Norfolk Island Freshwater Aquatic Survey 2009

Internal Project Report

Robert B. McCormack & Jason Coughran

26 March 2009

Reference Project 100014, Norfolk Island. - A Subset of the Australian Crayfish Project, No. 100001.

About This Project. Australian Aquatic Biological Pty. Ltd. conducts aquatic research around Australia. One of the major projects currently being conducted is Project No. 100001, the Australian Crayfish Project (ACP). The aim of the ACP is to survey the whole of Australia, to record and identify every species of freshwater crayfish. The project started in 2005 and will continue to at least 2012. The project extends to all Islands and Territories of Australia, and the present report embodies the findings for a subset of the ACP, Project No. 100014 Norfolk Island.

Disclaimer. Every effort has been taken to provide accurate information and taxonomic determinations, and to use names that are current at the time of report preparation. The authors accept no liability for errors and omissions.

1 Report Summary

Freshwater crayfish, shrimp and crabs are widely distributed across mainland Australia. Surrounding the mainland are a large number of significantly sized Islands with unique and unusual freshwater aquatic ecosystems. As part of the over-arching Australian Crayfish Project, all the larger Islands of Australia will be surveyed for freshwater crustaceans. As part of this program Norfolk Island was surveyed in early 2009 and the findings are presented in this report. No crayfish were recorded at any sites. The land crab was also unable to be located, although rumoured to exist on the Island. Other crustaceans such as the smaller crab, Amarinus lacustris, shrimps and amphipods occur on the Island. Apart from eels, the only fish recorded were three exotic species Gambusia, Guppy and Swordtail, all of which are widely recognized as serious ecological pests. The waterways of Norfolk Island appear to be in a highly degraded state and it is recommended that further research is undertaken to assess the ecological health of the streams and prioritize remediation work.

Key words: Norfolk Island, crayfish, shrimp, crab, Swordtail, Gambusia, Guppy, amphipod.

Introduction

Norfolk Island is a volcanic outcrop created approximately 3 million years ago and was discovered by Captain James Cook in 1774. It is situated 1600 km north east of Sydney and is a small (8 km by 5 km) isolated Island with unique flora and fauna. Norfolk Island was first colonised by Europeans in 1788 as a penal colony, but was abandoned in 1814. It was recolonised in 1825 only to be re-abandoned in 1855. In 1856 it was settled by descendents of the Bounty Mutineers whose home on Pitcairn Island had become overcrowded. Today, Norfolk Island is an external Australian Territory, with its own Norfolk Government. The Island has a rich and unique history and is now the focal point for a flourishing tourist trade.

Although Norfolk Island is known to support unique aquatic fauna, including other crustaceans such as shrimps and crabs, no crayfish species have been described from the Island. As part of the Australian Crayfish Project (ACP), the present project was established in order to survey the whole of Norfolk Island, to ascertain if there are any species of freshwater crayfish that occur on the Island.

Aim of This Study

The primary aim of Project No. 100014 was to determine if freshwater crayfish occur on Norfolk Island. The project also recorded information on the other aquatic fauna found on the Island, in order to facilitate the conservation and management of the aquatic ecosystems of Norfolk Island.

2 Research Methods

Field research was conducted by the team leader, Rob McCormack, with the support of the Norfolk Island Government, Norfolk National Parks rangers, Department of Water Environment Heritage and Arts staff, Norfolk Health & Quarantine staff and members of the local Norfolk community.

A large proportion of Norfolk Island was surveyed (Figure 1) to identify potential habitat areas. The survey was relatively unobtrusive and consisted of various methods: 1. Visual inspection. Observational surveys at sites to visually search for crayfish, or signs of crayfish (e.g. burrows, moulted shells, predation remains). 2. Active Habitat Search. This involved turning rocks and logs in the stream beds and banks to search for crayfish. This was extended to rocks and logs along the forest floor and mountain sides – mostly looking for land crabs or any terrestrial species of crayfish. 3. Netting. Scoop netting was undertaken using hand-held scoop nets to capture fish and crustaceans in aquatic weed beds, under ledges and in the substrate, etc. 4. Container Capture. Jars were used to directly capture some animals (mainly amphipods) that tend to skip and jump from nets. 5. Nocturnal Surveys. Spotlighting was undertaken at night, generally just involving visual inspection via hand held spot light to record the presence of aquatic animals active at night. These simple methods were used to find and capture freshwater aquatic animals on Norfolk Island.

