Factors Affecting Risk Perceptions about the Human Health Effects Resulting from Harmful Algal Bloom Exposure

Abstract

In the Great Lakes region, harmful algal blooms (HABs) are known cyanobacterial blooms that pose significant public health, environmental, and socio-economic risks. Risk information related to HABs is primarily communicated through state and local government agencies; however, the effectiveness of these communication strategies and how local stakeholders are learning about such risks remains unclear. The objective of this study is to examine how to effectively communicate HABs risks and understand public risk perceptions of HABs-related risks during recreational lake use in Michigan. Guided by the social amplification of risk framework, this qualitative study conducted fieldwork in 2021, including 27 semi-structured interviews with individuals from vulnerable populations. Interviews explored participants’ awareness, experiences, and communication preferences related to HABs. Results showed that while respondents were familiar with general algal ecology, they lacked knowledge about HABs-related health effects. Vulnerable populations reported greater trust in local networks, community leaders, and peers than in state or federal agencies, revealing a gap between trusted information sources and where official information is provided. Findings indicate that effective HAB communication must combine not only accurate scientific information but also include communication approaches that build trust, account for social context and audience characteristics, and actively involve communities in engaging with risk information.

Microscopic aquatic plants (here after algae) are important to ecosystems because, through photosynthesis, they produce oxygen that is utilized by millions of organisms (Buteyko 2010; Chapman 2013; Vidyasagar 2016). Under certain environmental conditions, however, algae can become a threat to aquatic ecosystems when they grow in excess creating nuisance conditions (Watson et al. 2016). In particular, blue-green algae derived from cyanobacteria (Cyanophyceae) can grow in excess leading to harmful algal blooms (HABs) that release toxins into freshwater systems and are toxic to humans in freshwater or marine systems (Schmidt et al. 2014). Nutrient-rich environments occur with the presence of high levels of nitrates and phosphates, leading to growth of harmful toxins, such as cyanotoxins and microcystins, that can cause serious detrimental human and animal health effects through inhalation, ingestion, or dermal exposure through community drinking water or activities such as fish or shellfish consumption, beachwalking, swimming, boating, recreational, charter, or commercial fishing, etc. (Hitzfeld et al. 2000; Butler et al. 2009; Brooks et al. 2015; Lekki et al. 2019).

Human illnesses caused by HABs can vary from mild symptoms such as mild allergic reactions to severe outcomes, including liver damage, and in rare cases, death (CDC 2024a, 2024b; EPA 2024a, 2024b; NOAA-NCEI 2024). The people most vulnerable to HABs risks following exposure are children under five years of age or adults 65 years of age and older, people with asthma, people with an underlying health condition, or people with a compromised immune system (Triezenberg and O’Neil 2023). Due to severe public health risks, environmental, and socio-economic effects that have occurred in the past decade, the appearance of cyanobacterial blooms in the Laurentian Great Lakes in the United States has become well known (Boyer 2008; Heisler et al. 2008; Walker 2014; Barlett et al. 2018; Moore et al. 2020; Sterner et al. 2020; Wang et al. 2021). Inland water HABs remain poorly understood across space and time because of how greatly their magnitude, frequency, and duration may vary (Steffen et al. 2014; Brooks et al. 2016). In the United States, HABs events have occurred more frequently than ever in the last few decades (Hoagland et al. 2002; NOAA-NOS 2024). According to the U.S. Environmental Protection Agency (EPA) (2024c) and National Oceanic and Atmospheric Administration - National Oceanic Service (2024), the appearance of HABs has been reported in every U.S. coastal state and in the Great Lakes. HABs have already become more frequent every year and the prevalence and severity of HABs are expected to increase in the future, exacerbating what some already label a global epidemic (Cosper et al. 1989; Hoagland et al. 2002; Carmichael and Boyer 2016; Hallegraeff et al. 2021). Given the likely increase in HABs prevalence and distribution and known negative human health effects of exposure, there is a need to better understand how people perceive HABs exposure risks in their own words to help provide information to empower them to make informed choices about their health, especially for those most at risk.

Risk Perceptions

Risk perception is widely known to be influenced by behavioral changes and has a direct impact on how individuals respond to risk and risk management activities (Frewer 2004; Kim and Song 2017; Ning et al. 2020). Communicating about health risks with intent to increase the public’s risk perception can be a challenge given that an individual’s perception is driven by multiple psychological factors (Frewer 2004). However, incorporating risk perception is a crucial component of health behavior change such as taking protective actions to reduce exposure to HABs if the health consequence is higher (Ferrer and Klein 2015).

It is the responsibility of state or local public health professionals to effectively inform (i.e., alert) and protect the public about environmental health risks (Frewer 2004; Carson et al. 2022). Unfortunately, public perception of risks tends to be excluded from policy processes by risk assessors (Frewer 2004). This is the case with the environmental public health hazard from HABs in the Great Lakes and associated inland lakes because little is known about how people perceive their risks (Steffen et al. 2014; Brooks et al. 2015; Borbor-Córdova et al. 2018; Gill et al. 2018; Moore et al. 2020).

