Forecasting future range of sea scallops using a trophically-linked species distribution model: Will climate change constrain scallop distribution in the Mid-Atlantic Bight?

Daphne Munroe, Rutgers University

Abstract

We propose to model the factors that determine the distribution of sea scallops in the Mid Atlantic Bight (MAB) and examine how this distribution may change under climate change scenarios. We will determine the realized niche for sea scallops with a correlative Species Distribution Model (SDM) based on habitat variables (primarily thermal parameters and substrate types) and compare this to a fundamental niche model based on documented thermal tolerances and preferred substrates. Spatial regions where the realized species distribution falls inside of the potential species distribution can be inferred to be areas where the distribution is constrained by other abiotic variables or biotic interactions (predation or competition), which can then be used to further refine the SDM. The resulting trophically-linked SDM will integrate minimally adequate SDMs for other species that were identified as significantly constraining sea scallop distributions. This integrated SDM, that includes ecological interactions, can then be used with oceanographic hindcast and forecast simulations to examine how the geographic distribution of sea scallops may change under different climate scenarios.

Of particular interest is the central and southern Mid Atlantic Bight region where the southern and inshore extent of the species distribution is limited by summer maximum bottom temperatures and where the offshore extent of the distribution is probably limited by prohibitively high recruit predation by sea stars (Astropecten americanus) which dominate faunal assemblages at greater depths in the MAB. The inshore extent of this predator, in turn, is limited by winter minimum bottom temperatures. Under this scenario, increased water temperatures would result in a contraction of sea scallop distributions in the MAB with summer maxima isotherms moving offshore and winter minima isotherms moving inshore. Sea scallops in this region are constrained to a narrow strip of habitat but currently support a large portion of the fishery. Thus, increasing bottom temperatures could result in a rapidly-contracting species distribution and a substantial loss of much of this fishery.