Seismic surveys (to map the ocean floor for oil and gas) produce a continuous underwater noise (greater than 230 decibels using an array of air guns) day and night for months and this will impact negatively on marine life evolved to rely on sound as a primary sense in the dark oceanic environment. Marine animals are highly sensitive to acoustic sound - marine fish and mammals depend on sound for communicating with group members and young, food-finding, reproduction, avoiding predators and hazards, navigation and sensing their environment.
There is no baseline research on the effects seismic surveys will have on this particular marine environment (Morgan Bay to Port St John’s) and seismic surveys in general have been known to have the following effects on marine life:
· Behavioural changes – in cetaceans in involve a change in dive times and time spent at the surface and energy costs (loss of energy) having to move over large distances to get away from disturbing sounds to name a few. Foraging and nursing may also be affected. Cetacean (dolphin and whale) calves separated from their mothers because of high noise levels would be unable to suckle.
· Stress – changes in body physiology which may affect growth, reproduction and also result in death.
· Physical – example being embolism and damage to body tissue. Temporary or permanent hearing loss.
Even though it is proposed that these surveys take place out of the migratory season (May to November) for the more notable larger species such as humpback and southern right whales there are semi-migratory and other species that will be in the survey block (December to April) which will be affected such as the deep diving beaked whales, Bryde’s whales and sperm whales. One of the beaked whales called True’s has never been seen alive at sea – known only from strandings in our area so we have no clear understanding of their distribution, abundance and behaviour. This example can be applied to many other marine mammals and marine life in general (turtles, squid and fish species in the mesopalgic zone [200 – 1000m in depth]). Deep diving beaked whales may surface too quickly and die from barotrauma as a result of seismic blasting. South Africa does not have an Environmental Management Plan which considers an Ecosystems Approach to Fisheries Management (EAF). The EAF is being promoted by fisheries scientists in SA.
South Africa also does not have a national guideline document related specifically to the undertaking of seismic surveys in SA waters. This document at the very least would consider the following:
. A policy context for seismic surveys
. A legislative context
. Potential impacts of seismic surveys on marine biota
. Responsibilities and
. Mitigation strategies
Presently some of the above is gleaned from international guidelines such as those from UK’s JNCC (Joint Nature Conservation Committee) which has measures proposed but lack a scientific basis or a proven efficacy.
The Marine Living Resources Act 1998 does not specifically refer to seismic considerations in the protection of marine mammals. It has been suggested that a Marine Mammal Plan is drafted to guide Environmental Management Plans for potentially detrimental activities in the oceans including that seismic surveys.
Research should be undertaken to determine areas (in the proposed survey range) that provide potential year-round critical habitats to endangered marine species, including key fish species. This will require the collation of baseline ecological data - considering an ecosystems approach to the whole area in question. A synthesis of this information should be tabled before an exploration permit is considered. Stand alone Marine Faunal Assessments or Fisheries Assessments normally included as part of an Environmental Management Plan (EMPlan) for an exploration permit will not suffice as these are only assessments and do not consider the ecosystem as a whole.
5 of SA’s 41 declared Marine Protected Areas (MPAs) are within the area known as the Transkei Block Exploration Right (ER) 12/3/252 – the target area for the proposed 3D seismic surveys and exploration. These MPAs are numbered 32-36 on the official MPA website (Amathole, Amathole Offshore, Dwesa-Cebe, Hluleka and Pondoland MPAs). Of concern is that the mitigating factors proposed such as a seismic buffer zone of 10 km from the coast and 2 km around the MPAs may not be effective considering the high source of sound (230 – 250 dB) and the ability of the sound to travel 10’s to hundreds of km’s. MPAs are a multidimensional approach to ecosystem protection and any potential permanent disruption to these habitats (such as seismic surveys) will work against the rationale and science which motivated marine biologists to have these areas declared.
Considering many marine animals use sound as the primary tool to navigate, communicate and to orientate within the relatively dark environment of the sea anthropogenic noise (such as seismic surveys) will further affect marine animals negatively through interference with important aspects of their lives such as foraging (and decreased feeding efficiency), schooling and migrating, mating (masking of mating calls) and disruption of homing or orientation to name a few.
In South Africa, there is only a single study on the impact of seismic surveys, which was undertaken off Port Elizabeth within the foraging area of the African Penguin (Spheniscus demersus) (Pichegru et al. 2017). Apart from Pichegru’s 2017 study, no research/experimental studies have been undertaken within South African waters on the impact of seismic surveys.
Scientific studies need to be undertaken in situ to provide quantifiable data on this subject before considering the permitting of seismic surveys. For cetaceans (offshore areas) the specialist report submitted as part of the EMPr relied on heavily historic whaling records (mostly dated from the 1960’s) and ‘information on smaller cetaceans in deeper water is particularly poor’.
In the light of the above another question would be ‘why would a special permit be granted (by DFFE) for a survey vessel to undertake seismic surveys when present legislation (Marine Living Resources Act 1998) states that no whales or dolphins may be harassed, killed or fished. No vessel or aircraft may approach closer than 300 m to any whale and a vessel should move to a minimum distance of 300 m from any whales if a whale surfaces closer than 300 m from a vessel or aircraft?’
Acoustic pollution is on the increase in SA. The development of the Oceans/ Blue Economy is being bolstered by initiatives without adequate environmental checks and balances in place, which will have a severe impact on marine species and marine ecosystems. Marine acoustic pollution (including ships noise) is currently under-researched and unregulated in South Africa – this is of concern.
Kevin Cole
Principal Museum Natural Scientist: East London Museum.
November 2021