On most occasions when we hear
about oil and fish together we think of some disaster in which fishes are
killed in large numbers and a bunch of associated ecosystem impacts. Though
this trend of thought does hold some truth it is not always so. Thanks to oil
platforms erected in the oceans there is as at least one positive relation
between oil and fish. The structures are favourable for fishes and other
organisms such that it acts as an artificial habitat. The lattices of the
platforms have a large surface area this is the type of habitat demersal fish
such as Rockfish seek. It provides them with shelter, food and a place to hide
and avoid predators (Goldfarb, 2014). Normally after oil activities have ceased
these platforms are decommissioned (Love et.al. 2015). This means that the
platform is removed; however the “Rigs to Reefs” concept considers the fish
habitat present. As a result the entire platform is not removed and the fish
get to keep their habitat. In some cases such as in Louisiana liability of the
rig is transferred from the operator to the state this was reported by (The
Environmental News Network, 2013).
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| Picture by the Gulf of Mexico Foundation |
The larger surface area of the
platform does not benefit just Rockfish but other fish as well. It provides
them with the same protection from predators. The surface area ratio provided
by the platform compared to that of the rocky seafloor can be more suitable for
fish. As a result the secondary production there is greater than that of
natural ecosystems. Secondary production is the sum of new biomass from individual
organisms in an area over a particular time period. This suggests that
organisms, fish in particular thrive better in the artificial habitat at the
platform. Also studies have shown that outside organisms also move to the
platform to live, they are said to be recruited. Another interesting fact is
that there are assemblages of fish at different heights of the platform (Claisse
et. al, 2014). The younger fish tend to be at the higher levels and move to
lower levels as adults. Sometimes adult fish leave the platform altogether to live
in other environments. However a true statement would be to say that without
the platform many fish species would not have survived in the open ocean. This
could be because of the food web that is developed at these platforms as there
are so many organisms present. Plankton is one food source fed on by small fish
and these fish provide food for larger fishes there. So predation is not absent
in this habitat just greatly reduced.
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| Picture taken from Flower Garden Banks, National Marine Sanctuary |
Some fish species at the platform are commercial fish and as
a result fishing activity there does contribute to the economy. However there
is a concern about the exploitation of fish there. This is as a result of the
biomass and population there developing so quickly that it gives the impression
that the population is resilient enough to support constant fishing. Another
unsettling factor is the possibility of seepage from the capped platform. This could
lead to contamination of fish at the platform. In a study done on a capped
platform, it was found that the fish there, had similar amounts of polycyclic
aromatic hydrocarbons (contaminant) when compared to fish away from the site. Therefore
this would suggest that contamination risk is low for a well capped rig.
Personally I believe the rig to reef concept is a great idea
and would hope to actually witness one in the near future.
References
Ben Goldfarb, 2014, Offshore Oil Rigs can provide prime fish
habitat, High Country News Retrieved from http://www.hcn.org/articles/offshore-oil-rigs-can-provide-prime-fish-habitat
The Environmental News Network, 2013. Oil Platform’s Effects
on Fish Populations, OilPrice.com Retrieved from http://oilprice.com/Energy/Energy-General/Oil-Platforms-Effect-on-Fish-Populations.html
JeremyT Claisse, Danile J. Pondella II, Laurel A. Zahn,
Chelsea M. William, Johnathan P. Williams and Ann S. Bull, Oil platform off
California are among the most productive marine fish habitats globally, Retrieved
from www.pnas.org/content/111/43/15462
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