Where’d everybody go?

The GOMCES crew has been back on terra firma for about two weeks now, giving everyone some time to reflect on this summer’s survey. Although we have yet to delve into the data analysis, when asked how the survey went, our first response is usually something along the lines of “It seemed like a ‘slow’ year.”

So, what does a “slow” year look like? That is a great question. While we don’t have a concrete answer yet, here are some observations that coincided with what seemed like a “slow” year.

First, let’s start with the physical setting. Many of these physical setting characteristics did not change among the survey years. For example, we surveyed many of the same transects this year as we have in past years, covering a similar range in depths/distances from shore and seafloor habitats. However, the physical properties of the water column are variable. These properties are also key components of the ecosystem, setting the stage for patterns of growth, survival, transport, and/or reproduction for many organisms.

As you may recall, we use a conductivity-temperature-depth (CTD) meter to measure several key physical properties. Comparable data are also available from monitoring buoys anchored at several locations within the Gulf of Maine. As it will be some time before we process our CTD data, we pulled water temperature data for three different buoys from the NERACOOS website to give us a general picture of what was going on with the physical oceanography this summer. The buoy data are displayed below, along with a map of the buoy locations for orientation. The blue line depicts the average temperature from 2001-2015, the yellow window shows the range in observed temperature values from 2001-2015, and the brown lines and points are the observed temperatures for the particular year of interest.

A sample of 2015 and 2016 water temperatures recorded at three monitoring buoys within the Gulf of Maine. 

The buoys tell us that in general 2016 has been a fairly warm year so far in the Gulf of Maine, with warmer water temperatures at depth (and at the surface) than the 2001-2015 mean water temperatures. That being said, there is some considerable variability around the mean – especially towards the southwest Gulf of Maine and Massachusetts Bay area. Although a plot of water temperature at one depth and a few different buoy locations doesn’t tell the full story about if the entire water column is “warmer” or “colder” than previous years, it does seem like overall conditions were warmer during this summer’s survey than years past (2015 data are shown for comparison).

Ultimately our project is focused on evaluating how such physical oceanographic changes affect the distribution and abundance of the biological organisms living in the coastal region. During this summer’s survey, there did seem to be considerable differences in the species we encountered and their abundances compared to past years. One of the most obvious differences was the number of gelatinous zooplankton we caught in the zooplankton ring nets and observed from the boat.

Gelatinous zooplankton are notoriously hard to sample with ring nets given their delicate bodies. So, instead of true counts, our biological oceanographer scores the sample from 0 to 10 based on how much gelatinous material is in the sample, with 0 being none and 10 being a lot. We are in the process of mapping these scores to compare with the earlier years (2015 example shown below). Already, though, the data suggest that gelatinous zooplankton abundance was down considerably compared to previous years, with most of the ring net tows scoring 0 or not much higher. In contrast, abundances of other zooplankton species, and especially the star-of-the-show Calanus finmarchicus, appeared to be on par with previous years. (You may remember from previous years’ blog posts that C. finmarchicus is a very large, fatty copepod that serves as a very important food source for many of the Gulf of Maine’s denizens, from juvenile fish to large baleen whales.)

2015 map of relative gelatinous zooplankton abundance throughout the coastal Gulf of Maine. 

In addition to being a slow year for gelatinous zooplankton, 2016 was also slow for the marine bird and mammal team. In total, the number of individuals observed in many of our marine bird groups were lower in 2016 than in 2015 or 2014. This includes species like Wilson’s storm-petrels, Great shearwaters, Arctic and Common terns, Atlantic puffins and Razorbills. Across the board, our preliminary data processing suggests that we encountered fewer individuals of these species in 2016.

