Identifying exotic and native species in Canadian eelgrass beds at a regional and national scale
Advised by Colin D. Levings, DFO, and Kai M. A. Chan, IRES, UBC, Vancouver, BC
I am working with a Fisheries and Oceans Canada (DFO) group, the Canadian Aquatic Invasive Species Network (CAISN), to identify aquatic nonnative species (ANS) in ports of British Columbia (BC). Seagrass beds in BC are an important fisheries habitat, nursery ground and coastal erosion buffer yet little work has been done to understand what ANS are present and how they might impact the services provided by Zostera marina eelgrass beds. To investigate ANS in Canada’s eelgrass beds I sampled benthic, epifaunal and mobile macroinvertebrates that utilize this habitat. ANS arrive and establish by surviving a series of filters. The first and arguably most important filter being the arrival vector, thus I tested the relationship of ANS richness to the two most common arrival vectors for ANS in BC: ship arrivals and aquaculture. I found aquaculture to be significantly related to the richness of ANS while ship arrivals demonstrated no relationship. After arrival an ANS must establish and survive. The environment in this new habitat acts as a second filter, preventing those organisms unable to adapt to the local condition from surviving. I tested to see what regional characteristics, such as sea surface temperature, human population densities, and native species richness, are likely determinants for survival of these ANS. My results suggest that for ANS in BC eelgrass, sea surface temperature is the most important filter for survival.
Mach, ME, CD Levings, PS McDonald, KMA Chan. 2011. An Atlantic infaunal engineer is established in the Northeast Pacific: Clymenella troquata (polychaeta: maldanidae) on the British Columbia and Washington Coasts. Biological Invasions. http://dx.doi.org/10.1007/s10530-011-0096-6
Mach ME, CD Levings, and KMA Chan. 2011. Invasion and eelgrass in Canada: Exotic species in Canadian eelgrass beds at a regional and national scale. [Poster, National] CAISN AGM. Quebec City, QC April 2011.
Considering science in species management: a case study of the non-native seagrass, Zostera japonica, in the Northeast Pacific
NPR interview with Tom Banse: Pacific Coast Shellfish Growers Seek Help To Fight Sea Grass Infestation
Proposed changes to management of Zostera japonica regulations in Washington State. Public hearings occurred in Olympia, WA on Nov 1st and 2nd to decide if this nonnative seagrass can be removed on commercially leased aquaculture lands in Washington.
Management of non-native species can be difficult as the relevant science needed to inform policy decisions often lags behind the occurrence and expansion of species introductions. As efforts to control or regulate non-native species transitions from a single-species focus to an ecosystem-based approach, research on the new community interactions is necessary to inform management decisions. This approach also requires resource managers to have the appropriate access to research on the species they manage. As a case study we examined some of the barriers to effectively manage a non-native species through a comprehensive bibliometric analysis of research on the Japanese seagrass, Zostera japonica. This species was introduced to the Northeast Pacific more than 60 years ago and currently resource agencies in Washington State, USA differ widely in management approach toward Z. japonica. Programs range from requiring mitigation to proposing to list Z. japonica as a noxious invasive weed, a decision whose outcome may entail considerable economic costs. There is an increasing need to determine the ecosystem role of introduced species to inform management.
Mach ME, S Wyllie-Echeverria and KMA Chan. In Review. Knowledge gaps impede management of a nonnative seagrass: environmental impacts of Zostera japonica in the Northeast Pacific. Submitted to Biological Invasions December 26, 2011
Research gaps for implementing ecosystem-based management in coastal marine systems.
Considering the ecosystem services, or benefits, that people derive from marine ecosystems and the impacts human activities have on these ecosystem services is a required step in establishing ecosystem based management (EBM) in marine coastal systems. Human activities have direct (e.g., shellfish aquaculture) and indirect (e.g., agriculture in terrestrial systems, damming in freshwater systems) effects on ecosystem service providers in estuaries and coastal marine systems, impacting the quantity and quality of services provided. EBM requires knowledge of scientific linkages between these activities, their inputs and impacts to providers, and how these impacts alter service output. Our study reviews the scientific literature on these linkages to understand where EBM is limited by gaps in scientific understanding of connections between these systems. Clarifying how these human activities link to the benefits derived from marine systems is the first step in establishing managment that crosses ecosystem boundaries.
Mach, ME and KMA Chan. 2011. Ecosystem services research for ecosystem-based management in British Columbia. [Symposia, International] 2nd International Marine Conservation Congress (IMCC2), Society of Conservation Biology. Victoria, BC. May 2011.
Mach ME, R Martone and KMA Chan. 2011. Research gaps for implementing ecosystem-based management in coastal marine systems. [Oral, International] IMCC2, Victoria, BC. May 2011.