Social Amplification of Risk Framework

We used the social amplification of risk framework (SARF) (Figure 1) to examine and explore how risk events are experienced, interpreted, amplified, and perceived in society (Kasperson et al. 1988; Pidgeon et al. 2003). We developed a modified SARF model (Table 1) for HABs and their exposure is the risk and risk event; personal experience and communication (direct or indirect) are information sources, individual senses, informal social networks, and professional information sources are information channels; opinion leaders, social and cultural groups, government agencies, voluntary organizations, and news media are social stations; and attitudes and behaviors are individual situations (Figure 2).

Figure 1.

Social amplification of risk framework (SARF) (Kasperson et al. 1988).

Table 1.

Modified social amplification of risk framework (SARF) to Great Lakes and inland HABs, 2021.

SARF dimensions	Our application to Great Lakes and inland lake communities	Modification rationale
Risk and risk event	HABs HABs exposure	To understand how risk events are experienced individually.
Information sources	Personal experience Communication (direct or indirect)	To understand how risk events are interpreted individually.
Information channels	Individual senses Informal social networks Professional information sources	To understand how risk events are amplified socio-culturally.
Social stations	Opinion leaders Social and cultural groups Government agencies Voluntary organizations News media	To understand how risk events are amplified socio-culturally.
Individual stations	Attitudes Behaviors	To understand how risk events are interpreted individually within a sociocultural context.

Figure 2.

HABs or HAB exposure human health effects risk perception framework, modified from Kasperson et al. (1988).

While traditional environmental public health outreach communication follows an alert approach, we took a community engagement approach (e.g., collaboration) (Frewer 2004; Carson et al. 2022). Community engagement approaches often convey important community voices to researchers and to policy makers (Clites et al. 2024). Qualitative research and thematic coding are an effective approach to revealing emergent perspectives from the respondents in their own words. In the case of HABs exposures, this addresses an important research and policy gap that is likely to be increasingly important as populations in the Great Lakes and associated inland lakes are likely to experience the disproportionate impacts HABs exposures that are likely to increase in the future.

The study objectives were to advance understanding on how local stakeholders interpret and respond to HABs by examining:

1. Stakeholder’s knowledge of algal ecology and HABs as environmental events, as well as attitudes and beliefs that shape HABs risk perceptions, with direct and indirect implications for human health risks; and

2. Their communication preferences and trusted information sources related to Great Lakes and inland lake HABs, with implications for effective public health communication.

Methods

The study explored vulnerable populations’ knowledge, communication preferences, and lake experiences in three Southeastern Michigan lakes: Belleville Lake (Wayne County), Ford Lake (Washtenaw County), and Lake Erie (Monroe County). The sites were selected because each experienced at least one confirmed HABs event and toxin advisory levels were exceeded every year from 2017 – 2020 (MDHHS 2021). Beyond the similarity of HABs events, these lakes differ in ecological and demographic characteristics that make them ideal for comparison. Demographically, the population density, socioeconomic status, and recreational dependence on local water resources may vary. Belleville and Ford Lakes are surrounded by suburban and semi-urban communities, where fishing, boating, and shoreline recreation are common. In contrast, Lake Erie communities have more direct economic ties to the lake through tourism, fishing, and water-based livelihood. Belleville and Ford Lakes are reservoirs within the Huron River watershed, which drains into the Lake Erie watershed (HRWC 2022). Because these lakes are hydrologically connected, nutrient inputs and pollution from upstream communities can accumulate and flow downstream, influencing the frequency and intensity of HABs across the watershed. Lake Erie, one of the Laurentian Great Lakes, is the southernmost, warmest, shallowest, and most biologically productive of the Great Lakes (Watson et al. 2016). It is the most seriously impacted by nutrient pollution and is believed to be more prone to eutrophication because of its shallower depth than the other Great Lakes (Derry et al. 2003; Brooks et al. 2015). Lake Erie is one of the best-publicized examples of the serious human impacts on water quality (Derry et al. 2003). Human impacts on the water quality of Belleville and Ford Lakes, including HABs, have had less media coverage. These ecological and social contrasts provide a valuable context for examining how watershed position and community characteristics shape HABs exposure, risk perception, and communication needs. Studying these lakes fills a critical knowledge gap by extending research on HABs beyond the well-documented Great Lakes to smaller, inland systems and the communities that rely on them.

Data Collection

Data collection occurred from June to July 2021, during the COVID-19 pandemic, which necessitated remote research protocols. Semi-structured phone interviews were conducted to understand participants’ experiences with lakes, perceptions of HABs risk, and preferred sources and modes of environmental communication. Each participant received a $5 Amazon gift card as compensation.

Participant Recruitment

We utilized a mixed-recruitment strategy of (1) posting flyers of the study in public spaces at 15 local and state parks surrounding these three lakes, and (2) handing flyers to park visitors (e.g., engaged in recreational activities, such as fishing or boating) inviting study participation. Additional participants were recruited through snowball sampling, where initial interviewees referred other potential participants within their communities (Goodman 1961; Kirchherr and Charles 2018). Both of these approaches allowed the study to expand the participant pool while maintaining focus on individuals with relevant exposure or experience with lakes. To increase participation in our study, the study included contacting local community members, such as anglers, event organizers, and park staff, to help identify and connect with potential participants. These informants helped connect researchers with additional participants who met the study’s criteria, particularly residents from vulnerable populations or those regularly engaging with lake environments. Most participants were recruited through snowball sampling, although all interviews were ultimately scheduled and conducted by phone, making it difficult to precisely quantify how many participants were initially recruited in person vs. snowball sampling referrals.