Along with lower total observation numbers, we also failed to encounter a tern or alcid foraging flock. In both 2014 and 2015, the marine bird and mammal crew observed at least a few of these foraging flocks, comprised of multiple species and at least 25 or more total individuals. With the exception of the shearwater foraging flock observed on the first day (keep in mind that these birds are currently “wintering” here and will soon return to their southern hemisphere breeding colonies to start their own breeding season), the crew did not come across any other foraging flocks in 2016. Of course, missing a foraging flock might just be a case of wrong-time/wrong-place. However, when combined with fewer total observations, it definitely contributes to the perception that 2016 was a “slow” year.

Where does that leave us? Well, a quick recap. 2016 appeared to be a “slow” year. Water temperatures seemed to be warmer than long-term averages, and especially, warmer than 2015 (which was a fairly cool year). Gelatinous zooplankton were less prevalent, while other zooplankton species, including Calanus finmarchicus, appeared to be similar in abundance to previous years. Total observation numbers of key marine bird species were lower than the past two years and we didn’t see as much foraging activity. We’ll also add that we saw fewer marine mammals and Mola molas (Ocean sunfish) in 2016 (remember that Mola molas eat primarily gelatinous zooplankton!).

There are many possible explanations for these yearly differences. Although it might just be a case of poor timing on our part, patterns may emerge during data analysis that will give us insight into the reasons behind the interannual variability. Right now, what really seems to be sticking out is the difference in the relative abundance of gelatinous zooplankton. That being said, we might be a bit biased since correlating the low gelatinous zooplankton year with lower marine bird/marine mammal observations and activity would strengthen our growing idea of the important (and underappreciated) role that gelatinous zooplankton may play in the Gulf of Maine food web. In any event, we are all excited to confront our knowledge of the Gulf of Maine coastal ecosystem with the data we have collected over the next few months.

Thanks for following along this summer! We hope to have some updates as we continue with our analysis. Additionally, although we are at the end of this project’s funding, we are hoping to secure funds for additional future surveys to keep this important effort going!

 

Rockweed sampling

Hello dedicated GOMCES blog readers!

We are assuming none of you have gone into severe withdrawal waiting for the next blog post while we have been on a week long hiatus. Much like the work for this summer’s survey, the blog posts have been coming in fits and starts. In past years, it was pretty easy to get into a routine: wake up, have an everything bagel, work, steam to the next port, have dinner, write blog, repeat. Getting into that same routine this year was a bit harder since it seemed like we never had two days in a row when we knew what our plan was going to be. While we were still able to get most of our survey work done, the blog posts got put on the backburner amidst the constantly changing schedule. But, rest assured, although they have been post-poned, they were not forgotten and we still have a few more interesting stories to share, including our adventure into rockweed mat sampling.

For those of you who have been reading since the beginning of the GOMCES project, you will be familiar with our newfound interest and appreciation for rockweed mats. In particular, there seems to be a strong connection between these rockweed mats and foraging marine birds. Despite our diverse science team, we didn’t anticipate sampling rockweed mats at the beginning of the project. Fortunately, we were able to make some adjustments before this year’s survey to bring Sam, our dedicated rockweed-sampler, on board for the cruise.

During the southern transects, Sam’s patience was put to the test as we did not encounter any rockweed mats along our survey transects. Luckily, things began to get more exciting as we came across our first rockweed mat on our eastern Penobscot Bay transect. As Capt. Bryan slowed down the Gulf Challenger, Sam, Julek and the rest of the GOMCES crew quickly went to work to collect the sample.

The rockweed sampling procedure is somewhat unique among our different data collection efforts, although, it does have some similarities to our biological oceanographic zooplankton sampling. While on the bow of the boat, Sam searches the area for mats. If she sees one, she then calls in the distance, angle, relative size and density of the mat to the data recorder down below. Depending on its characteristics, Sam then directs Capt Bryan to position the boat so that Julek can grab a quick sample of the rockweed using a dipnet. The sample is then put in a ziplock bag in a cooler until Sam has time to process it – usually after we had made it to our next destination port, resulting in long work days for Sam, and her helper, Aly!

