Expression of GH families in spring and winter; β-glucan utilization is upregulated in spring (GH17, GH16_3, and GH149), while α-glucan utilization is more prominent in winter (GH63, GH15, and GH57); (A) changes of GH expression are given as a ratio of TPM in spring metatranscriptomes divided by TPM in winter metatranscriptomes; values are plotted as log2-fold change; a GH family was defined as being upregulated in spring when log2-fold changes were >1 (TPM spring/TPM winter >2, green bars) and being upregulated in winter when log2-fold changes were <−1 (TPM spring/TPM winter < 0.5, black bars); gray bars show unregulated GH families not matching these thresholds; (B) average expression of GH families in TPM calculated from metatranscriptomes from all sampling time points; GH families shown are expressed in spring and winter (no infinite fold change) with TPM values > 10.