We used the U.S. EPA (2024d) description of HABs vulnerable populations as those who are elderly (65 years or older), pregnant or nursing mothers, and those with pre-existing conditions such as chronic kidney disease, diabetes, cancer, asthma, respiratory complications, liver conditions, and dialysis patients. We asked if potential respondents reside near Belleville Lake, Ford Lake, and/or Lake Erie, and claimed to be residents in Washtenaw, Wayne, or Monroe County. To verify residency, the study asked open-ended questions with the goal to confirm that participants live near the selected lakes in our study and are familiar with the local environment, without making them uncomfortable. A total of 40 individuals were contacted through snowball sampling or flyer recruitment. Of these, 27 people self-reported they met the study criteria and verbally consented to participate in this study. Participants were emailed a $5 Amazon gift card as an incentive. Michigan State University Institutional Review Board approved this study (#6225).

We completed semi-structured phone interviews during June - August 2021. Interview questions included fewer than 19 questions organized into three sections: communication preferences, lake experiences, and knowledge. The interview instrument (Appendix A) included key questions with follow-up probing questions. Each interview lasted approximately 30 minutes on average. Interviews were recorded and transcribed. We used NVivo 12 (Lumivero 2017) qualitative data analysis software to provide an organized structure for coding and analyzing interview transcripts using thematic analysis (Fereday and Muir-Cochrane 2006; Saldaña 2018). Thematic coding is a method to identify, organize, and describe themes found in the data and produce trustworthy and meaningful findings (Braun and Clarke 2006; Nowell et al. 2017). It involves searching for emerging themes through iteratively re-reading the data and pattern recognition, where emergent themes become the categories for analysis and stories to be explored (McNarmara 1999; Rice and Ezzy 1999; Fereday and Muir-Cochrane 2006; Kuczynski and Daly 2003).

We used NVivo 12 qualitative analysis software (Lumivero 2017) to organize and analyze interview transcripts using thematic analysis (Fereday and Muir-Cochrane 2006; Saldaña 2018). Thematic coding involves iteratively re-reading transcripts, identifying repeating ideas, and grouping emergent patterns into themes that describe participants’ experiences (Braun and Clarke 2006; Nowell et al. 2017). One researcher served as the primary coder and conducted all stages of coding. To enhance trustworthiness, coding decisions were discussed with the research team through regular peer-debriefing and memo-writing, which helped refine themes and avoid individual bias.

To provide structure at the start of the analysis, we developed an initial codebook with five domains, deduced from SARF (Kasperson et al. 1988). These domains served as provisional buckets for sorting early codes:

• Communication preferences

  • Format of information
  • Preferred messenger/sources
  • Perceived trustworthiness of sources
• Knowledge about HABs

  • Where/how participants learned about HABs
  • Misinformation or knowledge gaps
• Lake experience

  • Personal experiences or stories of the lake or HABs event
• Communication barriers

  • Lack of access or connection to sources
  • Language preferences
  • Perceived institutional responsiveness
• Risk perception and emotional responses

  • Beliefs about personal or community vulnerability
  • Perceived seriousness of HABs
  • Desired communication improvements
  • Suggested sources, channels, and content
  • Calls for greater transparency
  • Greater community inclusion
  • Desire for communication targeted to specific audiences (e.g., vulnerable populations)
• Other lake and risk-related concerns

  • Presence of per- and polyfluoroalkyl (PFAS) substances
  • Presence of E. coli
  • Consuming fish in the lake

Results

Knowledge of Algal Ecology and HABs as a Risk Event

Out of the 27 participants in this study, most study respondents expressed little to no prior knowledge of algal ecology. Fewer than five participants across the three selected lakes expressed awareness of the causes of HABs. Knowledge gaps were not concentrated in a single demographic or group; rather limited familiarity with HABs appeared consistent across participants. They often repeated “I literally know nothing about algae blooms, I feel like what I have seen was just like green, basically nothing crazy, not stinky but I would say was kind of gooey” (Participant 5). “You know don’t drink the water in the lake because it’s polluted, but we never experienced any kinds of sickness or illness or issues like that…” (Participant 7). “I don’t know, I really can’t say, it’s a natural phenomenon…I think it just has to do with global warming…water getting warmer, it can be just from a populated area, the water is going to be warmer, and because it is shallow…” (Participant 20).

Respondents who knew more about algae stated “I think we know when there is green stuff in the water it’s an algae bloom and we kind of just know from experience, we understand the hotter it gets the more it can cook. I call it Cookville lake” [i.e., Belleville Lake] (Participant 10). Others described its physical appearance and color: “I think I saw it [HABs] in 2015 and 2016 but it wasn’t as dominant, it wasn’t intrusive but yeah after that it’s just floating out there and it’s so green, like pea soup color and just not attractive…” (Participant 14). Respondents described HABs as “Caused by pollution, you know, that fertilizer in the water definitely accelerates all that, I don’t think there’s any doubt…but I think that in urban situations they can happen anywhere…” (Participant 15).