After the sample is collected and we reached our next port, Sam and Aly would work to process the sample. First, Sam took the sample out of the Ziploc bag and placed it in a bucket of fresh water, gently swirling while the sample was immersed in the fresh water for at least 10 minutes. This fresh water immersion process separates the animals living on the rockweed from the rockweed itself.

After separating the sample, Sam removed the rockweed and other large pieces of plant material from the bucket, leaving behind anything that fell to the bottom of the bucket. With the rockweed removed, Aly poured the remaining bucket contents through a small, sieve net.

With the larger pieces of seaweed removed, Sam and Aly work to pour the remaining sample contents through a small mesh net. 

This filtering process further isolated the small animal organisms living amongst the rockweed so that they could be stored in a small sample vial for later identification and counting.

 

Finally, the removed rockweed clumps and other pieces of organic matter were photographed and identified.

A collection of larger seaweed species, removed earlier in the process and placed aside for photographing and species identification.

Ultimately, Sam and her advisor at Unity, Dr. Emma Perry, hope to use these samples to characterize the invertebrate biodiversity and seaweed biodiversity among different rockweed mats. In doing so, they are hoping to investigate how these communities vary spatially, both in terms of their along-shore position (for example, Penobscot Bay vs. Jordan Basin) and their distance from shore. Are all of the communities similar, with the same organisms found in mats nearshore and offshore? Or, are there unique organisms found at different mats, either in different regions or at different distances from shore? While interesting as independent questions, the rest of us are also selfishly hoping that their findings may also shed light on why birds and other larger marine organisms seem to key in on these rockweed mats when foraging.

Casco Bay transect and unpredictable weather

Casco Bay Transect

On Wednesday, the crew departed from Portland and surveyed our Casco Bay transect before spending the night at the Bigelow Lab for the Ocean Sciences dock. The seas were calm and the sun shining, but not much was going on from a sampling or observing perspective. The major exception was the first occurrence of rockweed mats on survey transects. While on the first transect leg, we began to see small chunks of rockweed, mainly Ascophyllum nudosum and Fucus vesiclosus. As we got a bit father offshore to the northeast, the seemingly random, smaller chunks eventually turned into mats. Although easily seen from the boat, figuring out how best to record their presence and size along the transects proved a bit more challenging. Eventually, the observing team decided that we would record the presence or absence of discards every five minutes along with our buoy counts. For mats, we began recording the distance to the mat center, its size and also the density of the mat. This might not be the perfect sampling protocol and we may end up doing some refining as we continue along the coast, but for now, it will definitely help to give us a better idea of the distribution of rockweed mats and their association with foraging marine birds and mammals.

Unpredictable Weather

During the past two survey years, we have run into some weather when we got to Bigelow/Boothbay, preventing us from surveying offshore near Matinicus Rock and Seal Island — two important marine bird colonies within the Gulf of Maine. This year, though, it looked like maybe things would be different. After finishing dinner at the Bigelow Shore Facility, we discussed our plan to head offshore the next day before working our way back into Penobscot Bay and docking in Stonington for the night. Everything looked promising for a productive survey day, filled with puffins and razorbill sightings.

Unfortunately, the weather had other plans and things changed quickly overnight. When the crew got up the next morning, we were greeted by a wall of fog and some unpleasant seas.

The foggy view heading as the crew departed Bigelow and headed towards Penobscot Bay and Stonington. While calm in the Damariscotta River, we were quickly met with rough seas as we came out of the river and made the turn northeast.

Capt. Bryan and first mate Jim navigated us safely through the maze of buoys and between the different islands through some rough seas, while the rest of us lazily slept below. As we came into Penobscot Bay, the decision was made that we would head directly to Stonington as conditions were too poor to complete any sampling. We arrived in Stonington in the early afternoon and while Bryan and Jim got some much deserved downtime, the rest of us ventured into town for the afternoon, hoping for the weather to improve.

A gray day in Stonington.

