Ecosystem goods and services from Manila clam culture in Puget Sound: a modelling analysis

Abstract

The carrying capacity of a 2.4 ha Manila clam Venerupis philippinarum farm, using mechanised harvesting in North Puget Sound, WA, USA, was determined by means of an ecological model; the results were also scaled to Puget Sound as a whole. An individual Manila clam growth model was developed, calibrated and validated for the commercial farm, together with a macroalgal model to simulate fouling of the predator nets by seaweeds. Both models are based on our previously developed generic frameworks for bivalves (AquaShell) and seaweeds (AquaFrond). For the most part, equations are taken or adapted from the literature and parameterised for the studied site. The individual models were incorporated into the Farm Aquaculture Resource Management (FARM) model to simulate the production cycle, environmental effects and economic optimisation of culture. Both the individual and farm-scale models are built using object-oriented programming. Potential effects of clam production on seaweed growth were analysed and found to be about 10% above background. The FARM model was also used to classify the farm area with respect to its eutrophication status, by applying the Assessment of Estuarine Trophic Status (ASSETS) model. Farm production ranging from 32 to 45 t of clams per year is well reproduced by the model. Harvest yield is very sensitive to mortality, and profitability is very sensitive to seed costs. Manila clam culture provides a potential nutrient credit trading value of over US $41 000 per year, over 1000 Population-Equivalents (PEQ, i.e. loading from humans or equivalent loading from agriculture or industry) with respect to eutrophication control. The potential income would add 21% to the annual profit ($194 900) from clam sales. A scaling exercise to the whole of Puget Sound is in reasonable agreement with declared production (difference of 16%), and suggests that clams provide a significant ecosystem service, of the order of 90 000 PEQ per year.

Goods and services of extensive aquaculture: shellfish culture and nutrient trading

“…Figure 3 illustrates this for the Manila clam Venerupis philippinarum by means of an individual growth model applied in Samish Island, USA (Saurel et al 2014).…”

“…with mussels in Ireland (Nunes et al 2011), oysters in France (Raillard and Ménesguen 1994), or clams in the NW USA (Saurel et al 2014), the annualized eutrophication-related ecosystem service integrates: (1) the Year 3 cohort, much of which will be physically removed (harvested); (2) the Year 2 cohort, which will be harvestable only the following year; and (3) the Year 1 cohort, which will take a further 2 years to reach harvestable size.…”

“…More recently, as coastal aquaculture expansion has become a part of ecosystem-based management, and issues such as bioextraction have gained renewed traction (Lindahl et al 2005); models combining production and environmental interactions have became available at both ecosystem and local scales (Nobre et al 2010;Nunes et al 2011;Ferreira et al 2012Ferreira et al , 2014aFilgueira et al 2014;Saurel et al 2014).…”

Population dynamics of subtidal blue mussels Mytilus edulis and the impact of cultivation

“…Bivalve aquaculture provides ecosystem goods and services (Smaal et al 2001a, Newell 2004, Saurel et al 2014, Ferreira & Bricker 2016, including a reduction in eutrophication, increase in water column visibility and provision of habitat and food for higher trophic levels (Suchanek 1992, Inglis & Gust 2003, Newell & Koch 2004, Rönnbäck et al 2007, Diana 2009. A healthy mussel population, by means of extensive mussel culture, supports more subtidal biodiversity, and provides a food source for birds (Buschbaum et al 2009, Ysebaert et al 2009).…”

Production efficiency of mussel bottom culture

“…Bivalve aquaculture is providing ecosystem goods and services (Smaal et al 2001a, Newell 2004, Saurel et al 2014, Ferreira & Bricker 2016. These include among others, reducing eutrophication, increase water column visibility and provide habitat and food for higher trophic levels (Suchanek 1992, Inglis & Gust 2003, Newell & Koch 2004, Rönnbäck et al 2007, Diana 2009.…”