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I’m finalizing my presentation for next week’s 2016 International Coral Reef Symposium, and this reminded me that we didn’t put together any posts about our fieldwork so far this year! Both Sean McNally and me (Jessica Carilli) completed fieldwork during spring semester – together we collected coral core samples from St. John, USVI, and Sean joined the Baum and Cobb labs from University of Victoria and Georgia Tech to collect coral tissue samples, zooplankton biomass, and other samples and data from Kiritimati, Kiribati.

Our fieldwork in St. John was a bit special for me, as it was the first time I brought my children along on fieldwork. My son is now 4 years old, and my daughter was born last summer, so she was about 7 months old during our field expedition. Neither of my kids really ever took a bottle (despite my intense efforts), so for both of their infancies I’ve been essentially tethered to them in order to continue breastfeeding. This has not been easy. With my son, I decided to just forgo fieldwork for the time period when I was nursing, but I did bring him (and his dad) along to events like the 2012 ICRS, visiting labs in Queensland, etc. With my daughter, I decided that putting off fieldwork until she was done nursing wasn’t going to work – so she came along. We also decided that my son should come, too so he could experience a week outdoors as a break from the Boston winter. This meant the kids needed a full-time caretaker. I am extremely privileged, because I have a mother who is now retired, loves caring for her grandchildren, and can afford to pay her own way places to take care of them.  This, combined with the ease of acquiring medical care on St. John (should it be needed), meant that I could bring the little ones along while completing needed fieldwork.

Sand and baby thighs – a wonderful combo

The ocean is that way

There’s no need for an alarm clock when babies join for fieldwork

We were lucky to get a spot to stay in a cabin at VIERS with a kitchen. It’s always handy to have cooking capabilities, or at least a fridge, with kids who eat at random times and are weirdly picky – but for fieldwork which also can take place at odd hours this was extra helpful.

Three of my field assistants, preparing for takeoff

Sean McNally gets ready to swim our dive tanks to the site at Yawzi point. These tanks will drive the air-drill. This is what you do when the boat engine is broken.

Jess Carilli drills a core sample from a mostly-dead Siderastrea siderea coral head in Coral Bay, St. John

Sean arrives in Kiritimati soon to begin fieldwork with the Baum and Cobb labs. This is a repost from a blog Sean McNally and Jess Carilli originally posted on the Cobb lab website.

Hard corals are animals that host symbiotic algae in their tissues called zooxanthellae. Corals obtain most of their food from algal photosynthesis – the algae make sugars from carbon dioxide, water, and sunlight, and some of this gets leaked to the coral hosts, feeding them. Despite this effective relationship in which a heterotrophic animal benefits from photosynthesis of microscopic algae, additional nutrients such as nitrogen and phosphorus are necessary for plant and animal growth, and must be attained by the coral ingesting zooplankton, particulate matter, or dissolved compounds. In a perfect system the corals provide shelter and nutrients like nitrogen and phosphorus to the algae, and the algae provide the corals with sufficient food to grow. This symbiotic relationship allows corals to create hard skeletons. Over long periods of time, corals can grow into reefs large enough to view from space. However, chronic or episodic stress can push this relationship out of whack, leading to the coral host expelling its symbionts and becoming “bleached.”

This white Acroporid coral colony is completely bleached, with its white skeleton now visible through clear tissues. If it has enough fat stores, or is able to feed on zooplankton, it might survive this bleaching episode.

The main environmental stressor that causes large-scale coral bleaching is increased sea surface temperature. But why do corals bleach? That’s an important question. Bleaching is not as straightforward as it might seem, particularly because different colonies of corals of the same species—even ones that live right next to each other—might have very different responses to the same stress.

First, let’s get a little technical: The current theory is that increased light and temperatures cause direct damage to the photosystem II portion of the photosynthetic pathway in coral symbionts. Excess oxygen radicals are produced that build up and eventually become toxic to the coral host. This “oxidative stress” results in the degradation and eventual expulsion of symbionts from host tissue. Interestingly, corals can host different types of zooxanthellae, and these can differ in their thermal and light tolerance. One theory suggests that stressed corals bleach to swap out less tolerant for more tolerant symbionts.

However, once symbionts are expelled, corals can starve or become more susceptible to disease. Corals that bleach and survive might either eat enough zooplankton, or live off stored-up fat, to survive these lean times. Increasing seawater temperatures associated with global climate change are likely to result in more frequent bleaching events.

We are joining the Cobb and Baum labs on Kiritimati Island in March to help answer the questions:

What factors influence coral survival through an extreme bleaching event?

Are there characteristics we can identify that might predict coral survival in future events? Understanding why some corals resist or better recover from bleaching is crucial to better protecting reefs into the future.

Reefscape of diverse corals on the south side of Kiritimati (pronounced “Christmas”) Island.

Baby A already loves marine animals

Jessica Carilli is on maternity leave this fall after welcoming a new baby daughter into the world.

A new book chapter lead by Dr. Carilli is now out: “Historical Contaminant Records from Sclerochronological Archives” in the book Environmental Contaminants: Using natural archives to track sources and long-term trends of pollution.

In this chapter, we discuss using skeletal archives from hard and proteinaceous corals, bivalves, coralline algae, and sclerosponges to reconstruct contaminants introduced into the oceans and atmosphere – usually at annual or better resolution. We cover general physiology of these organisms and how they incorporate contaminant records, what has been done so far, and where we see potential for future expansion of work in this field.

This new book is written at a textbook level, and the table of contents is available here: http://link.springer.com/book/10.1007/978-94-017-9541-8

Feel free to contact me for a .pdf copy of our chapter!

Here’s a really bad-quality preview of Figure 1, a map showing the location of the various published sclerochronological contaminant records we discuss in the chapter:

In November, Dr. Carilli published new research with colleagues in Australia and Canada about recent climate change in the central Pacific. You can read the paper here, and a press release here.

Reefscape from the Gilbert Islands, Republic of Kiribati. Our new paper presents a water temperature and salinity record from a coral core collected in Butaritari, northern Gilbert Islands.