Scientific Collection Permits for this project were issued by the Australian Government, Norfolk Island Government Administration and The Norfolk Island National Parks and Botanic Gardens. Our thanks are extended to all for their assistance. Support and information was supplied by Ceaira Cottle, a student from Griffith University who is a local from Norfolk Island with a fantastic knowledge of the waterways and their aquatic inhabitants. Our special thanks are extended to Ceaira for all her help.

Rob McCormack sampling Bloody Bridge Creek Cockpit Waterfall Cascade Creek 3 Results and Discussion

1. Crustaceans

Freshwater Crayfish.

No species of freshwater crayfish were recorded during the surveys. Historical records indicate that freshwater crayfish have never been recorded from Norfolk Island in the past.

Figure 1. Map of survey sites for Norfolk Island in the present study. Base map sourced from Jasons Norfolk Island Visitors Map 2008 4 Freshwater Crabs/Land Crabs.

The freshwater crab Amarinus lacustris is known to occur on Norfolk Amarinus lacustris Island. Unfortunately, attempts to capture a specimen were unsuccessful during this survey. This indicated that they are not common or widespread on Norfolk Island. Other researchers and residents also consider them to be difficult to locate. Specimens for the ACP collection were collected by Ceaira Cottle, a student from Griffith University researching the freshwater shrimp of Norfolk Island. Ceaira is a Norfolk local and has previously found this elusive crab species at 2 locations on the Island – Bumboras Creek and Kingston.

Another crab species referred to as the Land Crab is also rumoured to occur on Norfolk Island. Anecdotal information suggests that land crabs were well known in the past on Norfolk Island but have not been seen in recent history. Comments received during conversations with several residents indicate that 20 years ago several specimens were captured and then no more were found until about 2 years ago, when a single specimen was collected.

Little was known about the land crabs prior to this study. Initial advice suggested that they were only very small. It was thus initially assumed that they may be around 6 mm carapace shell width, a similar size to freshwater crabs the ACP has recorded on North Stradbroke Island. However, later information indicated that the crabs were larger, in the order of 60 to 70 mm carapace width. This informant also indicated that the crabs are generally found within 1 km of the ocean, are hairy and purple in colour, and that the best way to find them is to turn logs in the forests as they are generally found under logs.

Despite turning many hundreds of logs, rocks, palm leaves, pine needles and ferns, no land crabs were sighted either during the day or at night. Additionally, no shells, claws or crab pieces were seen at any time. Hence, we were unable to confirm the presence of land crabs on the Island during this survey.

Various species of crickets and spiders were the main species found under rocks and logs 5 The small freshwater shrimp Paratya norfolkensis

Freshwater Shrimps.

Only one species of shrimp (family Atyidae) was recorded on Norfolk Island during this survey. The distribution of these shrimp species seemed to be very restricted. Although collected in large numbers, the shrimps were only recorded in Watermill and Town Creeks. These two creeks are relatively large and flow to the sea together at Emily Bay. They both enter the sea across a gentle gradient without any waterfalls. The other main creek system, Broken Bridge and Cascade Creek, enter the sea via waterfalls that may constitute an obstacle to mass shrimp migrations.

The small freshwater shrimp Paratya norfolkensis are endemic to Norfolk Island. These shrimp are present in high numbers and are a highly fecund species. Large numbers of shrimp carrying eggs were collected in the March 2009 survey. They were easily collected by scoop netting and were seen actively swimming through the creek both during the day and by spotlight at night. Potential fish predators may be relatively limited in comparison to mainland stream systems, but juveniles or moulting animals may be vulnerable to predation by the small fish species present, as well as insect larvae such as mudeyes (dragonfly Larvae). The only large fish recorded on the island were eels. Eels up to 0.7 m total lenght were observed and it is likely that larger specimens occur there, particularly in the dams and swamps, so eels would likely be a predator of shrimps. However, total eel numbers seem low. Bird predation would also be a factor but bird numbers and species likewise seemed low at time of sampling (March).