Some respondents were also aware of the limited in-home treatment options should HABs toxins contaminate drinking water. “…It’s really thick, it’s like neon green and it’s really just, yeah nasty” (Participant 10). “Last year in Lake Erie it was pretty bad, they couldn’t boil the water you know enough to kill the algae, and that’s kind of crazy, when you think about [it], if you can’t get the water hot enough. It’s no[t] livable. What’s going on with the system? How do they treat our drinking water and everything else? When they say, “hey don’t swim, don’t fish in it.” And it was pretty bad last year in Ford Lake, in Belleville it’s not as common” (Participant 20).

Participants had the most negative experiences with Ford Lake, followed by Belleville Lake, followed by Lake Erie. “They have fishing tournaments on the lake but not if they put in the notice…if you’re on the lake on a boat of course they’re not going to drive by and say, “get out of the water”, but on the beach they say “No swimming” (Participant 13). “In more recent years, yes, there has been here on Belleville Lake, there have been a few incidents where the water would get green and yucky and those, you know, we read that there’s those algae blooms going on” (Participant 7). Another respondent stated “I learned about HABs through word of mouth and my own personal experience of just visually seeing it…there’s some algae that grow[s] around some areas in the lake but like you gotta have kind of like stationary water that doesn’t move…” (Participant 10).

Communication Preferences of Great Lakes and Inland Lake Stakeholders

All of the participants indicated that they spoke only English. Although language was not measured quantitatively, interview responses indicated that English served as the primary medium for receiving and sharing risk information about lake conditions. However, during fieldwork we also observed multilingual signage, informal translation among families, and community Facebook groups where posts were occasionally shared in Spanish. These observations reinforced the importance of social and cultural context in how risk information is interpreted and circulated. Because this study was exploratory, our focus was less on counting language differences and more on understanding communication preferences among the vulnerable populations who frequent these lakes. Participants who visited Lake Erie relied more heavily on national and regional news coverage to stay updated on water quality conditions, especially when blooms were highly visible or received media attention. In contrast, users of the smaller inland lakes expressed greater trust in local knowledge systems, often depending on neighborhood Facebook groups, word of mouth, and nearby access points to learn about lake conditions.

Because this was a qualitative study, communication channels were not quantified per participant. Instead, interview data revealed patterns in how people accessed and trusted information about lake conditions. For Lake Erie visitors, national and regional news coverage was referenced most often and was generally viewed as credible, particularly during visible bloom events. In contrast, users of the smaller inland lakes described relying more on local knowledge systems, neighborhood Facebook groups, word of mouth, nearby access points, and local newspapers to learn about water conditions. Trust also differed across sources: respondents from inland lakes tended to place higher trust in local information shared by residents and community organizations, while Facebook groups occasionally generated mixed reactions due to political comments and uncertainty about accuracy. Although these channels were not counted individually, these qualitative patterns suggest that communication preferences and trust are shaped by place-based social networks rather than a single dominant source.

Newspapers were key information sources about Lake Erie water quality identified by respondents. “I read tons of newspapers [such as] the Detroit Free Press, The Detroit News, the Toledo Blade…” (Participant 14). Few respondents described government entities as the main source of information, however, when they did, they stated: “Michigan.gov is what I love, I googled it so maybe an Ohio government one popped up” (Participant 19). Others stated: “I probably checked the Sterling State Park site…” (Participant 20) and “The Monroe County website” (Participant 3). Respondents also listen to local radio stations, such as “WJR and WWJ” (Participant 21). For inland lake users, the local newspaper was an important information source, as described with “I typically get the Independent that Belleville paper” (Participant 12). In addition, a few other sources such as “the Huron River Watershed Council, and Mlive.com, it’s a website to local Ann Arbor” (Participant 14), DNR website (Participant 2), and “the Van Buren Township, probably what we might read from the local Environmental Quality people…” (Participant 7).

Private Facebook groups or other pages were described by respondents. For example, “Lake Erie Bolles Harbor and the different fishing ones I pretty much only use Facebook now it’s the most accurate you get to follow…” (Participant 19). Finally, other information sources for learning about lake conditions were: “…boat launches like the big ones by the metro parks like Lake Erie Metroparks… or like the different access points where people are actually going to be going in the water” (Participant 19). Another respondent indicated, “I have a Facebook page just for Ford Lake people and subjects our subdivision here but I think it gets passed beyond there so if I get something you know [by] email or Facebook post I will share it to the group” (Participant 14). Respondents described local organizations as information sources, such as the “Belleville Yacht Club (BYC) [that does] a lot of stuff for the community…” (Participant 2) and “… the Belleville Public Library…” (Participant 9).

A few respondents mentioned word of mouth or government-related projects for Belleville and Ford Lakes. “I’m probably a combination of things…word of mouth, just talking with other residents, you know that kind of stuff” (Participant 7). “Sometimes it’s the people that are living on the lake that do their own research and contact people to get answers and they’ll be honest and not gossip but share the facts that they have learned you kind of have to trust your sources and double check with more than one…” (Participant 13).

