<![CDATA[Philippine cities require dependable coastal protection, yet conventional smooth seawalls simplify intertidal habitat and can intensify ecological losses associated with marine urbanization. This integrative literature review examines how eco-engineering can retrofit or redesign vertical coastal structures to retain their safety function while providing habitat. Thirty-one peer-reviewed and institutional sources were synthesized across four themes: ecological effects of shoreline armoring, performance of habitat-complexity interventions, structural and maintenance requirements, and transferability to Philippine urban waterfronts. Evidence consistently favors small-scale additions of pits, crevices, ledges, textured panels, shaded cavities, and water-retaining pools; responses nevertheless vary with tidal elevation, wave exposure, material, pollution, propagule supply, and maintenance. A context-sensitive design is proposed in which the reinforced-concrete wall remains the primary load-bearing system and replaceable habitat panels are zoned vertically, fixed through inspectable corrosion-resistant connections, combined with lower-intertidal water-retaining units, and separated from structurally independent toe protection. Manila Bay is used as the principal application context because flood exposure, subsidence, dense infrastructure, degraded water quality, and large planned coastal investments make ecological co-benefits both valuable and difficult. The review concludes that eco-engineered seawalls are not substitutes for mangroves, tidal flats, setback, or pollution control. They are a pragmatic harm-reduction and habitat-support strategy where hard protection is justified and space is constrained. Philippine pilots should use reference sites, before–after-control–impact monitoring, native-species safeguards, life-cycle maintenance plans, and explicit structural acceptance criteria.]]>