There may be ecological threats to the shrimp. The streams on Norfolk Island are in apparently poor condition (see below). Extended dry periods may reduce the limited area of habitat available to the species. Climate change may also lead to altered hydrological regimes and fluctuations in the amount and quality of habitat.

Note: There have been reports a few years back of a species of Macrobrachium found on Norfolk Island, however, no specimens where recorded in this survey. 6 Amphipods.

The March 2009 survey suggests that Norfolk Island has a healthy population of Amphipods. They were found in good numbers at most sites. Turning rocks during the day often revealed a mass of these animals, jumping and flicking to rapidly disappear back under cover. However, spotlighting the creeks at night was a far more effective method of detection, revealing that they formed dense coverings over rocks or depressions. Specimens and DNA samples were collected from both wet and dry sites and have been registered with the ACP collection. Specimens collected at the time of this report have not been identified to species level but considered to be of the family Talitidrae.

Norfolk Island Amphipods

7 2. Fish

Eels.

Eels were observed during the March 2009 survey. No traps or baited lines were used, so only visual observations and incidental captures were available to verify the presence of eels. Small eels were found in Bloody Bridge Creek under rocks and one was added to the ACP collection. This section of creek above the Bloody Bridge was devoid of any other species and only eels were found. The creek was in a highly degraded state and no other fish or shrimp could be found. At night during a spotlight survey another larger eel, approximately 650 mm long, was seen in this section of creek above the Bridge. Freshwater eels were also observed in Cascade Creek above Cockpit Waterfall. These were larger eels around 700 mm long and were observed during spotlight surveys at night.

Although present on Norfolk Island, visual observations suggest that eels may occur in lower abundance than they do in coastal streams of mainland Australia, where a similar amount of visual survey effort would usually detect far more eels.

Norfolk Island freshwater eel from Bloody Bridge Creek

8 Female exotic swordtails (Watermill Creek, Kingston)

Exotic Fish – Gambusia, Guppy, Swordtail

No other native freshwater fish species were observed in this survey. Large numbers of small (>70 mm) exotic pest species were common in most creek systems, especially in the lower reaches. Most of the fish were Gambusia holbrooki (Gambusia, Mosquito fish) and Poecilia reticulata (Guppies). Gambusia is a native of North and Central America and the Guppy is a South American species. Both are used as aquarium pets around the world due to their hardy robust nature and bright colouration. They have become established and are recognized as invasive pest species in many parts of the world, including mainland Australia. These species can dramatically alter the ecology of waterways, and further research should be initiated to elucidate management options. Another exotic Poecilliid species was also recorded, but in small numbers. The Swordtail, Xiphophorus helleri, are bright orange and very outstanding amongst the schools of guppies and mosquito fish. They also have the potential to cause ecological damage, and are prevalent in some areas of mainland Australia, particularly the subtropical streams in southeastern Queensland and northeastern New South Wales.

A typical hand scoop with a 12 inch diameter scoop net, algae and a dozen or two exotic fish

9 Freshwater snails.

Two species of snails were captured from the streams of Norfolk Island. Freshwater snails when present were quite plentiful and easily captured. Although not identified to species level, it appears that representatives of both the families Planorbidae and Lymnaeidae were collected.

Lymnaeidae

2 species of freshwater snail found on Norfolk Island

Planorbidae

10 Other species.

Insect larvae, particularly dragonfly larvae, were observed at most sites, as were adult dragonflies flying over the streams. Tadpoles and frogs were not recorded at any survey sites, although there appeared to be suitable habitats present. It may be that they do not occur on the Island, or otherwise that they have been in decline. No other aquatic beetles or bugs or turtles were captured in this survey.

