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. 

Lenz, M., Ahmed, Y., Canning-Clode, J. et al. 2018. Heat challenges can enhance population tolerance to thermal stress in mussels: a potential mechanism by which ship transport can increase species invasiveness.  Biological Invasions. https://doi.org/10.1007/s10530-018-1762-8 (Online May 24, 2018)

Del Pasqua M, Schulze A, Tovar-Hernández MA, Keppel E, Lezzi M, Gambi MC, et al. 2018. Clarifying the taxonomic status of the alien species Branchiomma bairdi and Branchiomma boholense (Annelida: Sabellidae) using molecular and morphological evidence. PLoS ONE 13(5): e0197104. https://doi.org/10.1371/journal.pone.0197104 (Online May 10, 2018).

Newcomer, K.A., Marraffini, M.L,. and Chang, A.L. 2018. Distribution patterns of an introduced encrusting bryozoan, Conopeum chesapeakensis (Banta, Perez and Santagata, 1995) in an estuarine environment in upper San Francisco Bay. Journal of Experimental Marine Biology and Ecology 504:20-31. https://doi.org/10.1016/j.jembe.2018.04.001 (Online April 9, 2018).

Gestoso, I., Ramalhosa, P,and  Canning-Clode, J. 2018. Biotic effects during the settlement process of non-indigenous species in marine benthic communities. Aquatic Invasions vol 13. http://www.aquaticinvasions.net/2018/ACCEPTED/AI_2018_Gestoso_etal_correctedproof.pdf (Online March 2, 2018)

Davidson, I., Scianni, C., Minton, M., Ruiz, G. 2018. A history of ship specialization and consequences for marine invasions, management, and policy. Journal of Applied Ecology http://onlinelibrary.wiley.com/doi/10.1111/1365-2664.13114/pdf (Online February 19, 2018).


Abstracts

May 24, 2018

Lenz, M., Ahmed, Y., Canning-Clode, J. et al. 2018. Heat challenges can enhance population tolerance to thermal stress in mussels: a potential mechanism by which ship transport can increase species invasiveness.  Biological Invasions. https://doi.org/10.1007/s10530-018-1762-8

It is unclear whether transport by human vectors can increase the robustness of translocated populations and thereby enhance their invasiveness. To test this concept, we investigated the effect of heat stress on the tolerance of mussel populations towards a second stress event of the same kind. The heat challenges we mimicked can be faced by marine invertebrates that are transported through regions with high sea surface temperatures on ship hulls or in ballast water tanks. The study included 5 mussel species that were collected at sites in Brazil, Chile, Finland, Germany (Baltic Sea) and Portugal. In parallel laboratory experiments, monospecific groups of individuals were exposed to heat challenges that caused 60–83% mortality in the experimental groups within 15–28 days. The surviving individuals were exposed to a second stress event of the same kind, while their survival was then compared to the robustness of conspecifics that had not been exposed to elevated temperatures before. We observed that thermal tolerance was significantly enhanced by previous heat stress experience in case of Semimytilus algosus from Chile and in case of Mytilus edulis from Germany. Our results suggest that heat challenges, which marine invertebrates experience during transport, can enhance stress tolerance in founder populations of these species in their non-native range by potentially increasing the frequency of genetically adapted genotypes. This points at the necessity to learn more about selection acting on organisms during human-mediated transport—in the aquatic but also in the terrestrial environment.

May 10, 2018

Del Pasqua M, Schulze A, Tovar-Hernández MA, Keppel E, Lezzi M, Gambi MC, et al. 2018. Clarifying the taxonomic status of the alien species Branchiomma bairdi and Branchiomma boholense (Annelida: Sabellidae) using molecular and morphological evidence. PLoS ONE 13(5): e0197104. https://doi.org/10.1371/journal.pone.0197104 

This study was performed to analyse the genetic and morphological diversity of the sabellid annelid genus Branchiomma, with special emphasis on a taxon so far identified as Branchiomma bairdi. This species, originally described from Bermuda, has frequently been reported as an invader in the Mediterranean, the Atlantic and the Eastern Pacific, but recent observations have raised some taxonomic questions. Samples of this taxon were collected from five sites in the Mediterranean Sea, two sites in the original distribution area of Bbairdi in the Gulf of Mexico and four localities in the east Pacific and Atlantic Oceans where Bbairdi has been reported as invasive. The molecular results revealed a conspicuous genetic divergence (18.5% K2P) between the sampled Mediterranean populations and all the other ones that led to a re-evaluation of their morphological characters. The latter showed that the Mediterranean and extra-Mediterranean populations also differ in some discrete morphological and reproductive features. Consequently, the Mediterranean samples were re-designated as Bboholense, another non-indigenous species originally described from Philippines. Branchiomma bairdi and Bboholense differ in body size, development and shape of micro and macrostylodes, size of radiolar eyes and body pigmentation. Genetic diversity was high in Bboholense from the Mediterranean as well as in Bbairdi from the Gulf of Mexico, but low in Bbairdi populations outside their native range. The phylogenetic analysis revealed the presence of connections between the Mediterranean localities as well as between native and introduced Bbairdipopulations that focus the attention on the Panama Canal as important passage for the introduction of the species from the Gulf of Mexico to the north-east Pacific Ocean.

