Sentinels of Change
An integrative program of the Hakai Institute, UBC and local communities to deepen our understanding of Salish Sea biodiversity change at an unprecedented scale and resolution. The goals are to implement standard observation systems for biodiversity across a range of taxa, to conduct experiments to test hypotheses about the causes of diversity change, and to integrate knowledge from observation and experimental systems into a sustainable ongoing biodiversity observation system for the Salish Sea. We will focus our work on invertebrates and seaweeds, with an eye to integrating microbial and symbiont communities into biodiversity monitoring.
We are recruiting postdocs
An integrative program of the Hakai Institute, UBC and local communities to deepen our understanding of Salish Sea biodiversity change at an unprecedented scale and resolution. The goals are to implement standard observation systems for biodiversity across a range of taxa, to conduct experiments to test hypotheses about the causes of diversity change, and to integrate knowledge from observation and experimental systems into a sustainable ongoing biodiversity observation system for the Salish Sea. We will focus our work on invertebrates and seaweeds, with an eye to integrating microbial and symbiont communities into biodiversity monitoring.
We are recruiting postdocs
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Community interactions and sea star wasting disease
The direct effect of disease outbreak on a species can be altered by competition between host species that have differential susceptibility to disease. Sea star wasting disease (SSWD) caused sea star mortality by the millions along the North American west coast starting in 2013, and can infect up to 20 species of sea star. Following the outbreak, many sea star populations had large declines, including Pisaster ochraceus and Pycnopodia helianthoides. At the same time, some species have seen either no change, or even an increase in their populations, including Evasterias troschelii and Dermasterias imbricata. In my research I am interested in what drives the difference in response between different sea star species, and whether sea star diversity drives community response to SSWD outbreak and subsequent recovery. |
Environmental context alters cost of parasitism and host defense capabilities
Parasites can exacerbate or buffer host response to environmental conditions, and thus hosting a parasite can affect host performance. Likewise, environmental context can alter parasite performance directly, creating a range of host-parasite interactions across environmental gradients. Extant variation in species interactions across environmental gradients could give us insight into how species will respond to climate change. Using field outplants, I examine growth of a shell-boring endolithic cyanobacteria and its mussel host, Mytilus californianus across an intertidal gradient.
Parasites can exacerbate or buffer host response to environmental conditions, and thus hosting a parasite can affect host performance. Likewise, environmental context can alter parasite performance directly, creating a range of host-parasite interactions across environmental gradients. Extant variation in species interactions across environmental gradients could give us insight into how species will respond to climate change. Using field outplants, I examine growth of a shell-boring endolithic cyanobacteria and its mussel host, Mytilus californianus across an intertidal gradient.
Parasite reproduction and temperature
Changes in species interactions are the key link between climate affects on individuals and the responses of communities. Temperature has predictable, often non-linear, affects on many biological processes. Although vital to predicting how parasitism will respond to climate change, thermal responses of both host and parasite in key traits affecting transmission are just beginning to be quantified. Through a combination of temperature controlled laboratory experiments and an epidemiological model, I demonstrated that the relationship between host and parasite thermal performance could provide a predictive framework to evaluate how host-parasite pairs will respond to climate warming.
Changes in species interactions are the key link between climate affects on individuals and the responses of communities. Temperature has predictable, often non-linear, affects on many biological processes. Although vital to predicting how parasitism will respond to climate change, thermal responses of both host and parasite in key traits affecting transmission are just beginning to be quantified. Through a combination of temperature controlled laboratory experiments and an epidemiological model, I demonstrated that the relationship between host and parasite thermal performance could provide a predictive framework to evaluate how host-parasite pairs will respond to climate warming.
Drivers of parasite abundance
Parasite abundance within a community can be influenced by both biotic and abiotic factors. For example predators can keep parasite abundance low by selectively feeding on infected hosts, while high temperatures can eliminate parasite infection completely if infected hosts have a higher heat tolerance then their parasite. As part of a team of scientists, I investigated the relative importance of biological and physical drivers of parasite abundance and prevalence using the Rhizocephalan parasite Loxothylacus panopaei, that infects the mud crab Eurypanopeus depressus.
Parasite abundance within a community can be influenced by both biotic and abiotic factors. For example predators can keep parasite abundance low by selectively feeding on infected hosts, while high temperatures can eliminate parasite infection completely if infected hosts have a higher heat tolerance then their parasite. As part of a team of scientists, I investigated the relative importance of biological and physical drivers of parasite abundance and prevalence using the Rhizocephalan parasite Loxothylacus panopaei, that infects the mud crab Eurypanopeus depressus.
Predation and parasitism
There are multiple theoretical studies predicting the outcome of the addition of predators in host-parasite systems. In a direct developing and castrating system, high levels of predation on infected individuals will likely lead to a reduction in parasite infections, but empirical data is currently lacking. The Rhizocephalan barnacle parasite Loxothylacus panopaei provides an ideal system for investigating parasite response to predation. L. panopaei is invasive from the Chesapeake Bay to Florida and infects the mud crab Eurypanopeus depressus. It has been hypothesized that E. depressus maintains a small size because it is able to escape predation by hiding in the interstitial space between oyster shells. E. depressus with adult L. panopaei infections carry a large externa, the external reproductive organ of the parasite, which increases the crabs size and could decrease mobility. I investigated whether infected mud crabs were more susceptible to predation by the native blue crab Callinectes sapidus than their healthy counterparts. In all treatments infected crabs were consumed at higher rates then healthy crabs, with some predators exclusively consuming infected crabs. On average, infected crabs were consumed three times as often as healthy crabs. With predators selectively feeding on infected hosts the parasite populations could be driven to extinction. In this system, a native predator may be helping to protect the native crab species from its invasive enemies.
There are multiple theoretical studies predicting the outcome of the addition of predators in host-parasite systems. In a direct developing and castrating system, high levels of predation on infected individuals will likely lead to a reduction in parasite infections, but empirical data is currently lacking. The Rhizocephalan barnacle parasite Loxothylacus panopaei provides an ideal system for investigating parasite response to predation. L. panopaei is invasive from the Chesapeake Bay to Florida and infects the mud crab Eurypanopeus depressus. It has been hypothesized that E. depressus maintains a small size because it is able to escape predation by hiding in the interstitial space between oyster shells. E. depressus with adult L. panopaei infections carry a large externa, the external reproductive organ of the parasite, which increases the crabs size and could decrease mobility. I investigated whether infected mud crabs were more susceptible to predation by the native blue crab Callinectes sapidus than their healthy counterparts. In all treatments infected crabs were consumed at higher rates then healthy crabs, with some predators exclusively consuming infected crabs. On average, infected crabs were consumed three times as often as healthy crabs. With predators selectively feeding on infected hosts the parasite populations could be driven to extinction. In this system, a native predator may be helping to protect the native crab species from its invasive enemies.
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Maternal carryover effects in sea stars
In this six-rayed starfish - Leptasterias aequalis - larger mothers produce larger offspring, more offspring, and offspring with bigger nutrient stores. I was curious whether offspring size was set (genetic), or something that would change depending on how much food the mother was provided (plastic). In order to investigate this question, I collected mother starfish and their offspring in 2007. I took the 2007 juveniles and measured their size. I then fed the mothers for a year on a variety of diets (high, medium and low). In 2008 I collected the offspring of those same mothers and looked to see what size they were. Surprisingly, I found that my feeding treatments did not change offspring size. Instead, the beach a mother came from, and therefor her genetic background and full feeding history, seemed to have a greater effect on the size of her offspring. |
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Cover photo credit: Keith Holmes