Norfolk Island mudeyes (dragon fly larvae) were common at most sampling sites

11 The Norfolk Island Creek Systems

Background

Norfolk Island is a remote island located approximately 1600 km north east of Sydney. Norfolk and the smaller Phillip Island rise above sea level as minute protrusions on an otherwise submerged long, narrow, steep sided aseimic ridge – named the Norfolk Ridge and linking New Zealand some 1000 km to the south to New Caledonia, approximately 700 km to the north. Both Norfolk and the smaller Phillip Island are almost entirely volcanic in nature. Basaltic lava is predominant on Norfolk with two basic types of lava flow – sheet larva and pillow lava.

Norfolk Island is basically a plateau about 90 – 120 m above sea level with a network of small meandering rivulets at the base of shallow valleys. The plateau rises steeply from the sea with rough broken cliffs surrounding the island and only a few locations giving easy access to the water at Kingston, Cascade and Balls Bay. Rising above the plateau are 2 mountains – Mt Pitt (320 m) and Mount Bates (321 m). Both these mountains are located within Norfolk Island National Park which covers 650 ha.

The soils of Norfolk are deep rich red and chocolate brown basalt soils that offer good drainage being relatively porous. These soils in the semi tropical climate with good rainfall support a range of native plant species, from the iconic Norfolk Pine to palms and rolling green grazing lands used by the large herds of cattle that roam the island.

Historic St Barnabas Chapel

Barnabas Creek meanders gently through the valley below St Barnabas Chapel

12 The Rivulets.

There are no major rivers on Norfolk Island, just small rivulets or streams. Water flows are reliant on rainfall and water tables when available are relatively deep. At the time of this survey most streams were running at the lower sections.

Unfortunately all the streams surveyed appear to be in a highly degraded state. This was surprising given that the rest of the island has undergone extensive rehabilitation and the Island as a whole is a ‘jewel in the ocean’ - a high priority tourist destination. The land is exceptionally neat and tidy, the whole island is cared for and nurtured, yet the creeks appear to be neglected and heavily degraded.

The health of the creeks is suffering from four main problems:

1. Pollution. It appears that high levels of nutrients and pollutants are affecting most streams. This is most evident by the algae growing in the streams. Unfortunately, no water quality information is available from this survey but any future surveys need to gather water quality data as a priority task.

Bloody Bridge Creek 13 2. Weeds. There is a concerning proliferation of aquatic weed species on the Island. Many sites were over-run with exotic weed species like Water Hyacinth.

14 St Barnabas Creek

3. Cattle. The Island has a very large population of cattle that freely roam much of the Island. These cattle are allowed direct access to streams and in several areas the streams have been badly trampled and are eutrophic.

Cascade Creek

15 Gambusia Guppy

Norfolk’s exotic livebearers family Poeciliidae

Swordtail

4. Exotic Fish. Unfortunately the fish fauna is dominated by exotic pest species, Gambusia, Guppy and Swordtail. These species are all known to create ecological damage and drastically alter food webs.

Large schools of exotic fish are common in most of the lower stream sections

16 They general health of Norfolk Islands streams leaves much to be desired. Much work will be required to remediate the poor state the streams are in.

Conclusions

1. No crayfish were recorded from Norfolk Island. 2. Other crustaceans were recorded, but the land crab was unable to be found. 3. Apart from eels, the only fish species recorded were the exotic pest species, Gambusia, Guppy and Swordtail. These species are all in the family Poecilliidae and occur in most streams on the island in very high density. 4. The streams generally appear to be in very poor health, and further research should be initiated to assess the ecosystem health of the Island’s waterways and forumulate management options to restore the streams to their former state.

Bibliography

Jasons, Norfolk Island Visitors Map 2008 Sampson H, Geology of Norfolk Island, Booklet Quality Press, ISBN: 0-9757139-06

Contacts Ceaira Cottle, student, Griffith University Queensland Australia Lauren Hughes, Australian Museum Rodney Harvey, Department of Environment Heritage Water and the Arts

Norfolk Island Contacts

Alan McNeil, Norfolk Island Administration Albert Buffet Brooke Watson, Conservator Norfolk Island National Park Denise Quintal, EcoNorfolk Foundation Inc. Dr Coral Rowlston, Conservator Norfolk Island National Park Health and Quarantine Office Ron Ward, Ranger, Norfolk Island National Park Snowy Tavenev Todd Buffet