benthic ecology

My first offshore cruise in the Northwest Atlantic

Posted on Updated on

Click on the images to view larger versions.

For the past 6 days, I have been quite fortunate to experience my first offshore cruise in the Northwest Atlantic Ocean aboard the CCGS M. Perley – a Canadian Coast Guard research vessel. This is not my first time away from land – I’ve conducted research from fishing vessels in the Bay of Fundy and from zodiac in the Bras d’Or lakes. Even as a kid growing up in a small fishing community I was exposed to the sea, frequenting fishing vessels owned by friends’ parents. However, this was my first time venturing a substantial distance offshore on a large research vessel to sample the benthic diversity associated with the NW Atlantic.

As a recently hired biologist at Fisheries and Oceans Canada in Moncton, New Brunswick, I was offered the chance to assist in an annual (but temporary) scallop survey off the northern coast of New Brunswick. The five-year-long survey has been established since 2012, with this year being the last year of the survey. A bottom trawl is used to collect benthic samples. We trawled for 2 minutes at each site and organisms brought up were sorted, identified, counted, weighed, and measured on deck in between drags. This made for intensive 12 hour days, but the data alone provided enough currency and motivation to keep me going.

Sunsets are better at sea.
Sunsets are better at sea.

While the cruises are dedicated to assessing scallop populations off the coast of New Brunswick, data on a slew of other benthic species are collected. Indeed abundances and biomass of all collected species are recorded, along with other basic morphometrics of other key species (e.g. carapace morphometry of crabs and lobsters, and lengths of fishes). We also had a CTD on board, equipped with probes to measure depth, conductivity, temperature, salinity, dissolved oxygen, and pH.

Rock crabs (Cancer irroratus) were present in almost every drag.
Atlantic rock crab (Cancer irroratus).

The experience was nothing short of spectacular. I’ve come to note that sunrises and sunsets are much more appealing from sea. The diversity of animals was astounding and unpredictable from trawl to trawl – crustacaens, cnidarians, echinoderms, molluscs, poriferans, and fishes were all apparent in multiple trawls. The most common species were crustaceans. Shrimps (Argis dentata, Pandalus borealis, Pandalus montagui, and Sclerocrangon borea) and rock crabs (Cancer irroratus) really dominated the trawls.

Shrimps: Sclerocrangon boreas (A), Pandalus montagui (B) and Argis dentata (C). Pregnant Argis dentata (D) – note the bright teal eggs!
Shrimps: (A) Sclerocrangon boreas , (B) Pandalus montagui  (C) Argis dentata, (D) Pregnant Argis dentata – note the bright teal eggs!
We also recorded quite a few Acadian hermit crabs (Pagurus acadianus).
Acadian hermit crab Pagurus acadianus).

Closer to shore, lobsters (Homarus americanus) were quite abundant as well, while an abundance of snow crabs (Chionoecetes opilio) and toad crabs (Hyas araneus and Hyas coaractatus) were frequent at more offshore sites – in one trawl we hauled up >80 snow crabs! We also recorded quite a few Acadian hermit crabs (Pagurus acadianus).

 

Echinderms: (A) Strongylocentrotus droebachiensis, (B) Henrica sanguinolenta, (C) Solaster endeca, (D) Crossaster papposus.
Echinderms: (A) Strongylocentrotus droebachiensis, (B) Henrica sanguinolenta, (C) Solaster endeca, (D) Crossaster papposus.
Sand dollar (Echinarachinus parma)
Sand dollar (Echinarachinus parma)

In some of the trawls, a vast array of other species were evident. Echinoderms  were also abundant. Sea cukes (Cucumaria frondosa, Psolus fabricii), urchins (Strongylo- centrotus droebachiensis), sand dollars (Echinarachinus parma), sea stars (Asterias spp., Crossaster papposus, Henricia sanguinolenta, Leptasterias polaris, Solaster end- eca), and brittle stars (Ophiopholis aculeata) were quite abundant in many trawls – we even saw a couple of large basket stars (Gorgonocephalus arcticus)!

A number of bivalves were also present, including clams (Arctica islandica, Cyclocardia borealis, Cyrtodaria silique, Mactromeris polynyma, Serripes groenlandicus, and Yolida sp.,), scallops (Chlamys islandica, Placopectin magellanicus), and horse mussels (Modiolus modiolus). Similarly to bivalves, brachiopods were abundant at a number of sites. We also observed a number of gastropods (Buccinum undatum, Neptunea decemcostata, Colus stimpsoni, Aporrhais occidentalis, Lunatia heros) and chitons were abundant at a number of stations. Less common were sponges, jellyfishes, and sponges. Tube worms (Polychaeata) dominated the deeper muddy zones (>50 m depth).

Yolida sp. (clam)
Yolida clam (Yolida sp.)
Cyclocardia borealis (clam)
Heart shell (Cyclocardia borealis)
Placopecten magellanicus edge
Giant sea scallop (Placopecten magellanicus)
Serripes groenlandicus (clam)
Greenland cockle (Serripes groenlandicus)

Fishes were also present in a number of trawls. Species observed included American plaice (Hippoglossoides platessoides), Arctic alligatorfish (Ulcina olrikii), Atlantic poacher (Leptagonus decagonus), cunner (Tautogolabrus adspersus), fourline snakeblenny (Eumesogrammus praecisus), yellowtail flounder (Limanda ferruginea), winter flounder (Pseudopleuronectes americanus), longhorn sculpin (Myoxocephalus octodecemspinosus) shorthorn sculpin (Myoxocephalus scorpius), grubby (Myoxocephalus aenaeus), lumpfish (Cyclopterus lumpus), ocean pout (Zoarces americanus), sea raven (Hemitripterus americanus), and sand lance (Ammodytes sp.)

