Issue 9 ~ July 2019
The members quarterly of the Lower Breede River Conservancy Trust.
The Longsnout Pipefish
Pipefishes, together with the seahorses and seadragons form the family Syngnathidae.
Pipefish look like straight-bodied seahorses with tiny mouths. The name is derived from the peculiar form of the snout, which is like a long tube, ending in a narrow and small mouth which opens upwards and is toothless. The body and tail are long, thin, and snake-like. They each have a highly modified skeleton formed into armored plating. They feed mainly on live crustaceans and prawns.
Individuals can look so different from one another that it’s sometimes hard to tell exactly which species they belong to. Their lifestyle and the extraordinary way in which they reproduce make them vulnerable to environmental changes. This means that they can be useful indicators when we are monitoring the effects of human activities on biodiversity in the dramatically transforming estuarine and coastal shoreline areas where they live.
In 2007 a South African researcher argued that in the Indian Ocean Syngnathus acus is different from the populations found in the northern hemisphere. Specialists recognise the local variety as S. temminckii, and it was argued that the South African population be recognised as unique. S watermeyeri is a second known variation occurring in South Africa. It was believed to be extinct but has since been documented in two Eastern Cape estuaries.
Their presence can help to determine and monitor the health of a piece of coastline or an estuary. Reduced pipefish numbers could be a warning. If their numbers fall, we need to sound the alarm. Pipefish are adversely affected by environmental changes because of their restricted distributions, low mobility, small home ranges, and relatively low and slow reproduction rate. Habitat loss or alteration, therefore, seriously threatens their survival. The construction of housing and jetties on estuarine banks has reduced the distribution and abundance of eelgrass habitats that are critical for pipefish as nursery areas, feeding grounds, and shelter from predators. Although they may live in various habitats and have a moderately large geographical range, their complex life history and reproductive strategies make them highly vulnerable when their environments are altered.
The two species that are endemic to southern African coastal and estuarine waters are the long snout pipefish, Syngnathus temminckii, and the estuarine pipefish (also known less accurately as the river pipefish), S. watermeyeri which is not well understood. (The taxonomic status of most species of this genus is unclear.)
Like seahorses, they are uniquely different from most organisms, in that males rather than females take responsibility for bearing and rearing their young.
The male receives eggs from a female and carries them on his body surface or inside a specialized brood pouch under his trunk or tail. This ‘pregnant’ male fertilizes the eggs, provides nutrition and oxygen to the developing embryos for up to a month, and gives birth to live young. Paternal care and investment in reproduction is therefore substantial, while maternal care is slight or even nonexistent, as all the females do is provide the eggs. Thus the usual sex roles are reversed, and the females compete with one another in mating rituals.
Pregnant females display themselves vigorously by swimming up and down well above the seagrass beds, often in groups, while the males typically swim within the eelgrass from which position they select the most suitable mate. As a result, females have a higher potential reproductive rate than males – they produce more eggs than the males can brood during an equivalent period of time, and they can contribute eggs to more than one male. The males, on the other hand, are more choosey in selecting females (to ensure reproductive success), as the length of their brooding cycle or ‘pregnancy’ limits the number of times they can mate. The relatively low fecundity and long period of parental care makes pipefish vulnerable when their habitat is disturbed.
Pipefish are approuaching the ‘near threatend’ status on the IUCN Red List. Researchers tried to save and collect stranded pipefish in the East Kleinemonde river basin drained of water in August 2001 by artificial breaching to protect housing built below the flood line. About 50% of the biomass (vegetative macrophytes, fish, and invertebrates) was exposed and died. Most estuarine systems are now artificially opened by breaching because local developments have altered the freshwater flow patterns into these systems, thus affecting their natural opening and closing dynamics. Estuaries are artificially breached by means of a channel dug across the sand barrier (berm) to a level below the water level in the impoundment. Artificial breaching can make water levels drop from 2.8 m above sea level to 0.2 m below sea level in just a few hours, creating large and rapid changes in the environment, which, in turn, trigger major biological responses and damage to fish and other life.
Most pipefish live in tidal pools and other coastal habitats. However, one species lives in the intestine of a species of sea cucumbers!
By Nick Scholtz. Part Time Ranger.
This quarter is traditionally quieter than others, with rain and cold coupled with strong winter flushes and poor fishing. However, this year was one of the warmest and driest periods I have experienced along the estuary in my 16 years of working here.
A meeting between LBRCT and SAMSA was held in June and the outcomes were the most positive from any previous SAMSA interactions. The main issues around placing buoys in the estuary are to be sorted out as well as more future cooperation with SAMSA. Experience from previous attempts to place long term or permanent markers in the water is that due to the immense tidal currents in the estuary, current SAMSA requirements for expensive buoys would not make sense. In the meantime, we will continue to mark dangerous submerged obstacles such as tree stumps as these can cause serious injury.
