3 December 2011

Whelks in abundance in the Oosterschelde

Last wednesday we spotted a lot of whelks, Buccinum undatum (NL: wulk) while diving at Stavenisse Veerweg, Oosterschelde.
Cloaked. The whelk is a beautiful snail and one of the biggest in North-West Europe. The shell is up to 11 cm long, however I have once seen a whelk of about 16 cm long in the collection of a former member of the 'Strandwerkgroep Waterweg Noord'. Because of its size I mistook it at first for a red whelk, Neptunea antiqua (NL:noordhoren).

Till a few years ago whelks were quite rare because of tributyltin-poisoning.

Because of the housing shortage for common hermit crabs, Pagurus bernhardus (NL: gewone heremietkreeft) one of the members of the 'Strandwerkgroep Waterweg Noord' collected empty snails at the Kalkbranderij at Yerseke and threw them in the tidal zone near Kattendijke. Apart from one Neptunea contraria - not the most obvious house for a hermit crab because it is contrary coiled (hence 'contraria') - we never retrieved them (which is good!).
Specimen collected at Glasjesnol, Oosterschelde. Photo in aquarium.

Whelk laying its spongy egg masses. Naylor (2005, see literature): 'After mating, the female whelk will lay a mass of up to 2000 egg capsules. Each capsule contains approximately 1000 eggs.' Fortunately the parts per million of tributyltin in the water are low enough.

The head, tentacles, mantle and siphon with typical black flecks. At the base of the tentacles the eyes can be seen.
Five whelks feeding on a dead shore crab, Carcinus maenas (NL: strandkrab).

21 August 2011

Whales of Newfoundland (part 5)

Minke whale, Balaenoptera acutorostrata (NL: dwergvinvis)

A blog means regular posts, lazy bastard! Uh yes, sorry. I am really getting behind. I have been diving at Bonaire in January, (Northern) Ireland in July and the Netherlands from April till now and still I'm posting about Newfoundland 2010. So again: sorry.
My wife and I were lured to Newfoundland by the prospect of seeing whales in close proximity. Paul Dolk (see my post of december 25) told me in 2009 about a group of humpback whales that stayed in 'their' bay for two weeks. As close by as they could touch them in their boat.

We were not that lucky. We made several trips with Paul and Sandra, but all we saw was a glimpse of a fin whale about 100 m away.

So in the last week of our visit we made three whaling trips with Sea of Whales Adventures, owned by Kris and Shawna Prince.
It was a wonderfull experience: two quite rocky trips riding the waves and one with a dead calm sea. You still have to be lucky to see the whales from nearby, as we experienced. But no more complaining. Here are a few photo's I took. For really excellent whale pictures have a look at Paul Dolk's site here.
A blowing fin whale, Balaenoptera physalus (NL: gewone vinvis). As you can sea they are swimming at close distance from the coast. Kris recognizes whale-species by the shape of their blows.
He called them the greyhounds of the sea, because they are such agile and fast swimmers.
You just can't imagine what's down below: in this picture of a fin whale you see just 25% of the upper part of the animal! The largest fin whale ever found, measured 27 m (R. Wandrey, 2001).
The dorsal fin of individual specimens is easily identifiable, anyway for the specialists. And especially this one with its gnarled fin. He crashed in a propeller, got entangled in a fishing net or was bitten by a killer whale. Your guess is as good as mine. Kris has seen this fin whale before. He and others keep record of the whales they encounter. He showed us a list with pictures and names of frequently sighted whales.
Shawna told us that fin whales and blue whales are that rare that they mate with each other. And the offspring is able to reproduce!
Usually fin whales dive down gradually, so it is quite rare to see its fintail. Kris told me I was very lucky to have a shot!
The minke whale, Balaenoptera acutorostrata (NL: dwergvinvis) is a lot smaller: up to 10 m (R. Wandrey, 2001).
Not sure where the whales will show up? Look for circling gulls and other birds, who betray surfacing whales.
White beaked dolphin, Lagenorhynchus albirostris (NL: witsnuitdolfijn). Unfortunateley they weren't in a playful mood.
The humpback whale, Megaptera novaeangliae (NL: bultrug).
We saw them breach - jumping out of the water - several times, but too far too quick too soon.
After the breach...
This is why the whales are coming near the coast: to catch mouthfulls of capelin, Mallotus villosus (NL: lodde). Capelin jump on the sandy beaches and dig themselves in to spawn.

A lot of capelin is catched - I heard - especially for the Japanese market. The Japanese only want the female capelin and the males are just thrown away. If it's true it is a crime against nature. Eat them, sell them, make catfood out of them, but don't kill animals for nothing. Ofcourse it is the livelihood of a lot of people, but so is tourism and what about sustainability?
Whales are not the only creatures waiting for easy prey. It is also an easy pick for bald eagles, Haliaeetus leucocephalus (NL: Amerikaanse zeearend). Near Trinity we counted 22 bald eagles in approximately 150 m!
A young bald eagle is even bigger than its parents. Not as beautiful as an adult, but doesn't he look aggresive.
Capelin is just too easy to catch. This one wasn't hunting for capelin, but for bait we threw in the water.