Despite our wishes, the weather won again. Given poor weather forecasted for Friday-Sunday, the crew decided that our best bet would be to leave the boat in Stonington for the weekend and come back on Sunday night to try to complete the downeast work during the beginning of next week. So, with the new plan, everyone scrambled to find rides home. Thanks to some special help from the McGarrigle’s (Sam’s mom and dad), Bryan and I were able to make it to Bangor and are currently sitting in the Concord Coach bus station awaiting our ride and hoping for good weather at the start of next week to finish off the downeast section of our cruise.

Hope everyone has a good weekend and see ya Monday (hopefully)!

Offshore terns and the pteropod mother lode (not load)

Welcome back dedicated GOMCES blog reader(s)!

Before the holiday weekend, the crew finished up the southwestern region of the survey, completing the Isle of Shoals/Jeffreys Ledge transect. Overall, it was fairly quiet from the biological oceanography and fisheries acoustics side of things. However, the marine bird and mammal observing team was surprised to find a number of Common terns foraging farther offshore than we could remember observing them during the previous two years (maps coming once the internet is a bit faster!).

These observations were especially interesting given a recent email exchange we had with Linda Welch (Biologist, USFWS Maine Coastal Islands National Wildlife Refuge). In her email, Linda mentioned that tern numbers seemed to be down at many Maine coastal breeding colonies this year. Could this explain why we saw more terns than usual on the Jeffreys Ledge Transect? Perhaps! Seabirds nest on land, but they catch food at sea to feed themselves and their growing chicks. The farther the bird has to travel to feed, the longer the chicks have to wait between meals – beyond a certain distance (which varies a lot by species), the process becomes impractical. Therefore, parents are constrained to forage within some reasonable distance of the colony, even if the food is better elsewhere. In contrast, birds that fail to produce chicks are NOT restricted to foraging near the colony and presumably can follow the food wherever they happen to find it – possibly like the terns we observed foraging far offshore the other day.

Of course, this is all speculation based on a handful of observations, which is great for helping us to formulate hypotheses, but is a terrible foundation upon which to draw actual conclusions! So we will continue to observe and ponder and see what the full dataset tells us upon completion of the survey.

Wilkinson Basin and the pteropod mother lode

Yesterday morning, the crew met in Portsmouth to begin the trek up the Maine coast, starting with the Wilkinson Basin transect. There are two main reasons for sampling the Wilkinson Basin transect. First, it covers deep basin waters, which many times host great abundances of large, lipid rich zooplankton species, such as Calanus finmarchicus – a pivotal species within the Gulf of Maine food web. These basins are also a unique bathymetric feature to the Gulf of Maine and provide a good contrast to the shallow, coastal waters surveyed by many of the other transects. Second, the transect includes a biological oceanographic time series station that is sampled semi-regularly by researchers from UNH, GMRI and UMaine. So, while all of these transects are interesting for the fisheries acoustic and marine bird/mammal team, the Wilkinson Basin transect is especially relevant to the Biological Oceanography team on this project.

As Cameron poured the contents of the first zooplankton net tow through the sifting tray, the crew immediately noticed a collection of extremely small, dark colored organisms mixed in with the usual suspect, Calanus finmarchicus. We also noticed a larger, gelatinous looking species with orange coloring. Cameron took a closer look at the sample while we awaited his announcement … both new organisms were pteropods!

The two species of pteropods caught at the Wilkinson Basin time series station.

Pteropods are small, gelatinous mollusks (the phylum that includes snails, clams, squid, and many other easily recognizable marine creatures) and are a key prey item for many higher trophic level species. Pteropods are commonly referred to as “sea butterflies” because they have two wing-like lobes that help to propel them through the water. The smaller pteropods in our sample were members of the Limacina retroversa species in the Thecosomata order, the most common pteropod species in the Gulf of Maine. Over two years of surveys and almost a hundred zooplankton samples collected, this was the first time many of us had seen these little creatures in such quantities.

