Ocean Education

Seagrass Resilience – Dr. Johan Eklof Resilience and Seagrass Ecosystem Feedback

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Resilience can be defined as the capacity of a system to withstand stress. In seagrass ecology, the focus centres on the capacity for the seagrass ecosystem to remain within the same ‘regime’; essentially, a seagrass meadows capacity to maintain its own ‘structure and function’ i.e. it still looks and behaves like, a seagrass ecosystem!

Central to resilience thinking is the understanding that people are part of the natural world too, and therefore we humans, some remotely, and some intimately, interact with seagrass ecosystems for our survival. Some of our interactions can be positive, others negative, but it is the sum effects of these interactions that can transform one ecosystem (e.g. a seagrass ecosystem) into another (e.g. mud) causing an ecosystem ‘regime’ shift. What once was a seagrass meadow no longer looks or behaves like a seagrass meadow!

When we wipe out the most sensitive species in a seagrass meadow, humans reduce the resilience of the seagrass ecosystem to change. However, in contrast, when resilience is enhanced, the seagrass ecosystem is more likely to tolerate disturbance events without collapsing into a different state (e.g. mud) that is controlled by a different set of relationships. This new state of the system may also be less desirable if the productivity of the ecosystem i.e. the characteristics that benefit humans (called ‘ecosystem services’) are diminished. This is the case of when seagrass meadows become degraded and are depleted of their biodiversity. High biodiversity (including high genetic diversity) acts as an ‘insurance policy’ for seagrass ecosystems because it increases the chance that at least some species will be survive and sustain important ecological functions such as water purification and carbon fixation in a changing environment.

Johan’s keynote described three key considerations for ecosystems in the coastal zone.

  1. Biodiversity
  2. Trophic interactions
  3. Feedback mechanisms

Critically, he discussed that there has been an assumption that “we can afford to lose the most sensitive species” because there will be other species (that fulfill similar ecological roles available), but this is predicated on the assumption that species will go extinct randomly, which of course, they don’t!

Johan explores how in the past 10 years’ research has shown that seagrass meadows respond in different ways in different places depending upon local extinction events. In particular, he discusses the effect of the absence of top predators (top-down control) and how it interacts with ‘bottom-up’ effects such as the eutrophication of coastal seagrass meadows. He finally links these patterns to the positive and negative feedbacks witnessed in seagrass ecosystems and explores how seagrasses are ‘ecosystem engineers’ and therefore alter the abiotic and biotic environments in which they are found.

Johan’s take home messages:

  • High-diversity within and of trophic levels ‘insures’ seagrass ecosystems against environmental change
  • Strong feedbacks and mutualism within and across coastal systems make them more resistant to change.

He argues that to effectively manage our (humans) relationship with seagrass ecosystems we need to reduce pressures that push seagrass towards undesirable ‘regime shifts’ (e.g. seagrass to mud!) to strengthen response diversity, and to weaken undesirable feedback mechanisms whilst strengthening those deemed as desirable ones.


One Layer Deeper – The Challenges Facing Sustainable Fisheries in 2017 by Bradley MacDonald

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What is a sustainable fishery in 2017? It seems like it should be obvious: don’t catch too many fish. But sustainable fisheries are often way more complicated. So today, let’s go one layer deeper and ask: how?

I asked marine biologists from my past and present to weigh in. What does a sustainable fishery mean to them? What are the challenges in defining it? And what parts of fisheries sustainability do they wish made it into the mainstream conversation more often?

Their answers were rich, insightful, and even challenged some of my own beliefs.

No Emotional Harm

My simple starting point for sustainability (fisheries and otherwise) is that the activity does no harm ecologically, economically or emotionally.

– Dr. Wallace J. Nichols, author, Blue Mind, and Research Associate at the California Academy of Sciences

Nichols’ summary has universal appeal – simple, memorable, and broad. Ecological harm ranges from overfishing to bycatch to habitat damage. Economic harm would be something like closing a fishery, preventing fishing communities from making a living, or necessitating the use of a fishing subsidy. I feel like we all largely agree that those outcomes are to be avoided.

“It’s that third ‘e’ that is often left out,” Nichols told me. “A dehumanized workforce, for example, doesn’t meet this definition even if no harm is done ecologically and economically.”

That caught my ear. And it was something that everyone else I spoke with wanted to talk about, too. Emotional harm is a layer deeper than we all tend to go. That makes it an interesting place to start. For example, if a fisherman’s coastal fishing grounds have been closed, you might find him another job or give him a subsidy. But you’ve done emotional harm in disassociating him from his life on the water. Here’s an example.

