Category Archives: Sealife

Shifting Seasons of the Sea

Autumn’s Arrived, or at least it feels like it anyway

If you have been observing recent seasonal changes on the land that signal the end of the summer and of autumn’s arrival, you might be, like me, surprised that it feels a little early. Leaves of sycamore are turning that beautiful bronze colour, falling and scattering on the ground, flocks of migratory birds are gathering to begin their long journey south to warmer grounds and swathes of rowan berries are beginning to turn crimson. With still a week and a half of August left, this feels a bit premature, especially as there’s barely been a chance to pick a blackberry before they’ve gone over and turned into mush!

But shifting seasons is a reality and directly linked to climate change, and it goes much deeper than what we observe on our daily walks or drive to the shops. Changes in the timing of natural events such as the warming of the soil in spring or songbird migration can have harmful effects on ecosystems. Different species respond to different environmental cues, therefore resulting in species that rely on one another becoming out of sync. So for me it might mean an earlier and smaller blackberry crumble, but this shift is a much greater issue for plants and animals.

Sea-sonal Changes

Similar to that of the land, the marine biome experiences seasonal changes that are a critical driving force for natural events. Sea temperature, sunlight and ocean currents all play a triggering role. Plants grow and animals spawn, reflecting what’s happening on land, only sea temperatures lag about a month behind that of the atmosphere. The migration of leatherback turtles, which come from tropical waters to the Irish Sea in the summer and autumn months to feed on jellyfish and the growth of seasonal seaweeds, which provide important habitats for marine wildlife; these are just two examples of seasonal occurrences in the waters surrounding Wales.

Plankton shifting polewards

Minke whale’s are the smallest of the baleen whales, and feed on plankton using their mouths as filter feeders. Photo Credit: Eleanor Stone

But perhaps one of the most important events is the blooming of plankton. Acquiring its name from the Greek work ‘planktos’, meaning wanderer, plankton forms the basis of many marine food chains. Plankton blooms when water temperature, salinity and nutrient availability in the correct amounts are all favourable, and these conditions vary for each species. Phytoplankton are microscopic plants, and zooplankton are microscopic animals which feed on phytoplankton. From jellyfish to baleen whales, a great number of marine animals depend on plankton for food.

Lion’s mane jellyfish (Cyanea capillata) feed on zooplankton along with fish and other jellyfish. Photo Credit: Alexander Mustard

Yet, a recent study on zooplankton published in the journal Nature shows that this microscopic but vital fodder is shifting pole wards in response to climate change and an increase in ocean temperature. In fact, it’s found to have moved a whopping 602 Km on average since pre-industrial times. Apart from being greatly concerning for the marine species that rely on zooplankton, this study demonstrates that marine ecosystems have now entered the “Anthropocene”.

Photographs of plankton taken through a microscope. The far left is a zooplankton species, with the right hand two being phytoplankton. Photo credit: Allan Rowat

Why only talk about one study? Being at the bottom of the food chain within the world’s largest ecosystem, and the basis for all marine life that lies above it, the movement of plankton is highly indicative of what’s happening to other marine species too. Therefore, this study demonstrates the shifting of plankton is just the tip of the iceberg.

So the next time you see a berry ripen on a tree early, or you’re wondering why where did the last frost of the winter go, take a moment to ponder the sea, and what the seasons are doing beneath the surface of the ocean.

Creature Feature – Manx Shearwater

Don’t you just love a legend? I certainly do…I know its maybe an over-used term nowadays meaning something or some one extraordinary but my favourite marine creature is just that….extraordinary. It’s a survival legend, a navigational legend, a homing legend and its lifestyle is legendary.

Ok, so what creature am I talking about? Think bird, black and white, around blackbird-size but with longer wings. You might be thinking of a puffin and you’d be nearly correct as this bird’s Latin name is ‘Puffinus puffinus‘, confusingly! But its not a puffin … it is, drum roll, crash of thunder, the Manx Shearwater.

Yes, the ‘Manxie’, one of the UK’s most pelagic (totally marine-based except for breeding) seabirds and a pretty remarkable one at that.

Manx shearwater are a relative of the albatross and like that bird they make the ocean their home all year except for a short time in spring and early summer when nights are spent underground in remote island burrows, feeding and raising its chick.

It’s double life is amusing and unusual…at sea ‘manxies’ are a superb and efficient flyer, wheeling and looping over seas both calm and mountainous. Totally at home. They’re silent at sea, feeding and getting water from the fish they eat (herring being the favourite). Viewed from land ‘manxies’ are usually a fairly distant black then white shape as they turn in flight, showing, alternately, a black back and wings then a white tummy.