The large pteropod in our sample was Clione limacina, a member of the Gymnosomata order, also called “naked pteropods” because they lack a hard outer shell. Interestingly, these pteropods are a predator of Limacina pteropods. Given this predator-prey relationship, it makes sense to find two species from these different taxonomic orders at the same location.

During recent decades, interest in pteropods, and especially Thecosomata pteropods, has increased given the growing concerns of global climate change and its effects on marine organisms. While increasing temperatures driven by global climate change capture many headlines, ocean acidification is also a primary concern. Ocean acidification is the term used to describe the decreasing pH of the ocean (or the increasing concentration of hydrogen ions in the ocean). The process that results in ocean acidification brings back nightmares of organic chemistry, but here is my best explanation:

The atmosphere and the ocean are coupled together in many different ways. One of the consequences of this tight coupling is that as concentrations of CO2 rise in the atmosphere, the ocean absorbs some of this extra CO2. Once in the oceans, CO2 is quickly brought into chemical reactions (see here for a nice diagram), reducing the number of carbonate ions available to build shells and skeletons for organisms like Thecosomate pteropods. Even after formation, evidence suggests that increased CO2 levels can cause shell deterioration.

Within our region, there is still a lot of work left to be done to understand how the chemical makeup of the Gulf of Maine is changing and what this may mean for marine organisms. Interestingly, the work that has been done seems to suggest that the Gulf of Maine may be particularly vulnerable to ocean acidification for two reasons. First, many rivers and streams empty into the Gulf of Maine, and this freshwater runoff can drive pH down, especially in localized regions around river and stream mouths. Second, the cold Labrador Current brings a constant influx of cold water into the Gulf of Maine, and = colder waters are able to dissolve more CO2. Many researchers are currently investigating the unanswered questions concerning the potential effects of ocean acidification on shellfish and other populations in the Gulf of Maine. You can read more here.

Tomorrow we head to our western Penobscot Bay transect and plan to survey near some of the larger tern, puffin and razorbill colonies within the state, so be sure to check back for another update!

– Andrew, Aly and Sam

 

 

The Rockweed Mat Initiative and Our Newest Crewmember

As mentioned in the previous post, we’ve been joined this year by Samantha McGarrigle, a senior at Unity College in Unity, ME. Samantha is a native of Hampden, ME. She is currently pursuing a Bachelor of Science in Marine Biology and plans to continue on to study marine community ecology in graduate school after graduating from Unity next spring.

Samantha McGarrigle, intern extraordinaire

Sam’s main role with us this summer is to help document and investigate offshore floating macroalgal mat communities. In previous surveys, we noted that some birds seemed to be associated with such “seaweed” mats floating far offshore, and that the mats seemed to harbor little micro-communities of nearshore fish and invertebrates. Steve Kress and Paula Shannon of the National Audubon Society’s Project Puffin contacted us about seeing puffins return to colonies with rockweed, so we all wondered if these mats might provide easily detectable foraging opportunities for birds looking for small fish. This summer we hope to get a better sense of the distribution and abundance of these mats, in addition to sampling their associated communities that we have only glimpsed in previous work.

One of many floating macroalgal mats that we observed on downeast transects last summer.

Sam will be surveying for algal mats from the bow, alongside the bird observer (Aly or Andrew), so that we can document the location and approximate size of each mat we encounter on transect. She will be collecting meiofaunal (tiny animals) samples from up to 20 mats that she will be analyzing in conjunction with Dr. Emma Perry of Unity College. Dr. Robin Seeley (Cornell, Shoals Marine Laboratory) may be joining us for a day during the later part of the survey to help further the investigation.

To date, however, we have yet to observe a single algal mat on transect in 2016! If memory serves, though, we observed them mostly (if not entirely) in the downeast transects in previous surveys. As we are fond of saying, though, “zeroes are data, too!” – knowing where the mats are NOT may be just as important as knowing where they ARE. After all, there are no puffins in this part of the Gulf of Maine either – coincidence? (Probably.)

