Temperature, phenology, and turf macroalgae drive seascape change: Connections to mid‐trophic level species

Abstract

2019. Temperature, phenology, and turf macroalgae drive seascape change: Connections to mid-trophic level species.Abstract. Landscape patterns created by the structure and form of foundational species shape ecological processes of community assembly and trophic interactions. In recent years, major shifts in foundation species have occurred in multiple ecosystems. In temperate marine systems, many kelp beds have shifted to turf macroalgae habitats with unknown consequences on seascape patterns or changes in the ecological processes that maintain communities. We investigated the effect of turf macroalgae on seascape patterns in three habitats dominated by kelp and turf macroalgae and those that have mixed species composition. We also examined decadal elevations in temperature with known growth and reproductive phenology of kelp and turf macroalgae to provide a mechanistic understanding of the factors that will continue to shape these seascapes. Our results indicate that turf macroalgae produce a more heterogeneous habitat with greater primary free space than those that are mixed or dominated by kelp. Further, we examined the relationship between seascape patterns and richness and abundance of fishes in each habitat. Results showed that patch size was positively related to the abundance of fish in habitat types, suggesting that turf-induced heterogeneity may lead to fewer observed fishes, specifically the mid-trophic level species, cunner, in these habitats. Overall, our results suggest that persistence of this habitat is facilitated by increasing temperature that shorten the phenology of kelps and favor growth and reproduction of turf macroalgae that make them poised to take advantage of free space, regardless of season.

Taxonomic determination of the cryptogenic red alga, Chondria tumulosa sp. nov., (Rhodomelaceae, Rhodophyta) from Papahānaumokuākea Marine National Monument, Hawai‘i, USA: A new species displaying invasive characteristics

“…Nonetheless, the possibility exists that changing ocean and benthic community conditions associated with climate change delivered and enabled this new seaweed to establish and then thrive on PHA reefs. Although studies documenting changes in invasive seaweed distributions with climate change are limited, there is increasing evidence that climate change-related range shifts in seaweed distributions are likely to occur [ 52 ], and that benthic habitat transformations related to climate change increase the abundance of invasive seaweeds [ 53 ].…”

The impact assessment of thermal pollution on subtidal sessile assemblages: a case study from Mediterranean rocky reefs

“…Other studies in the region highlighted that the increased hydrodynamism caused by the outflow, with the ensuing increase in resuspension of sediments, could affect macrobenthic assemblages nearby the effluent (Marano et al, 2000). The proliferation of filamentous algae at I, and found in other areas subjected to thermal discharge (e.g., Choi, 2008), can be interpreted as a symptom of generalized environmental stress caused by the increase in seawater temperature (Johnson et al, 2017;Dijkstra et al, 2019), turbidity and sedimentation which favored this group of tolerant and opportunistic algae (Airoldi, 1998).…”

Resilience of cold water aquaculture: a review of likely scenarios as climate changes in the Gulf of Maine

“…Dijkstra et al . (2019, see their Fig. 1) demonstrated waves of colonization of invasive algae into Bioregion 1 in the 1990s, which was correlated at their sites with reductions in S. latissima and Chondrus crispu s Stackhouse 1797 (Irish moss).…”

“…In this regard, Dijkstra et al . (2019) described apparently diminished abundance of kelps at the southern edge of Bioregion 1 and a large increase in filamentous red algae, including the invasive Dasysiphonia japonica (Yendo) H.‐S.Kim 2012 that may diminish habitat for fish and invertebrates.…”