They’re incredibly shy…I’ve done lots of pelagic boat trips over the years and ‘manxies’ really are the least approachable and most easily spooked. Great shearwaters (twice as big and pretty rare in Cardigan Bay) will overfly a boat deck to cast an amused glance at the landlubbers, presumably in wonder but possibly to laugh at anyone being a bit seasick). Sooty shearwaters which seem to be the most confiding. Nice little story…I was on a boat 10 miles off Tynemouth in the North Sea once which was surrounded by several dozen sooties all dozing happily after feeding on the chum we’d put overboard.

But Manxies stay at arm’s length and keep away from people, a bit like storm petrels another ocean wanderer which shares the islands of Skomer and Skokholm in Pembrokeshire as a breeding site.

Come evening, a change occurs as the ‘manxies’ head for the nest burrow. They start to flock, the ones off their breeding sites on Skomer and Skokholm being in their thousands as they get ready to hit land. And when I say ‘hit’, that’s what I mean. The silent, gliding, sleek, superbly adapted day persona is replaced by an awkward, tumbling, clumsy and noisy nightmare of feathers as it crashes down with almost no control and very little elegance in its haste to slither and slide the last few feet to the safety of its burrow as it responds to its chick’s weird cooing calls and grunts.

The next time you’re on Skomer, what you notice, given the importance of the island in having a sizeable proportion of the world’s total manx shearwater population in residence, is the complete lack of ‘manxies’! They’re there of course, but quietly hidden, an eerie experience knowing so many thousands are dozing quietly beneath the ground.

Now to late summer and the first stirrings of the autumnal call to head south for the winter as the nights get longer and the air gets cooler.When many of our summer bird visitors decide to head south, perhaps for sub-Saharan Africa or thereabouts (and its still a pretty remarkable journey for all of them of course) our legend the ‘manxie’ just goes that teensy bit further…entirely over ocean, no land stops, till it gets to southern South America, about 8000 miles from the UK! There’s even a few each year that round Cape Horn and go up the coast of Chile…now that’s a long day out.

The even more remarkable bit is the return journey when they reverse this trip and can pinpoint the correct burrow on their island home when they get back…no map, no road signs! And the even, even more remarkable fact is that some Manxies have been ringed and recorded at 52 years of age, so that journey completed twice annually will bring up 830,000 miles on their dashboard odometers.

So if you’re on a Skomer evening seabird boat trip or even on New Quay harbour wall on a day with a good strong westerly breeze blowing and you’re lucky, no privileged, enough to see this extraordinary legend of a bird, wonder at its incredible lifestyle and wish it a safe return next season.

Written by Living Seas Wales Volunteer Andy Wise

Marine Mammal Skulls (and Crossbones)

A table with various mammal skulls on it.

The ‘Skull and Crossbones’ flag traditionally associated with pirates is, clearly, not the only skull found in/on the ocean. Invertebrates, such as jellyfish and octopus, do not have a vertebral column – meaning they are without a spine, or bones. However, other marine species, including our charismatic marine mammals, do have both skulls and (cross)bones!

Why should we study bones?

Looking at, and studying bones, can provide researchers with insights into the life that an organism once lived. Where the bones in question belong to an extinct species, we can learn more about organisms we will never see.

Lower jaw and teeth – Bottlenose dolphin © CBMWC

Skulls are no different. Animal skulls have evolved for millions of years for various purposes: protecting the brain and sensory organs, being one example. However they also have a role in behaviour, meaning that by studying skulls we can learn more about the diet and social patterns of the species in question.

Skull Basics

  • Teeth: Can indicate diet or hunting method. There are four different types of teeth: incisors, canines, premolars and molars. Generally herbivores (vegetation-eaters) have large incisors to graze on vegetation, and premolars/molars to grind their food. Carnivores (meat-eaters) on the other hand have small incisors, large canines and sharp premolars/molars. Omnivores (eat anything) will have all four teeth types, but their size will vary depending on the species.
  • Eyes: Eye size and location can indicate if a species is a ‘hunter’ or ‘prey’. Hunters (carnivores and/or omnivores) generally have large and forward facing eyes, allowing them to have binocular vision and good depth perception. Prey (herbivores) instead tend to have sideways facing eyes, to watch for approaching threats (i.e. predators).

Life in the ocean has seen various adaptations of these ‘general rules’ (i.e. cetaceans are more reliant on hearing/echolocation to ‘see’ their environment, than they are on their eyes – even though they are hunters).

Marine Mammal Skulls

Bottlenose dolphin (Dolffin trwyn potel)

Bottlenose dolphin skull

Bottlenose dolphin skull © CBMWC

Latin Name: Tursiops truncatus.

Skull size: This specimen is approximately 60cm in length.

Size of species: Bottlenose dolphins can grow up to 4m in length here in Cardigan Bay.