Until next time!

Here we go again!

And so begins the Summer 2016 Gulf of Maine Coastal Ecosystem Survey!

After an uneventful calibration day on Tuesday, we hit the seas yesterday morning to begin our third summer survey of the Gulf of Maine. The core research crew from last year returned (with Cameron on plankton, Julek on fish, and Andrew and Aly on birds) and were joined by Unity student Samantha McGarrigle who will be collecting data on floating rockweed mats. As always, Captain Bryan Soares is piloting the Gulf Challenger, and Deb is serving as deckhand-in-chief for the southern leg, flawlessly operating the winch and generally keeping us all safe and comfortable.

To review our purpose and methods for the uninitiated, our integrated ecosystem survey is an attempt to observe, sample and measure many different ecosystem components at the same time from the same survey platform. We travel set routes called “transects” dispersed over the Gulf of Maine coastal shelf, all the way from Cape Cod Bay up to far downeast Maine. As we survey each transect, we collect data on zooplankton, fish, and the physical characteristics of the water column. In addition to these data, we also record the distribution and abundance of all marine birds and mammals we observe as we travel along each transect. This multipronged approach allows us to paint a fuller picture of the ecosystem conditions during the time frame of each survey.

Aly and Andrew prepare to wrassle the CTD over the gate while Julek gives helpful last-minute scientific insights.

Yesterday, we surveyed two transects on Stellwagen Bank. While we didn’t get treated to the same humpback whale feeding frenzy we got to experience there last summer, we did get to document many shearwaters (a fairly even mix of Sooty, Greater, and Cory’s) and storm-petrels. We didn’t miss out on whales altogether, though; at the end of the first transect, we spotted a breaching humpback whale several kilometers distant.

The highlight of yesterday’s work came at the end of the final transect, when we came upon a developing forage flock of shearwaters, gulls, and storm-petrels. Aly was the observer on deck while Andrew tried to keep up with the instantaneous data entry down below. When first spotted, the forage flock numbered about 10 shearwaters, but as we drew closer, the flock quickly burgeoned to more than 75 birds as shearwaters and gulls approached from all directions, presumably drawn by the foraging activity of their compatriots. We performed our final depth profile and plankton sampling casts of the day as the feeding frenzy continued around the boat. Any chance to sample where birds are actively foraging is extremely valuable.

The early stages of the forage flock formation we documented on Stellwagen Bank.

While we sampled the water, Julek dropped a fishing line to the bottom in an attempt to catch fish that were showing up on his acoustics screen – the acoustic sampling is great for identifying size classes of fish, but not necessarily species, so it’s good to groundtruth when we can so that we can actually match fish species to signal characteristics. Almost immediately, he began reeling in a legal-sized haddock, followed by a couple more bites and two more haddock landings – clearly there were groundfish down below the forage flock.

Julek shows off the catch of the day — haddock from deep beneath our forage flock.

We bird researchers found this development particularly interesting, as we’ve recently had many discussions about “seabird forage facilitators.” Many seabirds in the Gulf of Maine are surface feeders, presumably spotting prey from the air and snatching it from the upper meter of the water column. However, fish can easily evade such aerial predators by staying below the well-lit upper meter of the water column. Of the forage flocks we’ve observed over the course of this project, all have been associated with what we’ve termed “facilitators” – bird (e.g., puffins), fish, or mammal species that can hunt at depths and may incidentally drive prey to the surface waters where they are vulnerable to surface-feeding seabirds. So was it a coincidence that haddock were active underneath yesterday’s forage flock? It’s an intriguing question that we’ll undoubtedly continue to explore as the survey progresses.

Unfortunately, today’s survey of Cape Cod Bay was not nearly so exciting. While there were a fair number of gull and shearwater spottings on the first transect, the second and final transect of the day included several miles with not a bird in sight. Tomorrow promises to be more exciting, however, as we’ll be heading out to Jeffrey’s Ledge. Stay tuned!