Individual Attitudes toward Risk and Lake Experiences

Participants expressed complex attitudes regarding how they perceive, interpret, and respond to environmental risks in lake settings. Many reported using visual cues, such as water color, to assess safety, green or murky water often signaled contamination, while clear or blue water indicated safety. HABs were described as disrupting usual recreation, including swimming, boating, fishing, and family gatherings. Participants frequently reported frustration or disappointment when blooms altered water clarity or odor, sometimes forcing them to leave early or cancel planned activities. Importantly, despite these negative perceptions, many participants demonstrated a strong, long-standing attachment to their local lakes. Several described decades of experiences and memories associated with the lakes, expressing sentiments such as, “It’s a dirty lake, but it’s our lake.” This illustrates that while visible environmental risks and HABs negatively influence behavior and attitudes, long-term familiarity and personal connection temper these perceptions, fostering continued engagement. Participants also highlighted concerns for children and pets, distrust toward institutions managing water quality, and uncertainty about health risks. Overall, these attitudes reflect behavioral changes consistent with the SARF: environmental cues and information sources amplify perceived risk, but personal attachment and local knowledge mediate responses and decision making.

Information System and Amplification Stations

Using SARF, this study examined how participants interpret and respond to HABs-related information through various information systems and amplification stations, including government agencies, local media, community organizations, and social networks. These channels serve as both sources and amplifiers of risk signals, shaping trust, perceived credibility, and behavioral responses.

Several respondents described a lack of confidence and trust toward government agencies that can be seen in the following quotes. “Honestly it’s hard to know who to trust” (Participant 7). I used to listen to this radio station guy, he’d say, “I love my country, but I fear my government”, and you know it’s to the point where I don’t trust what the government puts out” (Participant 1). Other respondents, regardless of which lake, expressed their distrust of private companies that are polluting and sending the wrong messengers to convey important environmental and public health information. “Oh, I don’t know, I have a tendency to believe them (DNR) more than I do corporations that are polluting. They don’t have an agenda, but corporate America does…” (Participant 24). “Sometimes there are private companies or even the DNR who send the wrong people. They have people who aren’t real[ly] familiar and don’t understand how knowledgeable their audience is. You can tell that they are uncomfortable with knowing how to answer the questions and they’re trying to sugarcoat things and not be honest with you and then you feel like you’re totally wasting your time…” (Participant 13).

In response to the question, “What do you think our communication campaign should target in terms of how to communicate HABs?”, a few answers included: “People need to have honest information” (Participant 1). Moreover, “…they need to at least like posting it at beaches. I feel like that’s where people would be swimming at least so people know that it could be harmful to certain people” (Participant 1). In addition, another participant expressed: “Yeah, I think they should include more information on HABs digitally. Usually, to know the presence of HABs, I have to go to the beach and check if it’s safe” (Participant 5).

After the interview process, participants were curious and asking questions such as what are the effects caused by HABs. After the conversation, one participant was appreciative of the explanation of some of the effects caused by HABs and said: “I think one of the key is and what you are doing right now, asking and giving people relative[ly] correct information” (Participant 26).

Other Concerns: PFAS, E. Coli, Fish Consumption Advisories, and Watershed Connections

Respondents also described concerns about other environmental public health topics, such as PFAS, E. coli, and fish consumption advisories, that may co-occur along with algal blooms. “I had to go surfing the net and read people’s comments to know about…that kind of thing [PFAS]” (Participant 1). Further, respondents stated “yeah, somebody from the state [or] somebody from the Watershed…brought up about Ann Arbor [that] every now and then when the rain come in and it’s so heavy [and] overloaded, they dumped their sewage into the river” (Participant 1). This suggests that participants who were aware of HABs were also more likely to think about other water-related environmental concerns, even though overall awareness was limited.

Discussion and Conclusions

It is encouraging that some respondents (fewer than five) knew about algal ecology, could recognize algae, and expected that blooms were associated with warmer temperatures and excess nutrients. However, given that HABs containing toxins can only be confirmed through laboratory testing, participants remain in a challenging situation: distinguishing between visually noticeable nuisance blooms and blooms that pose actual health risks is difficult. This creates a complex risk communication environment, as the timing, location, and toxicity of HABs are inherently uncertain. Across all 27 participants, no one in our research attributed health effects to HABs exposure, however, they also were unaware of the health effects from HABs exposure, regardless of their level of knowledge of algae ecology.

Our findings highlight the importance of local knowledge and tailored risk communication, particularly for populations most vulnerable to exposure. Participants described seeking HABs information through trusted, accessible, community-level sources, such as local Facebook groups, neighborhood networks, and word-of-mouth, rather than formal government or scientific information channels. In SARF terms, these social stations, social networks, and interpersonal channels serve as primary amplifiers of risk information for local users, whereas formal information channels, such as state websites or national news, were accessed less frequently or perceived as less relevant, particularly for inland lakes. This pattern illustrates how risk signals (e.g., visual cues like water color, social discussions about blooms) are filtered through personal experience and social context, amplifying or attenuating perceived risk.

