantifying the extent of niche areas in the global fleet of commercial ships: the potential for “super-hot spots” of biofouling.  Biological Invasions. Online March 2, 2017. doi:10.1007/s10530-017-1386-4

Abstract:

Niche areas of ships, such as lateral thruster tunnels, sea chests, and propellers, are often hot spots for the accumulation of biofouling organisms, a potential source of aquatic invasive species. Yet, the relative importance of different niche areas is poorly resolved, in terms of both total surface area and the associated biota (i.e., the species of organisms and their abundances). To address this information gap, a method was developed to estimate the extent of various niche areas in the global fleet of 120,252 commercial ships active between 1999 and 2013. The total niche area for these vessels was estimated to be 32,996 × 103 m2, representing approximately 10% of the total wetted surface area (WSA) available for colonization by biota. Considering the portion of niche areas relative to the total WSA, it was highest for passenger vessels (27%), followed by tugs (25%), and fishing vessels (21%), with niche areas representing a small portion of the WSA for bulk carriers and tankers (7–8%). Examining the different types of niche areas, thruster tunnels had the greatest total extent (10,189 × 103 m2), representing a disproportionately large contribution (>50%) of the total niche area for passenger vessels and tugs compared to other vessel types. This result, combined with the use and cleaning of thrusters, may render them “super-hot spots” of biofouling. The uneven distribution and extent of niche areas across vessels has implications for transfers of organisms and management strategies to reduce invasions associated with the surfaces of ships.

February 2017

Simkanin, C, I.C., Davidson, T.W. Therriault, G. Jamieson, J.F. Dower. 2017. Manipulating propagule pressure to test the invasibility of subtidal marine habitats. Biological Invasions. Online Feb 20, 2017

Abstract:

Global patterns show that estuaries are more invaded than open coasts and artificial habitats are more invaded than natural ones. The contention that artificial habitats in estuaries are more invasible than other habitats may result from variation in propagule supply, however, as artificial habitats are closely linked to vectors of non-native propagules, such as ships and boats. True comparisons of habitat invasibility require manipulations of propagule pressure, which has been historically difficult in marine systems. Using in-situ larval dosing, we delivered propagules of the widespread invasive ascidian Botrylloides violaceus into field mesocosms and assessed how habitat type (floating dock vs. benthic rock), resource availability (occupied vs. unoccupied plates), and propagule number (5, 25 and 50 larvae 225 cm−2) affected settlement (survival after 24 h) and recruitment (survival after 56 days) success. In-situ larval dosing was successful, and after eight weeks there were significant differences in recruitment due to initial dose-size, habitat type, and space availability. At the habitat scale, despite equal propagule delivery, PVC plates in natural benthic rock were not equally invasible and few propagules survived to recruitment. At the organism scale, increased habitat complexity, through facilitation by established fouling species, rather than freedom from space competitors, appears to be more important for B. violaceus to establish. Our results offer greater mechanistic understanding of broader invasion patterns between artificial and natural habitats. This work extends the possibilities for further research to counteract the confounding issue of unknown and unknowable propagule delivery when attempting to explain variation in invasion success.

January 2017

Davidson, I.C., M.S. Minton, K.J. Carney, A.W. Miller, and G.M. Ruiz. 2017. Pioneering patterns of ballast treatment in the emerging era of marine vector management. Marine Policy. Online,  Volume 78, April 2017, Pages 158–162.

Abstract: 

Human-mediated transfer and invasions of organisms have permanently altered distribution patterns on a global scale. In response to growing numbers and impacts of invasions, global-scale vector management is advancing to curtail unintentional and unwanted species re-distributions. In marine systems, ocean-going ships have been the major dispersal mechanism across biogeographic barriers, and maritime vector management has become a priority global initiative, including national regulations and recent ratification of an international convention to manage ballast water. This paper provides the first analysis of the pioneering patterns of ballast water treatment systems (BWTS) on board commercial ships, using vessel arrivals to the United States as a model system. Over an opening 28-month period, >200 unique vessels arriving to the U.S. reported BWTS operations, using 58 different systems to treat 4.42 million m3 of discharged ballast water. Although this volume represents <2% of all ballast water discharged in the U.S. per month during this period, there was substantial growth in treated ballast discharge throughout this time. Through 2015, ‘Filtration+UV’ systems were the most common BWTS type installed across all ship types. Currently, BWTSs occur on higher numbers of tankers and bulkers, but a higher proportion of passenger vessels, than other ship types. If BWTSs meet the required discharge standards as intended, this will cause a steep reduction in total discharge of organisms ≥50 µm compared to current practices. While several hurdles in fleet-wide BWTS adoption remain, including the timeline for BWTS installation across the global fleet, we are at a significant milestone in the history and evolution of global shipping, which is undergoing wholesale transition to a new and more effective global-scale ballast vector management strategy.

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