Smith lab & colleagues publish new paper looking at zooplankton on coral reefs

Most coral reef scientists study charismatic organisms, such as corals and fish, while very few scientists focus on plankton. Since coral reefs have an abundance of beautiful and colorful creatures, small and inconspicuous plankton may be less attractive to many coral reef scientists. Of the few existing coral reef plankton studies, most of them are either bacterioplankton or phytoplankton, which are “relatively” easy to handle. There have been far fewer studies of zooplankton, although they are one of the important key players in the lower trophic levels in coral reefs.
“Zooplankton is recognized as a “black box” among many scientists working on coral reefs,” says Ryota, a visiting scientist in the Smith lab. In fact, there was only one zooplankton ecology paper among more than 2,000 papers presented at the International Coral Reef Symposium (ICRS), or the so-called “Olympic games of coral reefs,” in Hawaii last year (June 2016).
However, zooplankton play a significant role in trophodynamics, serving as one of the important food sources to various reef fish and benthic planktivorores, including corals. “Approximately half of the benthic animals on coral reefs are filter feeders, or particle feeders, which feed on zooplankton and particulate organic matter,” says Ryota, “Even larvae and juveniles of many species of reef fishes grow by feeding specifically on zooplankton.”
Ryota and his team summarized the biomass and production of coral reef zooplankton in the past five decades, and focused on the paradox of reef zooplankton trophic structure, where there is abundant zooplankton biomass yet lower phytoplankton biomass in coral reef environments. This paradox has been discussed in previous studies, but they all are fragmentary and rather qualitative. Thus, comprehensive and quantitative studies were required to elucidate planktonic trophic structure in coral reef ecosystems.
The study team comprehensively investigated the biomass and production from bacteria, phytoplankton, protozoan (nano- and microzooplankton) and mesozooplankton in the coral reef waters of Okinawa, Japan, and compared the production from both the grazing phytoplankton food web and the microbial food web to that of mesozoopankton. They clarified that the grazing food web (phytoplankton), alone, did not satisfy the requirement of mesozooplankton throughout the year. Alternatively, the contribution of the microbial food web was important. Yet, the combined production from both food webs did not satisfy the mesozooplankton requirement in some seasons, emphasizing the importance of detritus in this food-limiting system.
“Detailed investigation on the origin and production of detritus will open the door for better understanding of pelagic trophodynamics in coral reef ecosystems,” Ryota said.
For more detailed information on this study, please see the full paper here!
Nakajima R, Yamazaki H, Lewis LS, Khen A, Smith JE, Nakatomi N, Kurihara H (2017) Planktonic trophic structure in a coral reef ecosystem – grazing versus microbial food webs and the production of mesozooplanktonProgress in Oceanography 156: 104-120.

Smith Lab & colleagues march (& swim) for science on Earth Day 2017!

This year on Earth Day (4/22/17) scientists, researchers, and science-supporters marched in 600 cities worldwide to show support for scientific research and scientifically informed public policies. During the Science March Dr. Jennifer Smith was conducting field research in Maui Nui along with Smith Lab members Dr. Emily Kelly and Samantha Clements, and Sandin Lab researcher, Nicole Pedersen, to collect coral reef images from Molokai, Lanai, and Kahoolawe for the 100 Island Challenge. The research team didn’t want to miss out on the global march and their chance to voice their support for scientific research, so they took their message underwater!

In addition to their underwater march for science, the research team also partnered with local scientists, managers, and enforcement officers on Maui at the Kahekili Herbivore Fisheries Management Area to host a “Swim for Science” and talk story event held in conjunction with the March for Science event held earlier in the day at UH Maui College and the Smithsonian Institution’s Earth Optimism Summit. The event attracted an estimated 50 community members, resource managers, scientists, and conservationists to the Kahekili Beach Park, where participants made signs on underwater paper to parade around the beach park before taking their message to the water. In the water, participants swam in front of underwater cameras with their signs displaying messages in support of scientific research and expressing #EarthOptimism and #OceanOptimism for the conservation success story of Kahekili’s Management Area. After the march, participants had the opportunity to talk story with scientists, managers, and enforcement officers about their work and how to engage in communicating with elected officials in supporting resource management and enforcement. Click here to read more about the event!