Sea Turtles in El Salvador

“I always hear people saying we need to provide alternatives [to fishing], but you know, a lot of fishermen just want to be fishermen. They don’t want to make tortillas, they want to be fishermen…maybe some of them will want to do that, but a lot of them, fishing is what they love.”

– Alexander Gaos, Co-Founder and Director,

Gaos works with small fishing communities throughout Pacific Latin America to promote sea turtle conservation. His perspective points to something raw and human going on. Solutions cannot be wholly academic. We need to put on our people hats. We need to remember what we’re asking of someone whose dad and granddad were fishermen – for whom pulling their boats out of the water is divorcing them from a way of life. Fisheries scientist Marisa Trego similarly told me that “if the fisherman or his/her community experience a decline in financial stability or food availability, the need to survive will take precedence.”

On the other hand, Gaos acknowledges that taking no action has devastating consequences. Lobster fishermen in El Salvador use gillnets that unintentionally catch non-target species, like critically endangered hawksbill sea turtles. “It wrecks the reefs, it kills hawksbills, and it kills other species as well,” Gaos says. “These artisanal fisheries aren’t necessarily causing less harm than commercial ones. They are much more ubiquitous than I think people realize. These gillnets that are out there are so effective that it’s not like the fisherman back in the day, who was throwing a line over the edge of his boat.”

This is a very, very important point. I say that because as consumers, especially in seafood sustainability, we typically believe that smaller is always better. But Gaos points out that “artisanal fishing has had a huge impact. It’s spread over a much larger scale as far as people and geography, so per boat it doesn’t have as big of an impact. But collectively, it sure does.”

It’s my own opinion that small-scale fishing is a good model for things like maintaining traditions and keeping businesses within local communities. But it doesn’t guarantee ecological sustainability. Large and small boats alike can do great harm, and we need to regulate both carefully. Gaos concurs, but reminded me that because artisanal fisheries involve a lot more people, they can be much harder to regulate from a logistical and political standpoint.

That brings us to fisheries management, where ecological, economic, and emotional sustainability intersect.

Fisheries Management: Cudgel or Cure?

“There’s already a lot of variability, and just dealing with that natural variability is really challenging for fisheries managers.”

– Dr. Sarah Wheeler, Ocean Science Trust

Fisheries managers play a crucial role in balancing the competing demands of ecosystems and economies, of hearts and mouths and wallets. They do this in part by deciding catch quotas, allowable gear types, and issuing permits within a fishery. But something as seemingly fundamental as a catch quota is not easy to decide.

It’s easy to think that once a fishery is “certified sustainable,” that’s the end of it. But the truth is messier. There can be a lot of science and biology that go into setting a harvest level. But, because the environment is so variable, it is sometimes difficult to link environmental conditions to fisheries production.

For example, you have some warmer years, you have some colder years, and the assumption is that they average out overall. Variables like this can affect the productivity of a fishery. The challenge managers face is setting the allowable catch at a level where the population can still withstand that environmental variability. There’s also concern that as variability increases (due to climate change), “average conditions” may no longer be stable. This means we would need to adjust for how we set harvest levels, possibly making them more flexible or responsive to environmental change.

Moving into the future, flexible management strategies will be essential. Set the catch limits too high, and your fishery could crash. But set them too low? That can have dramatic effects, too.

An anonymous federal fisheries scientist pointed out to me that “transfer effects” can occur when regulations are stricter. This results in “basically putting local fishers out of business.” The market demand for seafood still exists, however, “which opens up greater import of lower cost fish product [from other countries]. Most of which are not caught with the bycatch technology that we mandate in our own fleets.” This is a big reason I encourage eating local, or at least domestic, seafood.

If any of this is making your head spin, you’re not alone. Regulation is a double-edged sword, and its cuts are felt deeply by fishing communities and conservation groups alike.

So, why do I believe that ours (the U.S.) is a good system? Because it provides a mechanism for attempting to prevent harm and also to catch mistakes. When there is a system for catching mistakes, they can be measured, studied, and corrected. That is how solutions emerge.

California Sardine Fishery

It’s easy to be lulled into the sense that “science” has already figured everything out. Not so. True, the wealth of knowledge out there is tremendous. But the reality is that we’re still learning, and always will be.

Sardines, for example, tend to have a predictable response to climate, reproducing better in warm phases than in cool ones. Overfishing during one such cool period in the 1950s and 1960s crashed the California sardine fishery. By hammering them during a period when they were not reproducing fruitfully, we (unintentionally) decimated the population at the onset of a long cool phase.