While our findings suggest that many participants relied on community-level and informal sources, such as family networks, local Facebook groups, and conversations at the beach, to make sense of HABs, we acknowledge that our qualitative design and sample size do not support broad generalizations about all lake users or specific sub-populations. This study focused specifically on participants meeting selected criteria defined for vulnerability to HABs, as identified by the EPA, and aimed to capture patterns among those most at risk rather than quantify the prevalence of behaviors across the general population. Accordingly, our goal was not to count how many participants reported each information source, but to explore patterns and themes in how participants accessed and trusted information. Across interviews from all three counties, several respondents explicitly stated that they did not regularly consult state agency websites or formal advisories, and instead relied on locally accessible social networks or on-site cues (e.g., visual inspection of water, word-of-mouth, or local Facebook groups). Because qualitative research prioritizes depth of insight over representativeness, these findings should be interpreted as emergent patterns rather than population-level claims. Still, the consistency of this theme across geographically distinct inland lakes suggests that informal amplification stations may play an important role for certain lake users, particularly those who may have limited time, skills, or resources to access official information.

The study has several limitations. Our sample was small (n = 27) and self-selected, which may bias findings toward participants already engaged or interested in lake conditions. Qualitative interviews cannot quantify prevalence of perceptions, and our exploratory design did not measure trust or risk perception systematically. Despite these limitations, the results provide important insights into how lake users interpret HABs signals, select information sources, and make behavioral decisions.

Future research could expand sampling to include non-English-speaking visitors, first-time lake users, and more diverse demographic groups to better understand differences in risk perception and access to information. Linking participant perceptions with actual HABs monitoring data could clarify whether visual cues align with toxin presence, strengthening predictive and targeted risk communication. Additionally, studies using larger or mixed-method samples could assess the prevalence of informal information channels and explore how these trusted local networks might be integrated into state-level risk communication strategies.

From a practical perspective, these findings underscore the need for public health and environmental agencies to engage local social networks as part of HABs risk communication strategies. Posting accessible, timely, and accurate information in places where users are already looking, such as community Facebook groups, local newspapers, and popular access points, may increase the likelihood that at-risk populations receive relevant guidance. Integrating SARF insights with local knowledge and community trust networks can enhance the effectiveness of HABs communication, particularly as the frequency and severity of blooms increase.

The goal is to effectively communicate the technical risk information (environmental and health-related issues) and avoid having inaccurate perceptions of risk toward the hazardous event (Covello et al. 1986; Tomkins et al. 2018). Poor communication can lead to bigger problems between the public and those in charge of divulging such risks (health/communication experts), such as the public (nonexperts) being accused of ignoring existing information, and experts being perceived as secretive, containing technical jargon and complex objective analysis, and known not to be trusted (Bennett et al. 2019; Porat et al. 2020). According to the National Research Council (US) Committee on Risk Perception and Communication (1989), if nonexperts are not able to understand the selected information, it can lead to more challenges to receiving inaccurate and incomplete information from these experts. Trustworthiness, credibility, and accessibility are among the few challenges and concerns academia has expressed when discussing scientific information within the field of risk communication (Van der Meer and Jin 2020; Hyland-Wood et al. 2021). The opportunity for public health professionals is to partner with groups that the audience trusts.

This body of research directly links to our study’s findings by illustrating why many participants relied on local, informal, or familiar sources rather than official agencies when deciding whether lake water was safe. Prior research shows that when risk messages are overly technical, lack transparency, or come from institutions perceived as untrustworthy, the public turns to more accessible and trusted interpersonal channels. Our participants demonstrated this exact pattern, seeking information from community members, social media groups, or personal inspection of the water rather than state-level advisories. Among the problems and challenges risk communication faces, it can be criticized as “technical, complex and uncertain” (Covello et al. 1986). Some challenges include government agencies lacking the public’s trust (Covello et al. 1986; Van der Meer and Jin 2020) and relying on sources found in social media for accurate information (Pascual-Ferrá et al. 2022). According to Covello et al. (1986), several origins of risk communication problems derive from the message (government or industry data), the source (who is the messenger), the channel (what type of media), and the receiver (individual citizens). Although media disinformation has been a concurring issue in the past (Marwick and Lewis 2017), the spread of incorrect information has gained momentum in the field of science, and it can be very challenging in correcting (Waisbord 2015; Van der Meer and Jin 2020).

When it comes to public health and environmental-health related issues, the root of some challenges and risks communication faces can be tied to broader and unique social and cultural issues, including misinformation in social media platforms and mistrust toward health and government agencies (Covello et al. 1986; Frewer 2004; Van der Meer and Jin 2020). There is no ‘one size fits all’ strategy to effectively communicate risk (Hyland-Wood et al. 2021), however, drawing fundamental strategies and scholarships essential to obtain effective risk communication (in the realm of environmental-health related topics) we can explore challenges between existing information provided by government agencies vs. the public’s understanding, and highlight the importance of incorporating risk perception as a key variable to better understand public’s health behaviors toward the risk, and including more public engagement methods, creating a more effective way to bridge the existing gap between existing scientific information and the public’s understanding (Bennett et al. 2019). This is especially important in this context to understand factors affecting people at higher health risks from HABs and then design and implement intervention strategies and partnerships that effectively inform and empower the individuals who are most in need of the information that they will use.