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Citizen-supported science in the Gulf of Maine

Dr. Walter Adey has dedicated his career to studying the importance of seaweeds in the marine ecosystems of the Northwest Atlantic. Walter first surveyed the benthic communities of the Gulf of Maine fifty years ago. In the wake of the collapse of the famed New England cod fishery and half a century of climate change, the Gulf of Maine is no longer what it once was. This summer, Walter plans to revisit his original sites on his final voyage as captain of his hand built research vessel, the Alca i. The opportunity to resurvey these sites after 50 years will provide scientists with an unprecedented look at the effects of overfishing and climate change on marine ecosystems and will help us to better understand the challenges facing our oceans. Walter and several other early-career marine ecologists, including Smith Lab member Mike Fox, are working to raise money for the Gulf of Maine Expedition this summer. Please consider lending your support to this effort as the team prepares to examine the impacts of global climate change beneath the frigid waters of the North Atlantic. All donations to this project will directly support the expedition logistics and critically important research to unravel the impacts of global change on our oceans.

Click here to learn more & support this research!

 

American Geophysical Union (AGU) Eos article spotlights the Benthic Ecosystem and Acidification Measurements System (BEAMS) developed by a team of Scripps researchers

A paper published in 2016 by Scripps researchers, including some Smith Lab members, was recently featured in an American Geophysical Union (AGU) Eos article. The article spotlights the Benthic Ecosystem and Acidification Monitoring System (BEAMS) & its role in assessing reef health. Click here to see the full article!

 

A new study highlights the importance of surface biomass in the growth and recovery of giant kelp

Giant kelp is one of the largest and fastest growing organisms on the planet. Off the coast of California, this massive, golden-brown seaweed can reach heights of over 100 ft as it grows towards the well-lit surface waters. However, being this big can also have its disadvantages. Large waves can snap giant kelp fronds, removing biomass and sometimes even whole individuals. Understanding the consequences of this biomass loss on the growth of giant kelp is key to understanding the foundational role this species plays in giant kelp forests around the world.

Giant kelp forms elaborate underwater forests that have a way of making divers feel quite small (Photo credit: Scott Gabara)

Giant kelp forms elaborate underwater forests that have a way of making divers feel quite small (Photo credit: Scott Gabara)

As part of his master’s research at Moss Landing Marine Laboratories, PhD Candidate Mike Fox conducted a manipulative experiment that found that the removal of biomass significantly reduces growth in giant kelp. Stable isotope analysis of young giant kelp blades showed that these younger blades rely heavily on resources provided by older blades at the surface.  Much like vascular plants, giant kelp can move carbon and nitrogen throughout its body to fuel new growth. So, when biomass is removed from an individual, the resources that typically support new growth are also lost. This study highlights that the spatial variability of biomass loss among individual giant kelp plants may play an important role in the regrowth of these underwater forests following large storm events.

Click here to learn more!

Fox, M.D. 2016. Biomass loss reduces growth and resource translocation in giant kelp, Macrocystis pyrifera. Marine Ecology Progress Series, 562: 65-77. [pdf]

Book chapter recently published explores the role of marine macrophytes in nearshore systems

 

Smith lab Ph.D. candidate, Mike Fox, contributed to a book chapter recently published by colleagues in Marine Macrophytes as Foundation Species that explores the role of marine macrophytes as a source of energy and habitat for nearshore systems. A description of the chapter is below:

Foundation species disproportionately contribute energy and habitat to ecosystems and thus directly facilitate the maintenance of community structure and function. However, a foundation species may not provide the same energy and habitat from place to place due to variability in productivity and population dynamics. In this new book chapter our focus is to examine this important aspect of the foundation species concept through the lens of marine macrophytes (seaweed and seagrasses). Specifically, our chapter seeks to: (1) identify macrophyte taxa that are clearly disproportionate in their provisioning of energy and habitat to their associated communities; (2) describe some of the physiological features that facilitate the role of macrophytes as foundation species; and (3) discuss how variability in the productivity of marine macrophyte foundation species may impact their associated communities.

