April 08, 2020

Taxonomic Splits ... with some species left in genus limbo.

I’m getting a bit frustrated at seeing what were multiply identified species identifications being dropped back to genus level because of taxonomic changes often due to geography. Some examples include nudibranchs found near my home (Newcastle Australia) including what have been known as Goniobranchus roboi, Coryphellina rubrolineata and Goniobranchus tinctorius. It is good that someone has researched and decided that the Australian east coast variety does not conform to these species any more - but we DO have the organised with a location and a name (even if incorrect). I've got NO issue with some things only getting to genus or other levels based on observation ... things that required microscopic or DNA inspection etc. But it seems impractical when you have a group that has already been identified to a species level.

My point - keep some semblance of order rather than losing everything in the genus. Imagine you had a bucket of nails, bolts and screws and you were sorting them out into separate containers based on type, size etc , but when you look at a container of a particular sized screw you noticed some had a difference - stainless Steel and galvanised. So you separate them leaving the stainless steel ones in that container but you’ve got these other ones without a container. What do you do? Put them in a plastic bag in the same container as the stainless ones until you have a new container sorted for them or chuck them back into the general bucket? That seems to be what some of the guys who are fully into the science of taxonomy are doing with these currently grouped species - I’ve got an engineering background … practicality wins … temporary plastic bag every time. Can’t we make “temporary” classifications that allow these to be separated but still grouped? This was done very successful when the rainbow lorikeet species Trichoglossus haematodus was split - the Australian rainbow lorikeet T. moluccans was first moved to be a subspecies of T. haematodus (based of geography of observations) and then finally corrected.

Posted on April 08, 2020 05:41 by tonydiver tonydiver | 0 comments | Leave a comment

September 27, 2018

Moon Island

Moon Island is a fairly flat unspectacular rock off Reid's Mistake at Swansea NSW. It sits just outside the entrance to Swansea Channel a natural tidal waterway that connects Lake Macquarie with the Pacific Ocean. The land inhabitants of Moon Island mostly consist of nesting sea gulls though other sea birds, penguins and fur seals do land there to rest.

Between Moon Island and associated reef heading south and Swansea Heads is a shallow passage with a maximum depth of around 9 metres but generally shallower with a bottom comprising of sand, small rock outcrops, kelp and sea grass.

The north and northwest sides of Moon Island consists of kelp covered rocky reef sloping down from the island to around 15 metres; there are small drops, overhangs and a couple of large Admiralty anchors that date back to when sailing ships would anchor in the sheltered side of the island and be loaded with coal from barges floated down the channel.

The northeast to southern sides of the island are more extreme with 10 metre or deeper walls and may caves of various sizes. The depth drops to around 21 metres. The major dive sites are around this wall and just off it. Under the Tube a site on the northeast that features a steep wall, the amazing Slot cave, and several other caves including the Donut Cave. Eastern blue devilfish are often seen in this area.

The reef extends away from the island to the east. This reef is honeycombed with caves the biggest being The Temple ... a massive overhang cave with a large dark zone. The entrance is partially blocked by a large boulder that may have been due to a roof collapse. Grey nurse sharks shelter in this cave from late June til September. They also can be found in the Horseshoe Cave a shallower U-shape overhang that shelters colourful soft coral, bryozoan and sponge growth.

There are more caves to the west as this wall slowly slopes down as it swings around a pair of large bommies which includes The Arch. Weedy seadragons can be found in deep water kelp beds in 19-15 metres. Banded, spotted wobbegongs, bullrays and port jackson sharks can be found in the caves and ledges along the wall as well as resting hawksbill, green and loggerhead turtles.

South of Moon Island the area becomes covered with a maze of roughly parallel gutters and connections. The New Arch (or Wide Arch) is in this area.

I think Moon Island deserves protection. The coast between Port Stephens and the Central Coast is ignored by Fisheries authorities - there are no protected areas in Newcastle and Lake Macquarie LGAs yet there is Moon Island - the secret jewel on the NSW coast.

Posted on September 27, 2018 05:03 by tonydiver tonydiver | 5 observations | 0 comments | Leave a comment

Archives