Linking zooplankton assemblages with oceanographic zones in an Atlantic coastal ecosystem

Abstract

Shallow (5–35 m depth) coastal waters, with their proximity to human populations, are likely to experience greater changes to ecosystem structure and functions from climate change and human impacts than offshore waters. Concerns of declining fisheries landings and deteriorating habitat quality in Northumberland Strait led to an assessment by Fisheries and Oceans Canada of the state of the environment and biota including zooplankton during the summer. In this paper we describe spatial structure of zooplankton (three distinct assemblages) and determined that two oceanographic zones can explain the spatial variation. Using distance-based linear models, bottom water temperature and surface water salinity explained 16% to 25% of the variation in zooplankton composition for each year of the survey. We used retrospective analyses to estimate what the zooplankton assemblage may have resembled in the early 1990s from data of oceanographic conditions. Given the prediction of warming oceans by the Intergovernmental Panel on Climate Change, we provide a means of predicting zooplankton composition and their distribution, with implications for the planktivorous fishes that prey upon them.

Feeding Interactions between Fishes in a Coastal Ecosystem in the Southern Gulf of St. Lawrence, Atlantic Canada

“…; Darbyson et al. ; Debertin et al., in press). Similarly, the few published reports of Alewife marine diets (Stone and Daborn ; Smith and Link ) have described a diet dominated by euphausiids, mysids, and benthic organisms (e.g., Corophium amphipods and seven‐spine bay shrimp), unlike the diet observed in the present study.…”

“…). One important difference between offshore and coastal ecosystems is that sufficient light to support benthic photosynthesis reaches the bottom in over 50% of the Strait (Debertin et al., in press). Furthermore, the proximity to shore means that the coastal zone receives more allochthonous organic material (both natural and anthropogenic sources) than the more distant offshore waters.…”

Differences in diversity and community composition of the shell microbiome of apparently healthy lobsters Homarus americanus across Atlantic Canada

“…Bottom temperatures in the Northumberland Strait (LFA 25) can reach up to 18°C and are warmer than in the other sampled LFAs in this study. Additionally, LFA 25 is less exposed to large ocean currents; for example, the cold and nutrient-rich Labrador Current passes by close to LFA 33 and 34 and ocean currents are proposed to shape aquatic host-associated microbiomes ( Bundy et al, 2014 ; Debertin et al, 2018 ; Sousa et al, 2021 ). These factors may contribute to lower microbial diversity in LFA 25 compared to the other sampling regions.…”