During July we assisted CapeNature with the Coordinated Waterbird Counts. We also met with Mosselbay SAPS Water Wing to facilitate compliance efforts in the estuary to get locals and authorities to assist in problems such as overfishing, excess bait collection and the ban on night fishing. The office is also liaising with CapeNature and local Fishery Control stations for extra help over the busy times. LBRC has offered assistance in the form of extra staffing, boats and accommodation to assist these authorities. Some positive aspects that have come out is that SAPS will be doing operations along the Breede during busy times to help with compliance and will adopt a no-nonsense attitude with offenders.
Patrols in July showed little boating activity due to the weather. There were some good rains in the Worcester catchment that contributed to a flush at the end of the month. This washed out much of the Hyacinth and an alien weed that is occurring more frequently upstream, the Giant Water Fern or Salvinia sp. This floating weed is a concern as it has proliferated in the tributaries and channels.
Other observations are that there is an increase in the number of large skiboats fishing regularly at sea and concern is that very few checks are being conducted by the relevant authorities on these boats. Another concern is that the DeHoop conservation boat does not seem to operate anymore and with the increased fishing activity and other boats such as the long liner “White Rose” operating close to the MPA, the protected area and its fish are being targeted by poachers.
Infanta residents are continually worried about illegal camping and fires which can spread quickly into DeHoop Nature Reserve. We have committed to extra patrols to help and on the long and spring tide weekends, and noticed groups of fishermen staying overnight. This is a common problem as large groups of fishermen come to Infanta over spring weekends. They often camp illegally which is a problem due to the lack of camping facilities.
It is important to keep a presence on both sides of the estuary and we have secured a mooring on the Infanta side for our boat to access the bakkie which is also kept there during busy times. Thanks to all the locals who have put up signage regarding the night ban on their properties. This shows a willingness amongst the community in the area to assist in a much needed compliance effort.
Changes in salinity were observed between May and July due the arrival of the winter rainfall season. The increase in freshwater input into the system was a result of high rainfall experienced in the area as well as the Breede River catchment. In May and June sites near the mouth recorded high salinities due the marine influence. The arrival of good winter rainfall in July saw a significant decrease in salinity, even at those sites close to the mouth (less than 6 = 5.5 Practical Salinity Units). Freshwater conditions were recorded 17 km from the mouth in July.
The increase in freshwater into the Breede decreased the secchi depth (water transparency). Freshwater input from runoff carries a high suspensiod level which resulted in an increase in turbidity and therefore a lower water transparency. The arrival of winter saw the longitudinal water temperature drop from 20-23 ºC in May to 14-15.5 ºC.
Salinity (PSU) for May 2019 to July 2019
Temperature (⁰C) for May 2019 July 2019
Turbidity (m) for May 2019 to July 2019
Bird species trend
The monthly bird count data for the last quarter (May – July) recorded a variety of bird species with 46 species being seen. Many of the usual suspects were seen, Kelp Gulls, Cape Cormorants, Spur-winged Geese and African Fish-eagles. Some unusual birds were also recorded for the first time during this period: Crowned Cormorants, Black-Crowned Night Herons and Grey-Headed Gull. Crowned Cormorants are listed as a near-threatened southern African endemic and an uncommon bird along the Breede River Estuary.
Grey-Headed Gulls are common residents in southern Africa and appear to be occasional seasonal visitors to the area. The Black-crowned Night-Herons roost in White Milkwood trees further upstream. Groenpunt is yet again a very important feeding area for birds at low tide with several species being found on the exposed mudbanks in the area. Grey-headed Gulls, Black-winged Stilts, Pied Avocets, Little Egrets, Kelp Gulls and African Spoonbills were seen in the area.
There are still two domestic geese present in the area. The Reeds upstream had a low species diversity with species such as Cape Weaver being recorded.
Bird biodiversity for May 2019 to June 2019
Over the last quarter the important litter categories found on the various beaches in Witsand are similar to previous months. Plastic-related litter is important on Main Beach (58-84%) and Blokke (47.2-53.1%) over the last quarter. Gov. slip to Skuitbaai was dominated by glass-related litter (60%) due to several broken beer bottles found during surveys. Oysterbeds was dominated by glass-related litter once again (38.8%-47%) over the last quarter with glass pieces smaller than 2.5 cm the most numerous. Plastic-related litter was the second most abundant litter type (14-18%) followed by food wrappers (6-14%).
We hope you enjoyed this quarterly issue. Should you have any feedback, questions, or matters you would like us to cover in a future issue, please do not hesitate to write to us at email@example.com.