Biology ETDs

Publication Date

Summer 7-29-2025

Abstract

Climate change and shifts in human land use have caused extensive impacts to the connectivity, structure, and resilience of aquatic populations. Partial migration (PM), where only some individuals from a population migrate while the rest remain resident, can mitigate population-level responses to environmental stressors. However, little is known of the underlying mechanisms promoting variation in migration and whether these shift over time. In the Hudson River Estuary, striped bass (Morone saxatilis) are known to exhibit anadromous PM behavior. Here, I measured carbon isotopes (δ13C) of essential amino acids in striped bass scales to determine variation in contingent diversity over three decades. Our results revealed a dominant estuarine contingent that relied heavily on both freshwater and marine energy channels and persisted throughout the study period. Contingent diversity was negatively associated with freshwater discharge and positively associated with winter severity, indicating that thermal conditions and primary productivity play a role in migration behavior. As precipitation and temperatures are predicted to increase, a reduction in contingent diversity may compromise the energetic connectivity and resilience of striped bass populations, underscoring the need to conserve ecosystem function and connectivity across the full freshwater–marine gradient.

Language

English

Keywords

stable isotope analysis, partial migration, compound specific stable isotope analysis, fisheries

Document Type

Thesis

Degree Name

Biology

Level of Degree

Masters

Department Name

UNM Biology Department

First Committee Member (Chair)

Seth Newsome

Second Committee Member

Oliver Shipley

Third Committee Member

Thomas Turner

Download

Share

COinS