Key skull characteristics:

A) As a species which can grow up to 4m in length, the bottlenose dolphin has the largest skull of the marine mammals discussed here. They also have a long, prominent beak.

B) The nostrils point upwards allowing bottlenose dolphins to breathe easily when they surface. This is important because, like us, bottlenose dolphins are mammals.

C) You will see between 18 and 26 teeth on each side of the upper and lower jaws (that’s 72 to 104 teeth!), however these are not used to chew! Instead bottlenose dolphins swallow their meals whole!

Distribution in Wales: Bottlenose dolphins are generally found in coastal waters across north, west, and parts of south-west Wales. They can be found in Cardigan Bay all year round, with this being one of only two locations across the UK where the populations are confirmed as semi-resident.

Fun fact: Bottlenose dolphins produce distinctive, individual whistles by passing air through air sacs in their heads.

 

Common dolphin (Dolffin cyffredin)

Common dolphin skull © CBMWC

Latin Name: Delphinus delphis.

Skull size: This specimen is approximately 42cm in length.

Size of species: Common dolphins grow up to around 2m in length.

Key skull characteristics:

A) Because they grow to around 2m in length, common dolphin skulls are much smaller than those of bottlenose dolphins. Again, you will notice a prominent beak.

B) The nostrils point upwards allowing common dolphins to breathe easily when they surface. This is important because, like us, common dolphins are mammals.

C) Common dolphins have sharp, conical shaped teeth. Though, like bottlenoses, they are not used for chewing – they prefer to swallow their food whole!

Distribution in Wales: Common dolphins are generally an offshore species, however are sighted off the coast of Pembrokeshire more frequently than other coastal areas around Wales.

Fun fact: Common dolphins prefer to swim in deeper waters, and can sometimes be found in huge ‘super-pods’, made up of thousands of individuals.

 

Harbour porpoise (Llamhidydd harbwr)

Harbour porpoise skull © CBMWC

Latin Name: Phocoena phocoena.

Skull size: This specimen is approximately 26cm in length.

Size of species: Harbour porpoise reach lengths of only 1.5m – 2m.

Key skull characteristics:

A) As the smallest cetacean found in the UK, measuring just 1.5 – 2m in length, the harbour porpoise has a small skull. 

B) The nostrils point upwards allowing harbour porpoise to breathe easily when they surface. This is important because, like us, harbour porpoise are mammals.

C) Harbour porpoise have spade-shaped teeth which can be found in their – relatively – short beak.  

Distribution in Wales: Harbour porpoise are mostly seen within 6 miles of land across the entirety of the Welsh coast. Despite being shy, they are the most commonly sighted UK cetacean species. 

Fun fact: Harbour porpoise are generally quite shy, and are often found swimming alone – unlike dolphins!    

 

Atlantic grey seal (Sêl lwyd atlantig)

Atlantic grey seal skull © CBMWC

Latin Name: Halichoerus grypus.

Skull size: This specimen is approximately 24cm in length.

Size of species: Males Atlantic grey seals can grow up to 3m in length, while females reach up to around 2m.

Key skull characteristics:

A) Atlantic grey seals have large eye sockets for their large eyes. They rely on sight to hunt in dark, murky waters, and also have specialised lenses to focus well underwater.

B) Nostrils are front facing – just like ours! These can be opened and closed using special muscles.

C) Their teeth are very similar to those of a dog: sharp, conical, and perfect for eating fish! 

Distribution in Wales: Atlantic grey seals are found across the entirety of the Welsh coast, with around 5,500 individuals found in Cardigan Bay alone. Nearly half of the worlds population is found in the UK.

Fun skull fact: Crabeater seals (found in Antarctica) have sieve-like tooth structures to filter their favourite food: krill.

 

 

For more information about our native marine mammal species, why not check out our National Dolphin Day blog post. Or alternatively use CBMWC’s YouTube channel to learn more!

 

 

Disclaimer: Cardigan Bay Marine Wildlife Centre holds the appropriate licences to store skulls/bones in this way.

 

 

Main image: Various mammal skulls at our ‘Magnificent Mammals’ event at The Welsh Wildlife Centre © CBMWC

Rockpools by night

Picture/llun Allan Rowat

Nockpooling

On Friday the 1st May 2020 we had intended to run our infamous night-time rockpooling event, otherwise known as Nockpooling. We take our ultra-violet torch, put on some high-vis and head out exploring the inter-tidal zone in the dark. However, as we can’t venture out together to see what we can find, we thought we’d bring you a few reasons why nockpooling is not something to knock!

Sea Hare found during nockpooling event August 2019- we found 5 that night!

