Blog ecosystem modeling OSCAR

What are Local Fish Eating?

By: Sammie Alexander

As a member of the ecology team for the Potomac Environmental Research and Education Center’s (PEREC) summer OSCAR team project, my research goal is to investigate the predator-prey dynamics between fish and macroinvertebrates in two freshwater tidal Potomac River tributaries, Gunston Cove and Hunting Creek. This means, I examine the stomach content of 15 fish species known to inhabit both embayments in order to construct a food web for each location.

Ecopath with Ecosim ecosystem modeling Gulf of Guinea NCW Nigeria Nigerian Coastal Waters

Ecosystem Based Fisheries Management in Nigeria

By:  Tunde Adebola
The author (Tunde Adebola) taking water quality readings at the Lagos Lagoon in Nigeria.

I knew what I wanted to do for my PhD studies, and I also knew it would be challenging to pull this off successfully. After speaking with Dr. De Mutsert about my goals, she suggested to collect system-specific data to help with my research work, so I thought, “Sure, why not.”

Since I’m developing an ecosystem fisheries model for Nigerian coastal waters (NCW), it meant I had to travel to Nigeria at some point during my dissertation work, and this would be my first visit to my home country Nigeria since I came to the USA 10 years ago.
I set out early to develop the model for my dissertation since I knew it would takes considerable time and effort to build it from the ground up. It is a first attempt to building a coast-wide ecosystem model for Nigeria. I needed both detailed ecological information and reliable data for the model and also for my entire research.

Initial data used for this process was from internet sources and published literature but this changed when Sharon Bloomquist spoke about departmental research grants for PhD student in the fall of 2015. With Dr. De Mutsert help, I applied for this grant in order that I may go collect environmental data in the Nigerian coastal system and got grant monies in the spring of 2016.

As a developing country, Nigeria has many of the environmental problems associated with her stage of national development. Some important ecological problems include overexploitation of natural resources in some part of the country, desertification in the northern borders with the Sahara Desert, and oil pollution in the Niger Delta a region that has suffered from more than 60 years of oil exploration, exploitation and hydrocarbon pollution.

The growing coastal population has traditionally relied on coastal fisheries and are subjecting coastal resources to ever-increasing fishing effort since many coastal peoples have little or no alternative occupation than to fish. This problem is more critical in the Delta where oil pollution exacerbates an already difficult resource depletion situation, causing environmental damage and pollution estimated to cost $1 billion USD and approximately 30 years of remedial action to reverse.

The Niger Delta is so important that it is estimated that more than 80% of commercial fish stocks in the Gulf of Guinea adjacent to Nigeria’s shores either used this as habitat or transition between the sea and estuaries in their lifecycle migrations. Here and elsewhere along the coast, more than 300,000 small-scale fishermen are operating low technology-fishing vessels in addition to an industrial fishing fleet of approximately 250 trawlers.
Another issue of concern to my study is the nutrient subsidies from coastal areas that have resulted in eutrophication as evident by ubiquitous water hyacinth covering costal lagoons, salt marshes, and creeks along the 853 km coastline that boarders the nation’s shores with the Atlantic Ocean.

My aim in this research, is to investigate these three anthropogenic factors (fishing, eutrophication and oil pollution) in order to see the extent of their impacts on the coastal food web.

I hypothesize that fishing will reduce ecosystem biomass and secondary production in coastal waters and expect eutrophication to increase productivity up to an extent; especially in locations where nonlethal oxygen depletion occurred. The impact of petroleum hydrocarbon pollution will depend on weather conditions, amount of oil spill and the location in which spills have occurred. Impacts will be modeled singly and in combinations using a mass balanced approach in Ecopath with Ecosim fisheries management software.

I aim to provide information for advice about best coastal management practices in Nigeria and in other West African countries along the Gulf of Guinea.

Having a good dataset is an important step towards developing a reliable model to test scientific hypothesis about the impacts of fishing, nutrient enrichment and hydrocarbon pollution in Nigerian coastal food web.

I’m thankful for all who have supported my research from its inception especially my research committee, the Environmental Science and Policy graduate program and members of the Fish ecology lab.