April 9, 2018

Newcomer, K.A., Marraffini, M.L,. and Chang, A.L. 2018. Distribution patterns of an introduced encrusting bryozoan, Conopeum chesapeakensis (Banta, Perez and Santagata, 1995) in an estuarine environment in upper San Francisco Bay. Journal of Experimental Marine Biology and Ecology 504:20-31. https://doi.org/10.1016/j.jembe.2018.04.001

The factors shaping the distributions of nonindigenous species (NIS) are of particular interest for understanding their success and potential impacts within their invaded ranges. In the San Francisco Bay estuary, the encrusting bryozoan Conopeum chesapeakensis (Osburn, 1944; Banta et al., 1995) occurs in peak abundances in lower salinity hard substrate habitats, with lower abundances upstream and downstream; however, little is known about the factors that control its distribution. To investigate several hypotheses about what allows this broadly tolerant invader to be numerically dominant in this region, a field transplant experiment was conducted across three sites in upper San Francisco Bay estuary. Colonies settled on PVC plates in the peak abundance zone and transplanted to upstream and downstream treatment sites, or returned to the settlement site, which served as a control. Salinity, temperature, chlorophyll a levels, and the abundance of interspecific competitors varied at each site and were measured throughout the experiment. Mixed effects models incorporating these measurements compared net growth rate and zooid size observed across treatment sites. Colonies transplanted upstream experienced high barnacle settlement, a potential competitive threat, and decreased salinity, and exhibited an average net growth rate of 6.60 zooids/day. Colonies at the control site faced almost no potential interspecific competition, intermediate salinity, and had an average net growth rate of 4.96 zooids/day. At the downstream site, colonies grew an average of 4.62 zooids/day and experienced high potential competition from serpulid polychaete settlement and the highest salinity of all sites. The best-fit models indicated that overall abundance of potential competitors, especially the serpulid Ficopomatus enigmaticus (Fauvel, 1923), was negatively correlated with the net growth rate of C. chesapeakensis colonies. Zooid size was also negatively correlated with F. enigmaticus abundance and temperature, though the relationship weakened over time. Many colonies at both the upstream and downstream transplant sites experienced fast initial growth following transplantation, but then experienced partial colony loss corresponding with an increase in the abundance of potential competitors. In contrast, colonies at the control site showed slow but continuous growth throughout the study in absence of interspecific competitors. These results suggest that the numerical dominance of C. chesapeakensis in upper-estuary habitat may be partly explained by a lack of potential interspecific competitors. As San Francisco Bay and other estuaries face high invasion pressure in brackish upper-estuarine regions, understanding which factors influence the distribution of NIS can help predict impacts to resident communities.

March 2, 2018

Gestoso, I., Ramalhosa, P,and  Canning-Clode, J. 2018. Biotic effects during the settlement process of non-indigenous species in marine benthic communities. Aquatic Invasions vol 13. http://www.aquaticinvasions.net/2018/ACCEPTED/AI_2018_Gestoso_etal_corre...

Biotic interactions, particularly predation/grazing and competition, are key factors limiting the introduction success of nonindigenous species (NIS). In addition, positive interactions are considered important drivers of community structure, and both positive and negative interactions between native and NIS can determine the ability of communities to resist NIS invasions. This study was conducted in Madeira Island (NE Atlantic) to evaluate how predation and facilitation will affect settlement success of NIS. We manipulated the access of predators to bare and partially pre-invaded PVC settling plates to later be exposed to high propagule pressure of NIS in a marina environment. Results indicate that NIS diversity was greater in pre-invaded treatments, but only on those plates exposed to predators. Our findings suggest that positive interactions between established NIS and incoming settlers may promote the establishment success of newcomer NIS under predation pressure. 

February 19, 2018

Davidson, I., Scianni, C., Minton, M., Ruiz, G. 2018. A history of ship specialization and consequences for marine invasions, management, and policy. Journal of Applied Ecology http://onlinelibrary.wiley.com/doi/10.1111/1365-2664.13114/pdf 

1. Propagule pressure plays a key role in the successful establishment of introduced species. Explaining invasion patterns, predicting future invasions and reducing invasion rates are priority areas of research and management, especially in marine systems, which need more detailed correlates and invasion predictors.

2. The commercial maritime shipping fleet is the most prolific long distance anthropogenic transfer mechanism (vector) of marine non-indigenous species on a global scale, causing invasions of coasts by a wide diversity of organisms. Although most vessel arrivals provide an opportunity for organism introductions, there are often substantial differences among ship types—in both their “morphological traits” (structural design) and “behavioural ecology” (cargo delivery model and operational tempo)—that influence propagule delivery by ballast water and biofouling, the two dominant sources or sub-vectors for ship-mediated species transfers.

3. We reviewed ship specialization and its implications for marine invasion and vector management. First, we identified factors that affect ship-mediated propagule delivery characteristics (number, identity, diversity and quality/condition), classifying these as ship type independent or dependent factors. Second, we compared the relevance of these factors for both ballast water and biofouling. Third, we estimated and compared the magnitude of several key factors affecting propagule delivery among seven major ship types.

4. Typical voyage speed varies by 74% and port residence time varies sixfold among ship types. Similarly, typical ballast water discharge varies by an order of magnitude among ship types. These and other ship type dependent factors affect propagule delivery characteristics, resulting in uneven magnitude of species transfer among ship types.

5. Policy implications. Variation among commercial ship types is rarely integrated into analyses of marine bioinvasions and proxy measures of propagule delivery. Their inclusion may lead to more robust explanation, prediction and management of marine invasions. Risk analyses that account for differences among ship types and prevailing traffic directionality will likely offer greater insight than null models, which treat ships equally. Furthermore, ballast treatment technologies and hull husbandry may advance to reduce species transfers more effectively when tailored for different ship types, recognizing the variation and operational constraints (that affect propagule delivery) among the diverse range of ship types.

 

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).