22 April 2011

A few seaweeds of Newfoundland (part 4)

I made two snorkeling trips: one at Open Hall and one at Salvage (both Bonavista Bay).

At Open Hall I snorkelled around the wharf. A wharf that just looks like hundreds of others. Some of concrete and stone but most of wood (often filled with stones for reinforcement). Some modern, some derelict. The latter are very photogenic!

Growing on the wharf and rocks: common southern kelp, Laminaria agardhii. It grows to 3 m and its blade has ruffled edges in spring and summer.
What looks like hairs are hydroids (Hydrozoa), animals related to sea anemones and jellyfish. Bigger brown seaweeds are often overgrown with hydroids, moss animals (Bryozoa), colonial sea squirts (Tunicata) and other - especially red - seaweeds.
I am not entirely sure about the species. It looks a lot like sugar kelp (also sea belt; NL: suikerwier), Saccharina latissima (formerly known as Laminaria saccharina). As Gosner (1978) quotes in Peterson's (see literature): 'L. saccharina is a problematic species distinguishable only by microscopic section; some authorities consider L. agardhii a form of this species.'
There is a lot of study in the taxonomy of seaweeds and consequently in their nomenclature. You can wake me up in the middle of the night and I could tell you the Latin name of sugar kelp. But now even this name has changed. See the link at the right side of this page for the most recent Latin names.
The blades often have a ragged look. Sugar kelp is eaten by snails but the lesions are foremost caused by battering waves.
Stipe overgrown with colonies of moss animals.
Another species of the Laminariales: horsetail kelp (or oarweed, NL: vingerwier), Laminaria digitata.
And again a member of the order of Laminariales: dabberlocks (also edible kelp), Alaria esculenta. In Europe you will find this species only on exposed rocky shores. Click here for one of its relatives: Undaria pinnatfida.

Looking down the warf.
Exactly the same spot: underwater it is a landscape from a fairytale.
The third member of the Laminariales: smooth cord weed (GB: bootlace weed, NL: veterwier), Chorda filum. It grows up to 4.5 m but is no more than 6 mm thick.
Entangled smooth cord weed. Will it ever disentwine?
Left: sugar kelp. This specimen is quite thin, opposed to the more common leathery ones. As with a lot of seaweeds: the habit of growth is quite variable.
Dulse, Palmaria palmata (NL: rood lapwier). From Gosner (1978): 'Dulse, one of the edible seaweeds, is still harvested in the Canadian Maritimes and the Bay of Fundy, and packets of dull-red dried weed may be found in specialty stores. The texture of fresh dulse has been compared to salted rubberbands but improves on drying.'
A lot of seaweed specimes are commercially collected and cultivated around the world. The hankering for ecofriendly products will only increase the demand.
Salvage: this is where I had my second snorkelling trip. I found it rather poor, but maybe that was due to the amount of fresh water pouring out into the bay.
One of the top predators of seaweeds: green sea urchins, Strongylocentrotus droebachiensis. They grate almost every - not too large - organism off the substrate.

It seems that the rather calciferous coral weed (NL: koraalwier), Corallina officinalis, is not juicy enough for sea urchins.
Horsetail kelp, Laminaria digitata.
Possibly black whip weed (NL: zweepvormig zeekoord), Chordaria flagelliformis.
Sugar kelp (middle), dabberlocks (right) and other unidentified seaweeds.
Typical 'monoculture' seaweed growth: almost all the specimes in the small tidal zone belong to the Fucales.
A bay near Durrell at low tide with the same typical algal growth. At first it looked like coasts I know from France, Great Britain, South Africa, New Zealand an the west coast of Canada. So I thougt: excellent coast for beachcombing. You just have to lift the seaweeds to find crabs, starfish, sea anemones, snails etc. But unfortunately I just found some snails and a few little crustaceans.
The most common Fucales: in the centre bladder wrack (NL: blaaswier), Fucus vesiculosus and left knotted wrack (NL: knotswier), Ascophyllum nodosum. Both seaweeds have air bladders to keep them upright at high tide.
The 'bubbles' in the centre aren't air bladders but so called receptacles: reproductive bodies.
Top and below: bladder wrack with two or more coupled air bladders in the blade.
Knotted wrack has a single air bladder. This seaweed lives almost exclusively on sheltered shores. The bigger the air bladder, the more sheltered its environment.

The third member of the Fucales: (quite certain) spiral wrack (NL: kleine zee-eik), Fucus spiralis.

As for identification: are you a fan of Science Fiction and Startrek? If so, then you are familiar with the tricorder. I expect that one day we will beachcomb with a DNA-tricorder in our hand for easy identification of organisms.

Possibly gut weed (NL: echt darmwier), Ulva intestinalis (formerly known as Enteromorpha intestinalis). Ulva's are hard to identify. One of the species that makes 'rockcombing' hazardous: green weeds like these make rocks very slippery.

With thanks to Dr. Herre Stegenga, National Herbarium of the Netherlands, Leiden University Branch, for his assistance.