Lake Ness Project - Algae, Invertebrates, and Fish

Lake Ness - Algae, Invertebrates, and Fish

In the near shore reaches of the lake, down to a depth of 40 meters, growths of native freshwater kelp (Lessoniaceae) are quite common. This provides a habitat for various animals.

 

On the very floor of Lake Ness, and in some shallower reaches, various varieties of endemic algal mat can be quite common. These range from as small as a coin to extensive expanse several meters across. (Archaea+Bacteria).

 

The shallower reaches of the lake floor commonly host one of 3 species of freshwater sponge. These greenish sponges can range from the size of your hand to the size of a man’s head. (Spongilidae)

 

The flatworms (Tricladida) form a unique radiation in Lake Ness not seen elsewhere. The Painted Ticket Worm is a brightly colored species no longer than a man’s fingernail, commonly bright orange spotted with blue, this warns of the fact that this small predatory invertebrate is highly poisonous. The much larger Hammerhead Eel Worm is striped in olive brown and black and measures as long as a man’s middle finger, and can be found at many levels of the lake. Both of these species are active predators of other invertebrates, and are extensively adapted to aquatic locomotion.

 Freshwater mussels of the Unionidae are common encrusting organisms in the shallower rocky-shored reaches of the lake; these are closely related to the genus Margaritifera.

 Freshwater snails of the Viviparidae are common underwater grazers at many levels of the lake, though they tend to prefer areas rich in algae and Cyanobacteria.

Ostracods form ubiquitous plankton at all levels of the lake (Candonidae).

Another common widespread form of plankton is Copepods (Cyclopidae). Both of these groups provide food for various other invertebrates and fish of the lake.

 Leeches of the genus Hirudo are common in both the shallows of the lake and the upper reaches of the marshes that extend to the Southwest

Fairly typical freshwater crayfish are common in the Lake Ness (Astacidae). However, in the abyssal depths of the lake floor are found a couple of genera of endemic crayfish found nowhere else, such as the Pale Squatter (Astacidae) a large form (30cm long) which somewhat resembles squat lobsters in shape.

 

Waterlouse are common in the weed choked shallows and among the kelp, and are food for various small fish such as stickleback. (Isopoda, Asellidae).

 

In the deep abyssal reaches of the lake, Gammarid Amphipods form a unique radiation not found elsewhere. Bumblebee Gammies have large swimming legs and can commonly be seen at depth swimming about in a manner similar to boatmen, Pale Gammies are a large ornate species also commonly seen at this depth. Both these species feed mainly on lakebed muck, which is made of rotting organic matter and detritus.

 

Various other invertebrates are very common in the lake which can be found in many other countries nearby. These include water fleas (Cladocera), more typical planarian flatworms (Tricladida), Pea Mussels (Pisidium) and freshwater snails of the genus Lymnaea.

 

The Monstrum Worm (Eunicidae) is an unusual endemic species found in the deepest waters of the lake. Reaching 3 meters long and being of a fair girth, this worm is an open water swimmer which actively hunts fish and crustaceans in the water column.

 

The Longicollum Nudibranch (Euopisthobranchia) is one of the most incredible invertebrates of the lake. This gigantic relative of the sea hare has an extensive skeleton of muscular hydrostats which allow it to reach up to 5 meters at full extension. Being herbivorous, these enormous slugs mostly feed on algae, aquatic plants, and above all kelp; it is thought that their grazing keeps kelp from completely choking the near shore parts of the lake. When harassed by predatory vertebrates, it will not hesitate to let loose a cloud of noxious purple ink to repel them.

 

The Elephant Squid (Decabrachia incertae sedis) is another incredible mollusc, a 5 meter long freshwater squid that is unknown anywhere else, completely endemic. Being a pelagic predator, it sits upright in the water, never resting on the floor, it regularly surfaces in order to inflate a large air sac on its back, which it uses to regulate its buoyancy. Some of its fore-arms have evolved as muscular extension of the siphon which allows this animal to inflate the sac, often this protuberance above the surface is all that is seen, or occasionally the hump-like air sac.

 

The native fish of the lake and nearby marshes are remarkable in their diversity. Fish common elsewhere are still found, such as stickleback (Gasterosteus) and brook lamprey (Lampetra), but the isolation provided by the lake has provided many surprises.

 

Nearhsore waters form refuges for many kinds of smaller fish. Large snakelike pipefish (Sygnathidae) up to 80 centimetres long are common among the kelp and weeds, and are also found in the marsh. Endemic shallow-water gobies come in various sizes but are mostly generalized in shape.

 

Further out, the kelp forests provide homes for some truly formidable piscine predators. The Arthurian Pike (Esocidae) is an enormous predator that commonly reaches 2 meters long, a lurking, grouper-like predator that can eat small and mid-sized fish, reptiles and amphibians. 

These somewhat deeper areas are also home to foraging fish such as relatives of the carp (Carassius) and small trout related to the Gillaroo (Salmo).

 

A subspecies of the Wels Catfish (Siluridae) is also common in near shore waters out to a mid depth. Though this fish is often elusive it has been known to attack humans in the shallows. Individuals here form a distinct race that is much larger than elsewhere, reaching up to 4.5 meters.

 

On the sea floor in the deeper parts of near shore waters (10-30m) lives the Humped Giant Ray (Dsyatidae), a freshwater ray which is armoured and reaches up to 2.5 meters across. It regularly surfaces in order to shake off parasites, and its humped profile is a common sight on clear days.

 

Further out in the pelagic reaches of the lake, we see ubiquitous baitfish like smelt (Atherinidae), and common food fish such as the filter-feeding herring (Clupeidae) as well as a whitefish (Coregoninae) and a variant of the Atlantic Salmon (Salmo salar). These huge shoals of fish are the staple of diets of various larger vertebrates that haunt the lake.

 

The deepest reaches of the lake play host to abyssal species which are somewhat reminiscent of pelagic forms found in other deepwater lakes, such as small Sculpin (Cottidae) which form huge shoals, large eel-shaped Gobies (Gobiidae) are one of the endemic predators often found at this depth.

 

The dominant predator of the deeper reaches of the lake is the Ness Eel (Congridae), a stout creature which reaches up to 10 meters long. This form is migratory, and travels to the North Sea in winter in order to breed. It feeds mainly on other kinds of fish, but does sometimes wander into the shallows during migration, in which case they may become a danger to vertebrates such as humans or livestock.

 

The Albionian Sturgeon (Acipenseridae) is another fish of large size commonly seen in the lake, though unlike the eels, it actually comes here to breed in the winter, afterward returning to its life in the sea. It uses suction to feed both on the lake floor and in the water column; both fish and invertebrates are a common component of its diet. This fish is large with a distinct profile, reaching a length of up to 4.5 meters, when sighted at the surface, its plate-like back scales are prominent.

 

A somewhat serpentine subspecies of the Greenland Shark (Somnoisidae), is not native to the lake but has been noted as a fairly common vagrant visitor, as it will wander up the rivers and sea lochs in pursuit of the various abundant food sources that occur here.

Stay tuned for the final entry, Tetrapods!

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