This is where flexibility comes in. The harvest levels were probably set right…for an average year. But several consecutive below-average years occurred, and the fishery crashed as a result. There are now special rules around the sardine fishery and it is one of the textbook examples of a fishery in which flexible management decisions can be made within a fishing season based on environmental conditions.

What Exactly is Flexible Fisheries Management?

One side of flexible fisheries management is closing or reopening a fishery mid-season based on environmental conditions. But another side of adaptable management is helping fishermen to target other species when their primary fishery is closed or unproductive. To understand this issue, you have to also understand that having a fishing permit is often tough to get (and expensive). So once you have one, you’re not going to let it go. But what if we made those permits more flexible, or made it easier to lease fishing permits?

Say, for example, that the sardine fishery above is closed. In the same season, what if there is a boom in market squid or another species? If we intentionally enabled and permitted fishermen to pivot and target secondary fisheries, they could target non-sensitive species in years when they’re doing better. In turn, they would reduce effort on sensitive species.

Coastal Logistics

So what’s the catch? Well, even if we manage flexibly, there are serious logistical challenges to making it work.

A hugely diverse and asset-heavy infrastructure of equipment and support networks exists to catch fish. So even if you gave fishermen a flexible permit, there’s a lot more at play.

You need the right kind of boat, the right kind of gear, a port that can process it, an ice plant, and access to planes or trucks that can distribute your fish to an appropriate market. This highlights the difficulty of switching fisheries. Building flexibility into that without asking fishermen to buy “one of everything” is a tough nut to crack. They’d be drowning in debt before they ever touched the water.

Like Solving an Ocean Rubik’s Cube

If we make permits more flexible, one method of attack is obvious: what else with the same gear type can they fish that’s doing well that year? This is a good start, but fishermen may find that there are not many compatible options within geographic range of their boat.

Some NGOs offer buy-back programs to help fishermen get off one gear type or boat type and on to another. Typically, this helps fishermen move onto a more sustainable fishery that commands a solid market price. Removing destructive fishing practices is a positive benefit of doing this.

However, emerging catch-share programs typically limit the number of vessels in a fishery. This may prevent or make it very difficult for fishermen to transition into a new fishery. The cost of entry into a catch-share fishery can be exceptionally high, and shares are often heavily consolidated by big business. That rabbit hole of a topic is the focal point of The Fish Market, a new book by Lee van der Voo.

One of the most promising possibilities is to develop co-op fishing communities, in which permits, boats, and gear are held by the community, not the individual. Many fishing communities are in favor of this type of solution. This would offer more mobility within the community to target healthy fisheries and not spend effort on less healthy ones. It would also allow for permits to be accessed by younger fishing generations, as older generations (read: most of the fishermen out there today) retire.

Still No Cure-All

No panacea has emerged yet. We’re still waiting for an AirBnb-equivalent for fishing boats and gear to upend the industry and change the game. Until then, there are still amazing ways to directly support fishermen, whether you buy directly from a local boat or fishmonger, or buy online through sustainable seafood delivery programs like Dock to Dish, Vital Choice, and Sea to Table.

Continuing the conversation remains mission critical. Minimizing the ecological, economic, and emotional harm of our fishing activities is a generational challenge.

What do you think? What are our best bets for sustainable fisheries? And how do we protect the cultural and ecological heritage that fishing communities have stewarded for so long? Leave a comment and keep the conversation going.

Seagrass-Herbivore Interactions: present, past and future

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The second day of the 12th International Seagrass Biology Workshop kicked off with a plenary lecture by Teresa Alcoverro, one of the worlds leading scientists in the field of seagrass-herbivore interactions.

Seagrasses are marine flowering plants, evolved from life on land about 100 million years ago. In coastal areas all over the world, seagrasses form extensive meadows, providing both food and shelter for all kinds of organisms. Seagrass and their associating fauna have a million year old co-evolutionary history. Some grazers like molluscs and isopods have specialized in eating the algae living on seagrass leaves; other organisms such as sea urchins, certain species of fish, turtles and dugongs eat the leaf tissue itself and therefore have a negative impact on the plants. The degree of impact will vary with the size, feeding preference and with the grouping behaviour and home range of the grazer. Schools of fish that exclusively eat all the young leaves for example will have a greater impact than small molluscs that forage on old leaves and additionally eat other benthic algae. The closer you look the more trophic layers you can discover in a seagrass ecosystem. Seagrass meadows are hotspots for herbivores and as a consequence these meadows attract predators. Predators show a preference for fragmented seagrass patches with a lot of edges. Alcoverro found that the fear generated by the presence of predators (e.g. sharks) in turn can reduce the amount of herbivory (e.g. turtle grazing), up to 50%. Cold spots of predators are richer in biodiversity of both prey species and other organisms, leading to the conclusion that herbivores, both direct and indirect shape these seagrass ecosystems.