To achieve the goal of effectively communicating environmental health hazards, such as those from HABs, to prevent members of the public from learning about them through direct and personal experiences and impacts, we recommend following risk communication strategies. Use existing sources that community members rely on for information. For Great Lakes HABs, it is the major newspaper serving its geographic area and for inland lakes, it is local newspapers, community events and websites, and private social media groups. Make information available locally, such as boat clubs, boat launches, parks, campgrounds, beaches, libraries, etc. Make information available to be shared digitally, especially through private groups on social media. Convey the complexities of algae. For example, algae are an important part of ecosystems, however, in some cases they may grow in excess and become nuisance, and occasionally they produce toxins that are harmful to the health of humans, animals, and the environment. Toxins in HABs can only be confirmed through laboratory testing, and because little is known about inland HABs over space and time, if you observe a nuisance algal blooms, assume it is toxic until laboratory tests can be completed. Focus on audiences who are at elevated risk for health effects from HABs exposure.

However, because the trustworthiness of the information is likely dependent on effective engagement, we recommend these strategies if you are an environmental engagement or communications professional. Take time to prepare yourself. Ask about their experiences. Be receptive to people’s attitudes, including emotions, about the risk or their experiences. In other words, pay attention to how the audience describes their information sources, channels, and their social and individual stations. Be prepared to provide up-to-date evidence-based information. Be prepared to state what is unknown and if there is a plan to address unknowns. Ask people what they need and want, i.e., give them a voice. Listen to what people tell you, i.e., respect them. Because HABs may be co-occurring with other environmental issues, the issues and context may be very complex. Utility of a community engagement approach is that it contributes to trust-building and community voice, leading to agency and empowerment at the heart of solving complex public and environmental problems (Balasz and Morello-Frosch 2013; Carson et al. 2022).

Understanding the public’s perception of the risks, needs, and concerns, and integrating public engagement such as searching for more community engagement and community intermediators can allow risk communication about environmental-health risks to become more effective, improve mistrust toward media information, obtain a better health behavior, and even achieve a higher level of knowledge toward the risk. Finding new and engaging ways to incorporate effective risk communication would not only help prevent future incidents, or events, but share common knowledge to better communicate environmental health risks in the future. The need for better effective communication about HABs requires integrating community engaged methods such as listening to the public’s concern and exploring ways on how to better develop trust. Attitudes are based on feelings, thus by becoming more empathic, we are not only increasing a better level of understanding of potential risks caused by HABs but potentially minimizing incidents and exercising better health behaviors in the future. A limitation of this study is that it was conducted in 2021 during the COVID-19 pandemic when people were saturated with health risk communication and health officials were focused on the pandemic.

Research Implications.

• Vulnerable populations rely on trusted, accessible, community-level sources for information about HABs exposure risks.

• Public health professionals could be more effective in communicating with their audiences if they partner with groups most trusted by vulnerable audiences.

• Communication strategies should address knowledge gaps and tailor messages to the social and cultural context of the audience.

• Collaborating with communities to co-develop communication efforts can enhance understanding, build trust, and support improved health outcomes related to HABs exposure.

• The perceived trustworthiness of information depends on both the accuracy of the content and the credibility and engagement techniques of the professionals delivering it.

Biographies

Alexandra Benitez Gonzalez is a doctoral student in the Information and Media Program in the College of Communications Arts and Sciences at Michigan State University. Specializing in science communication, her research interests include understanding the types of public engagement efforts, support, and barriers environmental scientists encounter when communicating with nonscientific audiences. She is interested in the role of identity, and how scientists could communicate more strategically to bridge the gap between scientific knowledge and public understanding. She recently received her master’s degree in the Department of Fisheries and Wildlife, College of Natural Resources which focused on understanding how health risks from Harmful Algal Blooms in the Great Lakes are being communicated and how vulnerable populations were learning about its risks. She may be contacted at 404 Wilson Rd., College of Arts and Sciences, Room CAS 378, East Lansing, MI, USA, benite18@msu.edu.

Heather A. Triezenberg (corresponding author) is Associate Director and Extension Program Leader for Michigan Sea Grant with Michigan State University Extension. She provides leadership and operations support for Michigan Sea Grant’s outreach program through MSU Extension’s Community, Food, and Environment Institute, and is jointly appointed with the Fisheries and Wildlife Department. Her research focuses on Extension-based needs assessments, evaluation, and public perceptions using community-engaged approaches. She may be contacted at 446 W. Circle Drive, Justin S. Morrill Hall of Agriculture, Room 73, East Lansing, MI, USA, Phone: 517-353-5508, Fax: 517-884-8511, vanden64@msu.edu.

Diane Doberneck is the Director for faculty and professional development in University Outreach and Engagement and Adjunct Associate Professor in the Department of Community Sustainability at Michigan State University. She provides leadership for University Outreach and Engagement educational programs, coordinates a Graduate Certification in Community Engagement, and conducts research about community-engaged scholarship. Her research interests are many, including effective strategies for professional development for stakeholder and community engagement, especially related to sustainable communities and environmental conservation. Connect with her at connordm@msu.edu.