1) Mindful Rockpooling – During the day, peering into a rockpool, it can often look like there’s not much going on until you start delving beneath rocks and drawing back the long locks of seaweed. But once the sun goes down, these pools can transform into crowded cities, of non-stop movements.  Some creatures can be shy in the day and want to avoid predation, so the best time to come out and feed is at night. You can often see animals you’d be hard pushed to find in the day, swanning about the pool by night.

Snakelocks anemone under UV light. Photo credit: Allan Rowat

2) Rockpool rave – If mindfulness doesn’t grab you, how about it’s the closest some of us get to a night out?! Certain plants and animals have funky chemical reactions going on in their body, or the bacteria living on their skin does, meaning they emit light. This is called bioluminescence, and it’s thought that up to 90% of animals living in the deep ocean do this.

Other plants and animals fluoresce, meaning that they absorb light and remit it as a different colour, but there needs to be a light source for this to occur, so unlikely to happen in the deep ocean. On a dark night with a UV torch to hand allows for the perfect environment to see this happen! Some anemones, seaweeds, molluscs and crustaceans have the ability to fluoresce. It’s not fully understood why creatures do this, but theories include avoiding predation and attracting food.

Nockpooling at Trearddur Bay, August 2019

3) Adventure – Heading out at night always feels like more of an adventure, and the experience feels even more special with the day dwelling beach goers indoors, as most of the time you will have the shore to yourself.

4) Night sky delight – if you time it right, you can sometimes be lucky enough to combine good rockpooling tides with a meteor shower for an extraordinary experience.

5) The treat at the end – it goes without saying that the best end to all explorations and adventures is earning yourself a big mug of hot chocolate once you return home before tucking yourself into bed and dreaming of all the exciting creatures you found!

Always remember to check the tides before you head out rockpooling, let someone know you’re going and ensure that you take a torch and you know how to make your way back to safety if the tide does start to come in. And of course, return the creatures safely and gently to the same rockpool you found them in! It is their home after all 

Introducing Cardigan Bay’s Bottlenose Dolphins

Cardigan Bay is home to the UK’s largest, semi-resident population of bottlenose dolphins. The Living Seas team based at Cardigan Bay Marine Wildlife Centre (CBMWC) have been monitoring the dolphin population since 1996!

At this time of year we start to record increased sightings of bottlenose dolphins in Cardigan Bay. CBMWC founder and owner of Dolphin Survey Boat Trips, Steve Hartley, had a close encounter with a group of dolphins on 23rd March in New Quay Bay, after they approached his boat the Anna Lloyd. Thank you to Steve for sharing this amazing video with us!

Want to discover more about dolphins? Our Living Seas team have answered some of the most commonly asked dolphin questions below.

What do they look like?

Cardigan Bay’s bottlenose dolphins are some of the largest in the world, growing up to 4m in length. They have a rounded forehead and short beak. Adults are dark grey in colour with light undersides whereas, younger animals are lighter grey in colour and new-borns often have distinct lines called foetal folds down their sides.

Bottlenose dolphins have sickle shaped dorsal fins and our research team use nicks, notches and scaring (see photo below) to identify individual animals.

© Dr Sarah Perry

What do they eat?

They eat a wide range of schooling and bottom dwelling fish, squid and crustaceans but they can adapt their feeding behaviour to local conditions and food sources. Dolphins use echolocation to find and catch their prey.Click here to listen to an echolocation recording

Bottlenose dolphins have one set of between 80 and 100 conical shaped teeth which last their entire lifetime. However, they don’t chew their food, they use their teeth to grab and secure prey before swallowing it whole!

How do they communicate?

Bottlenose dolphins are sociable animals and can form groups made up of several dolphins to over 100. They use whistles to communicate with each other! It’s thought that each dolphin has its own unique whistle which is used to identify an individual, like a name. Click here to listen to a whistle recording.

© Dr Sarah Perry

Our Favourite Fact!

Dolphins don’t sleep like we do, they have to remain conscious because they actively need to come to the surface to breathe. So, when they sleep they turn off one half of their brain and the other half stays awake so they can keep breathing and monitoring their environment!

Donate for Dolphins

If you have enjoyed discovering our dolphins then you can support out vital work by donating to the Dolphin Appeal here.

National Dolphin Day 2020!

The 14th April is National Dolphin Day and our Living Seas Team had planned to spend the day marine mammal watching around the coast of Wales!  Due to COVID-19 that’s not possible so instead we’re celebrating by introducing you to four different cetacean species that can be seen in Welsh waters.

Bottlenose Dolphins

Risso’s Dolphins

 

Common Dolphins

 

Harbour Porpoise

You can support our Living Seas work by becoming a member of or donating to The Wildlife Trust of South and West Wales or North Wales Wildlife