Seagrasses in return have evolved to deal with grazing by using either avoidance or tolerance mechanisms. Seagrasses and their symbiotic epiphytes are known to contain several chemical components that could act as defenses, but their actual role in defense is probably low. Apart from self-defense, seagrasses were found to have certain escape mechanisms in order to avoid herbivore grazing: seagrasses can, for example, temporally increase their production when herbivore densities are low or have unpredictable or synchronized reproduction. Tolerance mechanisms focus on compensating for biomass loss due to herbivore grazing; for instance increased photosynthesis in existing leaf material or even increased growth rates. These mechanisms explain why grazing can actually have a positive effect on seagrass productivity – but only until a certain level. When turtle populations recover and their number rises, which is currently the case in certain marine protected areas, they can overgraze and deplete seagrass meadows, moving from one patch to another while the meadows they leave behind may not recover. Therefore, a fine balance between herbivores, seagrass standing biomass and highly resilient seagrass meadows are key to preserving both functional groups: we need to monitor the productivity, herbivory and predatory rates to truly understand the ecosystem and to be able to predict the future of seagrass meadows. Global change will for example lead to a rise in seawater temperature. How this temperature change will affect the aspects of seagrass-herbivore interactions is a one of the main questions for future seagrass research.

Nate’s Corner: Big Blue TED Talks

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Every so often, when I feel like I should be working but am lacking the motivation to do anything really worthwhile, I watch TED talks. Watching eloquent, well-prepared thought leaders pace along the stage while pitching these “ideas worth spreading” is the perfect cure for procrastinitis. But if you’re anything like me, the talks you normally end up spending fifteen to twenty minutes of your time absorbing were chosen solely on their title and view count. Go browsing with the original goal of learning about sustainable and innovative business ventures, end up watching a video entitled “How to be happy, bilingual, stress-free, and filthy rich in just six hours” with 100 trillion views. That’s just how it goes. So, in order to help TED share some of its underappreciated ideas, I’ve compiled a list of some ocean-related TED talks that are from the past year that certainly deserve more views than they have. Check them out, feel free to let me know what you think of each in the comments section and if there are any that I missed. Enjoy!

The case for fish farming” – Great synopsis of the potential benefits of aquaculture, and how this type of agrarian mentality could drastically improve our world’s fisheries. There’s a reason, however, that some folks are still hesitant to embrace aquaculture and the speaker doesn’t go into too much detail as to how we can address the industry’s current shortcomings. I give it three clams*.

Our campaign to ban plastic bags in Bali” – Inspiring story of how to girls from Bali changed the entire Island’s perception of plastic and became the loudest voice against plastic bags. Four clams!

The four fish we’re overeating and what to eat instead” – If you want to start eating more sustainably and only have fifteen minutes, this is a perfect place to start. Paul’s presentation on the current state of our seafood industry will convince the casual seafood consumer that its time to start looking into options beyond shrimp and tuna. Five clams.

How we can make crops survive without water” – Thought-provoking segment on how science can use genes from “desiccation” plants to address potential instances of food shortages over the next few generations, while also addressing the current GMO-phobia within the United States. Three clams.

Glow-in-the-dark sharks and other stunning sea creatures” – Gotta be honest, this is a talk you have to watch the whole way through. I originally listened to this as a podcast on my phone, and as charismatic and passionate as David is, I just wasn’t feeling it. The visuals really make this segment, and ultimately will change the way you see (nice one Nate) our underwater ecosystems. Three clams.

My country will be underwater soon – unless we work together” – Most of you have never heard of the Republic of Kiribati, a small island nation located in the central Pacific Ocean. Consider this episode an introduction to the island and to Anote Tong, the current President of Kiribati. In it, President Tong makes a heartfelt plea to all developed nations to cut carbon emissions and to consider the effect refusing to do so will have on the Kiribatis of the world. A charismatic, well-spoken, humble world leader, President Tong will have you emotionally-invested in a people and a nation that, twenty minutes ago, did not exist to most people. Four clams.

*I’m rating things by clams these days.