Abigail Bennett is an Associate Professor in the Department of Fisheries and Wildlife at Michigan State University. She is an interdisciplinary social scientist with a background in human geography and policy studies studying aquatic food systems in the context of global change. Her work aims to inform policy, investments, and governance that support sustainable livelihoods and food security from fisheries and aquaculture. She may be contacted at 480 Wilson Rd., Natural Resources Building, Room 334C, East Lansing, MI, USA, benne592@msu.edu.

Mark Rey became affiliated with Michigan State University after eight years as the nation’s Under Secretary for Natural Resources and Environment at the United States Department of Agriculture (USDA). As an Administration official, Mr. Rey successfully passed Senate confirmation. He held a position as senior staff at the United States Senate Committee on Energy and Natural Resources. Mr. Rey teaches undergraduate and graduate students at Michigan State University as an Executive in Residence, and he is also affiliated with the Livingston Group, a public policy consulting firm. Mark may be contacted at 202-669-9902 or markrey8@aol.com.

Appendix A. Risk assessment and communication campaign of harmful algal blooms: Case study of freshwater lakes in Michigan interview questions, 2021

Communication Preferences

• 1
  What is the best way to communicate with you about health risks and concerns? (follow-up with probing questions a-h)

  1. What kinds of visuals?
  2. What kind of design formats do you like?
  3. What is some sort of key element?
  4. Where do you usually look for health related information?
  5. What sources?
  6. Online? Hardcopy?
  7. What about them is useful/effective to you?
  8. What about them is not useful/what don’t you like about them?
• 2
  When it comes to health-related risks and concerns, what sources do you trust the most? And why? (follow-up with probing questions a-e)

  1. Would you trust government agencies?
  2. Local news?
  3. Friends and family?
  4. Who on the internet?
  5. How do you feel about Facebook pages?

     1. Instagram?
     2. Twitter?
     3. If we were to develop a page to learn about HABs, how would that be something you could benefit from?
• 3
  Do you speak any other languages besides English? (follow-up with probing question a)

  1. If there was another language besides English that resources should be distributed, what language would that be? (County specific)
• 4
  When visiting lakes, are there any public signs, messages, or billboards that you pay attention to? (follow-up with probing questions a-b)

  1. What kinds of signage do you see?
  2. What kind of information?
• 5
  Where do you find it to be more effective to communicate lake related information? (follow-up with probing questions a-c)

  1. Calendar events? Water quality?
  2. Online?

     1. Where online?

        1. Examples: FB? Lake association newsletters? Other?
  3. Hard copy?
• 6What color comes into your mind when you think “Risks”?
• 7What color comes into your mind when you think “Health”?

Experiences

• 8
  Walk me through a usual day visiting a lake or river (follow-up with probing questions a-d)

  1. What lakes/rivers do you usually visit?
  2. How often?
  3. What kinds of activities do you do in or nearby the lake, river, or pond? (Prompts)
  4. With whom do you attend such activities the most (if any)?
• 9
  In the lakes/rivers that you usually attend, how often would you encounter a HAB event? (follow-up with probing questions a-c)

  1. Where would you say you encounter HABs the most?
  2. What kinds of activities are you doing when encountering a HAB?
  3. What do you do after seeing a HAB?
• 10
  Can you share a personal experience encountering HABs? (follow-up with probing questions a-c)

  1. When was this event?
  2. Were you alone?
  3. What did you do afterwards?

     1. Did you report it?
     2. To whom?
• 11
  If they had an experience with HABs, ask: When encountering a HAB event, what are your initial thoughts? (follow-up with probing questions a-b)

  1. Attitude?
  2. What kind of concerns do you have? (if any)
• 12
  If they did not have an experience with HABs, ask: Do you have different thoughts/concerns about HABs from what you know? (follow-up with probing questions a-b)

  1. Attitude?
  2. What kind of concerns do you have? (if any)
• 13How do HABs influence your experience when attending your usual lake/river near you?

Knowledge

• 14
  What do you know about HABs? (follow-up with probing questions a-b)

  1. Concerns?
  2. Awareness?
• 15
  Where did you learn about HABs? (follow-up with probing questions a-b)

  1. Have you sought information on HABs before? If so, where?
  2. What made you search information about HABs?

     1. Personal experience?
     2. Government related agencies/communication?
     3. Social/cultural media? Such as FB, Twitter, local blogs
     4. News?
     5. Family/friends?
• 16
  What information do you already know about HABs? (follow-up with probing questions a-f)

  1. Health effects?
  2. Environmental effects?
  3. Potential health risks?
  4. What causes them, why are they harmful, etc.?
  5. Where do you think they are most prominent?
  6. Who do you think can get affected by these HABs?
• 17Do you believe HABs information is easy and accessible to obtain? If so, how?
• 18Who would you say are part of the vulnerable population if exposed to HABs?
• 19
  What information would you like to know about HABs? (follow-up with probing question a)

  1. What information do you think is necessary to know about HABs?