By Louw Claassens, PhD, Director of the Knysna Basin Project, South Africa
Member, IUCN Seahorse, Pipefish and Seadragon Specialist Group
Seahorses and pipefish are famously difficult to track down because of their cryptic nature and sparse distribution. So, how do we go about gathering the data needed to effectively conserve these rare and cryptic species?
I think the Estuarine pipefish (Syngnathus watermeyeri), found in only a few South African estuaries, is a perfect example of an animal that has gone through quite a rollercoaster in terms of conservation approaches. It was discovered in 1963 by JLB Smith and at that time its range was restricted to three estuaries: Kariega, Bushmans and Kasouga. It was not seen again for 40 years after its discovery and we thought it was extinct. Its IUCN Red List status was changed from Vulnerable to Extinct in 1994. This classification was, however, a bit preemptive! After more surveys in other estuaries close to the Kariega and Bushmans estuaries, the Estuarine pipefish was rediscovered in 1996. This rediscovery came about as a result of intensive surveys in the Kleinemonde estuaries as part of a PhD research project. So, perhaps these fish were always in these adjacent systems, and just not observed?!
After its rediscovery the Estuarine pipefish was again found in the Kariega and Bushmans estuaries and even as recently as 2018 these pipefish were successfully found during ad hoc surveys.
The indigenous range for the Estuarine pipefish: Kariega, Bushmans, Kasouga, Kleinemonde West and Kleinemonde East Estuaries.
Considering the history of this species, how do we go forward in understanding its actual conservation status? What is its range? Distribution? Has it always been in these systems and our sampling approach and efforts were just not able to detect it? Maybe this pipefish is found in more South African estuaries, but no one has ever really looked for it?
The best pipefish sampling team in the world: (from left) Nina de Villiers, Johan Wasserman and Georgia Nester.
In 2019 a team of researchers from South Africa and Australia were awarded a National Geographic Recovery of Species on the Brink of Extinction grant. An important aim of this project was to develop the tools needed to effectively conserve this species. To do this, we must understand what drives the survival of this species and to do that we need to ensure that our sampling approach is effective in finding these animals. Through this project we will develop a Recovery Action Plan for the Estuarine pipefish.
Our first fieldtrip took place in October 2019 and as a starting point, we focused on the five estuaries where this pipefish was previously found – Kariega, Bushmans, Kasouga, Kleinemonde West and Kleinemonde East. We surveyed these systems using a seine net, a similar approach used in all past surveys, to develop a baseline of the abundance and distribution of the pipefish. This approach entails dragging a 5 x 1 m seine net in a semi-circle across eelgrass beds with the hope that a pipefish will get caught in the net. Figure 3 gives some perspective of the size of eelgrass beds we were faced with and even with three seine net sweeps per sample site, it does seem like a fallible approach in finding rare and cryptic pipefish!
An aerial photo showing how a seine net was used to collect pipefish within large beds of eelgrass (Photo by Jason Boswell)
To test the effectiveness of our conventional sample approach to detect pipefish, we combined it with Environmental DNA (eDNA) sampling. What is eDNA you might ask? As suggested by the name, this approach looks at all the DNA bits in the environment (either in the sediment or water) to determine what species are found in this system. For the Estuarine pipefish we are developing a species-specific test -think of it as a magnet that will pull out all Estuarine pipefish DNA bits in a sample. For this eDNA work we have teamed up with the TrEND lab, Curtin University, Australia and Georgia Nester has taken on the challenge as part of her PhD project.
An Estuarine pipefish. Note the inflated belly which indicates that this male is pregnant. (Photo by Jason Boswell)
What did we find during our first fieldtrip? Most importantly, we found Estuarine pipefish! We found 8 pipefish in total, 2 from the Kariega estuary and 6 from the Bushmans estuary. We surveyed 23 sites in both the Bushmans and Kariega estuaries and collected habitat and water quality data for these sites. We also collected eDNA samples from 15 sites in each estuary. The data collected will be used to determine what drives the occurrence of this species in these estuaries – is it specific habitat characteristics or is it water quality? We will also see if eDNA effectively detects the pipefish (as we collected eDNA samples from sites where we successfully found pipefish!), as well as testing if this approach detects pipefish at additional sites (where seine netting was not able to find any).
What are our next steps? Once we have the results from the eDNA analysis we will plan our next move. If this approach is effective in finding pipefish, we will take our act on the road to more South African estuaries, to see if this critter can be found in other similar systems. We will also repeat our seine net surveys to collect more data on the abundance, distribution and environmental conditions for this species.
You might think this is quite some effort for a small, nondescript fish? Well, we definitely want to conserve the Estuarine pipefish. But, in addition to protecting this single species, testing the efficacy of eDNA to detect rare and cryptic fish has the potential to influence how we study and monitor these animals in the future. Exciting times!