Yellowtail flounder ()
American plaice (Hippoglossoides platessoides)
Fourline snakeblenny
Fourline snakeblenny (Eumesogrammus praecisus)
Atlantic poacher (Leptagonus decagonus)
Atlantic poacher (Leptagonus decagonus)
ocean pout (Zoarces americanus)
Ocean pout (Zoarces americanus)

.

 

 

 

 

 

Of course other species have been observed on trawls that I have not attended. The above list is nowhere near exhaustive, but is an overview of the species that I observed during my time on the M. Perley. The experience was fantastic, and I look forward to the next opportunity to get back to a place with a flat horizon.

Until then, it’s back to manuscripts and grant proposals…

Advertisements

When history meets ecology: Connecting European exploration and biodiversity in the northwest Atlantic

Posted on Updated on

Hediste diversicolor (top; E. Kristensen, marinespecies.org) and Corophium volutator (bottom; M. Storey, bioimages.org.uk)
Hediste diversicolor (top; E. Kristensen, marinespecies.org) and Corophium volutator (bottom; M. Storey, bioimages.org.uk)
Although it doesn’t happen often, the intersection of academic fields (such as history and science) can lead to exciting and important discoveries. For example, historical records of human migration and modes of transportation can provide insight into the broad-scale distribution of various organisms, ultimately telling us how and when certain animals arrived where they are today. In fact, the above-mentioned example has recently provided insight into where some species of marine organisms in the northwest Atlantic Ocean originated from, along with when and how they likely got there.
Using genetic techniques, Tony Einfeldt, a Ph.D. student in Dr. Jason Addison’s lab at the University of New Brunswick in Fredericton, NB, Canada, and his colleagues  have discovered that benthic marine worms and amphipods, which reside within mudflats of the northwest Atlantic coast, likely arrived there in the ship ballast of early European explorers. Einfeldt et al. compared the genetic structure of various populations of ragworms (Hediste diversicolor) and amphipods (Corophium volutator) residing within the Bay of Fundy and the Gulf of Maine to those along the Atlantic coast of Europe. Similarities in the genetic identity between North American and European populations are highly suggestive that the northwest Atlantic populations originated from the European coast. As Einfeldt states, “We can tell where they came from because the genetic identity of both species in the Bay of Fundy matches that of those in Europe.” Furthermore, with such precise technology and methodology, Einfeldt et al. were able to isolate two separate introductions of these species from Europe, with Bay of Fundy populations likely originating from the Bay of Biscay in France and Gulf of Maine populations coming from more northerly European nations (Norway, Denmark, Germany, etc.).
But how did they get there? To answer this question, Einfeldt et al. attempted to match the movement of these benthic invertebrates with human movement throughout history. Of course, one mode of the intercontinental dispersal of marine organisms is through the ballast water of ships, as ships empty and refill their ballast when they dock, allowing species from one coast to enter the ship through refilling and be introduced to another coast through emptying. But the species studied by Einfeldt et al. are not among those found in modern ballast water, likely because they are infaunal organisms, meaning that they reside within bottom sediment of marine intertidal areas (i.e., mudflats). However, historically, not all ballast was in the form of water. Early European explorers, including those to first cross the Atlantic, most often used rocks for ballast, along with (you guessed it) mud! In fact, the earliest known European ships to have used mud and rocks for ballast are those of Samuel de Champlain and Henry Hudson in the 1600’s, although dry ballast was used up until the 1800’s, making the point of introduction quite difficult to identify.
Some marine species in the northwest Atlantic, such as H. diversicolor and C. volutator, may have arrived here through the ballast of early European explorers. Source: Wikipedia
Some marine species in the northwest Atlantic, such as H. diversicolor and C. volutator, may have arrived here through the ballast of early European explorers. Source: Wikipedia
Although the time window of introduction is quite wide (~200 years), the results of Einfeldt et al. provide strong evidence that the presence of H. diversicolor and C. volutator along the Atlantic coast of North America is a result of European exploration and migration to North America. What’s more is that these two species are important drivers of their respective ecosystems, particularly in the Bay of Fundy. Many species of fish feed on these benthic invertebrates, while migrating shorebirds often depend on the abundance of these species in Bay of Fundy mudflats for food during annual migrations. Ultimately, if these species were never introduced to the northwest Atlantic coast, the diversity of animals that reside there, either permanently or temporarily, may be very different than it is today.

Acknowledgements

I’d like to thank Tony Einfeldt of UNB Fredericton for taking the time to chat and provide input into this post. I also want to thank Shane Fowler, CBC correspondent, for sparking my interest in publishing this post and for his dedication to the promotion of science in New Brunswick.
For those interested, the peer-reviewed publication in Invertebrate Biology can be found here.