Trading green backs for green crabs: The potential impact of European green crab on shellfish harvest in Puget Sound
Advised by Kai M. A. Chan, IRES, UBC, Vancouver, BC
Non-native species represent a threat to native biodiversity and can have immense impacts on biological communities, altering ecosystem function and services. Theoretical studies on high-impact invasive species are important for predicting changes in community structure and function, especially when economically important species and services are at risk. The European green crab, Carcinus maenas, is regarded as a future threat to nearshore ecosystems of Puget Sound, WA with populations already established along the outer coasts of Washington and Vancouver Island. We used a predation model to predict the effects of this key marine invader, C. maenas, on commercially important shellfish in Puget Sound. C. maenas causes a loss of hardshell clams, Pacific oysters, mussels and Dungeness crab, which will reduce the total revenue from these fisheries and likely the number of jobs associated with harvesting and processing. These shellfish also act as important filters, reducing the high concentrations of nutrients and toxins released from urbanized areas into Puget Sound. Estimates of revenue loss due to reductions in commercial shellfish harvest by green crab predation range from $9 to $26.8 million USD. This translates to a loss of up to 826 jobs associated with these shellfisheries if green crabs invade at high densities. Additionally, this invasion will likely exacerbate the loss of biodiversity already occurring, and alter important habitats within Puget Sound.
Presented at WSN, Winner of best student poster.
Risk assessment by a marine snail
Marine snails have two predator avoidance strategies: withdrawing into the refuge of their shells and fleeing by crawling away. Here we exposed the marine snail, Nucella ostrina, to water-borne cues from injured prey and a common predatory crab, singly and in combination. We determined whether snails avoided cues from the different cue sources and quantified how long snails spent in passive avoidance (i.e., withdrawn in the shell) before switching to active avoidance behavior (i.e., crawling away) under different cue combinations. Active avoidance behavior was induced by all cue treatments, but the proportion of snails exhibiting passive avoidance and the time taken to switch from passive to active avoidance depended on cue combination. Cues from injured prey induced rapid initiation of active avoidance and little passive avoidance, while cues from crabs alone increased the incidence of passive avoidance and increased time spent withdrawn in the shell; suggesting that alarm cues from injured prey and predator cues elicit opposite behavioral strategies in N. ostrina. The combination of cues from injured prey and crab cues induced an intermediate response; snails remained in their shells longer than those exposed to injured prey alone and initiated crawl-away behavior sooner than those exposed to crabs alone. These results suggest that different risk cues interact additively in providing risk information for N. ostrina. Future studies of antipredator behavior in marine snails should consider the possibility that different types of risk cues may induce different types of avoidance behavior.
Mach ME and PE Bourdeau. 2011. To flee or not to flee: Risk assessment by a marine snail in multiple cue environments. JEMBE. http://dx.doi.org/10.1016/j.jembe.2011.08.018
How do the levels of genetic exchange in the Atlantic silverside Menidia menidia correspond to heritable phenotypic variation along latitudinal gradients?
Masters Student, Boston University, MA
Advised by Paul H. Barber, Ph. D.
My Masters thesis looked at genetic exchange in the Atlantic silverside Menidia menidia and how barriers to this exchange correspond to heritable phenotypic variation along its latitudinal gradient. Menidia menidia live in coastal estuaries from Florida, US to Prince Edward Island, Canada and migrates offshore each winter to the inner continental shelf. This migration should encourage population mixing and prevent local adaptation in coastal populations, however previous studies have shown M. menidia populations to show countergradient variation in growth rate, sex determination, and vertebrate number along its latitudinal gradient suggesting that migrating silversides are returning to their natal estuaries. Contrary to these previous studies, results demonstrate subtle but signiﬁcant (FST = 0.07; P \ 0.0001) genetic structure among three phylogeographic regions that partially correspond with biogeographic provinces, suggesting regional limits to gene ﬂow. Tests for non-equilibrium population dynamics and latitudinal patterns in genetic diversity indicate northward population expansion from a single southern refugium following the last glacial maximum, suggesting that phylogeographic and phenotypic patterns have relatively recent origins. The recovery of phylogeographic structure and the partial correspondence of these regions to recognized biogeographic provinces suggest that the environmental gradients that shape biogeographic patterns in the Northwest Atlantic may also limit gene ﬂow in M. menidia, creating phylogeographic structure and contributing to the creation of latitudinal phenotypic clines in this species.
Mach ME, EJ Sbrocco, LA Hice, TA Duffy, DO Conover, PH Barber. 2011. Regional differentiation and post-glacial expansion of the Atlantic silverside, Menidia menidia, an annual fish with high dispersal potential. Marine Biology 158(3):515-530 DOI: 10.1007/s00227-010-1577-3