Graham, M.H., Fox, M.D., and Hamilton, S.L. Macrophyte productivity and the provisioning of energy and habitat to nearshore systems. 2016. In: Marine Macrophytes as Foundation Species (ed. Olafsson, E.), Science Publisher/CRC Press, Boca Raton, FL. ISBN 978-1-498-72324-4,pp. 131-160

 

Click here to read more!

Smith lab and colleagues find that Crown of Thorns (COTS) larvae can take up organic matter derived from corals

Crown-of-Thorns Starfish Larvae can feed on Organic Matter Released from Corals

Ryota Nakajima, Nobuyuki Nakatomi, Haruko Kurihara, Michael D. Fox, Jennifer E. Smith, and Ken Okaji

Abstract: Previous studies have suggested that Crown-of-Thorns starfish (COTS) larvae may be able to survive in the absence of abundant phytoplankton resources suggesting that they may be able to utilize alternative food sources. Here, we tested the hypothesis that COTS larvae are able to feed on coral-derived organic matter using labeled stable isotope tracers (13C and 15N). Our results show that coral-derived organic matter (coral mucus and associated microorganisms) can be assimilated by COTS larvae and may be an important alternative or additional food resource for COTS larvae through periods of low phytoplankton biomass. This additional food resource could potentially facilitate COTS outbreaks by reducing resource limitation.

Click here to read more!

Do different species of herbivorous fish have unique grazing roles on coral reefs, or are they all grazing alike?

Coral reefs are home to a large diversity of organisms.  The herbivorous fishes, those fish that eat algae in competition with corals, are no exception to such diversity.  But do the many species of herbivores have unique grazing roles on reefs or are all herbivorous fishes grazing alike?

 

This was the focus of a study recently published in Oecologia by marine ecologist Emily Kelly and colleagues in the Smith and Sandin Labs of the Center for Marine Biodiversity and Conservation at Scripps, along with researchers at the Hawaii Division of Aquatic Resources, and NOAA’s Coral Reef Ecosystem Program in Hawaii.

 

The research team quantified fish foraging behavior, stomach contents, and feeding selectivity to determine the role of individual herbivore species on a reef in Maui, Hawaii.  They found important differences across herbivores in the types of algae different fish consumed and the impact of each bite.

 

“At first pass we often think about all herbivores consuming the same algae in the same way on coral reefs- these fishes are the lawn mowers of reefs, mowing down algae that competes with coral.  But what we find is that in fact these herbivores could be seen as many different types of gardening tools, each with a slightly different function in grazing. Therefore, understanding the role of individual herbivorous fish species is important for knowing how the herbivore community as a whole can influence reef composition and reef health,” says Kelly, lead author of the study.  “This finding is especially important given that we as humans put a lot of pressure on coral reefs, including through overfishing.  Knowing that herbivore species are grazing different algae and in different ways is important for managing a diverse community of herbivores to promote healthy reefs,” she says.

 

Further, the researchers found that using only one method of inquiry into feeding suggested that all fish were grazing similarly on the reef, but using three methods revealed more differences in feeding across fishes.

 

Along with Kelly, Scripps researchers Yoan Eynaud, Samantha Clements, Molly Gleason, and Jennifer Smith were co-authors on the study.

Click to read more!

Investigating functional redundancy versus complementarity in Hawaiian herbivorous coral reef fishes
Kelly, E.L.A., Eynaud, Y., Clements, S.M. et al. Oecologia (2016). doi:10.1007/s00442-016-3724-0
scripps oceanography uc san diego